A 2-μm InGaP/GaAs Class-J Power Amplifier for Multi-Band LTE Achieving 35.8-dB Gain, 40.5% to 55.8% PAE and 28-dBm Linear Output Power

This paper describes the first linear multistage class-J power amplifier (PA) fabricated in a 2-mu m InGaP/GaAs HBT process for multi-band long-term evolution (LTE) applications. It includes a three-stage topology composed by a pre-driver, driver, and a class-J main stage, to optimize the output power and power-added efficiency (PAE) over 1.7-2.05 GHz, thus encapsulating the LTE bands 1 to 4, 9 to 10, 33 to 37, and 39. This is achieved through a novel analog pre-distorter linearizer, which features two sub-circuits for AM-AM and AM-PM linearization. The PA prototype meets the standard's adjacent channel leakage ratio (ACLR < -30 dBc) at a maximum linear output power of 28 dBm. Tested at 2.05 GHz and for a 16-QAM scheme, the maximum error vector magnitude is 3.38% at a 28-dBm output power, which corresponds to a PAE of 40.5%-55.8% across bands. The input return loss is < -15 dB and the maximum power gain is 35.8 dB, while demonstrating an unconditional stable characteristic from dc up to 5 GHz. The die area is 950 mu m x 900 mu m. The performance metrics compare favorably with the state-of-the-art.