Conception of an emitter for transcutaneous power and high-speed data transmission

In this paper, we present an emitter conception for radiofrequency transmitter system dedicated to cochlear prosthesis apparatus. The main function of this system is to allow a transcutaneous power and data transmission from an external part, the digital speech processor, to an internal part, the implant. Radiofrequency transmission was assured by an inductive link including two coils that are located on either side of the skin. The operating frequency should be around 12 MHz in order to minimize power absorption (in any other case between 10 and 20 MHz). In such transmission mode used for this apparatus, speech would be processed numerically and converted to pulse train which would be transmitted until the inner ear. Hence, our purpose was the conception of a data external emitter stage located in the external part, the speech processor. Emitter module has been conceived around a numeric control unit based on DE amplifier class and using a CP/spl I.bar/FSK modulator (continuous phase frequency shift keying). Numeric control unit included a Manchester encoder operating with a VCO (voltage controller output). We optimized our conception by using CMOS 0.35/spl mu/m technology for the conception of the different modules.