A bidirectional neural interface IC with high voltage compliance and spectral separation

This paper presents a fully integrated, bidirectional, neural interface, which is composed of a high voltage (HV) stimulator and a low voltage (LV) neural front-end with active, spectral separation. The stimulator uses a supply of ±9V in order to achieve a high voltage compliance (VC), whereas the recorder has a supply voltage of 3 V for high power efficiency. By using a HV transistor to separate the two parts, a safe operation of stimulator and recorder with different supply voltages can be guaranteed. Thereby the presented architecture can deliver a maximum stimulation current of ±10mA with a dynamic range of 50 dB and a VC of ±8.2 V. The implemented recording part consumes 52 μW and achieves a simulated input referred noise of 2.5μVrms in the low frequency band from 0.1 Hz to 200 Hz and 3.1 μVrms in the high frequency band from 200 Hz to 7.5 kHz. The combined recorder/stimulator requires 0.378 mm2 per channel. A prototype of the interface has been implemented and manufactured in a standard 0.18 μm HV CMOS technology.