A CMOS Synchronized Sample-and-Hold Artifact Blanking Analog Front-End Local Field Potential Acquisition Unit With ±3.6-V Stimulation Artifact Tolerance and Monopolar Electrode-Tissue Impedance Measurement Circuit for Closed-Loop Deep Brain Stimulation SoCs

Abstract

In this paper, an analog front-end (AFE) local-field potential (LFP) acquisition unit with real-time stimulation artifact removal is proposed and verified for closed-loop deep brain stimulation (DBS) applications. The proposed acquisition unit is called the synchronized sample-and-hold stimulation artifact blanking (SSAB) AFE LFP acquisition unit. Both right-leg-driven (RLD) circuit and monopolar electrode-tissue impedance (ETI) measurement circuit associated with the AFE amplifier are also proposed. During closed-loop stimulations, the artifact removal is realized through the SSAB-IPC by blanking the AR-CCIA with a clock synchronized to the stimulation-enable signal and holding the amplifier at its state before stimulation through a sample-and-hold operation. After stimulation, the acquisition unit can quickly recover from the holding state back to the LFP recording state to reduce the discontinuity in LFP recording. The proposed acquisition unit was fabricated in 0.18-um CMOS technology. With the RLD circuit, the measured CMRR is 124 – 145 dB in the signal bandwidth. The fabricated monopolar ETI measurement circuit has a measurement error less than 8.3% with an extra power consumption of 2.65 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $</tex-math> </inline-formula> W. The experimental results have shown that the proposed SSAB AFE LFP acquisition unit is feasible for the integration of SoCs in real-time closed-loop DBS systems for various applications.