This paper presents a new offset-biased autozero comparator for the design of an ultra low-power charge redistribution Successive Approximation Analogto- Digital Converter (SA-ADC) dedicated to biomedical applications. The circuits are realized in CSM 0.18μm CMOS technology. The simulated results have shown that the power consumption of the 10-bit ADC is only 6.2μW at a single supply of 1.8V whilst sampling at a frequency of 64kHz, with conversion time of 187.5μs. The energy per quantization level is less than 0.1pJ/level.