A 44-GHz-high IP3InPHBT MMIC amplifier for low DC power millimeter-wave receiver applications

This paper reports on what is believed to be the highest IP3/P-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(T)'s and f(max)'s of 70 and 200 GHz, respectively. The 44-GHz amplifier design consists of four prematched 1 x 10 mu m(2) four-finger (40-mu m(2)) heterojunction bipolar transistor (HBT) cells combined in parallel using a compact 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 de power of 120 mW, the amplifier obtains a peak IP3 of 34 dBm, which corresponds to an IP3/P-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-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.