Teledyne LeCroy QPHY-DDR2 - Manual (Page 26)

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QPHY-DDR2-OM-E Rev A
Differential (or Single-Ended) Probe Selection
The PCF200 fixture calibrates probes differentially or in single-ended mode depending on the type of probe used.
The selection is done automatically when the probe is detected. If No Probe is detected, the selection is done
manually. When calibrating D620 probes, they are automatically detected and Differential is checked.
Deskew All (or Common Skew)
This is the deskew amount applied to all channels. The time entered in this field is the absolute time by which all
waveforms displayed by the oscilloscope are delayed in time. This value effectively adjusts the zero time
reference of the system. See Deskew Theory of Operation in the TF-DSQ Operation Manual for details.
Common Mode Voltage Selection
Differential probes allow the common mode voltage component to be applied during the DC calibration for
improved calibration accuracy in situations where probe gain or offset correction depends on common mode
components. See DC Calibration Theory of Operation or Differential and Single-ended Probe Basics in TF-DSQ
Operation Manual for details.
Advanced Probe Calibration
When the Advanced Mode checkbox is checked, you can perform the DC calibration and the deskew calibration
separately by pressing Gain/Offset Only or Deskew Only.
When performing DC calibration, you have the option to apply a common mode component to the differential DC
levels applied to the probe during calibration. See DC Calibration Theory of Operation or Differential and Single-
ended Probe Basics in TF-DSQ Operation Manual for details. Use this with TF-DSQ. DO NOT use with PCF200
connected to Fast Edge output.
After performing the deskew calibration, you have the option to apply a common skew value to all channels to
adjust the zero time reference of the system.
If you know the risetime of the signals being measured, you can enter the measured risetime of the signals in the
Rise Time field to obtain a further skew correction that accounts for the risetime. If the risetime entered is less
than the risetime measured during the calibration, no correction is applied; otherwise, the system calculates a
correction to account for the signal risetime. This makes it important to enter the measured risetime, meaning, the
risetime of the signal the oscilloscope measures (or will measure). Refer to the Deskew Risetime Adjustment
Theory of Operation in the TF-DSQ Operat
or’s Manual on the LeCroy website for details.
D620 Probe Calibration Procedure
The PCF200 fixture is used to calibrate D620 probes. Prior to beginning your measurements
 Assemble the PCF200 fixture
 Attach the fixture, as described in PCF200 Fixture Overview.
 Access the Probe Calibration Menu in Advanced Mode
Follow the instructions for each probe used:
 Connect the probe to the oscilloscope channel
 Attach the probe to the PCF200 fixture
 Press the Deskew Only button in the Advanced Probe Calibration Menu.
 Wait a few seconds as the probe is calibrated.
 When the calibration completes, remove the probe from the PCF200 fixture
Now you are ready to probe the circuit and perform your measurements. If power is interrupted during your
measurements, reboot the oscilloscope and manually recall your settings.