2017 Volume 14 Issue 8 Pages 20170219
This paper presents an energy-efficient 500 kS/s 8-bit SAR ADC with a novel dynamic comparator. The proposed dynamic comparator employs a cross-coupling cascode based preamp and an inverter-based pseudo-latch. This approach achieves a 40% higher speed, a 24% lower power consumption, and a similar input-referred noise level, compared with a conventional double-tail dynamic comparator. Moreover, only one single phase clock is required for the proposed comparator. The prototype ADC was fabricated in a 0.5 µm CMOS process with an active area of 0.18 mm2. Operating under a 1.8 V supply with Nyquist frequency input signal, the ADC consumes 18.2 µW at 500 kS/s and achieves SNDR and SFDR of 47.5 dB and 63.2 dB, respectively. Walden FoM of 188 fJ/conv.-step is achieved.