High IP3-low DC power 44 GHz InP-HBT amplifier

Abstract

This paper reports on what is believed to be the highest IP3/P/sub DC/ power linearity figure of merit (LFOM) achieved from a MMIC amplifier at millimeter-wave frequencies. The 44 GHz amplifier is based on an InP HBT technology with f/sub T/s and f/sub max/s of 70 GHz and 200 GHz respectively. The single stage design consists of four pre-matched 1/spl times/10 /spl mu/m/sup 2/ four-finger HBT cells combined in parallel which consumes 48 mA of current through a 2.5 V supply. At this bias, the amplifier obtains a gain of 5.5-6 dB over a 44-50 GHz frequency band and achieves a peak gain of 6.8-7.6 dB under a bias current of 80 mA. At the low bias current of 48 mA and a total DC power of 120 mW, the amplifier obtains a peak IP3 of 34 dBm at 42 GHz which corresponds to a record IP3/P/sub DC/ power ratio of 21:1, a factor of 2 better than the state-of-the-art MMCs reported in this frequency range. The IP3 characteristics of the 44 GHz amplifier also indicate that the maximum IP3 and optimum 1P3/P/sub DC/ LFOM both occur at lower V/sub ce/'s for low current density operation, enabling the high LFOM. These characteristics make InP HBTs attractive for low power MM-wave receiver applications.