Envelope tracking RF power amplifier with lead-lag modulator

Abstract

Envelope tracking (ET) can increase RF Power Amplifier (PA) efficiency by manipulating its supply voltage in harmony with the transmitted signal. The lead-lag modulator described here uses a switched mode power supply (SMPS) for the low frequency envelope content and a linear amplifier (LA) with a synthetic output impedance for the high.When tested with an 8 dB peak-to-average power ratio (PAPR) 5 MHz bandwidth 3GPP Long Term Evolution (LTE) signal, the complete PA achieved a DC-to-RF efficiency of 46% at 6 W output power with a first channel adjacent channel power ratio of -27 dBc.Index Terms -Active circuits, amplifiers, energy efficiency, power amplifier switched mode power supply.