A multi-path ring amplifier with dynamic biasing

This paper presents a new method for ring amplifier biasing to improve their stability while maintaining high slew rate. A multi-path ring amplifier is proposed for switched capacitor applications that allows accurate charge transfer at high speeds. Dynamic biasing improves large signal slewing without affecting residue amplifier settling performance. Stable operation is possible because the auxiliary path turns off dynamically, allowing the main path to be optimized for accuracy. The proposed multi-path amplifier was used in the first stage of a pipelined ADC in 180nm CMOS. Measurements show SNDR, SNR, and SFDR of 73.6 dB, 74.6 dB and 85.5 dB respectively, sampled at 10 MS/s, and consumes 7.68 mW.