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Introduction IGBT and MOSFET are fully controlled devices and are voltage-driven, that is, the device is turned on or off by controlling the gate voltage. In fact, the structure of the IGBT is an NPN-type MOSFET plus a P-junction, that is, an NPNP structure, which is a P-type BJT driven by MOS in principle. So what is the difference between them? What is the specific connection of them? MOSFET BJT or IGBT - Brief Comparison Catalog Introduction Ⅰ MOSFET & IGBT Review Ⅱ Si IGBT vs SiC MOSFET Ⅲ Different Requirements for Si IGBT and SiC MOSFET 3.1 ON & OFF State 3.2 Short-Circuit Protection 3.3 Interference and Delay Ⅳ IGBT Working Principle by Analogy with MOSFET Ⅴ FAQ Ⅰ MOSFET & IGBT Review MOSFET is a metal-oxide-semiconductor field effect transistor, or metal-insulator-semiconductor. The source and drain of it can be swapped, and they are both N-type regions formed in the P-type backgate. In most cases, these two regions are the same, even if the two ends are reversed, it will not affect the performance of the device. Such devices are considered symmetrical. According to the polarity of its "channel" (working carrier), MOSFET can be divided into two types: N-type and P-type, usually also called NMOSFET and PMOSFET, abbreviations including NMOS, PMOS, etc.IGBT (insulated gate bipolar transistor), is a composite fully controlled voltage-driven power semiconductor device composed of BJT (bipolar transistor) and MOS. Have the advantages of high input impedance of MOSFET and the low on-voltage drop of the GTR. When the GTR saturation voltage is reduced, the current carrying density is large, but the driving current is large; the MOSFET driving power is small, the switching speed is fast, but the on-state voltage drop is large, and the current carrying density is small. The IGBT combines the advantages of the above two devices, and the driving power is small and the saturation voltage is reduced. In simple terms, an IGBT is equivalent to a thick base PNP transistor driven by a MOS. Figure 1. N-MOSFET Architecture Ⅱ Si IGBT vs SiC MOSFET Since the differences between IGBT and MOSFET in structure, working principle and application range are quite detailed, it is impossible to express clearly in one sentence. Next, we will compare the differences between silicon (Si) IGBTs and silicon carbide (SiC) MOSFETs in detail.The electrical parameters and characteristics of Si IGBT and SiC MOS drivers are quite different. The requirements for driving of SiC MOS are also different from those of traditional silicon devices. They have the characteristics of low on-resistance and small switching loss, which can reduce device loss and improve system efficiency, and more suitable for high frequency circuits. It is widely used in new energy vehicle motor controller, vehicle power supply, solar inverter, charging pile, UPS, PFC power supply and other fields.The difference between the two is mainly reflected in the GS turn-on voltage, GS turn-off voltage, short-circuit protection, signal delay and anti-interference, as follows: Characteristic Si IGBT SiC MOSFET Drive Requirements Switching Frequency Low, >30kHz High, 50~500kHz 1) Use high power gate resistors. 2) Optimize the cooling environment. 3) Improve the efficiency of the DC-DC conversion circuit and reduce the overall loss of driving power. Threshold Voltage 5V-6V 1.6V-4.5V Negative pressure shutdown/Miller clamp to prevent false turn-on Switching Time 300ns 50ns 1) Use digital isolation driver chip, the signal transmission delay can reach 50ns, and it has relatively high consistency, and the transmission jitter is less than 5ns. 2) the low transmission delay push-pull chip is selected. Switching-On Time 15V 15V~22V 1) Priority is given to stabilizing the negative voltage to ensure that the shutdown voltage is stable. 2) A negative voltage clamping circuit is added to ensure that it does not exceed the standard during shutdown. Switching-Off voltage -15V~-5V -5V~0V Short-Circuit Withstand Time <10μs 2~5μs A diode or a resistor string is used to detect short circuits, and the shortest short-circuit protection time is limited to about 1.5μs. CMTI 15kV/μs 100kV/μs 1) The common mode anti-interference ability reaches 100kV/μs to transmit the isolation chip for signal transmission. 2) The optimized isolation transformer design is adopted, and its primary side and the secondary side are shielded to reduce mutual crosstalk. 3) The Miller clamp is used to prevent the influence of the switch of the same bridge arm.   Ⅲ Different Requirements for Si IGBT and SiC MOSFET For a fully-controlled switching device, configuring an appropriate on-off voltage is of great significance for the safety and reliability of the device. Due to the difference between IGBT and MOSFET, the requirements for the two are also different.IGBT is a field-controlled device whose turn-on and turn-off are determined by the voltage between the gate(G) and the emitter(E). The working principle of MOS tube (enhancement mode NMOSFET) is to use VGS to control the amount of "induced charges" to change the condition of the conductive channel, and then to control the drain current. 3.1 ON & OFF State 1) Silicon IGBT: Silicon IGBTs of various manufacturers have the same turn-on and turn-off voltage requirements.· The typical turn-on voltage is required to be 15V.· The shutdown voltage value range is -5V~-15V, and customers can choose the appropriate value according to their needs. The common values are -8V, -10V, -15V.· Prioritize stable positive voltage to ensure stable turn-on.2) Silicon carbide MOSFET: Different manufacturers have different switching voltage requirements:· The turn-on voltage is required to be higher than 22V~15V.· The shutdown voltage is required to be higher -5V~-3V.· Prioritize negative voltage stabilization to ensure stable turn-off voltage.· Increase the negative voltage clamping circuit to ensure that it does not exceed the standard when it is turned off. 3.2 Short-Circuit Protection The switching device has the risk of short circuit during operation, and configuring a suitable short circuit protection circuit can effectively reduce the damage caused by the short circuit during the use of the switching device. Compared to Si IGBTs, SiC MOSFETs have shorter short-circuit withstand times.1) Silicon IGBTThe time of surrender and short-circuit of Si IGBT is generally less than 10μs. When designing the short-circuit protection circuit of it, set the detection delay and corresponding time of short-circuit protection to 5-8μs.2) SiC MOSFETGenerally, the short-circuit withstand capability of SiC MOSFET modules is less than 5μs, and short-circuit protection is required to work within 3μs. A diode or a resistor string is used to detect short circuits, and the protection time is limited to about 1.5μs. 3.3 Interference and Delay 1) The impact of high dv/dt and di/dt on the system.When the switching action is performed under the condition of high voltage and high current, the switching of the silicon carbide MOSFET device will generate high dv/dt and di/dt, which will affect the driver circuit. It is very important to improve the anti-interference ability of the driver circuit for the reliable operation of the system. the following way to achieve.· Add common mode choke coil and filter inductor to the input power supply, which reduce the interference of driver EMI to low voltage power supply.· A low-pass filter is added to the rectification part of the secondary side power supply, which reduce the interference of the driver to the high-voltage side.· Use an isolation chip with a common mode immunity of 100kV/μs for signal transmission.· Optimize the isolation transformer design, and use shielding layer on primary side and secondary side to reduce crosstalk between each other.· Use Miller clamp to prevent the influence of the switch of the same bridge arm. 2) Low transmission delayUsually, the application switching frequency of silicon IGBT is less than 40kHZ, and the recommended application switching frequency of SiC MOSFET is greater than 100kHz. The increase of application frequency makes MOS require the driver to provide lower signal delay time. The transmission delay of the SiC MOSFET drive signal should be less than 200ns, and the transmission delay jitter should be less than 20ns, which can be achieved by the following methods.· Using digital isolation driver chip, the signal transmission delay can reach 50ns, and it has relatively high consistency, and the transmission jitter is less than 5ns.· Select push-pull chips with low transmission delay and short rise & fall time. Due to the conductance modulation effect, the on-state specific resistance of high voltage SiC IGBTs is much lower than that of power SiC MOSs, and does not change much as the blocking voltage rating increases. When the conductance modulation effect is fully exerted, the on-state voltage drop of the IGBT drift region is only related to the bipolar diffusion coefficient and bipolar lifetime of the carriers, and will not change with the increase of the on-current. When the operating temperature changes, the on-state voltage drop of the SiC high voltage IGBT decreases with the increase of the junction temperature. This is mainly because the bipolar lifetime of the extra carriers in the SiC epitaxial layer will increase with the increase of temperature. Although the diffusion coefficient will shrink to some extent with the increase of temperature, the greater prolongation of lifetime will eventually make the the bipolar diffusion length increased, thereby reducing the on-state voltage drop. It is especially true in n-channel devices.This is in sharp contrast to the larger increase in the forward voltage drop of the power MOS at high temperature. Silicon carbide p-channel IGBTs have higher on-state voltage drop than n-channel IGBTs at the same current density due to their larger channel resistance, but their volt-ampere characteristics do not change much with temperature. As for the applications, this is undoubtedly an advantage. Figure 2. Comparison of characteristics between SiC IGBT and power MOS under the Same Condition of Withstand Voltage of 20kV. It is not difficult to calculate from the intersection of the equal power consumption curve in the figure and the on-state characteristic curves of these devices: corresponding to the same power consumption of 300W/cm2, the ratio of the on-state current of the silicon carbide IGBT to the silicon carbide power MOS versus p-channel devices and n-channel devices are different, they are 1.5 and 1.8 at room temperature, respectively, and increase to 2.7 and 3.5 at 225°C, indicating that high-voltage and high-current SiC IGBTs are more suitable for high-temperature applications.In a word, compared with Si IGBT, SiC MOSFET not only improves system efficiency, power density and operating temperature, but also puts forward higher requirements for the driver. In order to make silicon carbide MOSFET better in the system, it is necessary to give SiC MOSFET a appropriate driver.   Ⅳ IGBT Working Principle by Analogy with MOSFET IGBT is a Darlington pair composed of GTR and MOSFET: part of which is MOSFET driver, and the other part is thick-base PNP transistor. Figure 3. IGBT Architecture Its simplified equivalent circuit is shown in the figure below, and RN in the figure is the modulation resistance in the base area of the PNP transistor. It can be clearly seen from this circuit that the IGBT is a composite device of Darlington configuration composed of transistors and MOSFET, where the transistor in the figure is a PNP transistor, and the MOSFET is an N-channel field effect transistor, so the IGBT of this structure is called an N-channel IGBT, and its symbol is N-IGBT. Similarly there are P-channel IGBTs, namely P-IGBTs. Figure 4. Simplified Equivalent Circuit The electrical graphic symbols of the IGBT are shown in the figure. IGBT is a field-controlled device, and its turn-on and turn-off are determined by the voltage UGE between the gate and the emitter. When the gate-emitter voltage UCE is positive and greater than the turn-on voltage UCE (th), a channel is formed in the MOSFET and is a PNP. The N-type transistor provides the base current to turn on the IGBT. At this time, the holes (minority carriers) injected into the N- region from the P+ region modulate the conductance of the N- region, reduce the resistance RN of the N- region, and make the IGBT also has a small on-state voltage drop. When no signal or reverse voltage is applied between the gate and emitter, the channel in the MOSFET disappears, the base current of the PNP transistor is cut off, and the IGBT is turned off. It can be seen that the driving principle of IGBT is basically the same as that of MOSFET.① When UCE is negative: J3 junction is in reverse bias state, and the device is in reverse blocking state.② When UCE is positive: UC< UTH, the channel cannot be formed, and the device is in a forward blocking state; UG> UTH, an N-channel is formed under the insulating gate, and conductance is generated in the N- region due to the interaction of carriers modulation so that the device is conducting forward. Figure 5. Hybrid Switch Using Si IGBT and SiC MOSFET 1) ONThe structure of IGBT silicon is very similar to that of power MOSFET, and the main difference is that JGBT adds a P+ substrate and an N+ buffer layer, in terms of it, one MOS drives two bipolar devices (devices with two polarities). The application of the substrate creates a J junction between the P, and N+ regions of the tube. When the positive gate bias causes the inversion of the P base region under the gate, an N-channel is formed, and an electron flow occurs at the same time, and a current is generated exactly in the manner of a power MOSFET. If the voltage produced by this electron flow is in the range of 0.7V, J1 will be forward biased, some holes will be injected into the N- region, and the resistivity between N- and N+ will be adjusted, which reduces the power conduction the total loss of the pass and initiates a second charge flow. The end result is the temporary emergence of two different current topologies within the semiconductor layer: an electron flow (MOSFET current), and a hole current (bipolar). When UCE is greater than the turn-on voltage UCE(th), a channel is formed in the MOSFET to provide base current for the transistor, and the IGBT is turned on. 2) On-State Voltage DropThe conductance modulation effect reduces the resistance RN and reduces the on-state voltage drop. The so-called on-state voltage drop refers to the tube voltage drop UDS when the IGBT enters the on-state, and this voltage decreases with the rise of UCS. 3) Shut DownWhen a negative bias is applied to the gate or the gate voltage is lower than the threshold value, the channel is disabled and no holes are injected into the N-region. In any case, if the current of the MOSFET decreases rapidly during the switching phase, the collector current decreases gradually. This is because there are still minority carriers in the N layer after the commutation starts. This reduction in residual current value (wake) is entirely dependent on the charge density at turn-off, which in turn is related to several factors, such as the number and topology of dopants, layer thickness and temperature. The decay of minority carriers makes the collector current have a wake waveform. Collector current will cause increased power dissipation and cross-conduction problems, especially on devices that use freewheeling diodes.Considering that the wake is related to the recombination of minority carriers, the current value of the wake should be closely related to the Tc, IC of the chip, and has a close relationship with the mobility of holes. Therefore, depending on the temperature reached, it is feasible to reduce the undesirable effects of this current on the end equipment design. When a back pressure or no signal is applied between the gate and the emitter, the channel in the MOS disappears, the base current of the transistor is cut off, and the IGBT is turned off. 4) Reverse BlockingWhen a reverse voltage is applied to the collector, the junction is reverse biased and the depletion layer expands to the N-region. Because the thickness of this layer is reduced too much, an effective blocking ability will not be obtained, so this mechanism is very important. In addition, if the size of this region is increased too much, the voltage drop will continuously increase. 5) Forward BlockingWhen the gate and emitter are shorted and a positive voltage is applied at the collector terminal, the junction is controlled by the reverse voltage. At this time, the depletion layer of the N drift region is still subjected to the externally applied voltage. 6) LatchICBT has a parasitic PNPN thyristor between the collector and the emitter. Under special conditions, this parasitic device will turn on. This phenomenon increases the amount of current between the collector and the emitter, reduces the controllability of the equivalent MOSFET, and often causes device breakdown problems. The thyristor turn-on phenomenon is known as IGBT latch-up. Specifically, the causes of such defects vary, but are closely related to the state of the devices.   Ⅴ FAQ 1. Are there SiC IGBT?Along with the increasing maturity for the material and process of the wide bandgap semiconductor silicon carbide (SiC), the insulated gate bipolar transistor (IGBT) representing the top level of power devices could be fabricated by SiC successfully. 2. Where are SiC MOSFETs used?The primary automotive applications for SiC power MOSFETs, diodes, and modules are onboard electric vehicle (EV) chargers, DC/DC converters, and drivetrain inverters. Plug-in hybrid EVs and battery EVs (BEVs) use onboard chargers to “refuel” the vehicle battery either at home or at a public charging station. 3. What is SiC MOSFET?Silicon Carbide (SiC) MOSFETs exhibit higher blocking voltage, lower on state resistance and higher thermal conductivity than their silicon counterparts. SiC MOSFETs are designed and essentially processed the same way as silicon MOSFETs. 4. Can MOSFET replace IGBT?Due to the higher usable current density of IGBTs, it can usually handle two to three times more current than a typical MOSFET it replaces. This means that a single IGBT device can replace multiple MOSFETs in parallel operation or any of the super-large single power MOSFETs that are available today. 5. What are the advantages of silicon carbide?Silicon carbide MOSFETs have a critical breakdown strength that is 10x of silicon, and silicon carbide MOSFETs can operate at much higher temperatures, provide higher current density, experience reduced switching losses, and support higher switching frequencies. 6. What are the advantages of silicon carbide (SiC) over silicon (Si)?The advantage of SiC starts in the material itself having a 10x higher dielectric breakdown field strength, 2x higher electron saturation velocity, 3x higher energy bad gap and 3x higher thermal conductivity than Silicon. 7. What is the difference between silicon and silicon carbide?Silicon has a breakdown voltage of around 600V, while silicon carbide can withstand voltages 5-10 times higher. ... Silicon carbide can switch at nearly ten times the rate of silicon, which results in smaller control circuitry. 8. What is SiC in semiconductor?SiC (silicon carbide) is a compound semiconductor composed of silicon and carbide. SiC provides a number of advantages over silicon, including 10x the breakdown electric field strength, 3x the band gap, and enabling a wider range of p- and n-type control required for device construction. 9. Which is better MOSFET or IGBT?When compared to the IGBT, a power MOSFET has the advantages of higher commutation speed and greater efficiency during operation at low voltages. What's more, it can sustain a high blocking voltage and maintain a high current. ... The IGBT is also a three terminal (gate, collector, and emitter) full-controlled switch. 10. Why use an IGBT instead of a MOSFET?The main advantages of IGBT over a Power MOSFET and a BJT are: 1. It has a very low on-state voltage drop due to conductivity modulation and has superior on-state current density. ... It canbe easily controlled as compared to current controlled devices (thyristor, BJT) in high voltage and high current applications. 11. Why is MOSFET preferred?Mosfet provides a very good isolation between the gate and the other two terminals compared to bjt. Mosfet can handle more power compared to BJT. The mosfet has a very low power loss and a high speed. Voltage signals can easily operate a mosfet, so it is used in many digital circuits. 12. Where are MOSFETs used?Power MOSFETs are commonly used in automotive electronics, particularly as switching devices in electronic control units, and as power converters in modern electric vehicles. The insulated-gate bipolar transistor (IGBT), a hybrid MOS-bipolar transistor, is also used for a wide variety of applications. 13. Why IGBT is very popular nowadays?With its lower on-state resistance and conduction losses as well as its ability to switch high voltages at high frequencies without damage makes the Insulated Gate Bipolar Transistor ideal for driving inductive loads such as coil windings, electromagnets and DC motors. 14. How many terminals are in a MOSFET?four terminalsThe MOSFET has four terminals: drain, source, gate, and body or substrate. 15. Why is IGBT bipolar?IGBTs is a bipolar device that utilizes two types of carriers, electrons and holes, resulting from the complex configuration that features a MOSFET structure at the input block and bipolar output, making it a transistor that can achieve low saturation voltage (similar to low ON resistance MOSFETs) with relatively fast. 16. How many types of IGBT are there?two typesInsulated Gate Bipolar Junction Transistor (IGBTs) are normally classified into two types. (ii) Punch Through [PT-IGBT]. These IGBTs are also referred to as symmetrical and asymmetrical IGBTs. These varieties of IGBT differ widely with regard to their fabrication technology, structural details etc. 17. What is full MOSFET?MOSFET stands for metal-oxide-semiconductor field-effect transistor. It is a field-effect transistor with a MOS structure. Typically, the MOSFET is a three-terminal device with gate (G), drain (D) and source (S) terminals. 18. How does an IGBT work as a switch?As defined by being a transistor, an IGBT is a semiconductor with three terminals which work as a switch for moving electrical current. Just as the word “gate” suggests, when voltage is applied to the gate, it opens or “turns on” and creates a path for current to flow between the layers. 19. Can I use transistor instead of MOSFET?It very much depends on the application. BJTs can be cheaper than FETs. This is especially true for high voltage switching where the much larger die area of FETs make them much more expensive. 20. Can IGBT conduct in reverse direction?No. The IGBT cannot conduct current in the reverse direction (from emitter to collector) even with a positive Vge applied to it, because it has a bipolar-type structure. ... However, the gate has no control over this reverse current flow; it is simply the forward biasing of the diode that allows it.

ⅠIntroduction Channel MOSFETs are a type of Metal Oxide Semiconductor Device. It consists of the n-substrate in the center with a high concentration of light doping. This is a list of the three-terminal devices. It has unipolar characteristics because the majority of the charge carriers are essential for its operation. Because of the two p materials used in the circuitry, the majority of the carriers are holes. It is further subdivided based on the presence of channels.   Catalog ⅠIntroduction Ⅱ What is P-Channel  MOSFET? Ⅲ P Channel MOSFET Characteristics Ⅳ How P-Channel MOSFETs Are Constructed Internally? Ⅴ Types of P-Channel MOSFET 5.1 P Channel with Enhancement MOSFET 5.1.1  How a P-Channel Enhancement-type MOSFET Works? 5.1.2 How to Turn on a P-Channel Enhancement Type MOSFET? 5.1.3 How to Turn Off a P-Channel Enhancement Type MOSFET? 5.2 P Channel Depletion MOSFET 5.2.1 How a P-Channel Depletion-type MOSFET Works? 5.2.2 How to Turn on a P-Channel Depletion Type MOSFET? 5.2.3 How to Turn Off a P-Channel Depletion Type MOSFET? Ⅵ How to use only positive voltage in this p-channel MOSFET tutorial? 6.1 VGS Threshold 6.2 P-Channel MOSFET Tutorial and Explanation Ⅶ FAQ     Ⅱ What is P-Channel  MOSFET?   A MOSFET is formed when a lightly doped N-type substrate is connected to two highly doped P-type materials. Doping refers to the concentration of impurities added to the atom. The p-channel formed between the two P-type substrates could be the consequence of induced voltages or it could have existed previously.    MOSFET Symbol    Ⅲ P Channel MOSFET Characteristics   The voltage controlled devices are represented by MOSFETs.These devices have high input impedance values.The conductivity of the channel in a P-channel is caused by the application of negative polarity at the gate terminal.     Ⅳ How P-Channel MOSFETs Are Constructed Internally?    P-Channel MOSFET   A P-Channel MOSFET is consists of a P channel, which is a channel that is mostly made up of hole current carriers. N-type material is used for the gate terminals.  How the transistor operates and whether it turns on or off  is determined by the amount and type of voltage (negative or positive)     P-Channel MOSFET as a Switch. Turn ON a 12V Motor with Arduino. (Step-By-Step Guide)     Ⅴ Types of P-Channel MOSFET   The p-channel MOSFET’s are classified as:   (1)P-channel with the Enhancement MOSFET (2) P-channel with the Depletion MOSFET     5.1 P Channel with Enhancement MOSFET   This MOSFET is constructed with a lightly doped n-substrate. The length separates the two heavily doped p-type materials (L). This L is referred to as the channel length.   Above the substrate, a thin layer of type silicon dioxide is deposited. This layer is commonly referred to as the dielectric layer. The source and drain are formed by the two P types. The gate terminal is formed by the aluminum plating used above the dielectric. The ground is connected to the source and the body of the MOSFET.   The gate terminal has been subjected to a negative voltage. Because of the effect of capacitance, the positive concentration of charges settles below at the dielectric layer. Because of repulsive forces, the electrons present at the n substrate are shifted, and the uncovered value of the positive ions layer can be found there. In an n-type substrate, the holes, which are minority carriers, combine with a few electrons to form a bond.   However, further application of the negative voltage cracks the covalent bonds, thereby breaking the pairs formed between electrons and holes. It results in the formation of holes and an increase in the carrier concentration of holes in the channel. When a negative voltage is applied to the drain terminal, the channel becomes conductive, allowing current to flow through the transistor.     5.1.1  How a P-Channel Enhancement-type MOSFET Works? circuit example     5.1.2 How to Turn on a P-Channel Enhancement Type MOSFET?     To turn on a P-Channel Enhancement-type MOSFET, apply a positive voltage VS to the MOSFET's source and a negative voltage to the MOSFET's gate terminal (the gate must be sufficiently more negative than the threshold voltage across the drain-source region) (VGDS). A current will be allowed to flow through the source-drain channel as a result of this.   With a sufficient positive voltage, VS, applied to the source and load, and a sufficient negative voltage applied to the gate, the P-Channel Enhancement-type MOSFET is fully functional and operating in the active 'ON' mode.     5.1.3 How to Turn Off a P-Channel Enhancement Type MOSFET?   There are two ways to turn off a P-channel enhancement type MOSFET. You can either disconnect the bias positive voltage, VS, which powers the source. Alternatively, you can disable the negative voltage applied to the transistor's gate.     5.2 P Channel Depletion MOSFET When compared to n channel depletion MOSFETs, the formation of p channel depletion is simply in reverse. Because of the presence of p-type impurities in the channel, it is pre-built. When a negative voltage is applied to the terminal gate, the free holes that represent the minority carriers at the n-type are attracted to the channel of the positive type impurity ions. When a drain terminal is reverse biased in this condition, the device begins to conduct, but as the negative voltage in the drain terminal increases, the depletion layer forms.   This region is affected by the concentration of the layer formed by positive ions. The width of the depletion region influences the conductivity of the channel. The current at the terminal is controlled by varying the voltage value of the region. Finally, the gate and drain retain their negative polarity, while the source maintains its zero value.     5.2.1 How a P-Channel Depletion-type MOSFET Works?   circuit  P-Channel Depletion-type MOSFET   5.2.2 How to Turn on a P-Channel Depletion Type MOSFET? The gate voltage feeding the gate terminal should be 0V for maximum operation if you switch on a P-Channel Depletion-Type MOSFET. The drain current is at its maximum when the gate voltage is 0V, and the transistor is in the active 'ON' region of conduction.     5.2.3 How to Turn Off a P-Channel Depletion Type MOSFET?   There are two methods for turning off a P-channel MOSFET. You can either switch off the bias positive voltage, VDD, which powers the drain, or you can turn it back on. Alternatively, you can apply a negative voltage to the gate. The current is cut down when a negative voltage is used to the gate. As the gate voltage, VG, becomes more negative, the current decreases until it reaches cutoff, at which point the MOSFET is in the 'OFF' state. It prevents a great source-drain current from flowing.   MOSFET transistors are applied for switching as well as amplifying. MOSFETs are among the most widely used transistors today. Because of their high input impedance, they draw very little input current, which is simple to manufacture, can be made very small, and consume very little power.       Ⅵ How to use only positive voltage in this p-channel MOSFET tutorial?   6.1 VGS Threshold   VGSth: an abbreviation for Voltage Threshold from Gate to Source is one of their critical properties we need to know about using MOSFETs. The resistance between the DRAIN and SOURCE pins changes as the voltage difference between those two pins changes. This is the threshold at which a MOSFET turns on and off.   The resistance changes depending on whether the MOSFET is N-Channel or P-Channel.     6.2 P-Channel MOSFET Tutorial and Explanation   For a P-Channel MOSFET, look at the VGSth. VGSth is a negative value, as you may have noticed. As an example, consider the datasheet for an IRF5305.     specification   The specification of VGSth is -2.0V to -4.0V. So, how could this MOSFET work with an Arduino, LaunchPad, Raspberry Pi, or any other microcontroller? Is it really necessary to generate negative voltages?     It’s about the difference:   This is where the "negative voltage" myth comes into play: Because the datasheet says negative, you need negative voltage to work. Datasheets, on the other hand, never lie (except when they do...).   Let's take a literal look at what the specification says. "A negative four-volt voltage from gate to source." You could read it as "GATE voltage value minus SOURCE voltage value" in other words.   Consider the following voltages in this "high-side switch" configuration:     negative voltage     The GATE now has a voltage of 5 volts. The SOURCE is 5 volts as well. It means that the Vgs is 5V – 5V = 0V. In this case, the Vgs is 0 volts. This voltage indicates that the MOSFET is off, or that it is open.   This is the same circuit as before, but the GATE is now connected to ground rather than 5 volts.       circuit  example in 5 volts     Let's take another look at the SOURCE and GATE. The SOURCE remains at 5 volts. However, the GATE is now at the ground, indicating that it is 0V. If you subtract the GATE voltage from the SOURCE voltage, you get 0V – 5V = -5V. This will activate the MOSFET.   Have you noticed what just happened? Using only positive voltage supplies, we obtained a "negative" voltage...     Why use N-Channel over P-Channel?   A tutorial on when to use an n-channel and p-channel MOSFET would be required. A great application for P-Channel is in a circuit where the voltage levels of your load and logic are the same. For example, suppose you're attempting to activate a 5-volt relay with an Arduino. The current required by the relay coil is too high for an I/O pin, but the coil requires 5V to function. Use a P-Channel MOSFET to turn on the relay from the Arduino's I/O pin in this case.   If your load voltage is higher, such as 12 or 24V, you should consider using an N-Channel MOSFET in a "low side" configuration.   Ⅶ FAQ   1. How do you test P MOSFET? Hold the MosFet by the case or the tab but don't touch the metal parts of the test probes with any of the other MosFet's terminals until needed. 2) First, touch the meter positive lead onto the MosFet's 'Gate'. 3) Now move the positive probe to the 'Drain'. You should get a 'low' reading.   2. When would you use a MOSFET? Power MOSFETs are commonly used in automotive electronics, particularly as switching devices in electronic control units, and as power converters in modern electric vehicles. The insulated-gate bipolar transistor (IGBT), a hybrid MOS-bipolar transistor, is also used for a wide variety of applications.   3. What is MOSFET? MOSFET stands for metal-oxide-semiconductor field-effect transistor. It is a field-effect transistor with a MOS structure. Typically, the MOSFET is a three-terminal device with gate (G), drain (D) and source (S) terminals.   4. What are the types of MOSFET? Different Types of MOSFET Transistors PMOS Logic. As previously mentioned, the integration of a MOSFET allows for high levels of circuit efficiency when compared with BJTs. ... NMOS Logic. ... CMOS Logic. ... Depletion Mode MOSFET Devices. ... MISFETs. ... Floating-Gate MOSFETs (FGMOS) ... Power MOSFETs. ... DMOS.                  

The larger the resistance of the drive, the longer the turn-on time of MOSFET, and the longer the voltage and current overlap time in the switching time, the greater the switching loss. Therefore, the smaller the resistance, the better the drive resistance should be, provided that the drive resistance can provide enough damping to prevent the drive-current oscillation. When designing switch power supply or motor drive circuit with MOSFET, the factors such as on resistance, maximum voltage and maximum current of MOSFET should be considered. In general, the MOSFET tube can be divided into the enhanced and depleted, P-channel or N-channel is a total of 4 types, but the enhanced NMOS tube and PMOS tube are mainly used, in these two commonly mentioned enhanced type, the more commonly used is NMOS, The reason is its small on-resistance and easy to manufacture. However, it is not enough to consider these, because the current will have different losses in various devices, so we must ensure that sufficient current to drive the MOSFET.  Figure 1. MOS schematic diagram In this paper, we will discuss the calculation of the MOS gate drive resistor. The range of the MOSFET drive resistance is between 5~100ohms, so how to further optimize the selection of the resistance value in this range?  Equivalent Drive Circuit Figure 2. Equivalent drive circuit L is the PCB line inductor, according to the professional experience its straight line value is 1nH/ mm, considering other line factors, take L=Length +10 (nH), where Length unit is mm. Rg is the gate drive resistance, and the driving signal is a square wave with a peak value of 12 V. Cgs is the gate and source capacitance of MOSFET, with different tubes and driving voltage its value will be different, here is 1nF. VL+VRg+VCgs=12V Taking drive circuit: Getting differential equation of driving voltage of Cgs: Obtaining Transformation function by method of Laplace transform: This is a third-order system, which is an overdamped vibration when its poles are three different real roots, there are two same solid roots is critical damped vibrations, and there are imaginary roots is underdemped vibrations, which will generate waves of oscillation up and down at the gate of MOFET. This is something we do not want to see, so the choice of gate resistance Rg should make it work in the critical damping and over damping states, but the parameter error is actually working in the overdamped state. Based on the above, therefore, the minimum range of Rg values can be obtained according to the length of the line. Making the length of running line of 20mm and 70mm respectively: L20= 30nH , L70= 80nH, then Rg20=8.94Ω, Rg70=17.89Ω, Here are the voltage and current waveforms   Figure 3. Driving current ripple curve According to the diagram when the Rg is small, the driving voltage surge will be higher, more and more oscillation will exist when the L becomes large, and the performance of MOSFET and other devices will be affected obviously. However, when the resistance value is too large, the driving waveform will rise slowly, while it will have a negative effect when the MOSFET has a large current passing through. In addition, we should note that when L is small, the peak value of driving current is larger, and the output capacity of general IC is limited. When the actual driving current reaches the maximum value of IC output, the output of IC is equivalent to a constant current source. When Cgs is charged linearly, the rising of driving voltage waveform will slow down. The current curve may be shown on the follow (the inductance does not work because the current is constant), this may have an impact on the reliability of the IC, and a small step or burr may occur in the rise of the voltage waveform. Figure 4. Current curve The PWM OUT output of the general IC is shown in the left figure. The internal integration includes the current-limiting resistor Rsource and Rsink, usually Rsource > Rsink, but the actual values are related to the peak driving output ability of the IC. It can be approximately considered that R=Vcc/Ipeak. The drive output capacity of IC is about 0.5A, and meanwhile Rsource is about 20Ω. From the previous voltage and current curves, we can see that the IC driver can drive MOSFET,  but the drive line is usually not a straight line, the inductance may be greater, and in order to prevent external interference, it is necessary to use the Rg drive resistor to suppress. This resistance should be as close as possible to the gate of the MOSFET when considering the effect of the line distribution capacitance. Figure 6. PWM OUT The effect of Rg and L on rising time: (Cgs=1nF, VCgs=0.9*Vdrive) TR(nS)19492302045229Rg(ohm)10221001022100L(nH)303030808080 It can be seen that L has little effect on TR, but Rg has great influence on TR. TR can be estimated approximately by 2*Rg*Cgs. Usually, the rise time is less than 20 percent of the conduction time, and the loss of the MOSFET switch when it is switched on will not cause a heat problem. So when the minimum conduction time of MOSFET is determined, the maximum value of Rg is determined . Generally, the smaller the Rg is, the better, but if considering the EMI, its value should be taken as large as possible. The selection of resistor in MOSFET on-state is discussed above. In order to ensure the fast discharge of gate charge in MOSFET off-state, the resistance should be as small as possible, which is the reason of Rsink<Rsource. To ensure rapid discharge, a diode can be connected in parallel on the Rg. When the discharge resistance is too small, it will also cause resonance due to the inductance of the line (so in some applications there will be a small resistance on the diode.). But the reverse current of the diode is not conductive, at the same time, the Rg is involved in the reverse resonant circuit. Therefore, the peak of reverse resonance can be suppressed. This Diodes usually use a high frequency and small signal tube 1N4148. In practice, we should also consider the influence of the gate and drain of MOSFET and a capacitor Cgd. When MOSFET is on, Rg has to charge Cgd, which will change the voltage rise slope. When off, VCC will charge Cgs through Cgd. In this case, the charge on Cgs must be removed quickly, otherwise, it will lead to abnormal conduction of MOSFET. Figure 7. MOSFET schematic diagram FAQ   1. Why do MOSFETs need resistor? MOSFET gates are exceptionally high impedance. Just like a GPIO pin set to be an input, a pull-down or pull-up resistor helps keep the transistor on or off during power-on. ... When used with a switch or cable that could be disconnected, it is obvious to use a pull-down or pull-up resistor.   2. Do MOSFETs need pull down resistors? You either need a resistor to pull it down to ground or you need the input signal to drive it low. ... You only have to drain the inherent capacitance on the MOSFET gate when you're pulling it low so even at a high resistance to ground the RC time constant is usually relatively short.   3. Does Mosfet have resistance? The MOSFET behaves like a resistor when switched ON (i.e. when Vgs is large enough; check the data sheet). Look in the data sheet for the value of this resistor. It's called Rds(on). It may be a very small resistance, much less than an Ohm.   4. What is the purpose of gate resistor? A gate resistor is used is to slow down the turn-on and turn-off of the MOSFET. (This is more relevant to power circuits that switch a fair amount of current.)   5. What is Mosfet used for? The MOSFET (Metal Oxide Semiconductor Field Effect Transistor) transistor is a semiconductor device which is widely used for switching and amplifying electronic signals in the electronic devices. The MOSFET is a three terminal device such as source, gate, and drain.   6. What is Mosfet and how it works? In general, the MOSFET works as a switch, the MOSFET controls the voltage and current flow between the source and drain. The working of the MOSFET depends on the MOS capacitor, which is the semiconductor surface below the oxide layers between the source and drain terminal.   7. How Mosfet can be used as a resistor? When you slowly increase the gate voltage the MOSFET slowly starts conducting by entering the linear region where it starts developing voltage across it which we call as VDS . In this region, the MOSFET acts as a resistance of finite value.   8. Can Mosfet switch AC? Yes, but you need to connect two back to back to deal with the body diode. Connect the source terminals and gate terminals and connect a floating voltage supply between sources and gates. This circuit is typically called a solid state relay.   9. How much current can a Mosfet handle? Modern MOSFETs can have on resistances of less than 10 milliohms. A little math shows that this device can handle 10 amps with one watt converted into waste heat (power = current2 x resistance). Since many MOSFETs come in TO-220 packages, no heatsink is needed in this instance.   10. How many types of Mosfet are there? four types. There are two classes of MOSFETs. There is depletion mode and there is enhancement mode. Each class is available as n- or a p-channel, giving a total of four types of MOSFETs. Depletion mode comes in an N or a P and an enhancement mode comes in an N or a P.

The insulated gate bipolar transistor (hereinafter referred to as IGBT) is a composite device of MOSFET and GTR. Thus it has the advantages of MOSFET and GTR, it is an ideal switch device to replace GTR, which is widely used at present with its ability to turn off, and it’s also widely used in all kinds of solid-state power supply.     Catalog   I. What is IGBT? II. The Driving Requirement of IGBT III. The Overcurrent Protection Analysis of IGBT IV. Simulation and Experiment FAQ   I. What is IGBT?   The insulated gate bipolar transistor (hereinafter referred to as IGBT) is a composite device of MOSFET and GTR. Thus it has the advantages of MOSFET, including fast operation speed, high switching frequency, high input impedance, simple drive circuit, and good thermal temperature; it also contains the advantages of GTR, like large current-carrying capacity and high blocking voltage. It is an ideal switch device to replace GTR, which is widely used at present with its ability to turn off and is also widely used in all kinds of solid-state power supply.   And it requires a reasonable drive circuit, but its improper control may cause damage, such as IGBT damage due to overcurrent, and affects the performance of the whole machine. In a word, the drive circuit is very important to IGBT. So this paper mainly discusses the driving and short-circuit protection of IGBT, based on the analysis of its working principle, then designs and simulates the overcurrent protection of the drive circuit.     Electronic Basics #28: IGBT and when to use them     II. The Driving Requirement of IGBT   Driving Requirement IGBT is a voltage-type control device. To make IGBT turn on and off safely and reliably, the driving circuit must meet the following conditions.  And the gate capacitance of IGBT is much larger than that of MOSFET. To increase the switching speed, it is necessary to have a suitable gate bias voltage and gate series resistance.   Gate Voltage In any case, the gate drive voltage in the open state can not exceed the limited value (generally 20V) given by the parameter table, and the optimal gate forward-bias voltage is 15 V ±1.5V. This value is sufficient to allow IGBT to reach saturation and then getting conduction, which can minimize the conduction loss. In the case of gate voltage is cutting off with the value of zero, to reduce the turn-off time and improve the withstand voltage and anti-interference ability of IGBT, a reverse voltage of -5 ~ -15 V can be added between the gate and the source electrode when the IGBT is in a blocking state.   Gate Series Resistance Core The selection of appropriate gate series resistance (RG) is very important for the drive of IGBT. The effect of RG on switching loss is shown in Fig.1. Fig. 1 The Effect of RG on Switching Loss It is the dynamic current of charging and discharging the input capacitance rather than the DC current that is required in a static state, and the input impedance of IGBT is up to 109 ~ 1011. In this case, the DC gain can reach 108 ~ 109, almost without any power consumption.   To decrease the steepness of the front and rear edges of the control pulse, prevent oscillation and reduce the voltage tip pulse with a large IGBT collector, it is necessary to add a gate series resistor RG. When the RG increases, the on-off time will prolong and the energy consumption of the IGBT will increase; in turn, the RG reduces, the di/dt will increase and may damage IGBT.   Thus, according to the current capacity and voltage rating, and switching frequency of IGBT, it is necessary to select a suitable RG, usually from dozens of ohms to hundreds of ohms. To get a more specific value of RG, it is suggested to refer to the device manual. Fig.2 Main Circuit of Inverter Power Supply   Requirements for Driving Power The switching process of IGBT consumes a certain amount of power from the driving power supply. The difference between the gate forward bias voltage and the reverse bias voltage is the △VGE; working frequency is f, the gate capacitance is CGE; and the minimum peak current of the power supply is:     Overcurrent Protection for IGBT The overcurrent protection of IGBT is limiting the short-circuit current and its I-V track to the short circuit safe working area when the device overflows, and the IGBT is turned off before the device is damaged to avoid the damage of the switch tube. When the upper and lower arms conducting, the power supply voltage is almost all added to the two ends of the switch, at this time, the larger the short circuit current is, the smaller the saturation voltage drop will be, during this time, the device would be damaged due to the large current.     III. The Overcurrent Protection Analysis of IGBT   Based on the above analysis, an IGBT drive circuit which contains isolated optocoupler and over-current protection has been put forward in this article, as shown in Fig.3. Fig.3 The Drive and Overcurrent Protection Circuit of IGBT  In Fig.3, the high-speed optocoupler 6N137 realizes the electrical isolation of the input and output signals, which is suitable for high-frequency applications. The main drive circuit adopts push-pull output mode, which effectively reduces the output impedance of the drive circuit, improves the driving ability, and makes it suitable for the drive of high power IGBT.   The over-current protection circuit uses the principle of desaturation of the collector. When an over-current occurs, the IGBT will be turn off. The V1, V3and V4 constitute the driving pulse amplifier circuit; V1 and R5 constitute an emitter follower. The emitter follower provides a fast current source, which reduces the turn-off time. Using the collector desaturation principle, D1, R6, R7, and V2 form a short-circuit signal detection circuit. D1 is a fast recovery diode, to prevent the high voltage on the collector from running into the driving circuit when IGBT is turned off.   In order to prevent the power device from being misled by static electricity, bidirectional voltage regulators D3 and D4 are connected in parallel between the gate sources.   Normal When the control circuit sends a high-level signal, the optocoupler 6N137 turns on, V1, V2 turns off, V3 turns on and V4 turns off. And the drive circuit provides IGBT a driving voltage of +15V to turn it on. When the control circuit sends a low level signal, the optocoupler 6N137 turns off, V2 and V3 conduct, and the drive circuit provides a voltage of -5v to IBGT, making IGBT shut down.   Overcurrent When a short-circuit fault exists, the voltage of 15V is almost all added to the IGBT. At this time, the voltage of V2 cuts off in the short circuit detection circuit, and the electric potential of point A depends on the partial voltage of D1, R6, R7, and VCES.  When the main circuit works normally and the IGBT is on, the A point is kept low, which is lower than the B point potential. All A1 output low level, this time V5 cuts off, and the C point is high level.   So when operating normally, the input to the optocoupler 6N137 is always consistent with the output. When overcurrent occurs, the IGBT collector is desaturated, A point potential rises, when it is higher than B potential ( the setting potential), that is, when the current exceeds the designed fixed value, the A1 overturns and outputs a high level, meanwhile, V5 is switched on, thereby making C in a low potential state. The input signal to the optocoupler 6N137 is always low level regardless of whether the control circuit is sent to a high level or a low level to turn off the power tube. Thus, over-current protection is achieved until the circuit is troubleshot and then restarted.   Fig. 4 Strong Driving Circuit of IGBT with Short-Circuit Protection   IV. Simulation and Experiment   Input to the drive circuit with a high level of 15V and a low level of -5V square wave signal. The output waveform of IGBT is shown in Fig.5  Fig.5 IGBT Output Signal According to the above principle and analysis, the actual output waveform of the circuit is shown in Fig.6  Fig.6 Actual Circuit Output Waveform Conclusion (1) Providing -5V and +15V driving voltage for IGBT to ensure IGBT's turn on and off. (2) Having over-current protection to prevent the IGBT from being damaged when the current is overcurrent. (3) Using in a wide range because the circuit can dynamically adjust the maximum current according to the load. (4) Adopting discrete components as the driving circuits to reduce the cost of the whole system.     FAQ   1. How does an insulated gate bipolar transistor work? The IGBT combines the simple gate-drive characteristics of power MOSFETs with the high-current and low-saturation-voltage capability of bipolar transistors. The IGBT combines an isolated-gate FET for the control input and a bipolar power transistor as a switch in a single device.   2. Which insulated gate bipolar transistor? IGBTs are widely used as switching devices in the inverter circuit (for DC-to-AC conversion) for driving small to large motors. IGBTs for inverter applications are used in home appliances such as air conditioners and refrigerators, industrial motors, and automotive main motor controllers to improve their efficiency.   3. How do I trigger IGBT?   An IGBT is simply switched “ON” and “OFF” by triggering and disabling its Gate terminal. A constant +Ve voltage i/p signal across the 'G' and the 'E' will retain the device in its “ON” state, while deduction of the i/p signal will cause it to turn “OFF” like BJT or MOSFET.   4. Why use an IGBT instead of a Mosfet? The main advantages of IGBT over a Power MOSFET and a BJT are: 1. It has a very low on-state voltage drop due to conductivity modulation and has superior on-state current density. So smaller chip size is possible and the cost can be reduced.   5. Why IGBT is used an inverter? The Insulated Gate Bipolar Transistor (IGBT) is used in VFD inverter modules as the preferred electronic power switch for the following reasons. ... The IGBT has a fast switching speed. This minimises switching losses and allows for high switching frequencies which is good for motor harmonic and noise reduction.   6. What is difference between IGBT and SCR? SCR is a silicon control rectifier and igbt is a insulated gate bipolar transistor. ... scr has anode ,cathode and gate and igbt has base ,emitter, gate ,and collector. In the both devices gate terminal is used for triggering. Scr has only one insultive layer but igbt has 2 insulated silicon layers.   7. What is IGBT principle? IGBT Principle of Operation：IGBT requires only a small voltage to maintain conduction in the device unlike in BJT. The IGBT is a unidirectional device, that is, it can only switch ON in the forward direction. This means current flows from the collector to the emitter unlike in MOSFETs, which are bi-directional.   8. What causes IGBT failure? The failure modes for the IGBT are in the form of degradation of certain key electrical parameters (e.g., leakage current, threshold voltage) or the loss of functionality (inability to turn-off). The failure causes can be due to environmental conditions or operating conditions.   9. Is IGBT unipolar or bipolar? The IGBT cannot conduct current in the reverse direction (from emitter to collector) even with a positive Vge applied to it, because it has a bipolar-type structure.   10. Which IGBT used in VFD? IGBT (insulated gate bipolar transistor) provides a high switching speed necessary for PWM VFD operation. IGBTs are capable of switching on and off several thousand times a second. A VFD IGBT can turn on in less than 400 nanoseconds and off in approximately 500 nanoseconds.   11. Can we use IGBT instead of Mosfet? Due to the higher usable current density of IGBTs, it can usually handle two to three times more current than a typical MOSFET it replaces. This means that a single IGBT device can replace multiple MOSFETs in parallel operation or any of the super-large single power MOSFETs that are available today.   12. How fast can an IGBT switch? The typical switching time of IGBT is about hundreds of nanoseconds and the value varies with load current, junction temperature, and other factors [17–20]. However, the change of IGBT switching time is very small [4,5] (range from several to tens of nanoseconds) when the health status of the IGBT module changes.   13. Is IGBT faster than Mosfet? When compared to the IGBT, a power MOSFET has the advantages of higher commutation speed and greater efficiency during operation at low voltages. ... The IGBT combines the simple gate-drive characteristics found in the MOSFET with the high-current and low-saturation-voltage capability of a bipolar transistor.   14. How many IGBT are in a VFD? Six IGBTs. In a typical six pulse drive there are six IGBTs pulsing voltage up to 15,000 times per second. Since their introduction in the 1980's, IGBTs have literally switched up the market and now play a large role in many modern day power electronics applications where speed and process control are needed.   15. What is the function of IGBT? The IGBT combines, in a single device, a control input with a MOS structure and a bipolar power transistor that acts as an output switch. IGBTs are suitable for high-voltage, high-current applications. They are designed to drive high-power applications with a low-power input.   16. Is IGBT a rectifier? IGBTs have a pretty good current handling capacity when compared to standard BJTs (Bipolar junction transistor) and MOSFETs (metal–oxide–silicon transistor). IGBTs are devices whose switching is fully controlled electronically. Most standard rectifiers in the market are typically 6-pulse rectifiers.   17. How many types of IGBT are there? two types. The IGBT is classified as two types based on the n+ buffer layer, the IGBTs that are having the n+ buffer layer is called the Punch through IGBT (PT-IGBT), the IGBTs that does not have an n+ buffer layer are called the Non-Punch Through- IGBT (NPT- IGBT).   18. How do you prevent IGBT failure? IGBT turn-off requires that the IGBT be driven to the cutoff region of operation so that it can successfully block the reverse high voltage across it once the high-side IGBT has turned on. In principle this can be achieved by reducing the IGBT gate-emitter voltage to 0 V.   19. What is the difference between unipolar and bipolar devices? As their name implies, Bipolar Transistors are “Bipolar” devices because they operate with both types of charge carriers, Holes and Electrons. The Field Effect Transistor on the other hand is a “Unipolar” device that depends only on the conduction of electrons (N-channel) or holes (P-channel).   20. What is IGBT and Igct? GTO stands for Gate Turn-Off Thyristor, IGCT stands for Insulated Gate Commutated Thyristor and IGBT stands for Insulated Gate Bipolar Transistor. The comparison between the three devices are derived with respect to symbol, characteristic, advantages, disadvantages and applications.   You May Also Like The First Fully 2D FETs Lead A Faster Electronic Future The First Printed 2D Transistor Is Discovered by Researchers The First Chemical Circuit Developed Smarter transistors could be three times more efficient

A NIMS research group led by Jiangwei Liu (independent scientist, Research Center for Functional Materials) and Yasuo Koide (coordinating director in the Research Network and Facility Services Division) has succeeded for the first time in the world in developing logic circuits equipped with diamond-based MOSFETs (metal-oxide-semiconductor field-effect-transistors) at two different operation modes. This achievement is a first step toward the development of diamond integrated circuits operational under extreme environments.Diamond has high carrier mobility, a high breakdown electric field and high thermal conductivity. Therefore, it is a promising material to be used in the development of current switches and integrated circuits that are required to operate stably at high-temperature, high-frequency, and high-power. However, it had been difficult to enable diamond-based MOSFETs to control the polarity of the threshold voltage, and to fabricate MOSFETs of two different modes―a depletion mode (D mode) and an enhancement mode (E mode)―on the same substrate. The research group has successfully developed a logic circuit equipped with both D- and E-mode diamond MOSFETs after making a breakthrough by fabricating them on the same substrate using a threshold control technique developed by the group. The research group identified the electronic structure in the interface between various oxides and hydrogenated diamond using photoelectron spectroscopy in 2012. The research group then succeeded in developing a diamond MOS (metal-oxide-semiconductor) capacitor with very low leakage current density and an E-mode hydrogenated diamond-based MOSFET in 2013 after going through many difficulties. The group then prototyped logic circuits by combining diamond-based MOSFETs with load resistors in 2014. Finally, the group developed techniques to control D- and E-mode characteristics of diamond-based MOSFETs and identified the control mechanism in 2015. A series of these R&D accomplishments were introduced in AIP publishing news by the American Institute of Physics. These previous efforts led to the success made in this research project. The logic circuits with diamond-based transistors are promising devices to be used in the development of digital integrated circuits that are required to stably operate under extreme environments such as high-temperature as well as exposure to radiation and cosmic rays. This research was conducted in conjunction with the following projects: Leading Initiative for Excellent Young Researchers (Jiangwei Liu, representative), under the sponsorship of the MEXT Human Resource Development Program for Science and Technology; "Development of new functional diamond electronic devices using a large amount of polarized charges" (Yasuo Koide, principal investigator), under the category of Grant-in-Aid for Scientific Research (A) sponsored by the MEXT Grants-in-Aid for Scientific Research; and "Fabrication of high-current output fin-type diamond field-effect transistors" (Jiangwei Liu, principal investigator), under the category of Grant-in-Aid for Young Scientists (B) sponsored by the MEXT Grants-in-Aid for Scientific Research. Device fabrication was supported by the NIMS Nanofabrication Platform, established under the MEXT Nanotechnology Platform Japan program. Ref.DMN63D0LT-7DMN5L06VK-7

Linear Technology announces the LT3760, an 8-channel LED driver, utilizing a step-up DC/DC controller capable of driving up to a 45V string of 100mA LEDs per channel. Its internal 60V, 1MHz DC/DC boost mode controller is designed to operate as a constant current LED driver for up to 80 white LEDs. From a 12V input, the LT3760 can drive 8 channels, each with up to ten 100mA white LEDs in series while delivering efficiencies exceeding 92%. Its multichannel capability makes it ideal for medium and large-sized TFT-LCD backlighting applications. Its input voltage range of 6V to 40V makes it ideal for automotive, avionic, HDTV and industrial display applications. The LT3760 offers ±2.0% (±0.7% typical) LED current matching to ensure uniform brightness of the display. Dimming ratios as high as 3,000:1 can be attained by using True Color PWM™ dimming. A programmable 100kHz to 1MHz fixed frequency operation and current mode architecture offers stable operation over a wide range of supply and output voltages while minimizing the size of the external components. Additionally, the switching frequency is synchronizable to an external clock. Its thermally enhanced TSSOP-28 package offers a highly compact solution footprint for most LED backlighting applications. The LT3760 uses an external N-Channel MOSFET switch to provide a boost mode constant current source. However, even when VIN exceeds VOUT, the LT3760 will continue to accurately regulate the LED current. The internal boost controller uses an adaptive feedback loop to drive up to eight channels of ten 100mA LEDs to regulate the output voltage slightly higher than the required LED voltage to ensure maximum efficiency. If any of the LED strings experience an open circuit, the LT3760 will continue to regulate the existing strings and signal the FAULT alert pin. If higher current LEDs are required, multiple strings can be combined, enabling the LT3760 to drive up to four channels of ten 200mA LEDs or two channels of ten 400mA LEDs. Additional features include programmable LED current derating based on junction temperature and LED temperature and programmable output voltage limiting when all LED strings are disconnected. Summary of Features LT3760: Up to 45V of LEDs × 100mA, 8-Channel LED DriverWide Input Range: 6V to 40V±2.0% LED Current Matching at 20mA (Typ ±0.7%)Up to 3000:1 True Color PWM™ Dimming RangeSingle Resistor Sets LED Current (20mA to 100mA)LED Current Regulated Even for PVIN > VOUTOutput Adapts to LED VF for Optimum EfficiencyFault Flag + Protection for Open LED StringsProtection for LED Pin to VOUT ShortParallel Channels for Higher LED CurrentProgrammable LED Current Derating vs. TemperatureAccurate Undervoltage Lockout Threshold with Programmable HysteresisProgrammable Frequency (100kHz to 1MHz)Synchronizable to an External ClockThermally Enhanced 28-Pin TSSOP Package. The LT3760EFE is available in a thermally enhanced 28-lead TSSOP package in Kynix now. An industrial grade version, the LT3760IFE is tested and guaranteed to operate from a -40°C to 125°C operating junction temperature. Ref.KY32-LT3760EFE