Performing Calibration

• Setting Calibration Kit Values

• Measuring Data for Calculating Calibration Coefficients and Turning ON Calibration Function

• Preventing Operational Errors When Measuring Data for Calculating Calibration Coefficients

• Saving or Recalling Calibrated State (Retrieving or Writing Calibration Coefficients)

Other topics about Preparing for Accurate Measurements

Setting Calibration Kit Values

You can select either the E4982A option 700 (16195B 7-mm calibration kit) or a user-defined calibration kit. To make this selection, use the following command:

• :CORR1:CKIT

If you opt to use a user-defined calibration kit, you need to specify how you define the calibration kit and then enter the definitions.

Choosing the definition method (fixed or point-by-point)

• :CORR1:CKIT:LIST

Entering definitions

To define the OPEN, SHORT and LOAD standards, use the commands listed in the table below.

When you define the impedance value for the LOAD standard, you can choose one of the available parameter types by using the following command:

• :CORR1:CKIT:STAN3:FORM

Measuring Data for Calculating Calibration Coefficients and Turning ON Calibration Function

To measure the data for calculating the calibration coefficients, use the following command:

• :CORR1:COLL

This command obtains the data needed for calculating the calibration coefficients for both impedance and Rdc measurements. If you want to obtain the data for either impedance or Rdc measurement alone, use one of the following commands instead:

• :CORR1:COLL:RF

• :CORR1:COLL:DC

• Issuing the :CORR1:COLL, :CORR1:COLL:RF, or :CORR1:COLL:DC  command does not trigger the instrument to begin data measurement. Therefore, unless the trigger source is Internal trigger, you must trigger the instrument after issuing the command.

After obtaining the data for calculating the calibration coefficients for all of the OPEN, SHORT and LOAD standards (including the data for both impedance and Rdc measurements), issue the following command to calculate the calibration coefficients and turn on the calibration function:

• :CORR1:COLL:SAVE

• You cannot directly turn ON or OFF the calibration function.
• Instead, the calibration function is automatically turned ON when you issue the :CORR1:COLL:SAVE command after measuring the data required for calculating the calibration coefficients.
• Also, the calibration function is automatically turned OFF when you reset the instrument with the :SYST:PRES command or the *RST command or when you configure the measurement point setup table with the :SOUR:LIST command.
• To check whether the calibration function is currently ON or OFF, use the following command:
  :CORR1?

To define the standard values with the commands described so far, follow these steps:

If you use the same standards for both impedance and Rdc measurements or you omit Rdc measurement:

1. Connect the OPEN standard and then issue the :CORR1:COLL command, which designates STAN1 as the parameter. If the trigger source is not Internal trigger, you must trigger the instrument after issuing the command, This applies to steps 2 through 4 as well.

2. Connect the SHORT  standard and then issue the :CORR1:COLL command, which designates STAN2 as the parameter.

3. Connect the LOAD standard and then issue the :CORR1:COLL command, which designates STAN3 as the parameter.

4. To measure a low-loss capacitor, connect the low-loss capacitor and then issue the :CORR1:COLL or :CORR1:COLL:RF command, which designates STAN4 as the parameter.

5. Issue the :CORR1:COLL:SAVE command.

If you use different standards for impedance and Rdc measurements:

1. Connect the OPEN standard for impedance measurement and then issue the :CORR1:COLL or :CORR1:COLL:RF command, which designates STAN1 as the parameter. If the trigger source is not Internal trigger, you must trigger the instrument after issuing the command. This applies to steps 2 through 7 as well.

2. Connect the SHORT standard for impedance measurement and then issue the :CORR1:COLL or :CORR1:COLL:RF command, which designates STAN2 as the parameter.

3. Connect the LOAD standard for impedance measurement and then issue the :CORR1:COLL or :CORR1:COLL:RF command, which designates STAN3 as the parameter.

4. To measure the low-loss capacitor, connect the low-loss capacitor and then issue the :CORR1:COLL or :CORR1:COLL:RF command, which designates STAN4 as the parameter.

5. Connect the OPEN standard for Rdc measurement and then issue the :CORR1:COLL:RF command, which designates STAN1 as the parameter.

6. Connect the SHORT standard for Rdc measurement and then issue the :CORR1:COLL:RF command, which designates STAN2 as the parameter.

7. Connect the LOAD standard for Rdc measurement and then issue the :CORR1:COLL:RF command, which designates STAN3 as the parameter.

8. Issue the :CORR1:COLL:SAVE command.

Preventing Operational Errors When Measuring Data for Calculating Calibration Coefficients

To retrieve each standard's measurement data for calculating the calibration coefficients for Rdc measurement, use the following command:

• :DATA:RCAD{1-3}?

Since this command returns the Rdc measurement value for each standard, you can check whether this value is normal (within the limit range) to prevent operational errors (such as connecting the wrong standard) that may arise when measuring the data for calculating the calibration coefficients.

• The measurement data for the standards cannot be used for evaluating slight differences in measured values because it is raw measurement data that has not been calibrated and may differ from the specification value. For example, when the LOAD standard is an indicator, it exhibits an Rdc value quite similar to that of the SHORT standard; you should be careful not to inadvertently interchange the LOAD and SHORT standards because they are difficult to distinguish by their measured values.

The following table provides guidelines for determining the limit range (upper and lower limits) for testing:

In the table above, Short represents the Rdc value for the SHORT standard, Load represents the Rdc value for the LOAD standard, and Open represents the Rdc value for the OPEN standard.

For example, when the LOAD standard is a 50 Ω resistor, the limit ranges for the respective standards should typically be the following:

SHORT standard: 25 Ω or lower

LOAD standard: 25 to 100 Ω

OPEN standard: 100 Ω or higher

• When you validate the Rdc measurement results returned by the :DATA:RCAD{1-3}? command, you should use the absolute value for the following reasons. When you measure the SHORT standard, whose resistance is extremely low (nearly zero) and susceptible to disturbance during measurement, the command may return a small negative Rdc value. On the other hand, when you measure the OPEN standard, whose conductance is extremely low (nearly zero) and susceptible to disturbance during measurement, the command may return a large negative Rdc value (an inverse to a negative small conductance value).

The measurement data of the respective standards used for calculating the calibration coefficients for impedance measurement are stored in the calibration data array (see Calibration Data Arrays). You can retrieve this data with the following command:

• :DATA:CAD{1-8}?

• Note that the command shown above returns raw RF measurement data. Unlike DC measurement, you cannot simply compare the raw RF measurement data with the standard values to detect operational errors that may have occurred when measuring the calibration data.

Saving or Recalling Calibrated State (Retrieving or Writing Calibration Coefficients)

You can retrieve the calibration coefficients and save them to a file. Later, you can retrieve the calibration coefficients from the file and load them into the E4982A to restore the calibrated state at the time you saved the file.

The calibration coefficients for impedance measurement are stored in the calibration coefficient array (see Calibration Coefficient Arrays). To read or write the calibration coefficient array, use the following command:

• :DATA:CCO{1-6}

To read or write the calibration coefficients for Rdc measurement, use the following command:

• :DATA:RCCO{1-3}

• When setting calibration coefficients, note the following:
  1. To ensure that the instrument will provide correct measurement results, you must configure the instrument to use the same measurement points (point setup table settings) as when you obtained measurement data for calibration and then set all the coefficients.
  2. You must turn on the calibration functions before you set the calibration coefficients. To do so, follow the steps shown in Measuring Data for Calculating Calibration Coefficients and Turning ON Calibration Function before setting the calibration coefficients. This procedure includes only measuring tentative data and does not require you to connect the standard before issuing the data measurement command.

Sample Program

See Calibration and Compensation.