A 16-channel 220 µW neural recording IC with embedded delta compression

A 16-channel neural action potential recording IC suitable for large-scale integration with multi-electrode arrays (MEAs) is presented. A closed-loop gain of 60 dB in the action potential band is achieved by cascading differential gain-stages utilizing a novel CMFB circuit. An oversampling delta modulator (DM) is proposed to improve the noise efficiency factor (NEF) of the recording system. Moreover, in-site compression is achieved by converting the derivative of the neural signal. The DM employs a novel dynamic voltage comparator with a partial reset preamplifier, which enhances the mean time to failure of the modulator. The proposed architecture is fabricated in a 0.18 μm CMOS technology. The total power consumption for 16 channels is 220 μW from a 1.2 V power supply. The SNDR is measured at 28.3 dB and 35.9 dB at the modulator and demodulator outputs, respectively. The total integrated in-band input-referred noise including the quantization noise of the ADC is measured at 2.8 μV_rms, which corresponds to NEF=4.6 for the entire system.