A +/- 50-mV Linear-Input-Range VCO-Based Neural-Recording Front-End With Digital Nonlinearity Correction

作者：Jiang Wenlong^*; Hokhikyan Vahagn; Chandrakumar Hariprasad; Karkare Vaibhav; Markovic Dejan

来源：IEEE Journal of Solid-State Circuits, 2017, 52(1): 173-184.

DOI：10.1109/JSSC.2016.2624989

• Closed-loop
• front-end
• Horner's method
• neural-recording
• neuromodulation
• nonlinearity correction
• quantizer
• very large time-constant synthesis
• voltage-controlled oscillator (VCO)

Closed-loop neuromodulation is an essential function in future neural implants for delivering efficient and effective therapy. However, a closed-loop system requires the neuralrecording front-end to handle large stimulation artifacts-a feature not supported by most state-of-the-art designs. In this paper, we present a neural-recording front-end that has an input range of +/- 50 mV and can be used in closed-loop systems. The proposed front-end avoids the saturation due to stimulation artifacts by employing a voltage-controlled oscillator (VCO) to directly convert the input signal into the frequency domain. The VCO nonlinearity is corrected using area-efficient foreground polynomial correction. Implemented in a 40-nm CMOS process, the design occupies 0.135 mm(2) with an analog power of 3 mu W and a digital switching power of 4 mu W. It achieves ten times higher linear input range than prior art, and 79-dB spuriousfree dynamic range at peak input, with an input-referred noise of 5.2 mu V-rms across the local-field-potential band of 1-200 Hz. With on-chip subhertz high-pass filters realized by duty-cycled resistors, the front-end also eliminates the need of off-chip dc-blocking capacitors.

• 出版日期2017-1