Comparison of CMOS power amplifier topologies for a wideband Doherty architecture

Abstract

Two differential radio frequency (RF) power amplifier (PA) architectures are presented in this paper both of which can be used to implement a wideband Doherty PA. Classic PA architecture is compared to a SB (SB) PA in order to determine an architecture that offers the widest input impedance match without external component tuning. Both amplifiers presented in this paper have been designed to output an average of 10.5 dBm of continuous wave (CW) power with 1.8 V supply. The classic PA architecture is tuned to 1.9 GHz central frequency by external components and has a bandwidth of 500 MHz at S11=-10 dB. The SB PA architecture has an operating range spanning from 0.8 GHz to 2.2 GHz at S11=-10 dB. SB PA has a higher power added efficiency (PAE) at output compression point (OR-P1dB) in the whole 1.2 GHz-2.4 GHz range by 3 %-7 % with a peak efficiency of 31 %. The presented results indicate that a SB RF PA architecture can be implemented designing a wideband Doherty PA.