A 43% PAE inverse Class-F power amplifier at 39–42 GHz with a λ/4-transformer based harmonic filter in 0.13-µm SiGe BiCMOS

This paper presents a 2-stage Class-F
^-1
power amplifier in 0.13 μm SiGe BiCMOS process, achieving 43% peak PAE and 18 dBm Psat at 40.5 GHz. The PA utilizes simple but effective λ/4-transformer based 2nd harmonic-tuning load and relies on a native low capacitive reactance to short all other higher-order harmonics. This reduces the harmonic load complexity significantly and loss thereof, exceeding PAE over 40% at 39.5-42 GHz. The PA achieves >17 dB small signal gain, >15 dB power gain, and 16 dBm OP
_-1dB
at 39-43 GHz. The P
_out
for <;5% EVM is 15.5 dBm with QPSK/8PSK modulation signals, and 13.5 dBm with 16/64/128 QAM modulation signals. The PA occupies 0.95×0.6 mm
²
including pads.