Design of a two watt power amplifier in InGaP/GaAs HBT process for very high linearity wireless applications

This paper presents the design of a very high linearity two watt power/driver amplifier in InGaP/GaAs Heterojunction Bipolar Transistor (HBT) technology for wireless standards like WCDMA. High linearity was achieved through a novel circuit that minimizes the third order intermodulation distortion component in the output signal. The circuit utilizes the base-collector and base-emitter diode capacitances of a transistor biased in the saturation region to provide a nonlinear feedback path between the output and input of the amplifier. In the 2.14GHz WCDMA band, the amplifier demonstrated 51dBm of output third order intercept point at 17dBm/tone output power level with output 1dB compression point of about 32dBm The amplifier is externally matched, thus provides flexibility to optimize the amplifier across a specific frequency band of interest between 400MHz and 2700MHz.