A BiCMOS ENG amplifier with high SIR output

This work describes an integrated adaptive amplifier for recording nerve signals (electroneurogram or ENG) using tripolar cuff electrodes. The amplifier is fully implantable and its advantage is that it automatically compensates for cuff imbalance, a source of error that degrades ENG recording in conventional tripolar amplifier configurations. The resulting signal is appropriate for the control of implanted stimulators. Measurements indicated a high yield combined with large cuff imbalance correction capability, and most importantly a high signal-to-interference ratio (SIR) relative to previous configurations. The circuit was fabricated in 0.8 μm BiCMOS technology, has a core area of 0.68 mm², and dissipates 7.2 mW from ±2.5 V power supplies.