A Class E Digital Transmitter for 16-APSK

A digital transmitter architecture is described composed of two independent class E amplifiers with different saturate output powers (P OUT ). Their output ports are connected directly together without a switch or combiner. The two amplifiers are enabled or disabled by alternatively biasing their gates in synch with the envelope of the input signal. The transmitter is optimised for 16 state amplitude phase shift keying (16-APSK). Under simulation, the two class E amplifiers were optimised for a P OUT of 13.6 dBm and 22.7 dBm. 71.4% and 78.2 % power added efficiency (P AE) was achieved respectively. The same transistor was used for both amplifiers and the different P OUT defined by the quality factor (Q) of their output bandpass filter (BPF). A practical implementation achieved 49.8% and 45.6% PAE at P OUTS of 14.0 dBm and 20.3 dBm respectively. With a 16-APSK signal, 46.9% PAE was achieved at 19.8 dBm P OUT, with an error vector magnitude (EVM) of 5.7%.