A 15.2-ENOB continuous-time ΔΣ ADC for a 200mVpp-linear-input-range neural recording front-end

Abstract

Closed-loop neuromodulation with simultaneous stimulation and sensing is desired to advance deep brain stimulation (DBS) therapies. However, stimulation generates large artifacts (∼100mV) at the recording sites that saturate traditional front-ends. We present a 15.2b-ENOB CT ΔΣΜ with 187dB FOM, which along with an 8x-gain capacitively coupled chopper instrumentation amplifier (CCIA), realizes a front-end that can digitize neural signals (<2mVpp) from 1Hz to 5kHz in the presence of 200mVpp artifacts. Neural recording front-ends need to function within a power budget of 10μW/ch, input-referred noise of 4–8μVrms in 1Hz-5kHz, DC input impedance Zin, DC>1GΩ and high-pass (HP) cutoff <1Hz [1]. Prior work has addressed power and noise [1]-[2], but has limited dynamic-range and bandwidth (BW), making them incapable of performing true closed-loop operation.