A 0.8-V 420nW CMOS switched-opamp switched-capacitor pacemaker front-end with a new continuous-time CMFB

A low-voltage low-power pacemaker Front-End for detecting QRS complex is presented in this paper. The circuit includes a switched-opamp switched-capacitor (SO-SC) preamplifier with a gain of 40 db, a fourth-order Butterworth SO-SC filter with a sampling frequency of 1 kHz, and an opamp with a new continuous time common mode feedback (CMFB) circuit which is able to operate with a very low supply voltage. The whole circuit operates with a supply voltage of 0.8 V and consumes a power of 420 nW.