A Low-Noise Dynamic Comparator with Charge-Pump Pre-Amplifier

This paper presents an energy-efficient low-noise dynamic comparator with a passive charge-pump pre-amplifier (CPP). We demonstrate the effectiveness of a passive pre-amplifier, cascaded to a dynamic comparator, to reduce input referred noise (IRN) of the comparator by a factor of pre-amplifier gain. Furthermore, the passive pre-amplifier, originating from a switched-capacitor amplifier, consumes only switching power, making it less burdensome to add it to the dynamic comparator. The proposed dynamic comparator, designed in a 180-nm CMOS process, achieves 37.1 µV of IRN, 817 fJ of energy per conversion under a 1.2-V supply, and a sampling frequency of 80 kHz. This results in a figure-of-merit of 1.12 nJ·µV<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>.