Design Considerations for a Driver Power Amplifier with the Supply Modulation Concept

In this study, the design of a driver power amplifier with the supply modulation concept is investigated and realized. High-power amplifiers require significant input power at the peak power operation. To provide this specification, driver amplifiers, which directly affect the efficiency and linearity of the transmitter systems, are used as the input stage. Considering the composite power and spectral efficiencies of two-stage power amplifier modules, a deep Class-AB driver amplifier for the n78 5G band (3.3 - 3.8 GHz) is designed with a CGH40006P GaN high-electron-mobility transistor (HEMT). The driver power amplifier has an output power of 33.8 dBm at the 3-dB compression point, a small signal gain of 15.8 dB, and a power-added efficiency (PAE) of 68% at 3.5 GHz. Furthermore, the driver power amplifier demonstrates a PAE improvement of 10% with the supply-modulated operation.