Design of A Low Noise Single-Ended Sensor Interface Amplifier for Bio-potential Applications
Ahmed Naguib, Mohamed Taha · Journal of Engineering Science and Military Technologies /Journal of Engineering Science and Military Technologies · 2023
This paper discusses a low-noise read-out amplifier circuit for a biomedical sensor interface. The amplifier has two amplification stages with a Miller compensation capacitor that offers high gain with a large output swing. For power efficiency, all transistors are operated in a sub-threshold regime that makes the design suitable for implantable and portable medical devices. The proposed design works at the heart of bio-medical sensor interface circuits. It offers an amplification for different bio-potential signals such as electroencephalogram (EEG), electrocardiogram (ECG), and electromyogram (EMG) according to its bandwidth (BW). Furthermore, a small signal model analysis of the proposed amplifier is presented. A chopping technique is also proposed to reduce the sensor offset voltage and the flicker noise generated from sensor interface circuits. The proposed amplifier design achieves a gain and a BW of 62.16 dB and 506 Hz respectively. The input common-mode range (ICMR) varies from 0.3 V to 0.8 V with a phase margin (PM) of 62.57◦ at VCM equals 0.3 V and 66.8◦ at VCM of 0.8 V. The circuit is designed in 130 nm CMOS technology and consumes a power of 0.4 µW from 1 V supply. Also, the chopping technique reduces input-referred voltage noise from 38.445 µV/sqrt(Hz) to 3.06 µV/sqrt(Hz) within a frequency range from 0.01Hz to 500Hz.