Optimization of Horizontal Current Bipolar Transistor (HCBT) technology parameters for linearity in RF mixer

Double-balanced active mixer based on a Gilbert cell is designed and fabricated as the first RF circuit in Horizontal Current Bipolar Transistor (HCBT) technology. The maximum IIP3 of 17.7 dBm at mixer current of 9.2 mA and conversion gain of -5 dB are achieved. Three different HCBT structures are used in a mixer design to examine the effect of process parameters on mixer linearity. The main effect on the linearity has the n-collector doping profile since it governs the onset of Kirk effect. The improvement of 6 dB in IIP3 can be achieved by using the optimum HCBT structure, if switching quad transistors operate at or near the high current region. The circuit model parameters of three HCBT structures are extracted, accurately reproducing the measured device and circuit data.