Low size, low power, and wearable bio-signal recording systems require acquisition front-ends with high common-mode rejection for interference suppression and adjustable gain to provide an optimum signal level to a cascading analog-to-digital stage. This thesis presents the realization of microcontroller operated double-differential (DD) recording setup with automatic gain control (AGC) and automatic balance control, which can adjust the magnitude of recorded bio-potential signal to a target level and reject common-mode interference for full-bandwidth recording without filtering. Microcontroller code realizes the automatic control method of gain and balance adjustment by detecting, computing, and varying parameters to set timing clock pulses, which determine the gain magnitude and balance state. The automatic balance control compensates for imbalance in electrode interface impedance. The double-differential amplifier is implemented using two integrated variable gain amplifiers (ASIC) and one adder. Measured results of the variable gain amplifiers fabricated in 0.35 £gm CMOS technology show an input spot noise of 169 nV/¡ÔHz, a NEF below 10, and a circuit active area of 0.017 mm2 with a power consumption of 1.44 £gW. Measured results of the double-differential amplifier setup confirm interference suppression of 25.7 dB, tunable gain range of 39.6 dB, and 239 nV/¡ÔHz noise assuming ¡Ó10% interface mismatch. Practical measured examples incorporating the chips confirm gain control suitable for bio-potential recording and interference suppression in a balanced DD arrangement for electrocardiogram and electromyogram recording.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0816112-004753 |
| Date | 16 August 2012 |
| Creators | Teng, Hsin-Liang |
| Contributors | Jia-Jin Chen, Robert Rieger, Jih-Ching Chiu, Chung-Yao Kao |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0816112-004753 |
| Rights | user_define, Copyright information available at source archive |
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