Recent power amplifiers for transmit/receive (TR) modules have been configured in the Class AB or push-pull mode with a theoretical efficiency of 78.5% and an operational efficiency of only 20% at X-band (8-12.5 GHz) frequencies. In this paper, we present results of a simulation study of a new scheme of power amplifier, in particular, an optoelectronic (OE) Class AB push-pull microwave power amplifier (MPA). With this amplifier, high circuit efficiency and reasonable output power can be achieved at X-band by utilizing a pair of novel photoconductive semiconductor switches (PCSSs) based on intrinsic GaAs instead of the traditional microwave transistors.