Touchstone Calibration Wizard

Use the Ansys Calibration Wizard to characterize the effect of a probe or fixture, and remove the effect from a device under test, by reading and writing Touchstone files. There are three methods of calibration: Two-line, Thru-reflect-line, and Short-open-load-thru. Note that for measured data, it is often desirable to smooth the data before calibrating the fixtures.

Smoothing can be accomplished using the Network Data Explorer.

The topics for this section include:

Two-Line Method

Thru-Reflect-Line Method

Short-Open-Load-Thru Method

Two-Line Method

To implement the Two-Line method, select Tools > Calibration Wizard to open the Calibration Wizard dialog box, then select Two-line method from the Type drop-down list. The two-line calibration method removes the effect of the probe fixtures from a device under test and assumes that the effect of fixture 1 is identical to fixture 2.

Note: The two line method assumes the probe discontinuity can be represented as a simple shunt element. A larger probe will generate proportionally larger errors in calibration. Tolerance is at the user's discretion.

Note: There can be only one propagating mode on the transmission line. If there are multiple propogating modes, then calibration may fail.

The required input is:

Two Touchstone files (*.s2p), each of a thru-line of a given length plus the probe fixtures. The lines must be of different lengths.
The imported Zo uses Touchstone file (*.s2p) of an ideal line with no fixture effects. This Touchstone file may come from measurement or simulation. If no file is specified, the wizard will approximate the Zo.
A Touchstone file (*.s2p) of the desired device under test with fixture effects.

The output is:

A Touchstone file of the fixture.
A Touchstone file of the device under test with effect of the fixtures removed.
If you select Export Zo, the frequency dependent Zo of the calibration lines writes to the designated file.

Thru-Reflect-Line Method

To implement the Thru-Reflect-Line method (TRL), select Tools > Calibration Wizard to open the Calibration Wizard dialog box, then select Thru-Reflect-Line method (TRL) from the Type drop-down list. The Thru-reflect-line calibration method removes the effect of the probe fixtures from a device under test. Probe 1 and probe 2 are not assumed to identical.

The required input is:

Two Touchstone files (*.s2p), each of a thru-line of a given length plus the probe fixtures. The lines must be of different lengths.
For each port, you can specify either a single-ended (*.s1p) or a combined measurement (*.s2p) file. When a *.s2p file is specified, Port 1 will use the S11 values and Port2 will use the S22 values:
- For a short or matched measurement, the surplus inductance must be specified.
- For an open circuit reflection, the excess capacitance must be specified.
- If no value is given, an ideal reflect is assumed.

The imported Zo uses Touchstone file (*.s2p) of an ideal line with no fixture effects. This Touchstone file may come from measurement or simulation. If no file is specified, the wizard will approximate the Zo.
A Touchstone file (*.s2p) of the desired device under test with fixture effects.

The output is:

Touchstone files for the fixtures corresponding to Port1 and Port2.
A Touchstone file of the device under test with effect of the fixtures removed.
If you select Export Zo, the frequency dependent Zo of the calibration lines writes to the designated file.

Short-Open-Load-Thru Method

To implement the Short-Open-Load-Thru method (SOLT), select Tools > Calibration Wizard to open the Calibration Wizard dialog box, then select Short-Open-Load-Thru method from the Type drop-down list. The Short-Open-Load-Thru calibration method removes the effect of the probe discontinuities from a device under test and does not assume the port 1 and port 2 are equal.

The required input is:

One Touchstone file (*.s2p) of a thru-line of any length.
Three Touchstone files for each port corresponding to each measurement configuration: shorted, open and loaded. Each file can either be a single-ended (*.s1p) or a combined measurement (*.s2p) file. When a *.s2p file is specified, Port 1 will use the S11 values and Port2 will use the S22 values:
- For a short or matched measurement, the surplus inductance must be specified.
- For an open circuit reflection, the excess capacitance must be specified.
- If no value is given, an ideal reflect is assumed.

A Touchstone file (*.s2p) of the desired device under test with fixture effects.

The output is:

Touchstone files for the fixtures corresponding to Port1 and Port2.
A Touchstone file of the device under test with effect of the fixtures removed.
If you select Export Zo, the frequency dependent Zo of the calibration lines writes to the designated file.