CMOS Integrated Circuits for RF-powered Wireless Temperature Sensor

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School of Electrical Engineering | Doctoral thesis (article-based) | Defence date: 2015-12-04
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151 + app. 90
Aalto University publication series DOCTORAL DISSERTATIONS, 201/2015
This dissertation presents original research contributions in the form of twelve scientific publications that represent advances related to RF-to-DC converters, reference circuits (voltage, current and frequency) and temperature sensors. The primary focus of this research was to design efficient and low power CMOS-based circuit components, which are useful in various blocks of an RF-powered wireless sensor node.  The RF-to-DC converter or rectifier converts RF energy into DC energy, which is utilized by the sensor node. In the implementation of a CMOS-based RF-to-DC converter, the threshold voltage of MOS transistors mainly affects the conversion efficiency. Hence, for the first part of this research, different threshold voltage compensation schemes were developed for the rectifiers. These schemes were divided into two parts; first, the use of the MOSFET body terminal biasing technique and second, the use of an auxiliary circuit to obtain threshold voltage compensation. In addition to these schemes, the use of an alternate signaling scheme for voltage multiplier configuration of differential input RF-harvesters has also been investigated.  A known absolute value of voltage or current is the most useful for an integrated circuit. Thus, the circuit which generates the absolute value of voltage or current is cited as the voltage or current reference circuit respectively. Hence, in the second part of the research, simple, low power and moderately accurate, voltage and current reference circuits were developed for the power management unit of the sensor node. Besides voltage and current reference circuits, a frequency reference circuit was also designed. The use of the frequency reference circuit is in the digital processing and timing functions of the sensor node.  In the final part of the research, temperature sensing was selected as an application for the sensor node. Here, voltage and current based sensor cores were developed to sense the temperature. A smart temperature sensor was designed by using the voltage cores to obtain temperature information in terms of the duty-cycle. Similarly, the temperature equivalent current was converted into the frequency to obtain a temperature equivalent output signal.  All these implementations were done by using two integrated circuits which were fabricated during the year 2013-14. 
Supervising professor
Halonen, Kari, Prof., Aalto University, Department of Micro and Nanosciences, Finland
CMOS circuit, RF-to-DC converters, voltage reference circuit, current reference circuit, frequency reference circuit, temperature sensors
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  • [Publication 1]: Chouhan S.S. and Halonen K. The design and implementation of DTMOS biased all PMOS rectifier for RF energy harvesting. Proceedings of the 12th IEEE International New Circuits and Systems Conference (NEWCAS), Trois-Rivieres, QC Canada, pp. 444–447, Jun. 2014.
  • [Publication 2]: Chouhan S.S. and Halonen K. The DTMOS based UHF RF to DC conversion. Proceedings of the 20th IEEE International Conference on Electronics, Circuits, and Systems (ICECS), Abu Dhabi, UAE, pp. 629–632, Dec. 2013.
    DOI: 10.1109/ICECS.2013.6815493 View at publisher
  • [Publication 3]: Chouhan S.S. and Halonen K. Internal Vth cancellation scheme for RF to DC rectifiers used in RF energy harvesting. Proceedings of the 21st IEEE International Conference on Electronics, Circuits, and Systems (ICECS), Marseille, France, pp. 235–238, Dec. 2014.
    DOI: 10.1109/ICECS.2014.7049965 View at publisher
  • [Publication 4]: Chouhan S.S. and Halonen K. Threshold voltage compensation scheme for RF-to-DC converter used in RFID applications. Electronics Letters, vol. 51, no.12, pp. 892-894, Jun. 2015.
  • [Publication 5]: Chouhan S.S. and Halonen K. A novel cascading scheme to improve the performance of voltage multiplier circuits. Analog Integrated Circuits and Signal Processing, Springer, vol. 84, no. 3, pp. 373-381, Sep. 2015.
    DOI: 10.1007/s10470-015-0595-y View at publisher
  • [Publication 6]: Chouhan S.S. and Halonen K. Design and implementation of all MOS micro-power voltage reference circuit. Analog Integrated Circuits and Signal Processing, Springer, vol. 80, no. 3, pp. 399–406, Sep. 2014.
    DOI: 10.1007/s10470-014-0361-6 View at publisher
  • [Publication 7]: Chouhan S.S. and Halonen K. Design and implementation of a micropower CMOS voltage reference circuit based on thermal compensation of Vgs. Microelectronics Journal, Elsevier, vol.46, no.1, pp. 36–42, Jan. 2015.
    DOI: 10.1016/j.mejo.2014.09.015 View at publisher
  • [Publication 8]: Chouhan S.S. and Halonen K. A 0.67μW, 177 ppm/◦C all MOS current reference circuit in 0.18 μm CMOS technology. Submitted to IEEE transaction on circuits and systems-II: Express Briefs.
  • [Publication 9]: Chouhan S.S. and Halonen K. A micro power temperature compensated frequency generating circuit. Proceedings of 22nd European conference on circuit theory and design (ECCTD),Trondheim, Norway, Aug. 24–26, pp.1-4, Aug. 2015.
  • [Publication 10]: Chouhan S.S. and Halonen K. Design and implementation of micropower temperature to duty cycle converter using differential temperature sensing. Microelectronics Journal, Elsevier, vol. 46, no. 6, pp. 482–489, Jun. 2015.
    DOI: 10.1016/j.mejo.2015.03.014 View at publisher
  • [Publication 11]: Chouhan S.S. and Halonen K. Nano-ampere PTAT current source with temperature inaccuracy < ±1◦C. Electronics Letters, vol. 51, no. 1, pp. 60–61, Jan. 2015.
  • [Publication 12]: Chouhan S.S. and Halonen K. A low power temperature to frequency converter for the on-chip temperature measurement. IEEE Sensors Journal, vol. 15, no. 8, pp. 4234-4240, Aug. 2015.
    DOI: 10.1109/JSEN.2015.2414667 View at publisher