The advanced Combi 40+ cochlear implant

A 12-channel cochlear implant (CI) for high-rate pulsatile stimulation strategies is presented. Symmetric biphasic current pulses can be generated up to a maximum pulse repetition rate of 18.18 kpulses/second. The stimulation pulse amplitude can be selected within 1.5 microA-1.5 mA. Data and power are transcutaneously transferred using a single radiofrequency (RF) channel. A fully digital data transfer format is employed at an overall data rate of 600 kBit/second. The implant contains a single mixed analog/digital CMOS-ASIC (Application Specific Integrated Description) for data synchronization and stimulus generation. Stimulation signals are applied via a monopolar intracochlear multichannel electrode. Output capacitors for each channel are employed for safety reasons. A self-calibrating back telemetry system is included for estimating the channel impedances and field distribution along the electrode array. Dimensions of the ceramic package of the implant are only 33.50 x 23.40 x 3.95 mm3.