A new high-speed low-power and low-offset dynamic comparator with a current-mode offset compensation technique

Abstract

In this paper a new low-power high-speed offset-compensated dynamic latched comparator is presented. The proposed comparator uses a two-stage charge-steering preamplifier to achieve high pre-amplification voltage gain. Higher input voltage range of the latch stage significantly reduces the delay time of the latch and relaxes the need for high current in the regeneration process which ensures low-power structure. In addition, a new digitally controlled offset cancellation circuit based on the current-steering structure is used to reduce the offset of comparator. Offset voltage reduction in the startup time is the key advantage of the proposed calibration technique which does not require refreshing the offset cancellation process. Post-layout simulation results in 0.18µm standard TSMC CMOS process show that the designed comparator dissipates 135µW of power consumption from a 1.2V supply voltage and has the 1mV accuracy while operating at 1GHz clock frequency. The power and delay time of the proposed comparator are less than about 10% of the new state-of-the-art comparator. Furthermore, from the Monte-Carlo analysis, the standard deviation of the input referred offset voltage in typical process corner and temperature is obtained about 17.53/1.09mV before and after offset cancellation, respectively.