Wirelessly-Powered CMOS Front End for Locomotive IC Applications

Abstract

The steady leaps in miniaturization made in the realm of integrated circuit (IC) design has opened up prospects for a vast number of interesting possibilities. One of the possibilities is the idea of a locomotive integrated circuit. Unlike a typical IC that is soldered on a printed circuit board (PCB), locomotive ICs can be untethered and free to move around its environment. Recent research has demonstrated locomotive ICs that can potentially be used for non-invasive medical procedures including precise drug delivery targeted to specific problematic region of the body.

Recent research has demonstrated locomotion using a variety of schemes including using electrolytic bubbles and manipulation of Lorentz force in a uniform magnetic field. In this work a wireless front end for a locomotive IC that relies on surface acoustic wave (SAW) devices is explored. A SAW device is a piezoelectric material that converts electrical stimulus into mechanical vibrations. For this work, the SAW device has been designed specifically to enable the mechanical vibration generated by electrical stimulation at 177MHz to potentially actuate motion.

This work demonstrates a complementary metal-oxide semiconductor (CMOS) front end IC implemented in 180nm process that can potentially be used for locomo-tion by means of electrical excitation of a SAW device with an on-chip PLL frequency synthesizer. The energy required to power the IC is obtained through resonant wire-less power transfer between a pair of PCB inductor coils. The IC also contains power conditioning blocks that rectify the alternating voltage across the receiver inductor coil and generates a regulated DC voltage that powers the PLL frequency synthe-sizer. The entire proposed locomotive system consisting of PCB receiver coil, CMOS IC and SAW device fits inside an area of 1.5cmX1.9cm.