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A subthreshold MOS-based pseudo-resistor featuring a very high value and ultra-low distortion is proposed. A bandpass neural amplifier with a very low high-pass cutoff frequency is designed, to demonstrate the linearity of the proposed resistor. A BJT less CTAT current generator has been introduced to minimize the temperature drift of the resistor and make tuning easier. The standalone resistor has achieved 0.5% better linearity and a 12% improved temperature coefficient over the existing architectures. A neural amplifier has been designed with the proposed resistor as a feedback element. It demonstrated 31 dB mid-band gain and a low-pass cutoff frequency of 0.85 Hz. The circuit operates from a 1 V supply and draws 950 nA current at room temperature. [ABSTRACT FROM AUTHOR]

This work presents a low-power biopotential amplifier integrated circuit (IC) for implantable neural recording prosthetic devices which have been implemented using 0.18-m CMOS technology. The proposed neural recording amplifier is based on a capacitive-feedback architecture and utilizes a low-power two-stage source-degenerated operational transconductance amplifier (OTA) with a modified current buffer compensation for large open-loop gain, low-noise and wide bandwidth. The designed amplifier achieves a measured gain of 39.2dB with a bandwidth between 0.25Hz to 28kHz, integrated input referred noise of 5.79Vrms and noise efficiency factor of 3.16. The IC consumes 2.4W at 1.2V supply and the die area is 0.09mm2. [ABSTRACT FROM AUTHOR]