GaN FET Device Testing, SiC IGBT Testing, Optical Isolated Probe for HV Testing

Double Pulse Testing Double Pulse Testing
60V GaN Designs 60V GaN Designs
650V GaN Designs 650V GaN Designs
1000V+ SiC Designs 1000V+ SiC Designs
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HV optical probe testing GaN FET and measuring gate-drive signal and high voltage output

Most Confidence for GaN MOSFET and SiC IGBT Test

Teledyne LeCroy provides the most confidence for testing every power device — from low-voltage (60 V) GaN power MOSFETs to any type of GaN transistor used in 500 V applications (FETs or HEMTs) to SiC IGBTs commonly used at voltages of 1000 V (or more).

  • Optical isolated probes for safe and accurate HV testing
  • High CMRR, 60 V common-mode, 80 V dynamic range probes
  • High precision measurements with 12-bit resolution, 8 channel oscilloscopes
  • Simplified double-pulse testing and 3-phase power analysis software

Most Confidence for Wide-bandgap Device Design and Test

Teledyne LeCroy has the solutions you need for testing GaN MOSFETs and SiC IGBTs in a double-pulse test circuit, measuring switching performance in an inverter subsection, or testing complete system operation.

Gallium-nitride GaN MOSFET electrical schematic symbol

Double Pulse Test for GaN and SiC

Perform double-pulse testing on your GaN MOSFET and SiC IGBT power semiconductors
  • HV optical isolated probes with exceptional CMRR and high precision
  • 60 V common-mode probes with high accuracy and signal fidelity, lowest noise, and high CMRR
  • 12-bit resolution oscilloscopes provide precise measurements and low noise at fast GaN and SiC rise times
Explore More about Optical Probes
Explore More about 60 V common-mode probe
Explore More about 12-bit high-definition oscilloscopes
: Gallium-nitride GaN MOSFET inverter subsection simple schematic

Inverter Subsection Validation

Capture, measure and validate inverter subsection GaN and SiC switching performance and timing
  • Correlate GaN and SiC gate-drive signals to device output switching
  • Widest range of HV probes, from cost-effective to premium performance, all with class-leading CMRR.
  • Simplified measurements and plots of dead-time vs. time over thousands of switching cycles.
Watch Webinar How to Measure Inverter Dead Times and Input/Output Power
Schematic for silicon-carbide SiC IGBT power conversion system with three-phase output filtering transformer

Power Conversion System Testing

Complete GaN and SiC-based system performance testing, from input to output.
  • Capture the full range of signals and correlate control activities to power conversion system behaviors.
  • Wide range of HV probes for AC input, HV output, gate-drive and device output switching signals.
  • Dedicated power analysis application software
Explore More about probes
Explore More about application software

Double Pulse Test Procedure for MOSFETs and IGBTs

The double pulse test procedure is used for evaluating the in-circuit dynamic behavior of power semiconductors. Double pulse testing uses gate-drive signals to stress the DUT and measure energy loss during device turn-on/turn-off, as well as measuring reverse recovery of the diode.

Double pulse test procedure electrical circuit with MOSFET power semiconductors
Double pulse test procedure electrical circuit for low-side test of MOSFET power semiconductor
Double pulse test procedure electrical circuit for high-side test of MOSFET power semiconductor
Double Pulse Test showing GaN MOSFET output voltage (Vds), drain current (Id) and gate-drive voltage (Vgs)
Double pulse test setup with optical isolated probe, HV differential probe, current probe, AFG, power supplies and oscilloscope testing a GaN MOSFET

Test Circuit

LO Device Test

HI Device Test

Test Challenges

Equipment Needed

Two identical power semiconductor devices are connected in a half-bridge configuration. There are three testing modes for the lower (LO) device and same three testing modes for the upper (HI) device. Measuring the HI device requires an appropriately-rated HV isolated probe, with the HV isolation equivalent to the DC Bus voltage.

  • Test Mode 1: The tested device is in the ON state and conducting current, the other device is OFF.
  • Test Mode 2: The tested device is in the OFF state and blocking current, the other device remains OFF.
  • Test Mode 3: The tested device is again in the ON state and conducting current, the other device remains OFF.
Watch Webinar How to Perform Double Pulse Testing on GaN and SiC Devices

The inductor is set to switch position 1 and the circuit is operated in three consecutive modes. First, the LO device is driven ON by a simulated gate-drive pulse and the HI device operates in a free-wheeling mode (left image). Then, the LO device is driven OFF (middle image) and current continues to flow in the inductor (but does not increase). Finally, the LO device is driven ON again and reverse-recovery diode current briefly flows through the HI diode shortly after the transition to ON condition, adding to the LO device conduction current during this time (right image). During operation in all three modes, the LO device gate-drive pulse and LO device output voltage and conduction current is measured.

    The inductor is changed to switch position 2 and the circuit is operated in three consecutive modes. First, the HI device is driven ON by a simulated gate-drive pulse and the HI device operates in a free-wheeling mode (left image). Then, the HI device is driven OFF (middle image) and current continues to flow in the inductor (but does not increase). Finally, the HI device is driven ON again and reverse-recovery diode current briefly flows through the LO diode shortly after the transition to ON condition, adding to the HI device conduction current during this time (right image). During operation in all three modes, the HI device gate-drive pulse and HI device output voltage and conduction current is measured.

      Engineers designing and using power semiconductor devices want to minimize losses during switching and conduction operations to maximize efficiency. Engineers must:

      • 1. Accurately measure gate-drive (Vgs) signal rise time and signal fidelity/shape on both LO and HI devices (Vds)
      • 2. Precisely measure device output voltage during switching, conduction, and off (blocking)
      • 3. Precisely measure drain current and calculate efficiency during various operating modes
      • 4. Accurately characterize the diode's reverse-recovery current to calculate energy and efficiency losses (for MOSFETs)

      Teledyne LeCroy is uniquely able to offer the highest precision oscilloscopes and probes (and complimentary hardware and software) for the most accurate and precise device characterization.

      • 12-bit high definition oscilloscopes (HDO®) with 0.5% gain accuracy and lowest noise at full bandwidth
      • Optical and electrical isolated voltage probes with superior CMRR, high accuracy and precision calibrations
      • Probes custom-tailored to the needs for 60 V GaN, 500 V GaN, and 1000+ V SiC testing
      • Measurement software, power supplies, and arbitrary function generators that create varying-width gate-drive signals
      Explore More recommended Teledyne LeCroy equipment list for Double Pulse Testing

      60 V GaN MOSFET Design Testing

      Typical differential probes operate with differential and common-mode ratings of ~24 V maximum (sometimes up to 42 V). High voltage differential probes don't have enough bandwidth, may not have enough accuracy at lower voltages, and may have too much tip capacitance. Optical isolated HV probes are costly and have unnecessary isolation performance. Optimized probes are needed – Teledyne LeCroy has them.

      60 V GaN Design Test Challenges and Needs

      60 V GaN designs must have high efficiency to maximize battery life. To maximize efficiency, 60 V GaN MOSFETs use rise times as fast as 1 ns. Lower-cost, high performance probes are needed to measure all signals — gate-drives, device outputs, DC voltages and system outputs.

      • High bandwidth (1 GHz) for measuring 1 ns rise times
      • Flexibility to use one optimized probe for every in-circuit measurement (gate drive, DC link, device output, system output)
      • Faithful signal capture with great rejection of interference and low added overshoot
      • Low-noise, high-channel count signal acquisitions

      Watch Webinar Best Practices for 48 V Power Conversion Testing
      Cascaded H-bridge GaN system powered by 60V battery

      Use One Optimized Probe For Every In-Circuit 60 V GaN Measurement

      Optical probes are too expensive and/or have too much performance for the lower dV/dT and common-modes present in 60 V designs. High voltage differential probes are not performance optimized for this application. Only one differential probe – the Teledyne LeCroy DL-HCM Series – is optimized for 60 V GaN probing.

      • 60 V common-mode voltage rating, 80 V differential voltage rating
      • Measure 1 ns rise times with up to 1 GHz system bandwidth (using a 1 GHz oscilloscope)
      • Easily accessibility with small size and a wide variety of tips and leads

      Explore More
      60v-common-mode-differential-probes

      Faithful Reproduction of Gate-drive and Device Output Signals

      DL-HCM series probes have the high performance required to faithfully measure your high-speed gate-drive and device output signals.

      • Low additive noise due to low, switchable attenuation
      • Most faithful signal reproduction with 0.5% gain accuracy, 0.1 dB LF flatness, 80 dB CMRR and low additive overshoot
      • Gate-drive measurements with 8.9 Vmax or 20 Vmax dynamic range, and low input loading (200 kΩ // 0.6 pF)
      • Device Output measurements with 80 Vmax dynamic range

      Watch Webinar Best Practices for 48 V Power Conversion Testing
      Comparison of high common mode differential probe to a HV differential probe for a 60 V common-mode GaN MOSFET high-side gate-drive measurement

      Dual-purpose to Also Measure DC Link and System Output Signals

      Measure every in-circuit signal, regardless of where it is in your circuit, with switchable attenuation for higher voltages.

      • DC Link ripple measurements using minimum 1.6 Vp-p measurement range with only 3.25 mVRMS additive noise
      • System Output measurements (line-ref or line-line) with 80 Vp-p differential capability
      • 60 V common-mode rating
      48V power conversion system with DC bus and other signals acquired

      Lower-cost High Voltage Differential Probes (HVD Series) For Lower Bandwidth Measurements

      System output measurement often don’t require high bandwidth, but still require high accuracy, low noise, and good noise immunity (high probe CMRR). If probe pricing is a challenge, HVD Series probes can balance price and performance for some GaN system measurements.

      • Device Output measurements with 400 MHz bandwidth model
      • System Output measurements with 120 MHz to 400 MHz models
      • Great price vs. performance — low noise and 65 dB CMRR at 1 MHz (30 dB or better than competitive probes)
      • 1% gain accuracy (two times better than competitive probes)
      • Common-mode rated to 1 kV, 2 kV or 6 kV

      Explore More
      Watch Video High Voltage Differential Probes – Superior Performance
      HVD series high voltage differential probe product line image

      Capture Every Detail with High Oscilloscope Resolution at Full Bandwidths

      Teledyne LeCroy High Definition Oscilloscopes (HDO®) provide 12 bits of resolution all the time at full oscilloscope bandwidth ratings. Once you use a Teledyne LeCroy HDO, you’ll never want to go back to using another oscilloscope.

      • No tradeoff of resolution, sample rate or bandwidth
      • Clean, crisp waveforms
      • More signal details
      • Unmatched measurement precision


        Explore More about HDOs
        Download White Paper
        Watch Webinar Comparing High Resolution Oscilloscope Design Approaches
        48V power conversion signal acquisition with Teledyne LeCroy High Definition Oscilloscope (HDO) product line from 200 MHz to 8 GHz in the foreground

        More Capability for Inverter Subsection and System Test

        Teledyne LeCroy oscilloscopes and software application packages provide faster and more complete debug of half-bridge, full-bridge and cascaded H-bridge inverter subsections and systems.


          Explore More in this webinar series about 3-phase power and motor drive inverter subsection, control and power system testing
          VFD output, DC Battery, and mechanical signals of battery-powered drill with power calculations table

          650 V GaN MOSFET Design Testing

          Fast rise times combined with high switching voltages make it difficult to make interference-free measurements. Confidence is needed in the signal acquisition to ensure that measured signals accurately portray the signals in the circuit.

          650 V GaN Design Test Challenges and Needs

          The high dV/dt and voltage ratings of 650 V GaN MOSFETs implemented in 500 Vdc designs require specialized optical probes, high-quality high voltage differential probes, and high-resolution, low-noise oscilloscopes.

          • Probes with the best CMRR ratings and isolation to be most immune to high dV/dt in-circuit interference
          • Optimized 1000 V range to capture 500 V output switching plus unexpected overshoots and transients
          • Faithful and interference-free reproduction of signal shape with low additive noise and overshoot
          • Ability to capture many signals simultaneously and assess timing, power and other performance
          Half-bridge AC-DC power supply using GaN FETs

          GaN FET Output Measurements with Optical Probes (HV)

          Optical isolation provides the best noise immunity at the fastest dV/dt while also providing safe operation, high signal fidelity and the easiest connections to in-circuit signals in compact GaN designs.

          • High dV/dt capability for device output measurements (1840 V/ns using 1 GHz bandwidth / 435 ps rise time DL10-ISO optical probe with 1000 V tip)
          • Exceptional noise immunity with 160 dB CMRR rating
          • Best gain accuracy (1.5%) using a precision gain calibration, low drift
          • Most faithful signal reproduction, low additive overshoot
          • Very flexible tips make it easy to connect to signals in compact GaN designs

          Watch Video Overview of DL-ISO Optical Probe
          Watch Video Comparison of DL-ISO to Tektronix IsoVu
          HV optical probe for GaN MOSFET HV output measurements

          GaN Gate-drive Signal Measurements with Optical Probes (HV)

          Optical isolation provides the best noise immunity at the fastest dV/dt while also providing safe operation, high signal fidelity and the easiest connections to in-circuit signals in compact GaN designs.

          • Very low signal loading with high impedance, low capacitance tip (1 MΩ // 2.1 pF typical)
          • 435 ps rise time (1 GHz bandwidth DL10-ISO optical probe connected to 1 GHz oscilloscope)
          • MMCX connectivity and very flexible tips make it easy to make it easy to connect to GaN gate-drive signals in compact GaN designs
          • Exceptional noise immunity (160 dB CMRR) and gain accuracy (1.5%) with low overshoot

          Watch Video Overview of DL-ISO Optical Probe
          Watch Video Comparison of DL-ISO to Tektronix IsoVu
          GaN gate-drive signal measurement using optical probe HV

          DC Link and System Output Measurements with HV Differential Probes

          HVD3000A series differential probes provide high CMRR over a broad frequency range to simplify the measurement challenges found in noisy, high common-mode power electronics environments. The probe’s design is easy-to-use and enables safe, precise high voltage floating measurements.

          • 1 kV or 2 kV rated models from 120 MHz to 400 MHz bandwidth
          • 65 dB CMRR at 1 MHz – 50x better than competitive probes
          • 1% gain accuracy with lowest additive noise and overshoot
          • High offset capability and AC coupling for DC Link ripple measurements

          Explore More
          Watch Video High Voltage Differential Probes – Superior Performance
          HV differential probe for GaN measurements

          Capture Every Detail with High Oscilloscope Resolution at Full Bandwidths

          Teledyne LeCroy High Definition Oscilloscopes (HDO®) provide 12 bits of resolution all the time at full oscilloscope bandwidth ratings. Once you use a Teledyne LeCroy HDO, you'll never want to go back to using another oscilloscope.

          • No tradeoff of resolution, sample rate or bandwidth
          • Clean, crisp waveforms
          • More signal details
          • Unmatched measurement precision

          Explore More about HDOs
          Download White Paper
          Watch Webinar Comparing High Resolution Oscilloscope Design Approaches
          500V power conversion signal acquisitions (Vds, Vgs, Id) with Teledyne LeCroy High Definition Oscilloscope (HDO) product line from 200 MHz to 8 GHz in the foreground

          More Capability for Inverter Subsection and System Test

          Teledyne LeCroy oscilloscopes and software application packages provide faster and more complete debug of half-bridge, full-bridge and cascaded H-bridge inverter subsections and systems.

          • 8 channel oscilloscopes (16 channels using OscilloSYNC™) provide capability to view all switching events at one time
          • Powerful, deep toolbox with many automated timing and other measurements
          • Application specific power packages make it easy to correlate control events to power events, or even to a single device switching cycle

          Explore More in this webinar series about inverter subsection, control and power system testing
          Inverter subsection test using 8 channel oscilloscope and high voltage differential probes

          1000 V (and higher) SiC IGBT Design Testing

          SiC IGBT devices are commonly used at higher switching voltages and currents and share many characteristics with well-known silicon devices. SiC devices are increasingly deployed in 800 V traction inverters and next-generation utility transmission and distribution system power conversion designs.

          SiC IGBT Design Test Challenges and Needs

          SiC IGBTs with ratings of 1200 V, 1700 V and 3300 V are employed in cascaded H-bridge and multi-level cascaded H-bridge designs to achieve very high operating voltages at high power levels. High-performance, robust probes are needed to measure the wide range of signals found in these designs.

          • 1500 Vdc systems that need high performance measurements and 1500 V safety-rated probes.
          • Probes that can measure everything from low-voltage gate-drive signals to very high voltage (5 kV class, or higher) system outputs
          • High performance signal acquisitions with interference-free reproduction of signal shape, low additive noise and overshoot
          • Ability to capture many signals simultaneously and assess timing, power and other performance
          3-phase cascaded H-bridge using SiC IGBTs with output transformer filtering

          Optical Probes (HV) for SiC Gate-drive and Device Output Signals

          Optical isolation provides the best noise immunity at the fastest dV/dt while also providing safe operation, high signal fidelity and square header connections to in-circuit signals in SiC designs

          • 350 MHz bandwidth (1.1 ns rise time) with 160 dB CMRR rating for best noise immunity
          • Highest accuracy (1.5%) with precision gain calibration and low drift
          • Interchangeable tips to permit measurement of both gate-drive and device output signals
          • Square header connection to SiC signals and very flexible tips make it easy to connect to signals in SiC designs

          Watch Webinar How to Test GaN and SiC Designs and IGBT Devices
          Watch Video Overview of DL-ISO Optical Probe
          Watch Video Comparison of DL-ISO to Tektronix IsoVu
          HV optical probe with tip for 1000V measurements

          Highest Performance 6 kV Common-mode HV Differential Probe for 5 kV Class Apparatus (HVD3605A)

          The Teledyne LeCroy HVD3605A high voltage differential probe is the only HV differential probe worth considering for >1500 V SiC measurements and combines exceptional noise immunity with high performance.

          • 6000 VRMS common-mode safety rating
          • Uniquely noise immune with 50 dB CMRR at 1 MHz in highest voltage range – no comparable probe comes close.
          • Only probe that permits AC line, DC link, and system output voltage probing up to 4160V apparatus ratings
          • Industry's best offset capability (6000 V)
          • 1% gain accuracy

          Explore More
          Watch Video High Voltage Differential Probes – Superior Performance
          HV differential probe with 6 kV common-mode rating

          1500 V Common-mode Safety-rated HV Differential Probe per IEC/EN 61010-031:2015

          Utility grid-tied solar photovoltaic (PV) inverters, uninterruptible power supplies (UPS) and welding systems commonly use 1500 Vdc buses to minimize system cost. Teledyne LeCroy’s HVD3206A or HVD3220 are ideal for this application.

          • 1500 VDC (CAT III) and 2000 V (DC+peak AC) (CAT I) safety rating – unique in the industry
          • Low-attenuation (500x) with 2000 V differential voltage rating
          • 120 MHz or 400 MHz bandwidth ratings
          • 65 dB CMRR at 1 MHz (50x better than competitive 1 kV-rated probes)
          • 1% gain accuracy

          Explore More about 120 MHz model
          Explore More about 400 MHz model
          Watch Video High Voltage Differential Probes – Superior Performance
          HV differential probe with 2 kV common-mode rating

          Capture Every Detail with High Resolution at Full Bandwidths

          Teledyne LeCroy High Definition Oscilloscopes (HDO®) provide 12 bits of resolution all the time at full oscilloscope bandwidth ratings. Once you use a Teledyne LeCroy HDO, you'll never want to go back to using another oscilloscope.

          • No tradeoff of resolution, sample rate or bandwidth
          • Clean, crisp waveforms
          • More signal details
          • Unmatched measurement precision

          Explore More about HDOs
          Download White Paper
          Watch Webinar Comparing High Resolution Oscilloscope Design Approaches
          480 Vac motor drive output under dynamic operating conditions with zooms of voltage and current on right and Teledyne LeCroy High Definition Oscilloscope (HDO) product line from 200 MHz to 8 GHz in the foreground

          More Capability for Inverter Subsection and System Test

          Teledyne LeCroy oscilloscopes and software application packages provide faster and more complete debug of cascaded H-bridge and multi-level cascaded H-bridge inverter subsections and systems.

          • 8 channel oscilloscopes (16 channels using OscilloSYNC) provide capability to view all switching events at one time
          • Powerful, deep toolbox with many automated timing and other measurements
          • Application specific power packages make it easy to correlate control events to power events, or even to a single device switching cycle

          Explore More in this webinar series about inverter subsection, control and power system testing
          mda8000hd 16 channel oscilloscope

          Use our High Voltage Probe Selection Guide

          Explore our power electronics probes landing page and use our HV probe selection guide to determine the best high voltage probe to use based on your voltage rating, application, and semiconductor device material. Additional resources are listed below.
          Read App Note How to Choose the Best High Voltage Oscilloscope Probe in 5 Minutes
          Watch Webinar How to Choose the Correct High Voltage Probe
          Watch Webinar High Voltage Probe Real-world Examples and Comparisons
          Example high voltage probe selection table result

          Resources

          Technical Docs

          Videos

          Webinars

          FAQ
          Name
          Comparing High Resolution Oscilloscope Design Approaches

          This white paper provides an overview of the various high resolution design approaches, with examples of their impact on oscilloscope performance.

          		Download White Paper

          How to Choose the Best High Voltage Oscilloscope Probe in 5 Minutes

          Need to select a high-voltage oscilloscope probe? Confused by all the possible choices? Teledyne LeCroy offers the High-voltage Probe Selection Guide, an online tool to help you make an informed decision. Here's a breakdown of the basic points to consider.

          		Read App Note

          Recommended Equipment List for Double Pulse Testing

          Recommended Teledyne LeCroy test equipment for performing double pulse testing on 60 V GaN, 650 V GaN/SiC and 1000 V (or higher) SiC, complete with URL links.

          		Datasheet
          High Voltage Fiber Optically-isolated (HVFO) Probes – Superior Performance
          Current Probes
          DL-ISO Probe for GaN MOSFETs and SiC IGBTs
          Probe Compare: Teledyne LeCroy DL-ISO vs. Tek IsoVu for GaN/SiC Measurements
          Probe Compare Setup Details: Teledyne LeCroy DL-ISO vs. Tektronix IsoVu

          3-Phase Power and Motors Masters Webinar Series

          Join Teledyne LeCroy for this Learning Lab series on measuring high-power, three-phase and motor inverter and drive systems with an 8-channel high-resolution oscilloscope or motor drive analyzer.

          Register for all
          How to Measure Inverter Subsection Dead-times and Inverter Input/Output Power

          In Part 1 of our 3-phase Power and Motors Masters Webinar Series we describe techniques for measuring dead-times for gate-drive signals and device outputs to ensure that margins are achieved.

          How to Perform Static and Dynamic Power Analysis

          In Part 2 of our 3-phase Power and Motors Masters Webinar Series we describe the differences between static and dynamic power analysis and how to optimize setup and measurement for each.

          How to Correlate Control Events to Power Events

          In Part 3 of our 3-phase Power and Motors Masters Webinar Series we review examples of using calculated per-cycle power waveforms to validate and debug control system operation to power section behaviors.

          How to Measure Power During Volt-second and Other Short Power Periods

          In Part 4 of our 3-phase Power and Motors Masters Webinar Series we review examples of power calculated during power periods equivalent to a device switching time.

          How to Perform AC input and Inverter/Drive Output Harmonic Analysis

          In Part 5 of our 3-phase Power and Motors Masters Webinar Series we demonstrate how to perform total harmonic distortion (THD) and harmonic analysis on variable frequency waveforms on both AC line (50 or 60 Hz) inputs and variable frequency outputs.

          How to Measure Motor Mechanical Speed, Torque and Power Using Digital and Analog Sensors

          In Part 6 of our 3-phase Power and Motors Masters Webinar Series we focus on how to use the Motor Drive Analyzer (MDA) to measure motor mechanical shaft speed, torque and angle using a variety of analog, digital and serial data sensors.

          Probing in Power Electronics – What to Use and Why

          Power electronics designs have inherent measurement challenges. There are many specialized high and low voltage single-ended and differential probes to meet the specific needs of this market. However, proper probe selection and use is critical for operator, equipment and DUT safety and also has a large influence on the accuracy of the measurement.

          Register for all
          How to Choose the Correct High Voltage Probe

          In Part 1 of our Probing in Power Electronics webinar series we explain the different types of High Voltage probes and how to choose the best probe for the specific application.

          High Voltage Probe Real-world Examples and Comparisons

          In Part 2 of our Probing in Power Electronics webinar series we provide real-world application examples and high voltage probe comparisons to highlight the practical impact of each type’s strengths and weaknesses in different application examples.

          Comparing High Resolution Oscilloscope Design Approaches

          There has been an explosion in the market of high definition oscilloscopes at 1 GHz or more bandwidth with claims of 10-bit, 12-bit or even (remarkably!) 16-bit resolution. Oscilloscope manufacturers use a variety of design approaches to increase resolution, some of which impose other performance tradeoffs. Join Teledyne LeCroy for this two-part webinar series to gain a better understanding of various manufacturer’s claims.

          Register for all
          High-Resolution Oscilloscope Design Webinar: Part One

          Oscilloscope manufacturers use a variety of design approaches to increase resolution, some of which impose other performance tradeoffs. Join Ken Johnson for this two-part webinar series to gain a better understanding of various manufacturer’s claims.

          High-Resolution Oscilloscope Design Approaches: Part Two

          Oscilloscope manufacturers use a variety of design approaches to increase resolution, some of which impose other performance tradeoffs. Join Ken Johnson for this two-part webinar series to gain a better understanding of various manufacturer’s claims.

          Best Practices for 48 V Power Conversion Testing

          In this webinar we describe new products and best practices and measurement techniques for validation and debug of 48 V power conversion systems.

          Register
          How to Perform Double Pulse Testing (DPT) on GaN and SiC Devices

          In this webinar attendees will learn how to perform the double pulse test safely, and capture and characterize a GaN or SiC power semiconductor device’s dynamic response.

          Register
          Bench Power Supply Basics

          Choosing and using a Bench PSU: What to consider when purchasing a bench PSU: linear verse switch mode, total power, number of outputs, programmable, etc. Using a bench power supply: Know the tips and tricks for getting the most from your bench power supply: parallel and serial output configurations, 4 wire connections, using multiple power supplies on a single DUT, etc.

          Register
          How to Deskew Your Oscilloscope Probes for Best Accuracy

          In Part 2 of our Oscilloscope Coffee Break Webinar Series we explain deskewing to eliminate timing errors. Propagation delay differences between your probes and/or channels may affect timing measurement accuracy. Methods to minimize these errors will be described.

          Register

          How is a double pulse test performed on a GaN MOSFET or SiC IGBT?

          This link www.teledynelecroy.com/wide-bandgap#double-pulse-test has complete details. In summary, a half-bridge circuit is typically used, and is built with a switchable inductor at the mid-point of the half-bridge. A simulated gate-drive pulse is applied to either the low or high-side device and various measurements are made using appropriate isolated probes and oscilloscopes.

          Why is a high voltage optical probe used for floating measurements?

          A single-ended probe has a ground that effectively connects the oscilloscope ground and the device-under-test (DUT) reference ground. If the DUT reference ground cannot be at oscilloscope (earth) ground, then an isolated probe is needed for any measurement in a power conversion system in which the DUT reference is floating above earth ground. Optical isolation is expensive but provides superior performance, especially at higher floating voltages and higher switching voltages where EMI can interfere more with the performance of conventional (lower CMRR) electrically isolated probes.

          What is the difference between the Teledyne LeCroy DL-ISO and HVFO optical probe HV?

          The Teledyne LeCroy DL-ISO is a newer, higher bandwidth probe that is optimized for both small signal (e.g., gate-drive) measurements and higher voltage (device output) measurements. The DL-ISO is ideal for both GaN and SiC. The Teledyne LeCroy HVFO has lower bandwidth (consistent with Silicon and perhaps Silicon-carbide rise times) and is only optimized for small-signal measurements, but costs much less than the DL-ISO. This link https://www.teledynelecroy.com/probes/high-voltage-optically-isolated-probes has a short comparison.

          How does the Tektronix IsoVu compare to the Teledyne LeCroy DL-ISO optical isolated probe?

          Both probes have similar topologies. The Tek IsoVu probe has a 1 GHz probe bandwidth and a <1 GHz probe+oscilloscope bandwidth (when used with a 1 GHz oscilloscope) whereas the Teledyne LeCroy DL-ISO has a 1 GHz probe+oscilloscope bandwidth rating when used with a 1 GHz oscilloscope. Therefore, the IsoVu optical isolated probe usually has a slower rise time when connected to an oscilloscope whereas the Teledyne LeCroy DL-ISO always has the full-rated bandwidth (and a 435 ps rise time) as part of a probe+oscilloscope combination. The Tek IsoVu isolated probe leads are more rigid and less flexible than the Teledyne LeCroy DL-ISO, which is a disadvantage in probing tight circuits. The Teledyne LeCroy DL-ISO has lower noise and high accuracy, and a more faithful signal reproduction. However, the Tek IsoVu benefits from a second-generation design with a smaller probe size. Watch Video Probe Compare: DL-ISO vs. IsoVu for GaN/SiC Measurements for more details.

          What characteristics are needed in a probe for GaN gate-drive signal measurements?

          GaN gate-drive signals have very fast rise times and low amplitudes, and can be sensitive to loading from a probe. High bandwidth is required (typically 1 GHz, probe + oscilloscope combination). Low probe attenuation is ideal to minimize noise and maximize signal fidelity. High CMRR is required to appropriately reject the radiated interference from other in-circuit switching events.

          What characteristics are needed in a probe for SiC gate-drive signal measurements?

          SiC gate-drive signals are slower than GaN, and 350 MHz bandwidth may be sufficient for properly characterizing these signals. SiC is commonly used in 800-900 V switching applications (e.g., newest generation electrical vehicle propulsion motor drives) and may require probes with >1000V measurement ranges to measure the signal plus expected overshoot. Otherwise, the probe characteristics required are much the same as for GaN.

          Why is a specialized probe need for 48-60V MOSFET testing?

          The amplitudes in 48 to 60V applications are just above the common-mode and differential voltage ratings of conventional differential probes and well below the common-mode and differential voltage ratings of HV differential probes. HV differential probes rated for 1000V common-mode typically have switchable attenuators (e.g., 50x for an ~200V max differential voltage rating, 500x for ~2000V max differential voltage) and the high (50x) attenuation and larger than necessary differential voltage range adds noise to the measurement. Furthermore, most HV differential probes are usually limited to 200 MHz (there are a few exceptions, but 400 MHz is so far the upper limit) which limits their useful in GaN-based designs. Teledyne LeCroy’s DL-HCM is optimized for these voltage ranges in this particular application. Watch Webinar Best Practices for 48 V Power Conversion Testing for more details.

          Why are there so many different types of HV probes?

          There are many different applications for Si, SiC and GaN designs requiring difference performance and various acceptable price points. Watch Webinar How to Choose the Correct High Voltage Probe for details on selecting the right probe for your application. Watch Webinar High Voltage Probe Real-world Examples and Comparisons for additional details. If you have less time, Read App Note How to Choose the Best High Voltage Oscilloscope Probe in 5 Minutes.

          Should I overdrive my oscilloscope front-end to measure MOSFET or IGBT conduction loss?

          Historically, engineers would overdrive the oscilloscope front-end amplifier and use oscilloscope offset to view the conduction event and calculate losses. This method was error-prone (the offset circuit can add inaccuracy to voltage readings) and dependent on the ability of the oscilloscope front-end amplifier to be massively overdriven without causing signal distortion. Some (but not all) older oscilloscopes did have sufficiently fast overdrive recovery to perform this test, but more recent (<20 year old) oscilloscopes have front-end amplifiers optimized for improved noise performance and these amplifiers are less likely to tolerate being overdriven, so this method is not recommended.

          What is the best method to measure MOSFET or IGBT conduction loss?

          Many newer oscilloscopes have a higher resolution and lower-noise front-end amplifiers. A better technique for accurately capturing the conduction event is to acquire the full signal on a 12-bit resolution oscilloscope display and then use a vertical zoom to view the conduction event. The 16x better resolution (compared to 8-bit oscilloscopes) may not completely compensate for not overdriving the signal at the oscilloscope’s input, but it will provide more confidence in the ultimate measurement. Additional noise-reduction techniques (averaging, filtering, etc.) may improve performance further.

          What is the best method to measure MOSFET or IGBT switching loss?

          Switching loss is easily measured with a high quality HV isolated voltage probe, a means for measuring current (some type of clamp-on probe or current transformer for lower bandwidths, or in-series shunt resistor and appropriate differential voltage probe) and a 12-bit oscilloscope. Math may be used to calculate power loss during the switching event, or an application software program may also be used.

          What is a good replacement for the Teledyne LeCroy differential amplifier (Model DA1855A)

          The Teledyne LeCroy DA1855 and DA1855A series of differential amplifiers was manufactured from the late 1990s until the early 2020s. It functioned as a HV differential probe when connected to an oscilloscope with appropriate leads, and had attenuations as low as 1x in some HV modes and 10x gain in other modes, 100 dB CMRR, but only 100 MHz of bandwidth (not suitable for GaN or SiC). The AP033 operates up to 42V common-mode and has 10x gain and is suitable for shunt-resistor measurements. The DL-HCM has attenuation as low as 7x and may function suitable for small-signal measurement. For conduction loss measurements we recommend the technique described in the question “What is the best method to measure MOSFET or IGBT conduction loss?”.

          Is it acceptable to float the oscilloscope to measure high voltage signals if isolated high voltage probes are not available?

          It is not safe to float the oscilloscope above ground – there could be severe injury or death to the oscilloscope operator, damage to the oscilloscope and probe, and damage to the DUT. Floating the oscilloscope also requires a conscious decision to modify the oscilloscope from its stated use. For these reasons, ALL reputable companies and labs strictly prohibit floating an oscilloscope and require use of suitably rated high voltage probes. Furthermore, even if injury or death is avoided, the measurement fidelity of signals acquired by the floated oscilloscope may be impacted.

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