An active electrode (AE) for vital signal acquisition with accurately tunable high-pass corner frequency (fHP) has been proposed. The AE has been implemented with a standard 55nm CMOS process with a core area 0.11mm2. The post-layout simulation results show that up to 310Gohm of the PR value can be achieved. Compared with the conventional PR, the variation of the calibrated PR value is reduced by 3 decades within 0~85°C temperature under various process corners. In addition, the linear input range of the AE up to 164mVpp, demonstrating its potential capability to be applied to recording vital signals merged with large artifacts.