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Dissertation-M-Asgari-Aug-2018.pdf (5.9 MB)

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FULLY-INTEGRATED CMOS PH, ELECTRICAL CONDUCTIVITY, AND TEMPERATURE SENSING SYSTEM

Asgari, Mohammadreza
http://rave.ohiolink.edu/etdc/view?acc_num=akron1533827604228324

Abstract Details

2018, Doctor of Philosophy, University of Akron, Electrical Engineering.
First part of this research presents a fully-integrated multi-sensor chip using standard CMOS technology that contains three key components: pH, electrical conductivity (EC), and temperature. Two novel low-power, compact pH readout circuits have been proposed to overcome the nonidealities of ISFETs. In addition, a novel electrode implementation as EC sensor which eliminates the conventional post-processing steps is proposed. From a circuit point of view, a fully-integrated on-chip approach has been proposed to measure EC. In this method, a new variable-frequency oscillator stimulates the electrodes, and two variable-gain instrumentation amplifiers measure the equivalent voltage and current between the electrodes that are converted into EC. The detection range of the proposed EC sensor spans three orders of magnitude, from 0.02 to 10 mS/cm. Furthermore, a CTAT current source with diode connected transistors was used as temperature sensor. The total core area including all three sensors and readout circuits is 2.1 mm2. In the second part of this research, a novel 10-bit, 20 kHz bandwidth extended-counting ADC (EC-ADC) for our multi-sensor system has been proposed. This hybrid ADC is a combination of incremental sigma-delta and time-mode ADCs. By sharing the OTA and the comparator between two ADCs, the proposed approach shows the smallest core area amongst state-of-the-art ADCs with similar resolution and bandwidth. The core area of the proposed ADC is 0.0625 mm2, and the measured DNL and INL are +0.4/-0.4 and +0.84/-0.88 LSB, respectively.
Kye-shin Lee, Dr. (Advisor)
Joan Carletta, Dr. (Committee Member)
Ryan Toonen, Dr. (Committee Member)
Truyen Van Nguyen, Dr. (Committee Member)
Chelsea Monty, Dr. (Committee Member)
104 p.
Electrical Engineering
Multi-sensor system, standard CMOS technology, pH, Electrical-conductivity, ADC, sigma-delta ADC

Recommended Citations

Citations

  • Asgari, M. (2018). FULLY-INTEGRATED CMOS PH, ELECTRICAL CONDUCTIVITY, AND TEMPERATURE SENSING SYSTEM [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1533827604228324

    APA Style (7th edition)

  • Asgari, Mohammadreza. FULLY-INTEGRATED CMOS PH, ELECTRICAL CONDUCTIVITY, AND TEMPERATURE SENSING SYSTEM . 2018. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1533827604228324.

    MLA Style (8th edition)

  • Asgari, Mohammadreza. "FULLY-INTEGRATED CMOS PH, ELECTRICAL CONDUCTIVITY, AND TEMPERATURE SENSING SYSTEM ." Doctoral dissertation, University of Akron, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1533827604228324

    Chicago Manual of Style (17th edition)

akron1533827604228324
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This open access ETD is published by University of Akron and OhioLINK.