Design of a Low-noise Instrumentation Amplifier with Triple-MOS Pseudo-resistor for Bio-signal Acquisition in Consumer Electronics

Abstract

Low input-referred noise (IRN) and low-power instrumentation amplifier (IA) with small size are crucial for consumer bio-electronic applications. This paper presents a compact, noise-efficient capacitive-coupled IA designed for bio-signal acquisition. The proposed Triple-MOSFET pseudo-resistor (PR) provides ultra-high resistance, a wide operating voltage range, and high linearity. The IA, enhanced by chopper-stabilized technology, effectively reduces noise while minimizing current consumption. An area-efficient DC servo loop with Triple-MOS devices is employed to suppress electrode DC offset. Addi-tionally, parasitic effects are minimized based on layout design, maximizing the advantages of the positive feedback loop. The proposed IA is fabricated using a standard 180 nm CMOS process with an area of 0.49 mm², and operates at a supply of 0.8 V with a current consumption of 1.29 μA. The IRN of this IA is 0.97 μVrms within the 0.5–200 Hz and 2.31 μVrms within the 0.2–5 kHz, achieving competitive noise efficiency factor (1.4) and power efficiency factor (1.56). Furthermore, for a 2 mVpp sine wave input, total harmonic distortion is below -60.2 dB. The precise value of the positive feedback capacitor ensures that the input impedance reaches 628 MΩ at 50 Hz. A prototype test system based on the IA successfully acquired high-quality ECG and EEG signals from subjects. This efficient, low-noise, low-power acquisition chip has broad applications in portable cardiac monitors, brain-machine interfaces, and other biosensors, playing a significant role in enhancing the performance and reliability of these electronic devices.

Feng Yan

PhD Student

My research interests include circuit design of analog front end for biomedical applications and sensor interfaces.

Jingjing Liu

Associate Professor

My research interests include low-power smart micro-sensor integrated circuit design, image sensors, biomedical sensors, and energy harvesting circuits.

Kangkang Sun

PhD Student

My research interests include circuit design of analog to digital converter for biomedical applications and SAR ADC.

Bingjun Xiong

PhD Student

My research interests include circuit design of optical receivers and references.

Wenji Mo

Master’s Student

My research interests include circuit design of low-power RISC-V processors and self-powered SoCs.

Jian Guan

PhD Student

My research interests include the design of solar cells and energy harvesting circuits.