Design and evaluation of an integrated variable gain, low noise amplifier for medical application

• Main Authors: Chun-Yi Li, 李春億
• Other Authors: [e-mail]
• Format: Others
• Language: en_US
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/02608953442935518013

碩士 === 國立中山大學 === 電機工程學系研究所 === 99 === Acquisition of bio-signals is an important feature in advanced medical applications. In order to record bio-signals such as electrocardiogram (ECG) or electromyogram (EMG), a switched-capacitor amplifier with variable linear gain and low noise front-end is discussed in this thesis. The circuit is designed and implemented as an Application-Specific Integrated Circuit (ASIC). This ASIC consists of transconductance stage with custom-designed lateral bipolar transistors in the input stage, switched-capacitor integrating stage, sample-and-hold circuit and buffer output stage. Lateral bipolar transistors were chosen with the intention of reducing flicker noise compared to using MOS input devices. Using a switched-capacitor (SC) stage the gain is adjustable to accommodate input signals of different amplitude making it useful for the recording of different biomedical signals. Adjustable gain is achieved by varying the clock phase delay between two digital control signals which were generated by a microcontroller. Also, small size and low supply voltage operation (±0.9 V) are achieved. Therefore, this ASIC may be used in wearable or even with implantable medical applications. Measured results for test chips realized in TSMC 0.35 μm CMOS technology are reported confirming the correct operation of the circuit.