A Switched Capacitor based Micro-stimulator for Deep Brain Stimulation

Abstract

Gaurav, Bawa. A Switched Capacitor based micro-stimulator for Deep Brain Stimulation. (under the direction of Dr. Maysam Ghovanloo and Dr. Leda Lunardi)

This thesis presents a novel technique for the development of an implantable stimulator for Deep Brain Stimulation. The key idea is to harvest energy from an inductive link using an efficient switching mechanism at the secondary side. To validate the concept, extensive characterization was performed by simulating explicit differential equations in MATLAB in addition to a prototype implementation in standard CMOS technology. In principle, a zero current switching methodology at the secondary coil has proved to be extremely energy efficient due to no extra wastage of power in the parallel resonant circuits.

A high efficiency full-wave rectifier has been implemented in standard CMOS technology, which ensures a measured efficiency of ~ 85 % while delivering ~ 19 mW of power to the load at 500 KHz input frequency. The underlying principle is that of synchronous rectification, minimization of MOS switch resistance through biasing in deep triode and blockage of reverse currents from the load to source using a lossless capacitive voltage divider technique.

Dual-mode backtelemetry has been incorporated in a full-wave active rectifier with minimal area overhead and an increased data rate and reading range in measurement results, when the rectifier loading varies over time.