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Chapter 3
CHAPTER
ERROR MODELS FOR TWO-PORT S-PARAMETER MEASUREMENT
Of paramount importance in on-wafer transistor characterization at RF frequencies
is to properly correct the errors introduced by the VNA system and on-wafer parasitics
[66] [13] [21] [12]. The demand for increased measurement accuracy in on-wafer Sparameter measurement can be achieved by improving the hardware, the models used
for characterizing measurement errors, the calibration methods used for calculating
these errors, and the definitions of calibration standards [34]. The type of the error
model depends on the hardware topology of the VNA. There are three-receiver VNA
and four-receiver VNA for two-port measurement. The three-receiver VNA has one
reference receiver for detecting the incident signal, and two measurement receivers, one
at each port. The corresponding error model is a 12-term error model, 6 for forward
direction, 6 for reverse direction [67] [68]. For double-reflectometer VNA with four
receivers, a 8-term error model was introduced and solved in S-parameters and Tparameters [69] [70] [71]. The leakage terms can be added to the to the 8-term error
model, one for each measurement direction, increasing the number of error coefficients
to 10 [72] . Both the 8(10)-term model and the 12-term models are used for fourreceiver VNA, which even have their calibration procedures embedded in modern
VNAs. The error models and their corresponding calibration techniques are compared
in [73] [74] [68] [75]. If required, several techniques with different conversion
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