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between 20° and 160° at each frequency point. Therefore, the actual coverage range of a single transmission line is 8:1. In order
to cover a wider frequency range, multiple transmission line type standard calibration kits are required.
The transmission line type standard calibration kit should be particularly long at low frequency. The optimal length is 1/4 of the
wavelength corresponding to the geometric average frequency (square root of the product of the starting frequency × ending
frequency) within the frequency span.
d) Matching standard calibration kit
If the transmission line of specific length or loss cannot be made, use the matching standard calibration kit instead of the transmission
line.
The matching standard calibration kit is a low-reflection terminal to be connected to the port.
Use the matching standard calibration kit as the transmission line of high loss and infinite length in calculation of the error
coefficient of TRL calibration.
Change the impedance of the matching standard calibration kit into the reference impedance of measurement.
7.9.
Fixture Compensation Calibration
The fixture simulator function is used for network port impedance conversion..., 2-port fixture de- embedding, Port Matching... and
four-port fixture embedding/de-embedding in the mathematical sense.
It can be used to simulate various measurements based on measurement results in applications, and also rapidly simulate the
corresponding measurement results in a real-time manner. The measurement results of the port with the impedance of 50Ω can be
transformed into measurement results of any impedance by means of port impedance conversion.... The 2-port de-embedding
function can be applied to remove any network characteristic between the measurement end face and DUT end face, which is defined
in the Touchstone data file, so as to extend to the corresponding calibration surface. The Port Matching... function is used to transform
the original measurement results into the specific simulation result determined by inserting the matching circuit between the DUT and
test port (one-port). The four-port fixture embedding/de-embedding function is used to simulate embedding/de-embedding of the
four-port fixture, so as to obtain the simulation results of the tested device after embedding/de-embedding of part of the network.
The handling process of the whole fixture simulator is shown in Fig. 7.19.
Fig. 7.19 Handling Process of Fixture Simulator
S-parameter
The S-parameter of the fixture or matching circuit can be obtained at first to realize the above functions. It is represented by the circuit
model or Touchstone data file. Fixture embedding/de-embedding is realized according to the known S-parameter of the fixture.
Terms of fixture simulator
Enabling of fixture function
