An 85 dB DR 4 MHz BW Pipelined Noise-Shaping SAR ADC With 1–2 MASH Structure

A pipelined noise-shaping successive approximation register (NS-SAR) ADC with 1–2 multistage noise-shaping (MASH) structure is presented. Two-stage pipelined structure consisting of 5 bit NS-SAR and 4 bit NS-SAR quantizers enables 3rd-order noise-shaping. A single operational transconductance amplifier (OTA) is shared by an integrator for noise-shaping and a residue amplifier for pipelining to maximize the power efficiency. The measured dynamic range (DR) is 84.6 dB when the sampling rate is 83.3 MS/s, bandwidth is 4 MHz, and power consumption is 3.5 mW showing Schreier figure-of-merit (FoM_S,DR) of 175.2 dB. The proposed ADC structure greatly relaxes design requirement of each SAR quantizer and can achieve high resolution and wide bandwidth with good power efficiency.