An Analog Front-End and ADC Integrated Circuit for Implantable Force and Orientation Measurements in Joint Prosthesis

The paper presents an analogue front-end and ADC integrated circuit for processing signals of sensors implanted into joint prosthesis. The circuit is designed to be operated with Wheatstone bridge sensors, such as strain gauges, pressure, Hall Effect, magneto-resistive sensors, etc. It performs sensor supply multiplexing, sensor signal amplification with chopper modulation, offset compensation and 14-bit analog to digital conversion in a single chip. It can operate simultaneously up to eight sensors at an overall bandwidth of 8 kHz, and can be directly interfaced to a remotely powered RFID system in order to constitute a complete multi-sensor, low-power, small size and externally powered micro-system. Integrated into a 180 nm CMOS process, it measures 5 mm2, is supplied with 1.8 Volt and consumes 1.8 mW.