Modified elliptic response bandpass filtering integrated high‐efficiency GaN MMIC power amplifier at 24–28 GHz

Abstract

SummaryIn this paper, an out‐of‐band suppression enhanced high‐efficiency millimeter‐wave (mm‐wave) gallium nitride (GaN) microwave monolithic integrated circuit (MMIC) filtering power amplifier (FPA) is presented. A modified elliptic response bandpass filtering (BPF) output matching network (OMN) is used to achieve low loss and high out‐of‐band rejection. The circuit of the presented BPF OMN is given and its synthesized method is introduced. The simulated S‐parameters show that the OMN has a low‐loss in‐band response and a desired out‐of‐band rejection performance with two transmission zeros (TZs). To demonstrate this idea, a two‐stage 24–28‐GHz GaN MMIC PA is designed and implemented in a 0.15‐μm GaN‐on‐SiC process, with a mask area of 2.4 × 1.0 mm2. Experimental results show that the realized MMIC PA achieves a small signal gain of 18.8 dB from 24 to 28 GHz with ±1.2‐dB gain flatness and 40‐dB rejection at 19.43 and 33.8 GHz. The saturated power‐added efficiency (PAE) is higher than 29% from 24 to 28 GHz, with a peak PAE of 36.3% at 27 GHz. The output power is within the range of 33.8 to 35.6 dBm in the operating band. For a 100‐MHz five‐carrier LTE signal, the PA can achieve ACLR better than −40 dBc over the band with digital predistortion.