Low Power High Speed Switched Current Comparator

Current mode implementation provides an alternative to high speed data conversion systems for low voltage applications. The pursuing of speed and accuracy of data conversion makes comparator critical. This paper presents a novel switched current (SI) comparator which achieves high speed without sacrificing either accuracy or power dissipation. Employing a class AB current mirror as the input stage, the desired accuracy is attained and a dynamic class AB latched comparator is used to achieve high operation speed. Both of the input stage and the latched comparator are low power blocks and the average supply current is only 85 muA during comparison. The proposed comparator is designed and simulated in TSMC 0.25 mum CMOS process with 1.8 V supply voltage. The proposed SI comparator achieves a current sensitivity up to 0.2 muA and a sampling frequency up to 100 MHz, with only 153 muW of total power consumption.