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General electronic semiconductor

Summary and Analysis of Interference in Circuit Design:Circuit Problems, Reasons, Dealing Method

In the design of circuit systems, we often encounter things like this: when a circuit program is copied from the book completely, the result of the experiment is not correct. Why is it that? The reason is interference. We must do a good job of anti-interference in the process of the electronic circuit and program design.     Catalog I. Three Basic Element of Interference II. Suppressing Interference Sources     2.1 Common Measures to Suppress Interference Sources     2.2 Common Measures to Cut off the Path of Interference Propagation     2.3 Improve the Anti-interference Performance of Sensitive Devices III. Experience and Advice FAQ   I. Three Basic Element of Interference   a. Interference Source: Refers to the components, devices, or signals that cause interference, as described in mathematical terms as follows: some places where the figure of du/dt(voltage regulator factor) or di/dt(current rate of charge) is large may be the interference source. Also the lightning, relays, SCR, motor, high-frequency clock and so on may become interference sources.   b. Propagation Path: Refers to A path or medium in which interference travels from an interference source to a sensitive device. The typical path of interference propagation is the conduction of wires and the radiation of space.    c. Sensitive Device: Refers to an object that is susceptible to interference. Such as A/D or D/A converter, single-chip microcomputer, digital IC, weak signal, and so on. The basic principle of anti-jamming design is to suppress the interference source, cut off the path of interference propagation, and improve the anti-jamming performance of sensitive devices.   II. Suppressing Interference Sources   Suppressing interference sources is to minimize the du/dt and di/dt of interference sources as much as possible. Reduce the du/dt of the interference source by paralleling capacitors at both ends of the interference source; reduce the di/dt of the interference source by using the series inductance or resistance in the interference source loop and adding the freewheel diode. This is the highest priority and the most important principle in anti-interference design.   2.1 Common Measures to Suppress Interference Sources are as follows: (1) Add freewheel diode to the relay coil to eliminate the interference when disconnecting the coil. Only having a freewheel diode will delay the break time of the relay, therefore adding an extra more Zener diode will increase the number of operating times of the relay in unit time.   (2) Connect spark suppression circuit at both ends of relay contact(is usually RC; resistor is selected from several kΩ to dozens of kΩ; capacitance selects 0.01uF), so as to reduce the interference.   (3) Add filter circuit to the motor, pay attention to the capacitance, and inductance lead should be as short as possible.   (4) each IC on the circuit board should be connected with a high-frequency capacitor of 0.01 μ F to 0.1 μ F to reduce the influence of IC to the power supply. Pay attention to the wiring of high-frequency capacitance. The connection should be close to the power supply and should be as short as possible. Otherwise, it will increase the equivalent series resistance of the capacitance, which will affect the filtering effect.   (5) Avoid 90 degree fold line and reduce high-frequency noise when wiring.   (6) Connect the RC suppression circuit to both ends of the thyristor to reduce the noise caused by the thyristor (ps: if the noise is serious may break down the thyristor).   According to the path of interference, it can be divided into two types: conduction interference and radiation interference. Conduction interference is the interference that propagates through the wire to the sensitive device. The high-frequency interference noise is different from the useful signal in the frequency band, which can be cut off by adding a filter to the conductor, and sometimes it can be solved by isolating the optical coupling. Power noise is the most harmful, we should pay special attention to handling. Radiation interference refers to the interference which propagates through the space radiation to the sensitive device. The general solution is to increase the distance between the interference sources and the sensitive devices, to isolate them with grounding wires, and mask the sensitive devices.     2.2 Common Measures to Cut off the Path of Interference Propagation (1) Consider the influence of power supply on single-chip computers. A good power supply helps solve the majority of the jamming problems in circuit design. Many single-chip computers are sensitive to the noise of the power supply, so it is necessary to add a filter circuit or voltage stabilizer to the power supply of a single-chip microcomputer to reduce the interference. For example, a π-shaped filter circuit composed of magnetic beads and capacitors, in addition, a 100Ω resistor can be used to replace magnetic beads when the conditions are not high.   (2) If the I/O port of the single-chip microcomputer is used to control the noise devices such as motors, the I/O port, and the noise source should be isolated.( adding a π-shaped filter circuit)   (3) Pay attention to the crystal wiring. The crystal oscillator and single-chip microcomputer pin should as close as possible; the clock area should be isolated by grounding wire, crystal oscillator shell should be grounded and fixed. This measure can solve many difficult problems.   (4) Make reasonable partitions of the circuit board. Such as strong signal and weak signal, digital signal, and analog signal. Interference sources (such as motors and relays) and sensitive elements (such as microcontroller) should be isolated as far as possible.   (5) Separate the digital area from the analog area by landlines, and finally, connect to the power at one point. This principle is taken into account when the manufacturer makes the A/D and D/A chip pins arrangement.   (6) Single-chip microcomputer and large ground wire should be grounded separately to reduce mutual interference. High-power devices should be placed on the edge of the circuit board as far as possible.   (7) Use the anti-interference components such as magnetic beads, magnetic rings, power filters, and shielding covers in key places such as I / O portion, power lines, and circuit board connectors, which can significantly improve the anti-interference performance of the circuit.   2.3 Improve the Anti-interference Performance of Sensitive Devices To improve the anti-jamming performance of sensitive devices is to reduce the picking up of interference noise from the interference sources and to recover from abnormal state as soon as possible. The Usual Measures are as Follows: (1) Reduce the area of the loop in order to reduce the inductive noise.   (2) Power and ground wires should be as thick as possible, besides reducing the pressure drop, it is more important to reduce the coupling noise.   (3) The idle I / O port of SCM shouldn’t suspend, but connecting the ground or power supply. And the idle ends of other IC should be grounded or connected to power without changing the logic of the system.   (4) Using the power source monitoring and watchdog timer, such as IMP809, IMP706, IMP813, X25043, X25045, and so on, can greatly improve the anti-interference performance of the whole circuit.   (5) Under the condition that the speed can meet the requirement, the crystal oscillator of the single chip microcomputer is reduced and the low-speed digital circuit is chosen as far as possible.   (6) IC device is welded directly to the circuit board as far as possible.   III. Experience and Advice Software 1. Clearing the code space that is not commonly used, because this is equivalent to the NOP, can help programs recover when appearing program fleet.   2. Adding several NOP before the jump instruction, the same purpose as 1.   3. When there is no hardware WatchDog, an analog one can be used through software to monitor the operation of the program.   4. Dealing with the adjustment or setting of external device parameters, the parameters can be re-transmitted periodically in order to prevent the external device from making mistakes due to interference, so that the external device can be restored correctly as soon as possible.   5. Adding additive data to check anti-interference in Communication.   6. When there are communication lines, such as I2C or a three-wire system, it is found that the anti-interference effect of the Data line is better than that of the low one.   Hardware 1. The layout of grounding and power supply wires.   2. The decoupling of the circuit.   3. The separation of digital ground wire and analog ground wire.   4. Each digital element needs 104 capacitors between the grounding and the power supply.   5. In the applications with relays, especially in the case of high current, a 104 and diode can be combined between the relay coils to prevent the contact spark interference of the relay, and 472 capacitors installed at the contact point and the normal beginning.   6. To prevent the crosstalk of I / O port, the I / O port can be isolated by diode isolation, gate isolation, optocouple isolation, electromagnetic isolation, and so on.   7. Multi-layer board anti-jamming is certainly better than single-layer board, but its cost is several times higher.   8. Choosing an anti-jamming device is more effective than any other method.   FAQ   1. What is Circuit interference? Electromagnetic interference (EMI), also called radio-frequency interference (RFI) when in the radio frequency spectrum, is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction.   2. What causes electrical interference? What Causes Interference? Interference occurs when undesired radio signals or electromagnetic "noise" sources are picked up by consumer electronics products -most often telephones, audio equipment, VCRs or TVs. It usually results in noise, unwanted voices or distorted TV pictures. In most cases, the source is nearby.   3. What is meant by circuit design? As circuit design is the process of working out the physical form that an electronic circuit will take, the result of the circuit design process is the instructions on how to construct the physical electronic circuit.   4. What is circuit design theory? In integrated circuit design automation, the term "circuit design" often refers to the step of the design cycle which outputs the schematics of the integrated circuit. Typically this is the step between logic design and physical design.   5. Which software is best for circuit design? a. Eagle b. Altium c. Proteus d. KiCad e. Cadence OrCAD PCB Designer f. DesignSpark g. Protel h. Cadstar i. Sprint-Layout j. PADS PCB   6. How does circuit design work? Digital electronic circuit design takes the electrical signals in the form of discrete values. The data are represented in the form of zeros and ones. Digital circuits extensively use transistors, interconnected to give create logic gates that provide the function of Boolean logic.   7. How long does it take to design a circuit? Programming the Micro-controller. Division of labor will make the work more efficient and specializations and expertise are more focused. Normally, it only takes hours to program the microcontroller of a simple circuit but complex circuit diagrams may take 2 to 3 days.   8. Is circuit design difficult? Designing a circuit is easy if you the basic working principle of each & every electronics components you're going to use. But making it efficient is a bit time-consuming. Once you know the rules, it's normally not too difficult. Of course, some circuits are more difficult than others.   9. What are the types of circuit? There are 5 Main Types of Electric Circuit – Close Circuit, Open Circuit, Short Circuit, Series Circuit and Parallel Circuit.   10. What is the process of a circuit? The process of circuit design can cover systems ranging from complex electronic systems all the way down to the individual transistors within an integrated circuit. ... Typically this is the step between logic design and physical design.   You May Also Like Can We Manage to Recycle PCB Boards for Avoiding Harming the Environment? 10 Things to Consider While choosing a PCB Prototype Service Some Guides for Beginners Before You Create A Printed Circuit Board(PCB) Industrial Chain and Development Trend of PCB in China
kynix On 2018-09-11   426
General electronic semiconductor

Semiconductor Systems or Components

A Semiconductor is an element which is intermediate of conductor and an insulator. Semi-conductor is kind of material that contains electrical conductivity value between a conductor and an insulator such as copper or glass. Semi-conductors are the base of modern electronics. Semi-conductors are responsible for the computer Technology and its formation, which began in the mid of 20th century and still continuing.Semiconductor devices or electronic circuit components made from a material that is neither a good conductor nor a good insulator (called semiconductor). These devices have found wide applications because of their reliability, compactness, and very low cost. Semi-conductor systems or components are actually electronic components that take advantage of the electronic properties of the semi-conductor materials such as germanium, silicon and gallium arsenide. With the invention of the semiconductor devices have replaced most of the most of the vacuum tube applications. A semiconductor device is manufactured as either single discrete device or as integrated circuits. The integrated circuits include a few number to few million devices interconnected to a single semiconductor substrate. The cause why the semiconductor equipments are used in developing most devices is that the behavior of a semiconductor can easily be controlled by adding impurities which is or else called as doping. Transmission in a semi conductor occurs by free electrons which on the whole are called as the charge carriers.Semiconductors have massive impact on our society. Semiconductors mostly presents at the heart of microprocessor chips as well as transistors. Anything that's automated or uses radio waves depends on semiconductors. Today's mostly semiconductor chips and transistors are created with silicon. We may have heard words like "Silicon Valley" and the "silicon economy," and that's why -- silicon is the heart of any electronic device.A list of Semiconductor Components and devices includes Gunn diode, Avalanche diode, Light-emitting diode, PIN diode, IMPATT diode, DIAC, Schottky diode, Diode, Laser diode, Photocell, Tunnel diode, Solar cell, VCSEL, VECSEL and Zener diode are two terminal devices. The three terminal devices includes Darlington transistor, Bipolar transistor, Field effect transistor, IGBT, GTO, (Switched Gate Commuted Thyristor),SCR (Silicon Controlled Rectifier), SGCT, Thyristor, TRIAC, Unijunction transistor. The four terminal devices contains Hall Effect sensor (magnetic field sensor), Microprocessor, Multi-terminal devices comprises of Charge-coupled device (CCD), Read-only memory (ROM), Random Access Memory (RAM), and the list goes on.Written by  David John
kynix On 2016-08-12   425
General electronic semiconductor

GaN High-Electron Mobility Transistor Power Amplifier

Warm hints: The word in this article is about 1000 and the  reading time is about 6 minutes.SummaryFujitsu,a company that provide innovative IT services and digital technologies like mobile,AI,cloud or etc,announced the development of a gallium-nitride(GaN) high-electron mobility transistor(HEMT) power amplifier for use in W-band(75-110 GHz)transmissions in July 2017 at the 12th international Conference. To realize long-distance,high-capacity wireless communications,a promising approach is to utilize the W-band and other high frequency bands that encompass a broad range of usable frequencies, and increase output with a transmission power amplifier. At the same time, demand exists for improved efficiency in power amplifiers in order to mitigate the increased power consumption of communication systems. Fujitsu has now succeeded in developing a power amplifier for use in W-band transmissions that offers both high output power and high efficiency, improving transistor performance through the reduction of electrical current leakage and internal GaN-HEMT resistance. Fujitsu has achieved 4.5 watts per millimeter of gate width, the world's highest output density in the W-band, and has confirmed a 26% reduction in energy consumption compared to conventional technology. Fujitsu anticipates that setting this power amplifier between wireless communication systems in two locations will achieve high-bandwidth communications at 10 gigabits per second (Gbit/s) over a distance of 10km. Part of this research was carried out with support from Innovative Science and Technology Initiative for Security, established by the Acquisition, Technology & Logistics Agency (ATLA), Japan Ministry of Defense. Development Background Wireless data traffic from mobile communications has increased dramatically over the last few years, and with the spread of 5G and IoT devices it is predicted to increase at an annual growth rate of 1.5 times until the year 2020. In order to build this sort of high capacity next-generation wireless communications network, attention has been focused on wireless communication technology using the high frequency W-band. The range of frequencies that can be used in the W-band is very broad, and because communication speed can be rapidly increased in this band, it is well-suited for this kind of high bandwidth wireless communication. Conventional wireless communications technology, has allowed for performance of several Gbit/s over distances of several kilometers, but achieving an even greater increase in wireless communication distance and capacity utilizing the W-band demands further increases to the output of power amplifiers to boost signals during transmission. Issues To increase distance and capacity, it will be necessary to expand the frequency bandwidth that can be amplified while simultaneously supporting modulation methods that can transmit more information within the same frequency bandwidth, and a strong requirement is to have less distortion when the signal is amplified. Another pursuit is keeping in check the energy consumption of communication systems that accompanies greater distances and capacities, and the improved energy efficiency in power amplifiers.In order to both increase the distance and capacity of wireless communications and decrease energy consumption with indium-aluminum-gallium-nitride (InAlGaN) HEMTs, Fujitsu has developed two technologies that effectively reduce internal resistance and current leakage. Features of the newly developed technologies are as follows: Technology to reduce internal resistance Fujitsu has developed device technology that can reliably reduce resistance to one tenth that of previous technology when current flows between the source or drain electrodes and the GaN-HEMT device. The technology utilizes a manufacturing process that embeds GaN plugs directly below the source and drain electrodes, which generate electrons at high densities (fig. 1). It is necessary to transport the electrons that come from the source electrode to the two dimensional electron gas field as smoothly as possible. The structure of the previous technology causes the electron supply layer to become a barrier, however, and internal resistance increases between the source electrode and the two dimensional electron gas. By applying this new technology, Fujitsu succeeded in running high currents through the transistor with significantly less resistance (fig. 2). Technology to control current leakageA current leakage occurs when the two dimensional electron gas, which moves at high speed on the boundary at the top of the channel layer, takes a detour below the gate when the transistor is in its off-state. This leakage causes deterioration in the operational performance of the power amplifier. Normally, it is possible to reduce current leakage by placing a barrier layer beneath the channel layer, but in that case the amount of two dimensional electron gas also decreases, and leads to a reduction of the drain current. This new technology maintains high drain currents by effectively distributing indium-gallium-nitride (InGaN) to create a barrier layer below the channel layer. This reduces electron detours during operation, successfully providing significant reductions in current leakage(just see the fist and second picture).Effects The previous world record for power amplifier output density in the W-band for transmitters was 3.6 watts per millimeter of gate width with technology developed by Fujitsu Laboratories. This has improved significantly with the newly developed technology, which delivers power output of 4.5 watts per millimeter of gate width for a power amplifier designed to operate at 94GHz. In addition, this new technology achieved a reduction in energy consumption of 26% compared to the previous technology through a reduction in current leakage. It is anticipated that the use of this power amplifier will allow the achievement of high capacity, long distance wireless communications between two connected systems at different locations at over 10Gbit/s and at distances greater than 10km.Fujitsu aims to apply this technology broadly to the development of power amplifiers for purposes that call for wireless communications that offer long range and higher capacity, while offering easier installation than fiber optics. The goal is to commercialize this technology in high speed wireless communication systems by 2020, with an aim to employ it in such situations as a method of restoring communications when fiber optic cables have been severed by natural disasters or as a way of setting up temporary communications infrastructure when holding events.  Article provide by FujitsuArticle edited by kynix
kynix On 2018-02-01   424
LED

Modify An OLED Clock Using ESP32

A few months ago,I have see an article about desinging a nixie tube clock with an ATmega328 and ESP8266,and I had a big interest in it and I made one immediately according to the article's step.The ESP8266 connected to a Network Time Protocol (NTP) server was cheaper to implement than using an RTC due to the discrepancies between the defined clock speed and actual clock speed.  You can see the picture,nixie tubes came into existence during the time of vacuum tubes and before LEDs (at least in the context of the Soviet Union). Once LED technology made its way into the USSR, nixie tubes began to fade out. Even today when shopping for nixie tubes online, all of the tubes I’ve purchased have been sent from either Russia or Ukraine. It seemed fitting that I would follow in history’s footsteps and switch over to the cheaper, easier and safer LED technology (I may or may not have shocked myself a few times on the 170VDC supply when testing).  I would like to use seven-segment displays to solve this problem. However,I think it's a little expensive even today. I would like to try something different, something that you don't really see sommercially. Suddently,binary clocks come to my mind,it's interested programmer like me. After a time of consideration, I sticked with a digital display and kept going back to the seven-segment variety. Using our OLED breakout allowed me to recreate the look of a 7-segment display, but I can add animations when the digits change. I added animations that make the individual segments drop in and fall off of the display when the time changes.In my nixie tube clock,I first tried using ESP8266 control both WIFI and the nixie tubes,but the WiFi stack was just too large to avoid seeing the multiplexed nixie tubes flicker any time the 8266 needed to do something WiFi-related. This meant that I had to have two controllers on the board; an ATmega328 would handle the nixies, and the ESP8266 would be responsible for the time and web GUI for settings. After that, I found ESP32 Thing from Sparkfun when I browse google, The ESP32 have two cores, one is to hanle the wifi stack and the other for programming. and I thought of my clock immediately and  how much easier it would be to just have one device to program and not worry about how I would transfer information between the two. About the Clock Stands  See the above picture,my clock is still work in progress currently,the code requires hard coding the SSID and password for the wireless access point. I really liked the web GUI I made, which I can access from the ESP8266 to change settings for the access point’s SSID and password or to select the NTP server location, time zone and whether or not to adjust for daylight saving time. I have two problems now. The one is that I haven’t been able to implement the GUI quite yet due to library changes in WiFi.h to serve web pages, and this is where I could use some help. If you’ve made a web server for your ESP32, please let me know how you handled multiple pages. I’ve been scratching my head throughout the build on how to get this done. With the ESP8266, there’s on(const String &uri, handler function), but that seems to have been removed on the ESP32. And the another problem with both clocks is how I handle daylight saving. Currently with the nixie clock, I have a selection box that removes an hour, but I would like to have that happen automatically. The NTP time returned will allow me to figure out the date, but given that daylight saving time begins on the second Sunday of March and ends on the first Sunday of November, how would you efficiently program in that functionality? The clock is far from finished, and aside from the problems I’ve mentioned above, there are some minor things I would like to touch up and a couple of extra features I’d like to add. And a part of my code is as following:#include <SPI.h>  // Include SPI if you're using SPI#include <TimeLib.h>#include <WiFi.h>#include <WiFiUdp.h>#include <SFE_MicroOLED.h>  // Include the SFE_MicroOLED library const char ssid[] = "************";  // your network SSID (name)const char pass[] = "************";  // your network password static const char ntpServerName[] = "time.nist.gov";const int timeZone = -6;  // Mountain Daylight Time WiFiUDP Udp;unsigned int localPort = 8888;  // local port to listen for UDP packets time_t getNtpTime();void sendNTPpacket(IPAddress &address); //IO Pin Constants//Digit 0#define PIN_RESET_0 12#define PIN_DC_0    22#define PIN_CS_0    13 //Digit 1#define PIN_RESET_1 17#define PIN_DC_1    22#define PIN_CS_1    16 //Digit 2#define PIN_RESET_2 4#define PIN_DC_2    22#define PIN_CS_2    0 //Digit 3#define PIN_RESET_3 2#define PIN_DC_3    22#define PIN_CS_3    15  //7-Seg Pixel Constants for OLED#define A_X 59#define A_Y 14 #define B_X 35#define B_Y 38 #define C_X 6#define C_Y 38 #define D_X 0#define D_Y 14 #define E_X 6#define E_Y 7 #define F_X 35#define F_Y 7 #define G_X 29 #define G_Y 14 //Initialize DisplaysMicroOLED oled0(PIN_RESET_0, PIN_DC_0, PIN_CS_0);MicroOLED oled1(PIN_RESET_1, PIN_DC_1, PIN_CS_1);MicroOLED oled2(PIN_RESET_2, PIN_DC_2, PIN_CS_2);MicroOLED oled3(PIN_RESET_3, PIN_DC_3, PIN_CS_3); bool updateTime=1;byte old_minute=0,old_hour=0; time_t prev = 0, prevNow=0; void setup() {  Serial.begin(115200);   //Setup Displays  oled0.begin();  oled0.clear(PAGE);  oled1.begin();  oled1.clear(PAGE);  oled2.begin();  oled2.clear(PAGE);  oled3.begin();  oled3.clear(PAGE);    // Connect to WiFi  WiFi.begin(ssid, pass);   pinMode(5,OUTPUT);  //Use the built in LED for WiFi Connection Status  bool state = 0;  while (WiFi.status() != WL_CONNECTED) {    delay(500);    Serial.print(".");    state = !state;    digitalWrite(5,state);  }  digitalWrite(5,HIGH);   Serial.print("IP number assigned by DHCP is ");  Serial.println(WiFi.localIP());  Serial.println("Starting UDP");  Udp.begin(localPort);  Serial.println("waiting for sync");  setSyncProvider(getNtpTime);  setSyncInterval(300);   //Display Current Time  Update_Digit(oled0,hourFormat12()/10,32);  Update_Digit(oled1,hourFormat12()%10,32);  Update_Digit(oled2,minute()/10,32);  Update_Digit(oled3,minute()%10,32);  prev = now();  prevNow = now()/60;} void loop() {  yield();  //Let the ESP32 handle the wifi stack   //Print the current time to Serial (debugging)  if(now() != prevNow)  {    prevNow = now();    Serial.print(hour());    Serial.print(' ');    Serial.print(minute());    Serial.print(' ');    Serial.print(second());    Serial.println();  }   //Only update when the minutes change  if(now()/60 != prev)  {    prev = now()/60;     //Update Display    for(byte i=0;i<33;i++)    {      if(hour() != old_hour)  //Does hour need to be updated?      {        if((hour()/10)!= old_hour/10) //Which hour digit needs to update? Both?        {          Update_Digit(oled0,hourFormat12()/10,i);          Update_Digit(oled1,hourFormat12()%10,i);        }        else  //Just update the first hour digit        {          Update_Digit(oled1,hourFormat12()%10,i);        }              }       if(minute() != old_minute)  //Does the minutes need to updated?      {        if((minute()/10)!= old_minute/10) //Which digit needs to be updated? Both?        {          Update_Digit(oled2,minute()/10,i);          Update_Digit(oled3,minute()%10,i);        }        else  //Just update the first minute digit        {          Update_Digit(oled3,minute()%10,i);        }              }      delay(5); //Wait 5ms to slow down the animations    }    old_hour = hour();    old_minute = minute();  }} //Animations for changing numbersvoid Update_Digit(MicroOLED &oled,byte number, byte i){  oled.clear(PAGE);  switch(number)  {    case 0:      if(i<17)      {        oled.rectFill(A_X+(64-i*4),A_Y,4,22); //A        oled.rectFill(A_X-(i*3.6),A_Y,4,22); //A        oled.rectFill(B_X,B_Y,22,4); //B        oled.rectFill(C_X,C_Y,22,4); //C        oled.rectFill(E_X+(32-i*2),E_Y,22,4); //E        oled.rectFill(F_X+(32-i*2),F_Y,22,4); //F        oled.rectFill(G_X-(i*4),G_Y,4,22); //G      }      else          break;     case 1:      oled.rectFill(A_X-(i*2),A_Y,4,22); //A      oled.rectFill(B_X,B_Y,22,4); //B      oled.rectFill(C_X,C_Y,22,4); //C      oled.rectFill(D_X-(i*2),D_Y,4,22); //D      oled.rectFill(E_X-(i*2),E_Y,22,4); //E      oled.rectFill(F_X-(i*2),F_Y,22,4); //F    break;    default:    break;  }  oled.display();}
kynix On 2017-10-20   424
Sensor

Sensors are Always In a State of Rapid Progress

SummaryIf you have follow the informations of sensor,you will know that sensors are always in a state of rapid progress.Now I will state a few things to prove it in the following.Sensor,also called Transducer, is a kind of detection device,it can receive the measured information and then output them according to a certain rule or other needed form to meet the transport, handling,storage,recording,displaying and controlling of imformation,etc. Know more about it,you can read the article : Most Comprehensive Sicence Popularizing of Sensor (detection device) Researchers created quantum control technique for quantum sensorsAs we all known,there is a common problem that designers are harder to deal with quantum sensing devices. How,University of Sydney researchers have sloved this trouble associated with this super-sensitive tech. They have created quantum control techniques in collaboration with Johns Hopkins Applied Physics Laboratory and Dartmouth College. This development will allow next-gen ultra-sensitive sensors to identify small signals and reject unwanted background noise.By applying the right quantum controls to a qubit-based sensor,the team adjust its response in a way  that guarantees the best possible exclusion of the background clutter—that is, the other voices in the room. In order to obtain and analyze signals, measurement protocols are set in place. Over the years, these protocols have lagged behind the advancement of electronic devices. The disparity has led to a phenomenon known as “spectral leakage,” which occurs when quantum sensors return unclear results.What's more, the new control protocols have reduced spectral leakage by several orders of magnitude by using improved sensor hardware. All the approach is relevant to nearly any quantum sensing application and can also be applied to quantum computing as it provides a way help identify sources of hardware error.‘quantum control techniques' is a major advance in how to operate quantum sensors.  New sensors uses for effective control of enviroment pollutionEnviromental pollution issue are always paid great attention by human being as the development of all the world. A team from the Faculty of Physics of Lomonosov Moscow State University has suggested using porous silicon nanowire arrays in highly sensitive gas sensors which may be used both for effective control of environment pollution levels and for the monitoring of air composition in closed spaces,from classrooms to space stations.According to researchers, these devices will be able to detect the presence of toxic and non-toxic gas molecules in the air at room temperature.Each sensor consists of an array of 10 micron long organized silicon nanowires with diameters ranging from 100 to 200 nm. Each nanowire has porous crystalline structure. The size of silicon crystals and pores between them in individual nanowire, varies from three to five nanometers.ey can be obtained by means of a cheap method of metal-assisted chemical etching. It is based on selective chemical etching, i.e. partial removal of surface layer from a bulk crystalline silicon with the use of metal nanoparticles as a catalyst. Moreover, the procedure is quick—at least 100 elements can be produced in a lab within just one hour.Such porous nanowires have huge specific surface area due to which their physical and chemical properties are extremely sensitive to molecular environment. It was also found out that the obtained samples exhibited an effective photoluminescence in the red spectrum region at room temperature. What's important,this gas sensors based on porous nanowires both work at home temperatures and also are reusable, because the all observed effects were completely reversible. Military sensor systems collect accurate informationCollecting accurate user and environmental information such as enemy's location,survive shock, vibration, moisture plays an important role in military system. Deployment complaints about the platform aside, Lockheed Martin’s Electro-Optical Targeting System (EOTS) for the F-35 Lightning II is a high-performance, lightweight, multi-function sensing solution for precision air-to-air and air-to-surface targeting (Figure 4). Integrated into the aircraft fuselage with a rugged sapphire viewport, the device talks to the aircraft via a fiber-optic interface.Presented as the first sensor to combine forward-looking and infrared search along with track functionality, EOTS enables situational awareness and precision delivery of laser and GPS-guided weapons. Advanced EOTS, the next iteration, will incorporate enhancements and upgrades like short-wave infrared, high-definition television, and an infrared marker.Today’s military sensors must operate well on their own, and function as part of a combined-arms approach with an interlaced network of sensing, to detect threats of any nature from any direction. One such way to address this is with a battlefield awareness solution like 3D Advanced Warning System (3DAWS) from BAE Systems, which can provide universal threat detection to an aircrew with a layered countermeasure defense.The modular and expandable system can integrate with fixed- and rotary-wing aircraft and countermeasure systems, with the flexibility to work with existing radar or laser warning systems. The core of the 3DAWS suite is the passively-cued, semi-active radio frequency 3D Tracker element, which serves as an adjunct to current and future passive threat detection systems. 
kynix On 2017-12-28   421
General electronic semiconductor

Trojans are everywhere even the hardware

SummarryWhen I see this paper,The things occurred in my mind is that I need to let others to know it and prevent it.From morning until now,I always solve my computer's Trojans.This is terrible. Trojans may break our computer although it look like there doesn't matter.Trojans aren everywhere even the hardware in some instances, hardware Trojans could even open backdoors in custom silicon. BodyOutsourcing has reshaped the way electronics products are made – and helped to cut manufacturing costs massively. But, as production margins have fallen, so too has trust in the organisations that make up the supply chain. Companies which rely on outsourced manufacturing are having to come up with ways of ensuring that the products shipped to them have not had secure keys leaked or stuffed with viruses and compromised software. Even custom silicon is not safe.Almost a decade ago, researchers from Case Western Reserve University described to delegates at the IEEE High-Level Design Validation and Test Workshop the ways in which they could see hardware malware – or Trojans – being introduced to an IC-design project. The widespread use of foundry services, third-party intellectual property and standard-cell libraries – as well as designers bribed to make circuit-level changes – all provide ways in which Trojans could be sneaked into circuitry.Once it receives a trigger signal, the Trojan could open a backdoor to the group that wanted it introduced. In some use-cases, the Trojan may be introduced simply to compromise the product; no matter how it is used. However, the nature of IC design makes hardware Trojans difficult to deploy as they require skills and levels of access that are probably out of reach of most cybercriminals. But other, lower hanging, fruit remains available to them. State actors have the skills, access and motive that may make the surrepticious deployment of some kinds of silicon highly attractive to them. In practice, such organisations may not bother trying to introduce backdoors without the knowledge of the manufacturer or find other ways to make gain access to secrets. In 2015, the BBC identified declassified documents that confirmed the government convinced Crypto AG in the mid-1950s to compromise the security of its C-52 electromechanical encryption machines. Rather than making physical changes to the hardware itself, the company told the US National Security Agency (NSA) and the UK’s GCHQ which models target governments had bought – a practice that would allow the agencies to target decryption resources more effectively. In 2013, the NSA came under suspicion of encouraging the use of algorithms supplied by specialist RSA that had been subtly weakened to make decryption easier. While some ICs behave as if they have Trojans installed, in reality the backdoors were placed intentionally into the silicon by authorised designers. Usually, they are debug aids that were meant to stay secret, but often did not. Five years ago, Sergei Skorobogatov of the University of Cambridge and Christopher Woods of Quo Vadis Labs used side-channel emissions from the devices to uncover the key that would open the backdoor in the JTAG circuitry of an FPGA and to provide access to the encryption keys stored inside. Although side-channel emissions provide one way to determine whether an IC has been compromised with a backdoor, designers have other options available through the deployment of EDA techniques with Trojan detection in mind. As with anything in cybersecurity, a cat-and-mouse game has produced ever more subtle ways of introducing Trojans and more powerful ways of detecting them. The hardware Trojan is the subject of regular hacking competitions between research teams. For example, the Cyber Security Awareness Week (CSAW) organised by New York University has run several challenges around Trojans. In these challenges, red teams try to circumvent the detection mechanisms used by blue teams. 2013’s CSAW challenge focused on methods to beat FANCI, a largely effective detector developed at Columbia University and NYU. FANCI works on the basis that a Trojan would only have a loose connection to the design such that its logic would seem to be practically unreachable. Code-coverage analysis of the RTL can identify such unconnected lumps of circuitry and flag them up as possible Trojans. A couple of years later, the DeTrust technique created by Jie Zhang and colleagues at the Chinese University of Hong Kong showed one method for fooling FANCI: spreading the suspicious logic across many otherwise independent gates. Months later, Syed Haider and coworkers from the University of Connecticut developed the hardware Trojan catcher (HaTCH), designed to track down stealthier functions inserted at the logic level. Rather than isolate the Trojans before manufacture so they can be removed, HaTCH focuses on remediation. It adds tagging circuitry to legitimate cores that work to prevent any on chip Trojans from activating or succeeding in displaying malicious behaviour, such as opening a backdoor. A more wide-ranging technique that could serve as a defence against Trojans is to insist that all IP be supplied with formal proofs that describe the operations it would be allowed to perform. Any changes would be flagged by formal-verification tools during design and prototyping. Such approaches could still be vulnerable to attacks that tweak designs below the abstraction of RTL. As with the cases where the NSA is understood to have sought the help of manufacturers, weakened encryption is one of the most likely ways in which a practical hardware Trojan might work and evade detection by all but side-channel analysis. And it is possible using a tiny change at manufacture according. At the 2013 International Workshop on Cryptographic Hardware and Embedded Systems, Georg Becker and colleagues from the University of Massachusetts at Amherst showed a proof of concept that simply switched dopants used for one of the transistors in an inverter within a larger AOI standard cell (see figure 1). The result would be an inverter that generated a constant output.A transistor that no longer switched might be caught by a scan test looking for stuck-at faults. But embedded in a pseudorandom number generator, the inverter’s problem could be very hard to track down. Once there, the Amherst team estimated the fault could massively reduce the entropy of the random numbers it produced, resulting in very weak cryptographic keys. In 2014, Takeshi Sugawara of Mitsubishi Electric and a team from the company and Ritsumeikan University showed such a tiny change in manufacturing could be detected after the fact. A combination of focused ion beams and scanning electron microscopy can reveal the dopants diffused into the substrate. It is an expensive proposition, involving delayering of the design and extensive analysis against a layout that contains a map of the expected dopants. However, for the kinds of high-value cryptographic IC that might be the targets of well-financed attackers, it is arguably one more in a list of checks that are readily justified. As with other areas of embedded cybersecurity, the most feasible approach to dealing with the risk of hardware Trojans is one of focusing effort. Architectures such as Trustzone pull functions that need high levels of protection into a small portion of the overall SoC. In principle, this subset is much easier to verify than a design that calls for the either chip to analysed for vulnerabilities. If the secure core is guaranteed to not leak information or provide trapdoors, the value to an attacker of putting a Trojan in the more weakly protected part of the SoC diminishes greatly. For the user of SoCs and the buyer of IP to go into them, the question then becomes one of the level of expected risk and the degree of trust they can put in staff, suppliers and contractors.
kynix On 2018-01-24   419

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