A 1 µ A front-end for pacemaker atrial sensing channels

A low-power front-end for a pacemaker atrial sensing channel based on peak detection is presented. The very tight system specifications in terms of power consumption and output noise, the need to operate with a supply voltage decreasing from 2.8 V to 2 V during the battery lifetime, and additional functionalities with respect to standard front-ends, like gain programmability and early sensing, make the design of this system a challenge. The front-end includes a preamplifier and a 3rd SC filter, and it is fabricated in a 0.8 µm CMOS technology. It features a 1 µA current consumption from a single nominal 2.8 supply (which, however, can decrease down to 2V), 5.1 mVrms total output noise and a maximum voltage gain of 740.