OJAB  Vol.2 No.4 , November 2013
A Low-Power CMOS Analog Front-End IC with Adjustable On-Chip Filters for Biosensors
ABSTRACT
This paper presents a low-power CMOS analog front-end (AFE) IC designed with a selectable on-chip dual AC/DC- coupled paths for bio-sensor applications. The DC-coupled path can be selected to sense a biosignal with useful DC information, and the AC-coupled path can be selected for sensing the AC content of the biosignal by attenuating the unwanted DC component. The AFE IC includes a DC-coupled instrumentation amplifier (INA), two variable-gain 1st-order low pass filters (LPF) with tunable cut-off frequencies, a fixed gain 2nd-order Sallen-Key high-pass filter (HPF) with tunable cut-off frequencies, a buffer and an 8-bit differential successive approximation register (SAR) ADC. The entire AFE channel is designed and fabricated in a proprietary 0.35-μm CMOS technology. Excluding an external buffer needed to properly drive the ADC, the measured AFE IC consumes only 2.37 μA/channel with an input referred noise of ~40 μVrms in [1 Hz, 1 kHz], and successfully displays proper ECG (electrocardiogram) and electrogram (EGM) waveforms for QRS peaks detection. We expect that the low-power dual-path design of this AFE IC can enable it to periodically record both the AC and the DC signals for proper sensing and calibration for various bio-sensing applications.

Cite this paper
Lie, D. , Das, V. , Hu, W. , Liu, Y. and Nguyen, T. (2013) A Low-Power CMOS Analog Front-End IC with Adjustable On-Chip Filters for Biosensors. Open Journal of Applied Biosensor, 2, 104-111. doi: 10.4236/ojab.2013.24014.
References
[1]   L. S. Y. Wong, S. Hossain, A. Ta, J. Edvinsson, D. H. Rivas and H. Naas, “A Very Low-Power CMOS Mixed-Signal IC for Implantable Pacemaker Applications,” IEEE Journal of Solid-State Circuits, Vol. 39, No. 12, 2004, pp. 2446-2456. http://dx.doi.org/10.1109/JSSC.2004.837027

[2]   W. Hu, T. Nguyen, Y.-T. Liu and D.Y.C. Lie, “Ultralow Power Analog Front-End Circuits and System Design for an Implantable Cardioverter Defibrillator,” Proceedings of the IEEE-NIH Life Science Systems and Application Workshop, 2011, pp. 34-37.

[3]   X. D. Zou, X. Y. Xu, L. B. Yao and Y. Lian, “A 1-V 450-nW Fully Integrated Programmable Biomedical Sensor Interface System,” IEEE Journal of Solid-State Cir- cuits, Vol. 44, No. 4, 2009, pp. 1067-1077. http://dx.doi.org/10.1109/JSSC.2009.2014707

[4]   N. Verma, A. Shoeb, J. Bohorquez, J. Dawson, J. Guttag and A. P. Chandrakasan, “A Micro-Power EEG Acquisition SoC with Integrated Feature Extraction Processor for a Chronic Seizure Detection System,” IEEE Journal of Solid-State Circuits, Vol. 45, No. 4, 2010, pp. 804-816. http://dx.doi.org/10.1109/JSSC.2010.2042245

[5]   X. Liu, Y. Zheng, M. W. Phyu, F. N. Endru, V. Navanee-than and B. Zhao, “An Ultra-Low Power ECG Acquisition and Monitoring ASIC System for WBAN Application,” IEEE Journal of Emerging and Selected Topics in Circuits and System, Vol. 2, No. 1, 2012, pp. 60-70. http://dx.doi.org/10.1109/JETCAS.2012.2187707

[6]   R. Harrison and C. Charles, “A Low-Power Low-Noise CMOS Amplifier for Neural Recording Applications,” IEEE Journal of Solid-State Circuits, Vol. 38, No. 6, 2003, pp. 958-965. http://dx.doi.org/10.1109/JSSC.2003.811979

[7]   www.ti.com/product/ADS1291

[8]   E. Sackinger and W. Gug-genbuhl, “A Versatile Building Block: The CMOS Differential Difference Amplifier,” IEEE Journal of Solid-State Circuits, Vol. 22, No. 2, 1987, pp. 287-294.

[9]   R. Schreier and G. C. Temes, “Understanding Delta-Sigma Data Converters”, 1st Edition, IEEE Press, New Jersey, 2007.

[10]   W. Hu, Y.-T. Liu, D. Y. C. Lie and B. P. Ginsburg, “An 8-Bit Single-Ended Ultra-Low-Power SAR ADC with Novel DAC Switching and Digital Control Circuits for Bio-Medical Applications’,” IEEE Transactions on Circuits and Systems-I (TCAS-I), Vol. 60, No. 7, 2013, pp. 1726-1739.

[11]   www.physionet.org/physiobank/database/iafdb

[12]   A. Gerosa, A. Maniero and A. Neviani, “A Fully Integrated Two-Channel A/D Interface for the Acquisition of Cardiac Signals in Implantable Pacemakers,” IEEE Journal of Solid-State Circuits, Vol. 39, No. 7, 2004, pp. 1083-1093. http://dx.doi.org/10.1109/JSSC.2004.829921

 
 
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