Ultra Low Power Temperature Compensated Complementary Metal Oxide Semiconductor Ring Oscillator in Subthreshold

Document Type : Original Article


1 IC Design Research Laboratory, Electrical & Robotic Engineering Department, Shahrood University of Technology, Shahrood, Iran

2 Department of Medical Physics and Biomedical Engineering, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran


Low power consumption, low chip area and fabrication in the standard complementary metal oxide semiconductor (CMOS) process are vital requirements for oscillators used in low-cost bio-implantable and wearable devices. Conventional ring oscillators (ROs) are good candidates for using in biomedical applications. However, their oscillation frequency strongly depends on the temperature. In this study, a temperature compensated ring oscillator with low power consumption is proposed. The transistors of the proposed ring oscillator operate in the subthreshold region to achieve a low power and low voltage performance. Since, in the subthreshold region, the oscillation frequency of a conventional ring oscillator increases with increase in the temperature, two current sources are used to power the proposed subthreshold ring oscillator: a temperature independent current source and a complementary to absolute temperature (CTAT) current source. In the proposed circuit, the CTAT current forms a small part of the total supplied current and its duty is to compensate for the oscillation frequency deviation. Two prototypes of the subthreshold ring oscillator were designed and simulated for a target frequency of 1MHz using commercially available 0.18µm RF-CMOS technology. The thermal coefficient (TC) of the uncompensated ring oscillator was 2400 ppm/ºC from -40ºC to 85ºC, though applying the proposed technique reduces the TC of the ring oscillator to 80.4 ppm/ºC with total power consumption as low as 14.5µW.


Main Subjects

  1. Wang, T.-M., Ker, M.-D. and Liao, H.-T., "Design of mixed-voltage-tolerant crystal oscillator circuit in low-voltage CMOS technology", IEEE Transactions on Circuits and Systems I: Regular Papers, Vol. 56, No. 5, (2009), 966-974. doi: 10.1109/TCSI.2009.2016172
  2. Zong, Y., Dai, X., Gao, Z., Binns, R. and Busawon, K., "Simulation and evaluation of pulse-coupled oscillators in wireless sensor networks", Systems Science & Control Engineering, Vol. 6, No. 1, (2018), 337-349. https://doi.org/10.1080/21642583.2018.1496043
  3. Farzeen, S., Ren, G. and Chen, C., "An ultra-low power ring oscillator for passive UHF RFID transponders", 53rd IEEE International Midwest Symposium on Circuits and Systems, (2010), 558-561. doi: 10.1109/MWSCAS.2010.5548887
  4. Sundaresan, K., Allen, P.E. and Ayazi, F., "Process and temperature compensation in a 7-MHz CMOS clock oscillator", IEEE Journal of Solid-State Circuits, Vol. 41, No. 2, (2006), 433-442. doi: 10.1109/JSSC.2005.863149
  5. Lahiri, A. and Tiwari, A., "A 140µA 34ppm/°c 30 MHz clock oscillator in 28nm CMOS bulk process", International Conference on VLSI Design (VLSID), (2013), 173-178. doi: 10.1109/VLSID.2013.184
  6. Ueno, K., Asai, T. and Amemiya, Y., "A 30-MHz, 90-ppm/°c fully-integrated clock reference generator with frequency-locked loop", ESSCIRC, (2009), 392-395. doi: 10.1109/ESSCIRC.2009.5325940
  7. Sadeghi, N., Sharif-Bakhtiar, A. and Mirabbasi, S., "A 0.007mm2 108ppm/ºc 1-MHz relaxation oscillator for high-temperature applications up to 180 ºc in 0.13µm CMOS", IEEE Transactions on Circuits and Systems I: Regular Papers, Vol. 60, No. 7, (2013), 1692-1701. doi: 10.1109/TCSI.2012.2226500
  8. Chang, Y.-A. and Liu, S.-I., "A 13.4-MHz relaxation oscillator with temperature compensation", IEEE Transactions on Very Large-scale Integration (VLSI) Systems, Vol. 27, No. 7, (2019). doi: 10.1109/TVLSI.2019.2908204
  9. Tang, J. and Tang, F., "Temperature and process independent ring-oscillator using compact compensation technic", IEEE International Conference on Anti-Counterfeiting Security and Identification in Communication (ASID), (2010), 49-52. doi: 10.1109/ICASID.2010.5551842
  10. Katebi, M., Nasri, A., Toofan, S. and Zolfkhani, H., "A temperature compensation voltage-controlled oscillator using a complementary to absolute temperature voltage reference", International Journal of Engineering, Transactions B: Applications, 32, No. 5, (2019), 710-719. doi: 10.5829/ije.2019.32.05b.13
  11. Liu, Q., Chai, Ch., "A 1.8 GHz temperature drift compensated LC-VCO for RFID transceiver", Analog Integrated Circuits and Signal Processing, Vol. 105, (2020), 7-12. https://doi.org/10.1007/s10470-020-01694-x
  12. Rodrigues, G., Brito, D., Busse, H., Fernandes, J., Silva, J. and Rabuske, T., "A Temperature-Compensated 57 PPM/°C 10MHz, 2.4μW Stacked Ring Oscillator", IEEE International Symposium on Circuits and Systems (ISCAS), Korea, 2021. doi: 10.1109/ISCAS51556.2021.9401370
  13. Park, K.S., Khashaba, A., Abdelrahman, A., Li, Y., Wang, T., Xia, R., Pal, N. and Hanumolu, P.K., "A second-order temperature compensated 1μW/MHz 100MHz RC oscillator with ±140ppm inaccuracy from -40°C to 95°C", IEEE Custom Integrated Circuits Conference (CICC), USA, 2021. doi: 10.1109/CICC51472.2021.9431420
  14. Yan, L., Harpe, P., Osawa, M., Harada, Y., Tamiya, K., Van Hoof, C. and Yazicioglu, R.F., "24.4 A 680nA fully integrated implantable ECG-acquisition IC with analog feature extraction", IEEE Solid-State Circuits Conference Digest of Technical Papers (ISSCC), (2014), 418-419. doi: 10.1109/ISSCC.2014.6757495
  15. Yazicioglu, R.F., Kim, S., Torfs, T., Merken, P. and Van Hoof, C., "A 30µw analog signal processor ASIC for biomedical signal monitoring", IEEE Solid-State Circuits Conference Digest of Technical Papers (ISSCC), (2010), 124-125. doi: 10.1109/ISSCC.2010.5434026
  16. Chiang, Y.-H. and Liu, S.-I., "A submicrowatt 1.1-MHz CMOS relaxation oscillator with temperature compensation", IEEE Transactions on Circuits and Systems II: Express Briefs, Vol. 60, No. 12, (2013), 837-841. doi: 10.1109/TCSII.2013.2281920
  17. Wang, Y., Chan, P.K. and Li, K.H., "A compact CMOS ring oscillator with temperature and supply compensation for sensor applications", IEEE Computer Society Annual Symposium on VLSI (ISVLSI), (2014), 267-272. doi: 10.1109/ISVLSI.2014.15
  18. Filanovsky, I. and Allam, A., "Mutual compensation of mobility and threshold voltage temperature effects with applications in CMOS circuits", IEEE Transactions on Circuits and Systems I: Fundamental Theory and Applications, Vol. 48, No. 7, (2001), 876-884. doi: 10.1109/81.933328
  19. Huang, K. and Wentzloff, D., "A 1.2-MHz 5.8µW temperature-compensated relaxation oscillator in 130-nm CMOS", IEEE Transactions on Circuits and Systems II: Express Briefs, Vol. 61, No. 5, (2014), 334-338. doi: 10.1109/TCSII.2014.2312634
  20. Taur, Y. and Ning, T.H., Fundamentals of modern VLSI devices, Cambridge university press, (2013).
  21. Calhoun, B., Chandrakasan, A. and Wang, A., Sub-threshold design for ultra-low-power systems. 2006, Springer New York.
  22. Tajalli, A. and Leblebici, Y., Extreme low-power mixed signal IC design: Subthreshold source-coupled circuits, Springer Science & Business Media, (2010).
  23. Ueno, K., Hirose, T., Asai, T. and Amemiya, Y., "A 300 nW, 15ppm/ºC, 20ppm/ºC CMOS voltage reference circuit consisting of subthreshold MOSFETs", IEEE Journal of Solid-state Circuits, Vol. 44, No. 7, (2009), 2047-2054. doi: 10.1109/JSSC.2009.2021922
  24. Mandal, M. and Sarkar, B.C., "Ring oscillators: Characteristics and applications", Indian Journal of Pure and Applied Physics Vol. 48, (2010), 136-145.
  25. Najafizadeh, L., "Voltage references using mutual compensation of mobility and threshold voltage temperature effects", Ph.D. thesis, Alberta, (2004).
  26. Razavi, B., "Design of analog CMOS integrated circuits, Tsinghua University Press Co., Ltd., (2005).
  27. Palumbo, G., "Voltage references: From diodes to precision high-order bandgap circuits [book review]", IEEE Circuits and Devices Magazine, Vol. 18, No. 5, (2002), 45-45.
  28. Prijić, Z., Dimitrijev, S. and Stojadinović, N., "Analysis of temperature dependence of CMOS transistors threshold voltage", Microelectronics Reliability, Vol. 31, No. 1, (1991), 33-37. https://doi.org/10.1016/0026-2714(91)90342-5
  29. Filanovsky, I., "Input-free VTP and-VTN extractor circuits realized on the same chip", Analog Integrated Circuits and Signal Processing, Vol. 19, No. 2, (1999), 151-157. https://doi.org/10.1023/A:1008353815230
  30. Zhang, S., Li, A., Han, Y., Jie, L., Han, X. and Cheung, R.C., "Temperature compensation technique for ring oscillators with tail current", Electronics Letters, Vol. 52, No. 13, (2016), 1108-1110. https://doi.org/10.1049/el.2016.1039
  31. Choe, K., Bernal, O.D., Nuttman, D. and Je, M., "A precision relaxation oscillator with a self-clocked offset-cancellation scheme for implantable biomedical SoCs", IEEE Solid-State Circuits Conference-Digest of Technical Papers, (2009), 402-403. doi: 10.1109/ISSCC.2009.4977478