A 44-GHz-high IP3 InP HBT MMIC amplifier for low DC power millimeter-wave receiver applications

This paper reports on what is believed to be the highest IP3/P/sub dc/ power linearity figure of merit achieved from a monolithic microwave integrated circuit (MMIC) amplifier at millimeter-wave frequencies. The 44 GHz amplifier is based on an InP heterojunction bipolar transistor (HBT) technology with f/sub T/'s and f/sub max/'s of 70 and 200 GHz, respectively. The 44-GHz amplifier design consists of four prematched 1/spl times/l0/spl mu/m/sup 2/ four-finger (40-/spl mu/m/sup 2/) heterojunction bipolar transistor (HBT) cells combined in parallel using a compact /spl lambda//8 four-way microstrip combiner. Over a 44-50-GHz frequency band, the amplifier obtains a gain of 5.5-6 dB and a peak gain of 6.8-7.6 dB under optimum gain bias. At a low bias current of 48 mA and a total dc power of 120 mW, the amplifier obtains a peak IP3 of 34 dBm, which corresponds to an IP3/P/sub dc/ power ratio of 21:1, a factor of two better than previous state-of-the-art MMIC's reported in this frequency range. By employing a thin, lightly doped HBT collector epitaxy design tailored for lower voltage and higher IP3, a record IP3/P/sub dc/, power ratio of 42.4:1 was also obtained and is believed to be the highest reported for an MMIC amplifier of any technology. The new high-linearity HBT's have strong implications for millimeter-wave receiver as well as low-voltage wireless applications.