Highly efficient class-G supply-modulated amplifier with 75 MHz modulation bandwidth for 1.8–1.9 GHz LTE FDD applications

This paper presents a broadband and highly efficient class-G supply modulated amplifier system. The system covers the full LTE band 1805-1880 MHz. The core element is the class-G supply modulator which switches the supply voltage of the RF power amplifier between three discrete levels with a minimum pulse duration of 2.5 ns. Measurement results are presented for a carrier aggregated signal using five subcarriers with modulation bandwidths from 5 MHz to 20 MHz each. In combination with digital predistortion the system achieves 38.5% PAE with -41 dB EVM and -45 dB ACLR for a 75 MHz multi-carrier signal with a PAPR of 10.4 dB at 38.5 dBm average output power. The total efficiency enhancement achieved by the class-G modulation is 13 percentage points.