Improvements to On-Wafer Noise Parameter Measurements

A new system for measuring noise parameters on-wafer has been developed that incorporates three main new features: (1) the source can be tuned to any impedance including Zopt rather than pre-calibrated settings, (2) the system corrects for drift in second stage gain, and (3) calibration is simplified with an on-wafer noise source. This cold-noise measurement system uses a HP8510B network analyzer with a custom test-set that incorporates the input reflectometer between the DUT and tuner, and the output reflectometer between the DUT and the second stage. The noise figure of 0.25 mm pseudomorphic MODFETs were measured versus source impedance with the system. The standard four-parameter equation for modeling the dependence of noise figure on impedance was fitted to every measured data point (e.g., 32) including Fmin to better than 0.02 dB.