Design of CMOS telemetry circuits for in-vivo wireless sonomicrometry

In this paper we present the design and implementation of CMOS telemetry circuits that can be used for in-vivo wireless sonomicrometry. The proposed transmitter circuit uses a digital pulse modulator that directly drives a sonomicrometry crystal using a train of ultra-wide-band pulses. The receiver is also designed using a pulse modulator which is configured to measure the energy of the ultrasonic pings received by the crystal. Using measured results from a prototype fabricated in a 0.5-μm CMOS process we verify the operation of the telemetry circuits and using 1mm diameter sonomicrometry crystals we present measurement results using three types of phantom setups: (a) a saline bath; (a) a chicken bone/bone-marrow; and (b)chicken breast and tissue. The measurement results demonstrate that for the three phantoms the integrated telemetry system can be used for bi-directional data transfer at a rate of 1 Kbps with a power dissipation of 611 μW.