Differentially coupled outphasing WCDMA transmitter with inverse class F power amplifiers

This paper presents design and practical implementation of an outphasing WCDMA transmitter with highly efficient inverse class F packaged LDMOS power amplifiers (PA's). Both PA's are modeled as phase-modulated voltage sources connected in series, being differentially coupled at the output. The implementation of differential coupling with voltage sources is an alternative to the conventional design. The circuit operates as theoretically predicted. A peak power of 24 W with a peak drain efficiency of 61% and for a 5 dB PAR (peak to average ratio) QPSK signal a drain efficiency of 32 % is reported. The performance of the transmitter and measurement results are presented.