High Linearity Ka-band InP HBT MMIC Amplifier with 19.8:1 IP3/Pdc LFOM at 48 GHz

This paper describes the design and measured performance of a linear efficient Ka-band InP DHBT PA with an IP3/Pdc ratio (LFOM) of 19.8:1 at 48 GHz and 14.1:1 at 40 GHz. The MMIC PA is based on an InP DHBT technology with peak f
T
and f
max
of > 300 GHz and > 600 GHz, respectively, and achieves among the best LFOM at Ka-band above 40 GHz from a MMIC matched amplifier. The amplifier is a single stage four-way combined design optimized for a combination of power and PAE at < 2-dB compression. A peak PAE of 30.5% and associated Pout of 22.2 dBm is obtained at 40 GHz. The P1dB is 21.2 dBm with a PAE of 28.3% and a corresponding IP3 of 36.1 dBm. A remarkable IP3-P1dB = 14.9 dB is significantly higher than the~ 10 dB rule of thumb for semiconductors. At 48 GHz, a peak IP3 of 36.6 dBm and LFOM of 19.8:1 is achieved. Under a 200MHz QPSK modulation, linear PAE’s of 17.4-19.5% for EVM linearity of 5% under an optimum bias at 40 GHz was obtained. This work demonstrates among the highest IP3/Pdc LFOMs reported for a MMIC above 40 GHz.