A compact, low input capacitance neural recording amplifier with Cin/Gain of 20fF.V/V

This paper presents a compact and low input capacitance neural recording amplifier. By replacing a single feedback capacitor with a clamped T-capacitor network, the proposed amplifier can achieve same mid-band gain with less input capacitance, resulting in a smaller silicon area and higher input impedance. Fabricated in 0.35μm CMOS, the amplifier occupies merely 0.056mm². It achieves 38.1-dB mid-band gain with 1.6pF input capacitance, and hence has a C_in/Gain ratio of 20fF.V/V. It has an input referred noise of 6.72μV_rms over 8.4-kHz bandwidth and NEF of 4, and consumes 6μW. In-vivo recordings from an animal experiment are also demonstrated.