A Multi-Stage Zero-Crossing-Based Amplifier Using Floating-Inverter Amplifier With Background Offset Calibration and Self-Timed Loop

Zero-crossing-based amplifiers (ZCBAs) have been used in place of power-hungry operational amplifiers in many applications. We propose a novel five-stage ZCBA to break the trade-off between the slew rate and settling accuracy. Our proposed ZCBA uses a two-stage floating-inverter preamplifier and dynamic comparator with background offset calibration for high power efficiency. The amplifier is clocked by a self-timed loop to maximize the available time for amplification for improved gain. The scaled five-stage charge pump reduces the overshoot while offering a fast slew rate. Simulated in a 28-nm CMOS technology, the proposed ZCBA achieves a signal-to-noise ratio of 57 dB at a sampling rate of 40 MHz and consumes 1.45 mW under a 1-V supply.