A 500 MS/s Robust 2b/cycle Pipelined-SAR ADC Achieving 64.6-dB SNDR and 82.6-dB SFDR With Linearity Enhancement Techniques

This letter presents a 14-bit 500-MS/s 3-stage pipelined successive-approximation-register (SAR) analog-to-digital converter (ADC). By exploiting robust 2b/cycle SAR ADCs, this ADC incorporates significant voltage and time redundancy. High SFDR is achieved through several linearity enhancement techniques. First, a DAC splitting technique addresses the common-mode voltage matching problem between the input buffer and the sampling circuit. Second, a reference charge neutralization minimizes reference ripple. Finally, a digital harmonic correction is realized with a low-cost and low-latency LUT. Fabricated in a 28-nm CMOS process, the prototype ADC achieves 64.6-dB SNDR and 82.6-dB SFDR at Nyquist.