A Broadband Almost-Digital RF Transmitter With an Efficient Power Amplifier

A new architecture of an almost-digital RF transmitter is proposed. It consists of easy-to-have functional modules. Among the modules, a broadband Doherty amplifier is focused through a modified design approach. A proof-of-concept transmitter is built and measured. It demonstrates quite comparable performances: more than 40% of power-amplifier efficiency, adjacent channel leakage ratios between -26 and -37 dB, and average 2.6% of error vector magnitude over a frequency band from 0.7 to 1.1 GHz, which corresponds to a fractional bandwidth of 44%, when it is driven by a signal with 5.6 dB of peak-to-average power ratio.