A sub-micron CMOS programmable charge pump for implantable pacemaker

Abstract

In pacemaker design the main concerns are reliability, functionality, operating life and miniaturization. A fundamental role in miniaturization is due to the increased circuit integration; hence low power circuit solutions that can be integrated in sub-micron CMOS technology are highly desirable. This work proposes a voltage multiplier suitable for pulse output generation in an implantable pacemaker, implemented in a standard, low-cost CMOS 0.8 μm technology. The circuit can operate within a supply voltage range of 2.8 V to 2 V, corresponding to the voltage capability provided by the single lithium iodine cell, ubiquitously used in pacemaker. Fine programmability of the output has been achieved, thus allowing the choice of the optimum tradeoff between stimulation efficacy and battery longevity. Moreover the proposed solution takes care of minimizing the parasitic coupling and disturbances between the charge pump and other blocks in the system. Finally the measured steady state current consumption is smaller than 2 \mu {\rm A} @V_{dd}=2.8\ {\rm V}.