A Rail-to-Rail Input Class-AB Linear Amplifier with Improved Bandwidth and Slew-Rate for Envelope Tracking Supply Modulators

This paper presents a rail-to-rail input, class-AB output linear amplifier for an envelope tracking supply modulator for radio-frequency (RF) power amplifier applications. Flipped voltage follower (FVF) and slew-rate enhancement circuits are used to improve the bandwidth and the output slew-rate of the linear amplifier. This makes it suitable for high peak-to-average power ratio RF signals in modern mobile communication systems. The linear amplifier is designed and simulated in 180 nm CMOS technology. The simulation results show improvements of about 75% unity-gain-bandwidth, 111% rise slew-rate, 121% fall slew-rate, and 100% rail-to-rail input sine signal frequency, compared to a linear amplifier without both FVF and slew-rate enhancement.