UCLA

Cardiac pacemakers and spaceborne instruments require integrated circuits that prioritize low power consumption and high reliability to ensure their longevity over several years. This dissertation aims to enhance power efficiency and functionality of integrated circuits used in these applications.Modern leadless pacemakers have a limited battery lifetime of 1 to 2 years due to their small form factor, necessitating device replacement. To address this issue, a subcutaneous module with a rechargeable battery has been proposed to wirelessly power the pacemaker. However, the battery life of the subcutaneous module is also limited to a few hours due to the high power demand of its power transmitter (TX), making it impractical for an implant. This thesis presents a multi-pulse modulated power link with a wirelessly powered closed-loop cardiac pacemaker to significantly reduce the subcutaneous module power and extend the battery life to a month. Because the power provided by the subcutaneous module is largely reduced, a low-power closed-loop pacemaker is designed to accommodate the power budget. The proposed closed-loop cardiac pacemaker is able to receive bursts of power from the TX, store energy, demodulate pulses, stimulate the tissue, record cardiac signals and transmit the data back. The pacemaker only stimulates when the TX is “on” and uses the stored energy for sensing and data uplink. The pacemaker can apply monophasic, cathodic, current/voltage stimulation with a programmable pulse period and a programmable current/voltage amplitude. The proposed pacemaker advances state-of-the-art reducing the subcutaneous module power consumption making the wirelessly powered closed-loop pacemaker system feasible. For the spaceborne instrument application, the thesis addresses the effects of total ionized dose (TID) from gamma and cosmic ray exposure during a mission lifetime. This exposure can distort baseline readings in instrumentation by changing DC conditions of electronics, limiting the fidelity of collected measurements. To address this issue, a gamma dosimeter is integrated within a high-voltage (HV) CMOS process for system monitoring and calibrating high-voltage control circuitry for microwave-based spaceborne science instrumentation. The proposed CMOS dosimeter exploits differences in radiation sensitivity between the threshold voltage of the available I/O and core devices in HV CMOS. With a built-in dual-slope-based digitizer, the effects of clock variation and amplifier offsets are alleviated in the dosimeter, providing an accurate and temperature-independent measure of the total received dose.