Abstract: In order to ensure the long-term stable working state and detection resolution of implantable intraocular pressure sensor, a 10 bit, 20 KS/s low power successive approximation analog to digital converter (SAR ADC) for implantable intraocular pressure detection sensor application is proposed in this paper. The DAC adopts a full capacitance array design. The symmetrical capacitor array structure improves the matching accuracy of the scaling capacitor; Comparator with three-stage pre-amplifier and dynamic latch structure ensures the offset calibration function. The circuit is implemented with SMIC 0.18 μm CMOS technology and the post-simulation results show that the effective number of bits (ENOB) can reach 9.4 bit at 20 KS/s sampling rate, and the average power consumption is only 44.7 μW.