A 18 – 40GHz Monolithic GaAs pHEMT low noise amplifier

This paper describes the design and measured performance of 18-40 GHz MMIC low noise amplifier developed for mm-wave point to point, SATCOM, LMDS, VSAT and EW applications. A two stage amplifier has been designed and developed on 4-mil thick InGaAs pHEMT with a mature gate length of 0.15 mum low noise process from the foundry, namely, WIN Semiconductor Corp., Taiwan. Two range couplers were incorporated at the RF input & output of the two stage amplifier. This balanced topology enhanced the electrical specifications like stability, return losses and the output power. Rigorous sensitivity checks and electromagnetic simulations were carried at the design stage to ensure proper design centering. The measured data shows better than 3.6 dB of noise figure with an associated gain of 11 plusmn 0.5 dB gain flatness. Excellent input/output return losses better than 15 dB and 1 dB compression more than 6 dBm has been achieved over the entire frequency band of 18-40 GHz. The chip features a size of 2.4 mm times 2.1 mm.