A low/high-mode power amplifier with envelope-tracking operation

Abstract

This paper presents a low/high-mode power am plifier (PA) for long term evolution (LTE) applications that improves the efficiency in low-power regions. This PA operates in two modes through path control by a shunt switched-capacitor. We use an LTE signal at 1.71 GHz with 16-quadrature ampli tude modulation (QAM), 6.44-dB peak-to-average power ratio (PAPR), and a 10-MHz bandwidth (BW). The dual-path PA with a boosted supply modulator for the envelope-tracking (ET) operation exhibits a power-added efficiency (PAE) of 39.9% and an adjacent channel leakage ratio (ACLR)E-UTRA of -35.7 dBc at an average output power of 27 dBm. The dual-path PA also delivers a PAE of 30.3%, and ACLRE-UTRA of -32.8 dBc at an average output power of 15.5 dBm. Index Terms-Dual mode, envelope tracking (ET), high power mode (HPM), long term evolution (LTE), low power mode (LPM), power amplifier (PA), supply modulator (SM), switched capacitor.