Efficiency enhanced switched mode power amplifier for digital RF transmitters

This paper outlines a design concept of a PWM driven switched mode power amplifier (SMPA) with direct filter connect, making up all circuitry necessary for an energy efficient digital RF transmitter. For the output matching network design the simplified real frequency technique (SRFT) has been extended in a way to achieve high output power in signal band while reducing power consumption by controlling the termination for out of band components simultaneously. For concept verification the PA was designed and realized using a commercially available GaN 10W HEMT (Cree CGH40010F). The proposed PA shows a significantly increased DC to RF efficiency for PWM excitation.