Calibration Procedure for ±28 V, Common-Path Gate Resistor

The following calibration procedure is for the General Purpose ±28 v Gate Drive modules configured to use the RGON gate resistor for both FET Turn-on and Turn-off. Tthe IGON pins are used for the gate current measurement.

Initialize New Data EEPROMs

Oscilloscope Probe Compensation

Gate Voltage Calibration - VGS/VGE Probe

Gate Voltage Source Calibration - VGS/VGE Output

Gate Current Calibration - IG Probe

Gate Resistance Calibration - RG

High Voltage Probe Calibration - VDS/VCE Probe

Clamp Circuit Probe Calibration - VCLAMP Probe

Protection Probe Calibration - ID/IC

Oscilloscope Probe Deskew

After Compensation & Calibration and Deskew Completes

Calibration Requirements

Calibration requires the B2902A Precision Source/Measure Unit (SMU) and the following cables/adapters:

  • 1251-2277 Banana to BNC Adapter, quantity 1.
  • 8121-2816 BNC to SMA Cable, 1 m, 50 W, quantity 1.
  • 1168B Standard Probe Kit, quantity 2.
IMPORTANT: Make certain the B2902A is set for the correct ac line frequency. See Set/ Verify AC Line Frequency and Date/Time on the B2902A

Initializing PD1000-66848 and -66849 Modules for Calibration

The initialization procedure is very similar for both Common-Path and Split-Path configured modules.
the following example shows the Split-Path initialization.

Only the Keysight PD1000-66848 Low-Side and PD1000-66849 High-Side gate drive modules can be configured with split-path gate resistors (RG). The module is considered ‘blank’ until initialized. Additional calibration steps are necessary to calibrate the off-path.

Initialization of the module, for split-path configuration has a sequence of requests for the Low-Side Gate Drive Module only (PD1000-66848)! The High-Side Gate Drive Module is initialized with the same nominal values. The following example sequence configures with RG,ON= 5 W, RG,SHARED = 5 W, RG,OFF = 8.0 W.

For this example:

Nominal On-Resistance = RG,ON + RG,SHARED = 5 + 5 = 10 W

Nominal Shunt-Resistance = RG,ON = 5 W

Nominal Off-Resistance = RG,OFF + RG,SHARED = 8 + 5 = 13 W

RG,ON and RG,SHARED gate drive resistors should be the same value. The resistors are in series and form the complete gate drive resistor. For example, if both resistors are 25 W, the total gate drive resistor value is 50 W. RG,OFF may be a different value.

 

Initialize New Data EEPROMs for Split-Path Gate Drive Module

If the module is a blank board (has never been initialized), click Yes. If it has been initialized before, click No.

 

Enter the Nominal On-Resistance Value. In our example, enter 10. Click Ok.

 

Enter the Nominal Shunt Value. In our example, enter 5. Click Ok.

If the gate drive module is configured with Split-Path gate resistors, click Yes. If it is configured a a Single- or Common-path, click NO.

Enter the Nominal Off-Resistance Value. In our example, enter 13. Click Ok.

For maximum high voltage level, use the predefined value (28). Click Ok.

For minimum high voltage level, use the predefined value (0). Click Ok.
   
   

For maximum low voltage level, use the predefined value (0). Click Ok.

For minimum low voltage level, use the predefined value (-28). Click Ok.

For maximum high-low voltage difference, use the predefined value (0).

Click Ok.

For minimum high-low voltage difference, use the predefined value (1). Click Ok.

For the voltage threshold of the Low-Side Gate Drive module, usethe predefined value (NaN). Click Ok.

The module is now initialized and ready for complete Calibration.

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Oscilloscope Probe Compensation

As the first step calibrating the Double-Pulse Test system, the oscilloscope probes must be adjusted for low frequency compensation. For this, the 10076C and N2873A passive probes have built-in compensation RC divider networks. The N2819A Active Differential Probe also requires offset compensation.

Allow the oscilloscope and probe to warm up at ambient temperature for a minimum of 60 minutes (1 hour) before performing the adjustment.

Required Equipment

All equipment required for compensation and calibration were provided with the PD1500A test system. This includes:

  • Spring hook and ground clips for passive oscilloscope probes.
  • 5 cm Extension Leads and either Pincer or micro IC clips for the N2819A Differential probe.
  • Low Frequency Compensation trimmer/adjustment tools (small plastic screwdriver).

Compensating the 10076C and N2873A Probes

The Infiniium S-Series Oscilloscopes have a square wave reference signal available on the front panel to use for compensating the passive probes. Attach the spring hook and ground clip to the probe and then the square wave reference terminal.

  1. Refer to the N2873A Probe’s User Guide for instructions. A general description and procedure can also be found on page 5 (Hint #3) of the Keysight 8 Hints for Better Scope Probing.
  2. Connect the probe to the oscilloscope’s front-panel calibration output (a square wave label is seen near this output).
  3. Use the supplied trimmer tool to adjust the Low Frequency compensation to an optimum square wave response as shown below.

  1. Adjust so that the square wave on the oscilloscope screen looks square.

                      Undercompensated                                         Overcompensated                                           Optimum
Due to the 100:1 divider of the 10076C High Voltage Probe, the signal will appear to be very noisy. Therefore, it is beneficial to enable averaging in the Setup > Acquisition menu for suppressing this noise. Setting the number of averages to 16 will result in a clean signal.

Compensating the N2819A Differential Probe

The N2819A Active Differential Probe also requires offset compensation. This is described below and in the N2818/9A Differential Probes User Guide. Use the trimmer tool supplied with the probe to perform the offset zero calibration.

  1. Connect the probe to an oscilloscope channel input. Turn on the oscilloscope and wait for a minimum of 20 minutes to allow the oscilloscope and probe to warm up.
  2. Using the probe's 5 cm Extension Leads and the Pincer or Micro IC Clip connection accessories, short the + and - inputs together.

  1. Press Control > Autoscale on the oscilloscope.
  2. Press the channel button for the probe and set the oscilloscope channel to DC Coupled mode.
  3. Set the oscilloscope to Averaging mode (Setup > Acquisition... > Averaging Enabled, x8 or higher) to reduce oscilloscope noise, if needed.
  4. Set the vertical scale of the oscilloscope to 100 mV/div.
  5. Using the offset adjustment tool that comes with the probe, adjust the probe offset voltage to zero volts.

In the Compensation & Calibration section of the Control Software, software, click the Skip button when you have completed the probe compensation.

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Gate Voltage Calibration - VGS/VGE Probe

Hardware Setup

  • Connect the N2873A VGS/VGE Gate-Voltage-Probe into the VGS/VCE connector Deskew section of the Test Fixture

  • Connect the SMA-connector of the BNC-to-SMA cable to the SMA INPUT connector Deskew section of the Test Fixture

  • Connect the Banana-BNC adapter to BNC-end of the BNC-to-SMA cable

  • Connect the Banana-plug of Banana-BNC adapter into the Channel 1 FORCE-terminals of the SMU

  • The Safety Enclosure hood may be left open

 

Procedure

Click Start to perform the calibration and continue to the next step.

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Gate Voltage Source Calibration - VGS/VGE Output

Hardware Setup

    • Connect the N2819A Differential Oscilloscope Probe to the IG On Pins on the Low-Side Gate Driver Module. Carefully observe polarity when installing the probe.
    • Connect red Test-Hook Banana plug to FORCE-High-terminal on the B2902A/B SMU.
    • Connect red Test-Hook to Low-Side Gate Driver Module test point TP501.

    • Connect black Test-Hook Banana plug to FORCE-Low terminal on the B2902A/B SMU.

    • Connect black Test-Hook to Low-Side Gate Driver Module test point TP502.
    • The Safety Enclosure hood may be left open.

    Procedure

    Click Start to perform the calibration and continue to the next step.

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    Gate Current Calibration - IG Probe

    Hardware Setup

    • Connect the N2819A Differential Oscilloscope Probe to the IGON Pins on the Low-Side Gate Driver Module. Carefully observe polarity when installing the probe.
    • Connect red Test-Hook Banana plug to FORCE-High-terminal on the B2902A/B SMU.
    • Connect red Test-Hook to Low-Side Gate Driver Module test point TP505.
    • Connect black Test-Hook Banana plug to FORCE-Low terminal on the B2902A/B SMU.
    • Connect black Test-Hook to Low-Side Gate Driver Module test point TP507.
    • The Safety Enclosure hood may be left open.

    Procedure

    Click Start to perform the calibration and continue to the next step.

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    Gate On-Resistance Calibration - RG

    Hardware Setup:

    • Using one set of the U1168B Test Probe kit, connect red Test-Hook Banana plug to FORCE-High-terminal (red) on the B2902A/B SMU.
    • Connect red Test-Hook to Low-Side Gate Driver Module test point TP506.
    • Connect black Test-Hook Banana plug to FORCE-Low-terminal on the B2902A/B SMU.
    • Connect black Test-Hook to Low-Side Gate Driver Module test point TP501.

     

    • Using a second set of the U1168B Test Probe kit, connect red Test-Hook Banana plug to Sense-High-terminal (red) on the B2902A/B SMU.
    • Connect red Test-Hook to Low-Side Gate Driver Module test point TP507.
    • Connect black Test-Hook Banana plug to Sense-Low-terminal on the B2902A/B SMU.
    • Connect black Test-Hook to Low-Side Gate Driver Module test point TP509.

     

    • The Safety Enclosure hood may be left open for this calibration step.

    Procedure

    Click Start to perform the calibration and continue to the next step.

    There is no calibration for the 0W Gate Drive modules or the High-Side Gate Drive modules.

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    High Voltage Probe Calibration - VDS/VCE Probe

    Hardware Setup:

    • Install a High-Side Gate Drive Module (0 W Gate Resistor)
    • Install a 1200 V FET (for example, the SCT2080KE FET supplied with the PD1500A) in the High-Side position of the DUT module.
    • Remove any FET in the Low-Side position of the DUT Module.
    • Remove (do not install) the Low-Side Gate Drive Module.
    • Connect the 10076C High Voltage Probe to the DUT Module.

    • Remove all other cables and oscilloscope probes.

    Safety Enclosure hood must be closed for this test.

    Procedure

    After setting up the hardware as described above, click Start to perform the calibration and continue to the Clamp Circuit Probe Calibration.

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    Clamp Circuit Probe Calibration - VCLAMP Probe

    Hardware Setup:

    See Figure below.

    The High Side Force terminal on the B2902A SMU connects to the + pin on the Clamp Circuit Module. The Low Side Force terminal on the B2902A SMU connects to the – pin on the Clamp Circuit Module.

    Procedure:

    After setting up the hardware as described above, click Start to perform the calibration and then continue to the next step.

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    Protection Probe Calibration - ID/IC

    The PD1000-60002 Protection Probe requires Infiniium Oscilloscope Software for Windows 10, version 06.40 (or later) in the DSOS104 Oscilloscope. Verify the current installed version in the DSOS104 Help > About screen. You can download and install the latest version of firmware from: www.keysight.com\find\DSOS104A. Select Drivers, Firmware & Software, then Instrument Firmware/Software.

    Hardware Setup:

    Refer to Figure below.

    • Connect the PD1000-60002 Protection Probe to the Oscilloscope.
    • Connect the BNC to Banana Adapter to the BNC to SMA cable.
    • Connect the SMA end of the cable to the SMA connector on the PD1000-60002 Protection Probe. Use the 0.56 N-m (5 lb-in) 5/16 in. SMA Break-over torque wrench (provided with the PD1500A system) to tighten the cable to the PD1000-60002 Protection Probe.
    • Connect the banana plug cable to Channel 1 Force terminals of the B2902A SMU (2-wire measurement).
    • The Safety Enclosure hood may be left open for this calibration step.

    Procedure:

    After setting up the hardware as described above, click Start to perform the calibration and then continue to the next step.

    Use the 0.56 N-m (5 lb-in) 5/16 in. SMA Break-over torque wrench (provided with the PD1500A system) to tighten the cable to the PD1000-60002 Protection Probe. Failure to do so might cause extensive ringing in the DPT measurements. See appendix in the PD1500A Software Guide for SMA connector care and connection information.

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    Oscilloscope Probe Deskew

    A small propagation delay difference exists between different types of oscilloscope probes (e.g., voltage vs. current probes). Although this difference is small, it is significant and is caused by each probe’s unique internal circuitry and cable length. This propagation delay difference is known as “skew” and creates an error when calculating switching loss or measuring timing. In general, the outcome is that all probes must be aligned!

    Deskew is a process of applying a signal from the Waveform Generator to all four oscilloscope channels simultaneously. The PD1000A Control Software measures the time difference between channels relative to oscilloscope Channel 3. Finally, the oscilloscope automatically calculates and sets the channel-to-channel skew factor.

    After the Oscilloscope Probe Compensation and System Calibration, the last step is to run Deskew. Deskew has the greatest impact on both On and Off Delay times and hence affects the total Switching Time. Both On and Off Switching Energies are also affected.

     

    It is not necessary to run Deskew before each DPT test. However, it should be run whenever you change Gate Drive Test Modules, the probes, or when the ambient temperature changes more than ±5 ºC or when any other change is made to the DPT system. The Deskew numbers are stored in non-volatile memory; they are not erased when the oscilloscope is turned off.

     

    The following table lists the required alignment for the different measurements.

    Parameter Required Alignment
    Turn on delay td(on ) VGS, VDS
    Turn on rise time tr None
    Turn on Energy e(on) VGS, VDS, ID
    Turn off delay td(off) VGS, VDS
    Turn off fall time tf None
    Turn off Energy e(off) VGS, VDS, ID
    Reverse Recovery Time trr None
    Reverse Recovery Charge Qrr None
    Reverse Recovery Energy Err of Diode VDS, ID
    Gate Charge QGS, QGD, QG VGS, IG
    RDS(on) VDS (clamped), ID
    IV-Curve VGS, IG

    Connect Probes to Deskew Fixture

    After the Oscilloscope Probe Compensation and System Calibration, the last step is to run Deskew.

     

    Hardware Setup

    Because the oscilloscope has only four input channels and the DPT test fixture uses only four oscilloscope probes at a time, then only four probes may be deskewed at one time. Typically, either the N2819A Differential Probe (for measuring IG) or the N2873A (VCLAMP) probe are used in a DPT test; rarely are they both used at the same time. Deskew the probes that you will be using in your test. Figure below shows the typical configuration for Deskewing the oscilloscope probes.

    1. Locate the Deskew oscilloscope probe connectors on the main Test Fixture. See figure below.
    2. Remove the SMA cable from the Low Side SMA connector on the Test Fixture and connect it to the Cal (Deskew) Input SMA connector.

    The BNC connector (ID/IC) on the far right is for the PD1000-60002 Oscilloscope Protection probe cable that would normally connect to the Coaxial Shunt Resistor on the DUT Test Module.

    1. Connect the oscilloscope probes to the Deskew section of the Test Fixture.

    Procedure:

    1. After setting up the oscilloscope probes in the Deskew fixture, click Start to perform Deskew calibration.
    2. When complete, return the oscilloscope probes to the appropriate connectors on the DUT and Test Modules.
    3. Return the SMA cable from the Cal (Deskew) Input SMA connector to the Low Side SMA connector on the Test Fixture.

     

    IMPORTANT: The N2918A Differential Probe must face to the left; the Keysight logo must face toward the VCLAMP probe connector.

     

    IMPORTANT:Before running any Double-Pulse Test, make certain the Gate Drive Modules have the V/NC jumper installed and the I/NO jumper removed. Remove all cables from the B2902A SMU.

     

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    After Compensation & Calibration and Deskew Completes

    This concludes the Compensation & Calibration procedure.