A reactively load-modulated RF low-power amplifier with multilevel supply voltage for multi-standard RF front-ends

A combination of multilevel voltage supply and reactive load-modulation is proposed for the improvement of PA efficiency over a high dynamic range. Simple theoretical analysis is presented to justify the investigation of the proposed method. Moreover, a 20dBm reactively load-modulated PA is designed around a packaged GaAs E-pHEMT. The PA achieves >50% PAE up to 15dB output back-off at 2.3GHz under CW operation, and well above 40% from 1.8 to 2.5GHz and up to 10dB backoff. The application of reactive load-modulation is shown to counterbalance the efficiency degradation caused by the use of a small number of discrete supply voltages.