A 1-μA front end for pacemaker atrial sensing channels with early sensing capability

A low-power front end for a pacemaker atrial sensing channel based on level 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 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 third-order switched capacitor filter, and it is fabricated in a 0.8 μm CMOS technology. It features a 1 μA current consumption at a supply voltage of 2.7 V, and an input referred total noise of 6.9 μV_rms.