Computing the performances of a Gilbert cell microwave mixer

This paper concerns the design of mixers based on HBT Gilbert cell. In order to help circuit designers to choose and/or design transistors for optimum microwave performances, a sensitivity analysis of the conversion gain (Gc) has been performed. The study is based on the analytical expressions of maximum gain and cut-off frequencies previously demonstrated. High-order relative sensitivity computations with respect to transistor small-signal equivalent circuit parameters have been applied to those expressions. The method provides a classification of the transistor parameters according to their influence on each performance