Design of an Efficient 24–30 GHz GaN MMIC Power Amplifier Using Filter-Based Matching Networks

Abstract

A broadband GaN MMIC power amplifier (PA) with compact dimensions of 1.94 × 0.83 mm2 is presented for 5G millimeter-wave communication. To guarantee output capability at the operating band edges where serious performance degradation is likely to occur, the appropriate large-signal matching model and optimal impedance domain need to be carefully determined through load-pull analysis. Broadband matching networks (MNs) in the lowpass form are thereafter developed based on the Chebyshev filter synthesis theory. Using high-pass interstage MN in conjunction with parallel RC lossy circuits to compensate for the transistor’s negative gain roll-off slope ensures a flat frequency response. The input MN is designed as a band-pass filter due to the reactance extracted from the input side of the stabilized device exhibiting series LC resonance characteristics. Measured on-wafer pulsed results for the proposed three-stage PA demonstrate up to 30.9 dBm of output power, more than 28.6 dB of small-signal gain, and a peak power-added efficiency (PAE) of 35.6% at 27 GHz. Both uniform gain and saturated output power (Psat) are achieved across 24–30 GHz with fluctuations of less than 0.8 dB.