Abstract: High precision,high linearity and low power analog-to-digital converters (ADCs) are an important part of thein sensor systems.Compared with other types of analog to digital converters,successive approximation register (SAR) ADC has the advantages,for example: simple structure,small size,low power consumption,easy programmable and high degree of digitization,as a result,SAR ADC has been widely used in wireless sensor networks.In this work,a novel high-precision digital time-domain comparator which can be applied to both single-ended and differential SAR ADCs is proposed,this comparator proposed can achieve both high-resolution and high-speed.Compared with the traditional time domain comparator,the proposed time domain comparator has the characteristics of high precision and high speed.