A CMOS Readout Circuit for Resistive Transducers Based on Algorithmic Resistance and Power Measurement

Journal Article (2017)
Author(s)

Zeyu Cai (TU Delft - Electronic Instrumentation)

Luis E. Rueda Guerrero (Industrial University of Santander)

Alexander Mattheus Robert Louwerse (External organisation)

Hilco Suy (BL Environmental Sensors)

R Veldhoven (NXP Semiconductors)

Kofi A.A. Makinwa (TU Delft - Microelectronics)

Michiel A. P. Pertijs (TU Delft - Electronic Instrumentation)

Research Group
Electronic Instrumentation
Copyright
© 2017 Z. Cai, Luis E. Rueda Guerrero, Alexander Mattheus Robert Louwerse, Hilco Suy, Robert van Veldhoven, K.A.A. Makinwa, M.A.P. Pertijs
DOI related publication
https://doi.org/10.1109/jsen.2017.2764161
More Info
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Publication Year
2017
Language
English
Copyright
© 2017 Z. Cai, Luis E. Rueda Guerrero, Alexander Mattheus Robert Louwerse, Hilco Suy, Robert van Veldhoven, K.A.A. Makinwa, M.A.P. Pertijs
Research Group
Electronic Instrumentation
Bibliographical Note
Accepted Author Manuscript@en
Issue number
23
Volume number
17
Pages (from-to)
7917-7927
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Abstract

This paper reports a readout circuit capable of accurately measuring not only the resistance of a resistive transducer, but also the power dissipated in it, which is a critical parameter in thermal flow sensors or thermal-conductivity sensors. A front-end circuit, integrated in a standard CMOS technology, sets the voltage drop across the transducer, and senses the resulting current via an on-chip reference resistor. The voltages across the transducer and the reference resistor are digitized by a time-multiplexed high-resolution analog-todigital converter (ADC) and post-processed to calculate resistance and power dissipation. To obtain accurate resistance and power readings, a voltage reference and a temperature-compensated reference resistor are required. An accurate voltage reference is constructed algorithmically, without relying on precision analog signal processing, by using the ADC to successively digitize the base-emitter voltages of an on-chip bipolar transistor biased at several different current levels, and then combining the results to obtain the equivalent of a precision curvature-corrected bandgap reference with a temperature coefficient of 18 ppm/°C, which is close to the state-of-the-art. We show that the same ADC readings can be used to determine die temperature, with an absolute inaccuracy of ±0.25 °C (5 samples, min-max) after a 1-point trim. This information is used to compensate for the temperature dependence of the on-chip polysilicon reference resistor, effectively providing a temperature-compensated resistance reference. With this approach, the resistance and power dissipation of a 100 Ω transducer have been measured with an inaccuracy of less than ±0.55 Ω and ±0.8%, respectively, from -40 °C to 125 °C.