Sensitivity of narrow- and wideband LNA performance to individual transistor model parameters

Abstract

Although it is desirable for a transistor model to be as accurate as possible the extraction of model parameters from fabricated transistors is a time consuming and often costly process. An investigation of the sensitivity of LNA performance characteristics to individual parameters of the physics-based standard HBT model HICUM/L2 was therefore done to gain preliminary insight into the most important parameters for transistors used in actual circuits. This can potentially allow less strenuous accuracy requirements on some parameters which would ease the extraction process. Both a narrow- and a wideband LNA configuration were investigated. It was found that the series resistance parameters have a large impact on LNA gain, S11 and NF performance in both cases. Since the narrow band LNA relies heavily on the transistor characteristics to provide proper matching it was also very sensitive to changes in the parameters used in modelling the high frequency current gain and depletion capacitances of the transistor.