100 MHz, 85% efficient integrated AlGaAs/GaAs supply modulator for RF power amplifier modules

A 100 MHz DC-DC converter for RF power amplifier modules employing polar modulation is presented. A resonant low side gate driver and phase shedding/segmentation in the output stage are used for light load efficiency improvement. The proposed two-phases four-segments flip chip DC-DC converter is implemented in 0.5 μm AlGaAs/GaAs p-HEMT technology and occupies 2.5×2 mm² for the two segments. An efficiency improvement of 5% is achieved at 4.5 V to 1 V conversion using the resonant low side gate driver. The peak efficiency at 4.5 V/3.3 V and 2 A output current is 85% with the peak value maintained as the load current changes from 0.2 A to 2.8 A under phase shedding/segmentation.