Reconfigurable RF PWM PA architecture for efficiency enhancement at power back-off

A transformer-combined fully-integrated reconfigurable RF PA architecture for fully digital transmitters is proposed. The RF PA dynamically switches between several modes in order to achieve efficiency enhancement at power back-off and simultaneously producing a multi-level RF PWM signal. Multilevel RF PWM is realized by driving one or two power amplifiers (PAs) with a PWM signal, while the others are turned off or working at full power. This architecture is implemented in a 40nm standard CMOS technology where the PAE at 15dB back-off from the peak power is still 17% PAE while achieving 27% PAE at peak with 31.5 dBm peak output power. Therefore, this architecture is almost 3.5 times more efficient than a conventional class B architecture at power back-off.