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This comprehensive article introduces crystal oscillators in detail, covering what this component is, how it works, the various types of crystal oscillators available, and how to select the most suitable crystal oscillator for your project.I What is a Crystal Oscillator?This video explains the working and design principles of crystal oscillators, providing valuable insights for students and engineers in understanding the operational mechanisms and design considerations.A crystal oscillator is a type of electronic oscillator that utilizes the mechanical resonance of a vibrating crystal made from piezoelectric material to generate an electrical signal with a precise frequency. Typically, a wafer is cut from a quartz crystal at a specific orientation angle and combined with integrated circuits to form an oscillating circuit within a package.As mentioned above, the resonator plate can be cut from the source crystal at different angles. The cutting method significantly influences the crystal's aging characteristics, frequency stability, thermal properties, and other parameters. Most cuts are made for bulk acoustic wave (BAW) operation, while surface acoustic wave (SAW) devices are employed for higher frequencies.2025 Update: Modern crystal oscillators now commonly operate at frequencies up to several GHz, with advanced MEMS-based oscillators becoming increasingly popular for their improved shock resistance and faster startup times.Crystal Cut Types and SpecificationsCutFrequency RangeModeAnglesDescriptionAT0.5–300MHzthickness shear (c-mode, slow quasi-shear)35°15', 0° (<25 MHz)35°18', 0°(>10 MHz)The most common cut. The plate contains the crystal's x axis and is inclined by 35°15' from the z (optic) axis. The frequency-temperature curve is sine-shaped with inflection point around 25–35°C. Has frequency constant 1.661MHz·mm.SC0.5–200MHzthickness shear35°15', 21°54'A double-rotated cut (35°15' and 21°54') for oven-stabilized oscillators with superior temperature stability.BT0.5–200MHzthickness shear (b-mode, fast quasi-shear)−49°8', 0°A special cut similar to AT cut with different temperature characteristics.ITVariousthickness shearOptimized anglesA double-rotated cut with improved characteristics for oven-stabilized oscillators.XY (tuning fork)3–85kHzlength-width flexureStandard orientationSmaller than other low-frequency cuts, less expensive, has low impedance and low Co/C1 ratio. Chief application is the 32.768 kHz RTC crystal.Crystal Oscillator Key Features:High Stability: Crystal oscillators are used in applications requiring very stable frequency references.Superior Performance: Unlike LC and RC oscillators, crystal oscillator frequency changes minimally with temperature, supply voltage, or component value variations.Excellent Selectivity: Provides very good selectivity due to high Q-factor (Quality Factor).Working Principle of Crystal Oscillator:The crystal oscillator operates on the principle of the inverse piezoelectric effect. When an alternating voltage is applied to a properly cut and mounted quartz crystal, it produces mechanical vibrations at its resonant frequency.Equivalent Circuit of Crystal:The crystal can be represented as an RLC circuit in its electrical equivalent. It has two resonant frequencies:1) Series Resonant Frequency (fs)2) Parallel Resonant Frequency (fp)The RLC circuit provides frequency selectivity for oscillation, and when combined with an amplifier, creates a complete oscillator circuit.II Crystal Oscillator Operational PrincipleA crystal is a solid material consisting of atoms, molecules, or ions arranged in a regularly ordered, repeating pattern extending in all three spatial dimensions.Any object made of elastic material can potentially serve as a resonator with appropriate transducers, as all objects have natural resonant frequencies. For example, steel was often used in mechanical filters before quartz became prevalent due to its elasticity and high speed of sound propagation.When a quartz crystal is properly cut and mounted, it can be made to deform in an electric field by applying voltage to electrodes. This property is known as the piezoelectric effect. When alternating voltage is applied, the crystal produces mechanical vibrations, which in turn generate an alternating electric field.The quartz crystal oscillator can be electrically modeled as a two-terminal network with a capacitor and resistor in parallel, plus a capacitor in series. This network has two resonance points: the lower frequency (series resonance) and the higher frequency (parallel resonance).Due to the crystal's inherent characteristics, these two frequencies are very close. Within this narrow frequency range, the crystal oscillator behaves like an inductor, forming a parallel resonant circuit when appropriate capacitors are connected.Important Note: Load capacitance is a critical parameter. Selecting a parallel capacitor matching the crystal's load capacitance specification ensures operation at the nominal resonant frequency.Key Performance Parameters:(1) Total Frequency Tolerance: The maximum frequency deviation from the nominal frequency caused by all specified operating and non-operating parameters within a specified time period.(2) Frequency Temperature Stability: The maximum allowable frequency deviation over a specified temperature range under nominal power supply and load conditions.fT = ±(fmax-fmin)/(fmax+fmin)fTref = ±max[|(fmax-fref)/fref|，|(fmin-fref)/fref|](3) Frequency Aging Rate: The relationship between oscillator frequency and time under constant ambient conditions, typically specified as ±10ppb/day after 72 hours of operation.(4) Phase Noise: The ratio of power density in phase-modulated sidebands to carrier power at a specified offset frequency from the carrier.III Crystal Oscillator ParametersFrequency Accuracy: The maximum allowable deviation between the oscillator frequency and its nominal value under specified conditions, expressed as (fmax-fmin)/f0.Temperature Stability: The allowable frequency variation over the specified temperature range, calculated as (fmax-fmin)/(fmax+fmin).Frequency Tuning Range: The range of output frequencies achievable by adjusting variable elements in the crystal oscillator circuit.Voltage-Controlled Characteristics: For VCXOs, this includes:FM Deviation: Output frequency difference when control voltage varies from maximum to minimumFM Sensitivity: Frequency change per unit control voltage changeFM Linearity: Measure of linearity compared to ideal straight-line responseLoad Characteristics: Maximum frequency deviation due to load impedance variations within specified ranges.Supply Voltage Characteristics: Maximum frequency deviation due to supply voltage variations within specified ranges.Spurious Signals: Power ratio of discrete spectral components to the main frequency, excluding harmonics, expressed in dBc.Harmonics: Ratio of harmonic component power to carrier power, expressed in dBc.Frequency Aging: Systematic frequency drift over time due to component aging, particularly the quartz resonator.Daily Stability: Frequency variation measured over 24 hours after specified warm-up time.Startup Characteristics: Maximum frequency change within specified warm-up time, expressed as V = (fmax-fmin)/f0.Phase Noise: Frequency domain representation of rapid, short-term, random phase fluctuations caused by time domain instabilities.IV. Crystal Oscillator Frequency Stability & Input/OutputFrequency StabilityFrequency stability over operating temperature is one of the primary characteristics determining oscillator cost. Higher stability requirements or wider temperature ranges result in higher device costs.Crystal aging is a significant factor in long-term frequency stability. The aging rate follows a logarithmic curve and is most pronounced during the first year of operation. For applications requiring 10+ year operation, the aging rate is approximately three times that of the first year.2025 Update: Modern crystal oscillators now achieve aging rates as low as ±0.1 ppb/day for high-end OCXO units, and MEMS oscillators offer improved aging characteristics compared to traditional quartz devices.Other factors affecting frequency stability include supply voltage variations, load changes, phase noise, jitter, and electromagnetic interference (EMI). For industrial applications, vibration and shock specifications are critical, while aerospace applications require tolerance specifications for pressure changes and radiation exposure.Output TypesCrystal oscillators are available with various output types compatible with different logic families:HCMOS/TTL: Most common for digital applicationsACMOS: Low power applicationsECL: High-speed applicationsLVDS: High-speed differential signalingHCSL: High-speed current steering logicSine Wave: Analog applications requiring pure sinusoidal outputCritical specifications include symmetry (typically 45%-55%), rise/fall times (often <5ns for high-speed applications), and logic levels. Many DSP and communication chipsets require strict symmetry and fast edge rates.Phase Noise and JitterPhase noise, measured in the frequency domain, represents true short-term stability. It's typically measured from 1Hz to 1MHz offset from the carrier frequency. Crystal oscillators using fundamental or harmonic modes provide the best phase noise performance, while PLL-based synthesized oscillators generally exhibit poorer phase noise characteristics.Jitter, related to phase noise but measured in the time domain, is specified in picoseconds (RMS or peak-to-peak). Applications such as communication networks, wireless data transmission, ATM, and SONET require careful attention to both characteristics.V Crystal Oscillator ApplicationsCrystal oscillators serve as precision clock sources in microcontroller systems and can be categorized into two main types:Mechanical resonance devices: Crystal oscillators and ceramic resonators (suitable for Pierce oscillator configurations)RC oscillators: Lower cost but less accurate alternativesCrystal oscillators and ceramic resonators provide high initial accuracy and low temperature coefficients. RC oscillators offer quick startup and lower cost but typically achieve only 5%-50% accuracy over temperature and supply voltage ranges.Environmental ConsiderationsEnvironmental factors affecting oscillator performance include:Electromagnetic Interference (EMI)Mechanical vibration and shockHumidityTemperature variationsSupply voltage fluctuationsThese factors can cause frequency instability and, in severe cases, oscillator failure. Oscillator modules help mitigate many of these issues by providing complete, tested solutions with specified environmental tolerances.Power Consumption ConsiderationsPower consumption varies significantly by oscillator type:Discrete crystal circuits: 1-5mA typicalCrystal oscillator modules: 10-60mA typicalMEMS oscillators: 1-50mA depending on frequency and featuresUltra-low power oscillators: <1mA for battery-powered applicationsCommon ApplicationsGeneral oscillating circuits for frequency generationDigital clock generation for processors and microcontrollersMicroprocessor timing referencesConsumer electronics (TV, VCR, DVD players)Timekeeping applications (watches, clocks, RTCs)Communication systems (cellular, WiFi, Bluetooth)Test and measurement equipmentAutomotive electronicsIndustrial control systemsVI Crystal Oscillator TypesCrystal oscillators are classified into several categories based on their design and application requirements:By Temperature Compensation Method:TCXO: Temperature-Compensated Crystal OscillatorVCXO: Voltage-Controlled Crystal OscillatorOCXO: Oven-Controlled Crystal OscillatorDCXO: Digitally Compensated Crystal OscillatorMCXO: Microcomputer-Compensated Crystal OscillatorBy Circuit Configuration:Passive Crystal Oscillators: Require external oscillator circuitActive Crystal Oscillators: Complete oscillator with built-in amplificationBy Package Type:Metal Can: Traditional hermetic sealingCeramic: Good thermal propertiesPlastic: Cost-effective for commercial applicationsSMD: Surface mount for automated assemblyCommon Types and AbbreviationsAbbreviationFull NameTypical StabilityTCXOTemperature-Compensated Crystal Oscillator±0.1 to ±2.5 ppmVCXOVoltage-Controlled Crystal Oscillator±25 to ±100 ppmOCXOOven-Controlled Crystal Oscillator±0.001 to ±0.1 ppmDCXODigitally Compensated Crystal Oscillator±0.1 to ±1 ppmMCXOMicrocomputer-Compensated Crystal Oscillator±0.05 to ±0.5 ppmGPSDOGPS Disciplined Oscillator±0.001 ppmMEMSMicro-Electro-Mechanical Systems Oscillator±20 to ±100 ppm2025 Update: MEMS oscillators have gained significant market share due to their superior shock/vibration resistance, faster startup times, and programmability. They're increasingly used in automotive and IoT applications.Active vs. Passive Crystal OscillatorsPassive Crystal Oscillators:Require external oscillator circuit in the CPU/MCUTwo-pin, non-polar componentSignal level determined by the driving circuitCan work with various supply voltagesLower costRequire careful PCB layout and component matchingActive Crystal Oscillators:Complete oscillator with built-in amplificationFour-pin device with power supply connectionsFixed output signal levelBetter signal quality and stabilitySimpler connection (typically requires only power supply filtering)Higher cost but more reliable operationAvailable in various output formats (CMOS, TTL, LVDS, etc.)VII Crystal Oscillator Selection GuideSelecting the appropriate crystal oscillator requires careful consideration of application requirements and environmental conditions.Selection Criteria by Stability Requirements:±100 ppm or less: Standard XO or VCXO±5 to ±25 ppm: TCXO±0.5 to ±5 ppm: High-grade TCXO or ATCXO±0.1 to ±0.5 ppm: MCXO or DCXO±0.01 to ±0.1 ppm: OCXOBetter than ±0.01 ppm: GPSDO or atomic referenceApplication-Specific Considerations:Communication Systems:Cellular base stations: OCXO or high-grade TCXOMobile devices: TCXO with voltage controlWiFi/Bluetooth: Standard TCXOSatellite communication: OCXO with GPS discipliningComputing and Digital Systems:Microprocessors: Standard XO or TCXOHigh-speed processors: Low-jitter TCXO or MEMSReal-time clocks: 32.768 kHz tuning fork crystalsNetwork equipment: Low-jitter TCXO or OCXOTest and Measurement:Frequency counters: OCXOSignal generators: OCXO with low phase noiseOscilloscopes: Low-jitter TCXOSpectrum analyzers: Ultra-low phase noise OCXOEnvironmental Considerations:Temperature Range:Commercial (0°C to +70°C): Standard gradesIndustrial (-40°C to +85°C): Industrial gradesMilitary (-55°C to +125°C): Military-grade devicesAutomotive (-40°C to +125°C): AEC-Q100 qualifiedMechanical Environment:High vibration: MEMS oscillators or ruggedized crystalsShock resistance: MEMS or specially mounted crystalsSize constraints: Ultra-miniature packages (1.6×1.2mm or smaller)Power Consumption Optimization:Battery-powered devices: Ultra-low power TCXO or MEMSAlways-on applications: Low standby current oscillatorsPortable devices: Programmable MEMS with power-down modesPackage Selection:Through-hole: Traditional DIP packages for prototypingSurface mount: Various sizes from 7×5mm to 1.6×1.2mmUltra-miniature: Wafer-level chip scale packages (WLCSP)Development Trends (2025):Miniaturization: Continued reduction in package sizesIntegration: Multi-frequency and programmable outputsMEMS adoption: Replacing quartz in many applicationsIoT optimization: Ultra-low power and wireless-friendly designs5G/6G requirements: Ultra-low jitter and phase noiseAutomotive growth: AEC-Q100 qualified devices for ADAS and autonomous vehiclesTesting and Quality Assurance:Common crystal oscillator failure modes include:Internal leakage: Contamination or seal failureOpen circuit: Wire bond or connection failureFrequency drift: Aging or temperature effectsExternal component failure: Load capacitor issuesTesting Methods:1) Resistance Measurement: Use multimeter on high resistance range. Normal crystals should show infinite resistance in both directions. Any finite resistance indicates leakage or breakdown.2) Capacitance Measurement: Measure crystal capacitance using LCR meter or digital multimeter with capacitance function. Compare with expected values for the crystal type.3) Oscillation Test: Build simple test oscillator circuit to verify crystal functionality. Successful oscillation indicates good crystal condition.4) Frequency Accuracy Test: Use frequency counter to verify output frequency matches specification within tolerance.5) Temperature Testing: Verify frequency stability over specified temperature range.Recent Industry DevelopmentsIndustry Update: Leading manufacturers continue to push the boundaries of crystal oscillator performance. Recent developments include:Ultra-low jitter differential output oscillators achieving 65 fs phase jitterHigh-frequency fundamental (HFF) AT-cut crystals using advanced QMEMS processesImproved reliability compared to traditional 3rd overtone crystalsSupport for multiple differential output formats (HCSL, LVDS) in compact packagesEnhanced temperature stability for 5G and high-speed networking applicationsThe SG7050EBN series represents the latest advancement in differential-output crystal oscillators, operating from 100 MHz to 175 MHz with exceptional 65 fs phase jitter performance. This makes it suitable for 10-, 40-, and 100-Gigabit Ethernet applications in datacenters and telecommunications infrastructure.Frequently Asked Questions (FAQ)1. What is a crystal oscillator used for?A crystal oscillator is an electronic circuit that uses the mechanical resonance of a vibrating piezoelectric crystal to create an electrical signal with a precise frequency. It's used for timing references, clock generation, frequency synthesis, and signal processing applications.2. What are the advantages of crystal oscillators?Crystal oscillators offer very high frequency stability, precise and stable frequency generation, high Q-factor, low frequency drift with temperature and parameter changes, and excellent long-term stability compared to other oscillator types.3. What is the difference between a crystal and an oscillator?A crystal is the piezoelectric resonator element itself, while an oscillator is the complete circuit including the crystal, amplifier, and supporting components. The crystal provides the frequency reference, while the oscillator circuit sustains oscillation.4. How does a crystal oscillator work?The crystal oscillator circuit sustains oscillation by taking a voltage signal from the quartz resonator, amplifying it, and feeding it back to the resonator. The rate of expansion and contraction of the quartz determines the resonant frequency, based on the crystal's cut and size.5. What is the principle of oscillation?Electronic oscillators operate on the principle of positive feedback: a sensitive amplifier's output is fed back to the input in phase, causing the signal to regenerate and sustain itself through continuous positive feedback.6. What is the main feature of crystal oscillators?The most important feature is frequency stability - the ability to provide a constant frequency output under varying load conditions, temperature changes, and aging effects over long periods.7. Why is quartz crystal commonly used?Quartz is preferred due to its availability, mechanical strength, chemical stability, low cost, excellent piezoelectric properties, and predictable temperature characteristics. It also has a high Q-factor and good aging characteristics.8. Why are crystal oscillators more stable?Crystal oscillators are more stable because the mechanical resonance of quartz is highly stable and only minimally influenced by external factors like temperature, voltage, or component variations, unlike LC or RC oscillators.9. How do you test a crystal oscillator?Test methods include resistance measurement (should be infinite), capacitance measurement (compare to specifications), oscillation testing (build test circuit), and frequency accuracy verification using a frequency counter.10. Why are crystals used in microcontrollers?Crystal oscillators provide the precise clock signals required for microcontroller synchronization, ensuring accurate timing for instruction execution, peripheral operations, and communication protocols.11. Do crystal oscillators have polarity?Passive crystals (2-pin) have no polarity and can be connected in either direction. Active crystal oscillators (4-pin) have specific pin assignments for power, ground, and output that must be observed.12. Do crystal oscillators fail?Yes, crystal oscillators can fail due to mechanical shock, overheating beyond the Curie temperature, contamination, aging, or electrical overstress. However, they are generally very reliable components when properly used.13. Can crystals oscillate at multiple frequencies?Yes, crystals can oscillate at overtones (odd multiples of the fundamental frequency), but these are typically weaker than the fundamental. Circuits can be designed to operate crystals at their 3rd or 5th overtones.14. Why are oscillators used in electronic systems?Oscillators convert DC power to AC signals, providing timing references, clock signals, carrier frequencies for communication, and synchronization signals essential for digital and analog electronic systems.15. Why were crystal oscillators important for radio transmitters?Crystal oscillators provided the frequency stability needed for radio transmitters to maintain their assigned frequencies, preventing interference with other stations and ensuring reliable communication. They became standard in AM radio by 1926.Reference ComponentsLatest High-Performance Crystal Oscillators:SG7050EBN 125.000000M-DJGA3 - Ultra-low jitter differential oscillatorSG7050EBN 125.000000M-CJGA3 - High-frequency networking applicationsSG7050EBN 100.000000M-CJGA3 - 100 MHz precision referenceDisclaimer: This article has been updated for 2025 to reflect current technology trends and specifications. 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Bird’s new Wideband Power Sensor series of USB Thruline power meters feature five models each suited to a particular application. All capable of measuring True Average Power, Peak Power and Duty Cycle, as well as VSWR/Return Loss, Average Burst Power and CCDF, the WPS series will work with any modulation scheme.The vast majority of RF power meters on the market today, in the milliwatt range, are all focussed on measuring power levels of typically -10dBm +/- 30dB. However, Bird Technologies are one of the few manufacturers to offer RF enquirers equipment capable of measuring “real world” transmitter power levels without the need to use directional couplers or high power attenuators.These new USB Power Meters for “real world” RF power measurements cover; 350MHz to 4GHz (150mW to 150W); 350MHz to 4GHz (25mW to 25W); 25MHz to 1GHz (500mW to 500W); 150MHz to 4GHz (100mW to 25W) and 25MHz to 1GHz (100mW to 100W).Insertion loss is less than 0.1dB (typically 0.05dB) with a VSWR of 1.1:1max (typically 1.05:1), plus a directivity specification of typically 30dB. These parameters contribute to an average power accuracy for all models of ±4% of reading, or 0.17dB, over the full power range at +15 to +350C.All Bird Wideband Power Sensors come with ‘Virtual Power Meter’ software to allow connection to a PC. In addition the WPS will interface with the Bird 5000-XT Digital Power meter, or the majority of the Bird SA / SH series of Site Analysers or SignaHawks.Also announced is the new 7020 Power Sensor, a low cost USB Power Meter similar in operation to the 501XB range. The 7020 contains the same ‘True Average Power’ measurement capabilities within the frequency range of 350MHz to 4GHz (0.15W to 150W), and has an identical accuracy of reading at ±4% +0.05W, or 0.17dB. The 7020 Power Sensor is an ideal low cost, but accurate, USB power meter for many applications.Reference:1005919-1PCUC30M72AV  

The latest buzz in the information technology industry regards "the Internet of things"—the idea that vehicles, appliances, civil-engineering structures, manufacturing equipment, and even livestock would have their own embedded sensors that report information directly to networked servers, aiding with maintenance and the coordination of tasks.Realizing that vision, however, will require extremely low-power sensors that can run for months without battery changes—or, even better, that can extract energy from the environment to recharge.Last week, at the Symposia on VLSI Technology and Circuits, MIT researchers presented a new power converter chip that can harvest more than 80 percent of the energy trickling into it, even at the extremely low power levels characteristic of tiny solar cells. Previous experimental ultralow-power converters had efficiencies of only 40 or 50 percent.Moreover, the researchers' chip achieves those efficiency improvements while assuming additional responsibilities. Where its predecessors could use a solar cell to either charge a battery or directly power a device, this new chip can do both, and it can power the device directly from the battery.All of those operations also share a single inductor—the chip's main electrical component—which saves on circuit board space but increases the circuit complexity even further. Nonetheless, the chip's power consumption remains low."We still want to have battery-charging capability, and we still want to provide a regulated output voltage," says Dina Reda El-Damak, an MIT graduate student in electrical engineering and computer science and first author on the new paper. "We need to regulate the input to extract the maximum power, and we really want to do all these tasks with inductor sharing and see which operational mode is the best. And we want to do it without compromising the performance, at very limited input power levels—10 nanowatts to 1 microwatt—for the Internet of things."The prototype chip was manufactured through the Taiwan Semiconductor Manufacturing Company's University Shuttle Program.Ups and downsThe circuit's chief function is to regulate the voltages between the solar cell, the battery, and the device the cell is powering. If the battery operates for too long at a voltage that's either too high or too low, for instance, its chemical reactants break down, and it loses the ability to hold a charge.To control the current flow across their chip, El-Damak and her advisor, Anantha Chandrakasan, the Joseph F. and Nancy P. Keithley Professor in Electrical Engineering, use an inductor, which is a wire wound into a coil. When a current passes through an inductor, it generates a magnetic field, which in turn resists any change in the current.Throwing switches in the inductor's path causes it to alternately charge and discharge, so that the current flowing through it continuously ramps up and then drops back down to zero. Keeping a lid on the current improves the circuit's efficiency, since the rate at which it dissipates energy as heat is proportional to the square of the current.Once the current drops to zero, however, the switches in the inductor's path need to be thrown immediately; otherwise, current could begin to flow through the circuit in the wrong direction, which would drastically diminish its efficiency. The complication is that the rate at which the current rises and falls depends on the voltage generated by the solar cell, which is highly variable. So the timing of the switch throws has to vary, too.Electric hourglassTo control the switches' timing, El-Damak and Chandrakasan use an electrical component called a capacitor, which can store electrical charge. The higher the current, the more rapidly the capacitor fills. When it's full, the circuit stops charging the inductor.The rate at which the current drops off, however, depends on the output voltage, whose regulation is the very purpose of the chip. Since that voltage is fixed, the variation in timing has to come from variation in capacitance. El-Damak and Chandrakasan thus equip their chip with a bank of capacitors of different sizes. As the current drops, it charges a subset of those capacitors, whose selection is determined by the solar cell's voltage. Once again, when the capacitor fills, the switches in the inductor's path are flipped."In this technology space, there's usually a trend to lower efficiency as the power gets lower, because there's a fixed amount of energy that's consumed by doing the work," says Brett Miwa, who leads a power conversion development project as a fellow at the chip manufacturer Maxim Integrated. "If you're only coming in with a small amount, it's hard to get most of it out, because you lose more as a percentage. [El-Damak's] design is unusually efficient for how low a power level she's at.""One of the things that's most notable about it is that it's really a fairly complete system," he adds. "It's really kind of a full system-on-chip for power management. And that makes it a little more complicated, a little bit larger, and a little bit more comprehensive than some of the other designs that might be reported in the literature. So for her to still achieve these high-performance specs in a much more sophisticated system is also noteworthy."Related products:XC7Z100-2FFG900IXC7Z010-1CLG400IA2F200M3F-1FGG256 

A bump circuit with flexible tuning ability that uses 500 times less power and is smaller than previous circuits has been demonstrated by researchers at the University of Tennessee in the US."The challenges and requirements of the analogue deep-learning system inspired us to come up with this radically new design," said Junjie Lu, the lead author. "We implemented the bump circuit by preceding the current correlator with a novel nano-power tunable transconductor to achieve variable width and height. By significantly reducing the power consumption of the bump circuit, this work makes possible the realisation of analogue learning and signal processing systems that achieve better energy efficiency than their digital equivalents, and ultimately fully autonomous systems, which are able to get both information and energy from the environment without external intervention."Towards flexible transferThe bump circuit is a family of circuits with bell-shaped, non-linear transfer functions. First appearing in 1991, they are widely used to provide similarity or distance measures in analogue signal processing systems such as support vector machines, neural networks and analogue machine-learning systems.The original bump circuit design lacked the ability to change the width of its transfer function, which is desirable in many applications to represent distributions with different variance or templates with different model parameters. A common approach to solve this is to pre-scale the input voltage, but the circuits required are physically large and consume a lot of power. Other approaches also have limitations such as complex circuitry, large physical size, and a restricted number of possible widths achievable.Hidden depthsThe researchers from the University of Tennessee designed their circuit as an important building block in an analogue deep-learning machine, which is able to perform unsupervised learning and extract salient features from high-dimensional input data, with a much better power efficiency than the existing digital machine learning implementations.Large-scale systems require the computational element, or bump circuit in this case, to be very efficient in both power and area. It is also important that the output features, which are the confidence scores that the current input belongs to each of the previous observations, take both the mean distances and probabilistic variances into account. A bump circuit that has a tunable centre for mean tuning, width for variance tuning, and height for normalisation is therefore highly desirable, and if these three bump parameters can be individually tuned and controlled by a single signal, this would greatly help with on-chip trainability.To achieve the variable height and width, the researchers designed and incorporated a novel transconductor, linearised using the drain resistances of saturated transistors. They adopted a pseudo-differential structure to allow operation with a low supply voltage, and designed a common mode feedback circuit to provide common mode rejection for the pseudo-differential structure to get a tunable bump height.The whole circuit uses 18.9 nW power from 3 V supply which is 1/500 th of the power of the next best bump circuit with tunable width. Implemented in 0.13 µm CMOS, it is smaller in area by 6%, and has maximum flexibility through the individual tunability of the three key bump function parameters. Another feature is that multiple bump circuits can be easily cascaded to represent multivariate probability.A vision of the futureWith power scaling in CMOS tapering off, there has been renewed interest in analogue computation recently, and the researchers expect to see some very exciting results in this area. They are currently working to integrate low-power circuits, such as their bump circuit, into larger systems for real-world applications."One application area we've been working on is machine vision," said Lu. "We've been working with image processing and machine vision researchers to build a complete pipeline using analogue circuits. This circuit helps to provide a path to implementing multi-dimensional kernel methods for machine learning."Systems using the bump circuit could find application in many areas such as healthcare monitoring, environmental monitoring, process control and battlefield surveillance. In addition, the nano-power tunable linear transconductor developed in this work, which has the advantages of ultra-low power, large input range and gm tunability, could be used in a huge range of applications such as amplifiers, filters and oscillators.Related products:LMV1031UR-20LM4889MALM4867MTE

Parts fail and things break. It's a fact of life and engineering. Some component failures can be avoided by good design practices, but many are out of the hands of designers. Identifying the offending component and why is might have failed is the first step to refining the design and increasing the reliability of a system that has been experiencing component failures.How Components FailThere are numerous reasons for why components fail.Some failures are slow and graceful where there is time to identify the component and replace it before it fails completely and the equipment is down. Other failures are rapid, violent, and unexpected, all of which are tested for during product certification testing. Some of the most common reasons for components to fail include:Over currentOver voltageOver temperatureConnected incorrectlyChange in operating environmentManufacturing defectMechanical shockMechanical stressRadiationContaminationPackagingConnectionsAgingCascading failureCorrosionRustingOxidizingThermal runawayLoose connectionsElectroStatic Discharge (ESD)Electrical stressBad circuit design Component failures do follow a trend. In the early life of an electronic system, component failures are more common and the chance of failure drops as they are used. The reason for the drop in failure rates is that the components that have packaging, soldering, and manufacturing defects often fail within minutes or hours of first using the device. This is why many manufacturers include a several hour burn in period for their products.This simple test eliminates the chance a bad component can slip through the manufacturing process and result in a broken device within hours of the end user first using it.After the initial burn in period, component failures typically bottom out and happen randomly. As components are used or even just sit, they age.Chemical reactions reduce the quality of the packaging, wires, and the component, and mechanical and thermal cycling take their toll on the mechanical strength of the component. These factors cause failure rates to continuously increase as a product ages. This is why failures are often classified by either their root cause or by when the failed in the life of the component.Identifying a Failed ComponentWhen a component fails there are a few indicators that can help identify the component that failed and aid in troubleshooting electronics. These indicators are:Visible-The most obvious indicator that a specific component has failed is through a visual inspection. Failed components often have burnt or melted areas, or have bulged out and expanded. Capacitors are often found bulged out, especially electrolytic capacitors around their metal tops. IC packages often have a small hole burned in them where the hot stop on the component vaporized the plastic around the hot spot all the way through the IC package.Smell- When components fail, a thermal overload often occurs which causes the magic blue smoke and other colorful smoke to be released by the offending component. The smoke also has a very distinct smell and varies by type of component. This is often the first sign of a component failure beyond the device not working. Often the distinct smell of a failed component will stay around the component for days or weeks which can aid in identifying the offending component during troubleshooting.Sound- Sometimes components make a sound when they fail. This happens more often with rapid thermal failures, over voltages, and over current events. When a component fails this violently, a smell often accompanies the failure. Hearing a component fail is rarer, and it often means that pieces of the component will be found loose in the product so identifying the component that failed may come down to finding which component is no longer on the PCB or in the system.Testing- Sometimes the only way to identify a component that has failed is to test individual components. This can be very challenging on a PCB since often other components will influence the measurement since all measurements involve applying a small voltage or current, the circuit will respond to it and readings can be thrown off. If a system uses several subassemblies, often replacing subassemblies is a great way to narrow down on where the issue with the system is located. 

Inside a secretive AI nonprofit backed by Elon Musk and other Silicon Valley figures, a handful of robots designed to help out in warehouses are gradually learning how to do useful household chores.OpenAI, which was created to do basic AI research, is reprogramming robots developed by Fetch Robotics, a company that supplies warehouse automation hardware. Researchers at OpenAI are equipping the robots with software that lets them train themselves through trial and error.The effort reflects a bet that innovations in software and machine learning, rather than breakthroughs in hardware, are the way to give robotics remarkable new capabilities. Fetch makes a range of robots for warehouses, including systems that follow workers around a building, carrying items dropped into a basket. OpenAI is using a system that features a mobile base but also 3-D depth sensors, a 2-D laser scanner, and a robotic arm with seven degrees of freedom.In April, OpenAI recruited Pieter Abbeel, a professor at the University of California, Berkeley, and a leading expert on robot learning. Abbeel has shown how robots can use a machine-learning approach called deep reinforcement learning to acquire completely new skills that would be hard to program by hand, such as folding towels or retrieving items from a refrigerator. Google DeepMind, an AI subsidiary based in the U.K., uses this technique to get computers to play computer games at a superhuman level (see “Google’s AI Masters Space Invaders”).Abbeel’s robots learn tasks from scratch, using a neural network that receives sensor input and controls physical movement. The network adjusts its parameters automatically as it inches closer to its goal. A robot might try thousands of grips, for instance, in the process of learning how to hold a certain object.“If this goal can be achieved, then there will be economic and industrial benefits,” says Marc Deisenroth, an expert on reinforcement learning at Imperial College London. “Imagine a Roomba not only cleaning your floor but also doing the dishes, ironing the shirts, cleaning the windows, preparing breakfast.”Deisenroth says using off-the-shelf robots could drive costs down. “Currently, the software seems to be the bottleneck,” he adds. “However, independent of this, better hardware could also lead to substantial improvements.” Soft manipulators and elastic feet similar to a monkey’s feet are concepts that researchers have started working on, he says.Some manufacturers, including the Japanese company Fanuc, are testing reinforcement learning as a way to train industrial robots quickly in new tasks such as learning to grasp unfamiliar objects. When many robots work in parallel, the training time required is reduced accordingly. Robot researchers at Google are testing similar learning techniques.“Moving away from having to program robots by hand by endowing robots to learn autonomously is a key element for the future of robotics,” says Jens Kober, an expert on robot learning at Delft University of Technology in the Netherlands. Kober says having robots share the information they have learned will be crucial.While robots such as those made by Fetch are finding their way into many factories and warehouses, domestic robot helpers remain the stuff of science fiction. Performing seemingly simple tasks like washing dishes or folding laundry in a messy home setting is incredibly hard for a machine. A robot programmed the conventional way can easily be thrown off by an unfamiliar object or a slight variation in lighting.OpenAI confirmed that it is working with the robots from Fetch, but it declined to comment further. Melonee Wise, the company’s founder, couldn’t be reached for comment (see “Innovators Under 35: Melonee Wise”).OpenAI was created by Musk and a handful of well-known (and well-heeled) Silicon Valley entrepreneurs, including investor Peter Thiel, Y Combinator president Sam Altman, and the incubator’s cofounder Jessica Livingston. The nonprofit’s backers have committed $1 billion in funding to the project, and it is being led by Ilya Sutskever, a prominent AI researcher who left Google to join the project, and Greg Brockman, an early employee at the high-profile digital payment company Stripe.While OpenAI has committed to making the technology it develops publicly available, it could certainly benefit companies backed by Musk and Thiel, as well as those emerging from Y Combinator.