This paper studies several excellent works of comparator constructions of comparators and compares them with the Double-tail latch-type comparator. Based on the Elzakker comparator, the comparator with a dynamic bias reduced the use of energy by partly discharging the preamplifier's output nodes. Edge-Pursuit Comparator(EPC) demonstrates a new approach to reducing energy consumption by automatic energy optimization. Apart from the designs that optimize energy consumption. Low-Noise Self-Calibrating Dynamic Comparator provides the low-offset feature while in relatively low power consumption.