Wirelessly Powered, Batteryless Closed-loop Biopotential Recording IC for Implantable Leadless Cardiac Monitoring Applications

This paper reports on a low-power biopotential recording IC (Integrated circuit) for an implantable leadless cardiac monitoring application. The IC is designed to realize fully batteryless operation through wireless energy harvesting. The IC consists of an RF energy harvester, power management unit, biopotential acquisition instrument amplifier, ADC (Analog-to-digital converter), clock recovery unit, receiver, and transmitter. The energy harvester peak conversion efficiency is 26%, and the power management unit provides a 1.2 V stable supply to the system and transmitter. Two ISM bands with 40.68 MHz and 915 MHz center frequencies were utilized for the downlink and uplink. The proposed IC eliminates dependency on the local oscillator, and the downlink baseband signal allows both clock and data for the system's operation. The total power consumption of the IC is 8.8 mu W at the system clock's 100 kHz operation. The chip was implemented in the 180 nm CMOS process and was successfully verified for autonomous, closed-loop control under a batteryless environment.