Highly linear and reliable low band class-O RF power amplifier in 130 nm CMOS technology for 4G LTE applications

Abstract

This paper presents a highly linear low-band 706MHz LTE compatible class-O RF power amplifier in 130nm CMOS technology for handheld wireless applications. Class-O topology uses a combination of common-source and common-drain amplifiers working in parallel with high linearity without the need for digital predistortion(DPD). With continuous wave measurements, 1-dB compression point (P1dB) of 30.6dBm and peak power added efficiency (PAE) of 45.2% is achieved. For the modulated signal measurements, the amplifier is tested with 16-QAM 20MHz LTE signal with peak-to-average-power ratio of 6.54 dB. The amplifier meets the stringent LTE specs with an ACPR less than −30 dBc for both EUTRA and UTRA1 with average output power of 27 dBm and PAE above 20%. Owing to the voltage following between gate source junctions in the common-drain amplifier in addition to cascode structure of common-source amplifier, the stress is significantly reduced at the transistor terminals. The reliability is demonstrated by operating the amplifier in nominal and worst VSWR conditions.