184 μW ultrasonic on–off keying/amplitude‐shift keying demodulator for downlink communication in deep implanted medical devices

An ultrasonic on–off keying/amplitude‐shift keying demodulator using standard 0.18 μm CMOS technology is proposed, intended for recovering the identification number of an implanted medical device transmitted from an external base station. The CMOS integrated ultrasonic demodulator consists of a low‐noise amplifier, variable‐gain‐amplifiers, an offset cancellation circuit, an envelope detector circuit and a hysteresis comparator. Downlink data transmission of 50 kb/s data signals in the 1 MHz band is successfully demonstrated, the power consumption is about 184 μW from a 1.5 V supply. The architecture is described, and the measurements performed confirm the theoretical result.