A 250-μW, 18-nV/rtHz current-feedback chopper instrumentation amplifier in 180-nm cmos for high-performance bio-potential sensing applications

This paper presents a low-power, high-performance current-feedback instrumentation amplifier (CFIA) for portable bio-potential sensing applications. Noise analysis is performed to assign an optimized current for the input stage of the amplifier. Analysis on selecting nested chopping frequencies is p...

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Bibliographic Details
Published in:Analog integrated circuits and signal processing 2017, Vol.90 (1), p.137-148
Main Authors: Lee, Hyun-Sik, Nguyen, Van Nhan, Pham, Xuan Lap, Lee, Jong-Wook, Park, Hun-Kuk
Format: Article
Language:English
Subjects:
Amplification
Circuits and Systems
CMOS
Cutting
Electric potential
Electrical Engineering
Engineering
Feedback loops
Gain
Instrumentation
Instruments
Noise
Noise levels
Noise reduction
Power consumption
Power efficiency
Ripples
Signal,Image and Speech Processing
Voltage
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Summary:This paper presents a low-power, high-performance current-feedback instrumentation amplifier (CFIA) for portable bio-potential sensing applications. Noise analysis is performed to assign an optimized current for the input stage of the amplifier. Analysis on selecting nested chopping frequencies is performed, further reducing 1/ f noise and the residual offset. Enhanced power efficiency is achieved by sharing cascode branches and using a Class-AB output stage. Through these methods, a good balance between noise performance and other parameters such as output ripples and power consumption of the ripple reduction feedback loop (RRFL) is achieved. The amplifier is developed using a 1-poly 6-metal 0.18 μm CMOS process. Three gain stages with a gain-boosting input stage provide a low-frequency, open-loop gain >250 dB. When configured to a closed-loop gain of 60 dB, the amplifier achieves a noise voltage density of 18 nV / H z and a 1/ f noise corner of 3 Hz. With a current of 75 μA and a supply voltage of 3.3 V, a CMRR of 110 dB and a PSRR of 120 dB are achieved, with an average input offset of about 6.5 μV. The amplifier achieves a state-of-art noise efficiency factor of 4.2. Practical application of the CFIA is demonstrated with an in vivo electrocardiogram detection.
ISSN:0925-1030
1573-1979
DOI:10.1007/s10470-016-0853-7