A novel Darlington cascode broadband drive power amplifier in 2μm InGaP/GaAs HBT technology

A novel Darlington cascode drive power amplifier (gain block) with bandwidth from 0.1GHz up to 6GHz is proposed in 2μm InGaP/GaAs HBT technology offering f T ∼30GHz. This novel Darlington cascode topology is composed of a cascode power stage and a common collector input predistorted linearizer. The cascode power stage is used to achieve both advantageous power capacity and broad operation bandwidth for multi-system application. A positive AM-AM or negative AM-PM characteristic is obtained using the predistorter to achieve good OIP3 by adjusting feedback resistor and capacitor. Measurement results show that the proposed drive power amplifier achieved a gain of 24dB at 900MHz, 20dB at 2.4GHz, and 13dB at 5.8GHz respectively. The output 1-dB compression power is 23dBm at 900MHz with no more than 6dB compression up to 6GHz. Over than 35dBm OIP3 is obtained at 2.4GHz due to our advanced linearity topology. The chip size is only 0.27mm2.