An additive instantaneously companding readout system for cochlear implants

This paper presents an additive instantaneous companding technique in order to record the compound action potentials from the stimulated auditory nerve. This technique is intended to be combined with an analog to digital converter to achieve the 126-dB dynamic range that covers both stimulus (up to 20V), artifact and the neural response (down to 10μV). From the readout signal, the correct operation and placement of the cochlear stimulator can be estimated and useful information for further clinical studies can be obtained. The proposed system is designed to be implemented in AMIS I3T25 (high voltage) CMOS technology. Simulation results confirm the correct operation of the circuit.