CMOS Circuit Design for RF Sensors

This text discusses CMOS circuit design for sensor and actuators to be used in wireless RF systems. The main application is implantable transducers for biomedical purposes such as sensing of nerve signals and electrical stimulation of nerves. Special focus is put on the power and data link in a wireless system with transducers which are powered via the RF link. Alternative principles and methods are presented for the regulation of power to the sensors and for the distribution of data and power in an implanted transducer system. One of the main problems in such systems is the transmission of power via an RF link. This problem is analyzed in detail and solutions incorporating an RF magnetic link to the transducers are identified. The theoretical results are supported by experiments from CMOS chips including a system chip for functional electrical stimulation (FES). The work shows that a System on Chip (SoC) solution is feasible using CMOS technology for the RF sensors. The only components which cannot be integrated on the chip are the antenna coil and a capacitor for energy storage.