Accurate broadband on-wafer SOLT calibrations with complex load and thru models

Abstract

An improved vector network analyzer calibration approach is demonstrated that utilizes planar lumped short-open-load-thru (SOLT) standards and achieves accuracy comparable to TRL at high frequency, without the commonly occurring errors in TRL at low frequency. The approach relies on complex loadmodels for CPW and microsttip loads that are not currently available in VNA fmware. A non-ideal (lossy) model for the thru line standard is used to enhance results for calibrations involving non-zero length thru lines. GaAs microstrip and CPW substrates were used for the purpose of experimental verification. It is shown that the RF performance changes due to GaAs load fabrication variation can be addressed by "calibrating" or adjusting the load model with the measured DC resistance for a particular load.