Patent ID: 11892534
Assignee: ROHM CO., LTD.
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. A frequency characteristic measurement apparatus, comprising:
a calibration circuit configured to perform a short-open-load-thru calibration on cable end surfaces;
a first measurement circuit configured to measure a plurality of first S-parameters of a first substrate, after the short-open-load-thru calibration by the calibration circuit, wherein the first substrate includes a first fixture, a second fixture, and a device under test;
a second measurement circuit configured to measure a plurality of second S-parameters of a second substrate after the short-open-load-thru calibration by the calibration circuit, wherein the second substrate includes the first fixture and the second fixture; and
an extraction circuit configured to:
set an amplitude of a S-parameter of a plurality of third S-parameters of the first fixture of the second substrate to a first fixed value throughout an entire frequency range of a measurement range;
set a phase of the S-parameter of the plurality of third S-parameters to zero throughout the entire frequency range of the measurement range;
determine a set of S-parameters of the plurality of third S-parameters based on each of:
the set amplitude of the S-parameter of the plurality of third S-parameters,
the set phase of the S-parameter of the plurality of third S-parameters, and
the plurality of second S-parameters, wherein the plurality of third S-parameters includes the S-parameter and the set of S-parameters;

determine a plurality of fourth S-parameters of the second fixture of the second substrate based on each of:
the plurality of second S-parameters, and
the plurality of third S-parameters; and

perform a vector operation based on each of:
the plurality of first S-parameters,
the plurality of third S-parameters, and
the plurality of fourth S-parameters, wherein
the vector operation is performed to extract a plurality of fifth S-parameters of the device under test,
the extraction circuit assumes that a reflection of each of the first fixture of the second substrate and the second fixture of the second substrate, which are obtained by virtually dividing the second substrate into two parts at a center, on an end surface of the second substrate is equal to or smaller than a reflection on an end surface of the second substrate without the virtual division at the center,
the first substrate further includes at least one connector on each of a first end surface and a second end surface,
the second substrate has:
 a structure in which a part provided with the device under test is removed from the first substrate, and
 two optional connectors that are selected from among all of connectors installed on the first substrate to form a through-connection, and
a number of second substrates is a total number of combinations of selecting two connectors from among all of the connectors installed on the first substrate.