An 80-mV(pp) Linear-Input Range, 1.6-G Omega Input Impedance, Low-Power Chopper Amplifier for Closed-Loop Neural Recording That Is Tolerant to 650-mV(pp) Common-Mode Interference

作者：Chandrakumar Hariprasad^*; Markovic Dejan

来源：IEEE Journal of Solid-State Circuits, 2017, 52(11): 2811-2828.

DOI：10.1109/JSSC.2017.2753824

• Chopper amplifier
• closed-loop
• common-mode interference
• dynamic range
• electrode offset
• front-end
• harmonic distortion
• input impedance
• large time constants
• linearity
• low-noise
• low-power
• multi-rate duty-cycled resistor (MDCR)
• neuromodulation
• pseudo-resistors
• neural recording

Closed-loop neuromodulation is essential for the advance of neuroscience and for administering therapy in patients suffering from drug-resistant neurological conditions. Neural stimulation generates large differential and common-mode (CM) artifacts at the recording sites, which easily saturate traditional recording front ends. This paper presents a neural recording chopper amplifier capable of handling in-band 80-mV(pp) differential artifacts and 650-mV(pp) CM artifacts while preserving the accompanying small neural signals. New techniques have been proposed that introduce immunity to CM interference, increase the input impedance of the chopper amplifier to 1.6 G Omega, and increase the maximum realizable resistance of duty-cycled resistors (DCR) to 90 G Omega. These techniques enable our recording front-end to achieve a dynamic range of 74 dB (200 Hz5 kHz) and 81 dB (1-200 Hz). Implemented in a 40-nm CMOS process, the prototype occupies an area of 0.069 mm(2)/channel, and consumes 2.8 mu W from a 1.2-V supply. The input-referred noise is 5.3 mu V-rms (200 Hz-5 kHz) and 1.8 mu V-rms (1-200Hz). The total harmonic distortion for a 40-mVp input at 1 kHz is -76 dB. This work improves the input impedance by 5.3x for chopped front-ends, linear-input range by 2x, maximum resistance of DCR by 32x, and tolerance to CM interferers by 6.5x, while maintaining comparable power and noise performance.

• 出版日期2017-11