An Energy-Efficient Dynamic Comparator with Push-Pull Cross-Coupled Pre-Amplifier for SAR ADCs

A double-tail dynamic comparator with a push-pull cross-coupled pre-amplifier is implemented in a 28 nm CMOS process. The push-pull structure is a current reuse technique, which improves the energy efficiency of the comparator. A cross-coupled pre-amplifier structure introduced in [1] is added to achieve low-power and fast comparator decisions. By utilizing push-pull and cross-coupled structure, the comparator exhibits high energy efficiency. Operating under a 0.9-V supply, this comparator attains 46.71-μV input-referred noise and consumes 1.79 pJ per comparison, consequentially reaches 65-time energy efficiency than the standard double tail comparator [2] and 4.5-time than the Elzakker's comparator [3].