1. A low‐power opamp‐less second‐order delta‐sigma modulator for bioelectrical signals in 0.18 μm cmos
- Author
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Cardes Garcia, Fernando, Baladari, Nikhita, Lee, Jihyun, and Hierlemann, Andreas
- Subjects
ADC ,biosensor ,CMOS ,Delta-Sigma modulation ,neural interface ,VCO-ADC ,VLSI - Abstract
This article reports on a compact and low‐power CMOS readout circuit for bioelectrical signals based on a second‐order delta‐sigma modulator. The converter uses a voltage‐controlled, oscillator‐based quantizer, achieving second‐order noise shaping with a single opamp‐less integrator and minimal analog circuitry. A prototype has been implemented using 0.18 μm CMOS technology and includes two different variants of the same modulator topology. The main modulator has been optimized for low‐noise, neural‐action‐potential detection in the 300 Hz–6 kHz band, with an input‐referred noise of 5.0 μVrms, and occupies an area of 0.0045 mm2. An alternative configuration features a larger input stage to reduce low‐frequency noise, achieving 8.7 μVrms in the 1 Hz–10 kHz band, and occupies an area of 0.006 mm2. The modulator is powered at 1.8 V with an estimated power consumption of 3.5 μW. ISSN:1424-8220
- Published
- 2021