Dual Dynamic Biasing with Input Power Pre compensation for Class-A/AB enhancement

A novel dynamic biasing methodology specially oriented towards high-efficiency class-A/AB design is presented. To achieve flexibility in the efficiency/linearity tradeoff, the gate and drain voltages as well as the input power are varied as a function of the desired output power. The aim is Power Added Efficiency (PAE) maximization restrained by linearity conditions. Simulation results for a 30dBm GaAs pHEMT amplifier yielded gain levels between 10.5 and 11dB for the whole power range, phase variation limited to 2.6° only. The PAE was found to be 25% in average over the dynamic range. This is three times as large as the static bias case. The second and third harmonic vary from -58dBc to -25dBc and -62dBc to -42dBc respectively hence preserving linear behavior.