SEMICONDUCTOR INTEGRATED CIRCUITS

A CMOS analog front-end chip for amperometric electrochemical sensors

Zhichao Li1, Yuntao Liu2, Min Chen1, Jingbo Xiao1 and Jie Chen1,

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 Corresponding author: Jie Chen, E-mail: jchen@ime.ac.cn

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Abstract: This paper reports a complimentary metal-oxide-semiconductor (CMOS) analog front-end chip for amperometric electrochemical sensors. The chip includes a digital configuration circuit, which can communicate with an external microcontroller by employing an I2C interface bus, and thus is highly programmable. Digital correlative double samples technique and an incremental sigma-delta analog to digital converter (Σ-Δ ADC) are employed to achieve a new proposed system architecture with double samples. The chip has been fabricated in a standard 0.18-μm CMOS process with high-precision and high-linearity performance occupying an area of 1.3 × 1.9 mm2. Sample solutions with various phosphate concentrations have been detected with a step concentration of 0.01 mg/L.

Key words: CMOSanalog front-endelectrochemical sensorssystem-on-chip



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Fig. 1.  Functional blocks of the proposed chip.

Fig. 2.  Schematic and noise dedication in the charge integrator and the PGA.

Fig. 3.  Third-order incremental $\Sigma$-$\Delta $ ADC.

Fig. 4.  Schematic of the charge integrator and proposed sample solution.

Fig. 5.  Schematic of the single-ended operational amplifier utilized in the charge integrator.

Fig. 6.  Fully differential third-order incremental $\Sigma$-$\Delta$ modulator.

Fig. 7.  SNDR of 3rd order incremental feed-forward $\Sigma$-$\Delta $ modulator derived from matlab model.

Fig. 8.  Third-order cascade digital integrators for decimation filter with digital CDS function.

Fig. 9.  Timing diagram for digital CDS function.

Fig. 10.  Micrograph of the proposed chip.

Fig. 11.  Output voltage of the charge integrator with different input currents: 3 $\mu $A and 6 $\mu $A.

Fig. 12.  On-board system for testing the proposed chip using actual amperometric electrochemical sensors.

Fig. 13.  Differential output voltage of the PGA versus programmable gain settings (1/2, 1/4, 1, 2).

Fig. 14.  The final output digital code of the analog front-end chip testing sample solutions with different phosphate concentrations.

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    Received: 14 November 2014 Revised: Online: Published: 01 July 2015

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      Zhichao Li, Yuntao Liu, Min Chen, Jingbo Xiao, Jie Chen. A CMOS analog front-end chip for amperometric electrochemical sensors[J]. Journal of Semiconductors, 2015, 36(7): 075004. doi: 10.1088/1674-4926/36/7/075004 Z C Li, Y T Liu, M Chen, J B Xiao, J Chen. A CMOS analog front-end chip for amperometric electrochemical sensors[J]. J. Semicond., 2015, 36(7): 075004. doi: 10.1088/1674-4926/36/7/075004.Export: BibTex EndNote
      Citation:
      Zhichao Li, Yuntao Liu, Min Chen, Jingbo Xiao, Jie Chen. A CMOS analog front-end chip for amperometric electrochemical sensors[J]. Journal of Semiconductors, 2015, 36(7): 075004. doi: 10.1088/1674-4926/36/7/075004

      Z C Li, Y T Liu, M Chen, J B Xiao, J Chen. A CMOS analog front-end chip for amperometric electrochemical sensors[J]. J. Semicond., 2015, 36(7): 075004. doi: 10.1088/1674-4926/36/7/075004.
      Export: BibTex EndNote

      A CMOS analog front-end chip for amperometric electrochemical sensors

      doi: 10.1088/1674-4926/36/7/075004
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      Project supported by the National Key Basic Research and Development Project (No. 2015CB352103).

      More Information
      • Corresponding author: E-mail: jchen@ime.ac.cn
      • Received Date: 2014-11-14
      • Accepted Date: 2015-01-21
      • Published Date: 2015-01-25

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