An AC-Coupling Parallel Hybrid Supply Modulator Achieving 100MHz Envelope Tracking Power Amplifiers for Wireless Communications

A wideband hybrid envelope tracking supply modulator (ETSM) utilizing a switching converter (SW) with fast V
CAP
tracking path and a bandwidth and efficiency enhanced linear amplifier (LA) is presented. In addition to smaller ripple and lower losses of SW with 4.7uH inductance and 5MHz switching frequency, the use of the recommended fast V
CAP
tracking path produce a higher speed loop and wider converter bandwidth. The SW provides a high percentage of power amplifier (PA) supply load current, reduces the LA low-frequency current and ripple cancellation current, improves the overall system efficiency, while maintaining the best operating point of LA. Through the two proposed compensation methods, the unity gain bandwidth of LA exceeds 670MHz, which meets the strict requirements of 5G New Radio (NR). The supply modulator is fabricated in a 180-nm CMOS process. The post-simulation result shows the tracking of 100MHz sine wave with 79% peak efficiency at 2-W output power and the simulated tone difference reaches 22.6dB.