Class-AB Amplifiers and Deterministic Background Calibration

Abstract

A 12-bit 30-MS/s pipelined ADC is realized using single-stage, low-gain, switched class-AB amplifiers. Nonlinear errors due to finite gain are addressed using a deterministic digital background calibration scheme that employs amplifier duty-cycling to minimize the power overhead. The presented ADC occupies an active area of 0.36 mm2 in 90-nm CMOS. It dissipates 2.95 mW from a 1.2-V supply and achieves an SNDR of 64.5 dB for inputs near Nyquist. The corresponding figure of merit is 72 fJ/conversion-step.