A low-power continuous-time comparator with enhanced bias current at the flip point

Comparator is one of the most important fundamental cells for many mixed-signal circuits. The novel low-power CMOS voltage comparator proposed in this paper is composed of a conventional comparator and an auxiliary branch. The conventional comparator needs large tail current to get small propagation. In fact, the tail current at the flip point determines the comparator propagation. In this proposed comparator, the auxiliary branch can detect the flip point and compensate the tail current at this point. Therefore, the tail current can be biased at a much smaller value to decrease the power consumption with the same propagation as the conventional comparator. Based on a 0.5μm standard CMOS technology, the proposed comparator has been designed and verified adequately. Compared with the conventional comparator, more than 60% power reduction is achieved with same propagation delay.