Galvanic coupling provides a novel data transmission between sensor units for low frequency intra-body communication with electrodes attached to the human skin. In this work, that approach has been adapted to implantable miniaturized pills. A communication system for wireless data transmission in muscle tissue is developed capable of transmitting data on four channels concurrently with a throughput of 4.8kbit/s. The main focus is the future implantability of such a miniaturized system for medical long term surveillance of patients. To achieve this goal, circuit size, low power consumption and electrical safety have to be carefully considered. The implemented frequency division multiple access (FDMA) system works in the frequency range between 100 kHz and 250 kHz. Tests have been processed with 4 transmitters units. The system architecture features the possibility of migration into a single system-on-chip.

This paper analyzes the power-area trade-off of functionally equivalent architectural implementations of a speech enhancement algorithm for hearing aids. Gate-level simulations and measurements show that an optimum degree of resource sharing (0.60 mW in a 0.25 /spl mu/m CMOS process) is more energy-efficient than both the fully time-multiplexed (1.42 mW) and the isomorphic architecture (1.54 mW), without overly large area overhead (0.77 mm/sup 2/ against 0.43 mm/sup 2/ and 4.31 mm/sup 2/, respectively).