Ultra-low-voltage low-power dynamic comparator with forward body bias scheme for SAR ADC

Abstract

An ultra-low-voltage two-stage dynamic comparator is proposed with a forward body bias (FBB) scheme for successive approximation register (SAR) analogue-to-digital converters (ADCs). The proposed FBB scheme for a preamplifier and latch stage reduces the delay time remarkably under a low supply voltage. At 0.4 V, the power consumption is 4.48 nW, and the delay can be decreased to 593.9 ns for ΔVin = 0.1 mV and fclk = 100 kHz. The RMS equivalent input-referred noise of the comparator is 0.136 mV. The total offset is 13.7 mV, and offset fluctuation is 0.183 mV with the proposed structure. Both the input-referred noise and offset fluctuation are <0.5 least-significant bit for a 10-bit SAR ADC at 0.4 V.