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High-temperature Bulk CMOS Integrated Circuits for Data Acquisition

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2006, Doctor of Philosophy, Case Western Reserve University, Electrical Engineering.

In this research, a monolithic, high-temperature bulk CMOS data acquisition system for Wheatstone-bridge sensors has been developed. The main design challenges were 1) excess leakage current, 2) decreased carrier mobility, and 3) unstable threshold voltage. Design techniques were developed to overcome these high-temperature effects and allow the bulk CMOS IC to operate at temperatures > 250 degree C. Two generations of data acquisition ICs have been designed and characterized: an instrumentation amplifier and a sigma-delta modulator. Both were fabricated using the AMI 1.5-µm bulk CMOS process.

The Instrumentation Amplifier IC features a fully-differential, adjustable-gain amplifier with digitally programmable offset cancellation, and features a constant-gm biasing circuit, a fully monolithic oscillator, internal thermometer circuit and RTD sensor interface. The thermometer and RTD sensor interface perform well at temperatures for T < 225 degree C. The oscillator demonstrates a temperature stability of ~97 ppm/degree C for T < 290 degree C at the fast clock setting. The instrumentation amplifier shows excellent stability for T < 300 degree C. With GA = 6 and GD = 8, gain stability is 128 ppm/degree C for 25 degree C < T < 300 degree C.

The Sigma-Delta IC includes a sigma-delta modulator with correlated double-sampling (CDS) pre-amplifier, a stand-alone sigma-delta modulator, constant-gm biasing circuit, oscillator and internal thermometer circuit. The CDS pre-amplifier has an adjustable gain and digitally programmable offset cancellation. The stand-alone sigma-delta modulator has a peak SNR and SNDR of 94 dB and 90 dB, respectively, at 25 degree C, and 94 dB and 87 dB at 300 degree C. The gain stability of the CDS pre-amplifier for GA = 6, 12 and 24 is 62, 66 and 95 ppm/degree C, respectively, for 25 degree C < T < 300 degree C. At 300 degree C, the modulator with CDS pre-amplifier achieves a dynamic range of 110 dB including the stand-alone modulator range.

Steven Garverick (Advisor)
Mehran Mehregany (Other)
Christian Zoraman (Other)
Darrin Young (Other)
Chung-Chiun Liu (Other)
197 p.

Recommended Citations

Citations

  • Yu, X. (2006). High-temperature Bulk CMOS Integrated Circuits for Data Acquisition [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1144420886

    APA Style (7th edition)

  • Yu, Xinyu. High-temperature Bulk CMOS Integrated Circuits for Data Acquisition. 2006. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1144420886.

    MLA Style (8th edition)

  • Yu, Xinyu. "High-temperature Bulk CMOS Integrated Circuits for Data Acquisition." Doctoral dissertation, Case Western Reserve University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=case1144420886

    Chicago Manual of Style (17th edition)