A High-Efficiency Envelope-Tracking Supply Modulator Using a Class-G Linear Amplifier and a Single-Inductor Dual-Input-Dual-Output Converter for 5G NR Power Amplifier

Abstract

This article presents a hybrid envelope tracking supply modulator (ETSM) comprising a class-G linear amplifier (LA), a single-inductor dual-input-dual-output (SIDIDO) converter and a switching amplifier (SA) for 5G new radio (NR) power amplifiers (PAs). With an additional supply rail, the class-G LA detects the amplitude of the input signal in real-time, adaptively utilizes the higher supply rail when the signal exhibits large swings, and seamlessly transitions to the lower supply rail when the signal swing decreases. This operation effectively reduces the average voltage drop of LA’s bias, sinking and sourcing current, thus improving the supply modulator (SM) efficiency at tracking bandwidth (BW) as high as 200 MHz. To mitigate the distortion induced on the output envelope due to high-speed switching between the different supply rails, a smooth transition technique is introduced for high linearity. An SIDIDO converter is employed to generate the LA’s supply rails efficiently and cost-effectively. The SM is fabricated in a 65-nm CMOS process. It measures 83.4% peak efficiency when tracking the NR 200-MHz envelope with 1–5-V wide output swing range at the PA model of $5~\Omega $ in parallel with 200 pF capacitance.