Low-power, parasitic-insensitive interface circuit for capacitive microsensors

Fatemeh Aezinia; Behraad Bahreyni

Low-power, parasitic-insensitive interface circuit for capacitive microsensors

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Author(s): Fatemeh Aezinia ¹ and Behraad Bahreyni ¹
- Affiliations: 1: School of Mechatronic Systems Engineering, Simon Fraser University, Surrey, BC, Canada, V3T 0A3
Source: Volume 10, Issue 2, March 2016, p. 104 – 110
DOI: 10.1049/iet-cds.2015.0077 , Print ISSN 1751-858X, Online ISSN 1751-8598

Received 18/02/2015, Accepted 30/07/2015, Revised 23/07/2015, Published 01/03/2016

Capacitive transduction is ubiquitously employed at macro- and especially micro-scales due to their simple structure and stability. This study proposes a topology for a low-power readout circuit for differential capacitive sensors. The circuit includes two switched-capacitor blocks that produce signals that are proportional to the difference and sum of the sense capacitors. Outputs of these two blocks are fed to an analogue divider to produce a pulse whose width is proportional to the ratio of the difference to sum of the sense capacitors. In addition to providing adjustable sensitivity and noise levels, this also reduces the sensitivity of the sensor to common-mode parasitics at the circuit input. The circuit topology was realised in a standard CMOS 0.35 µm technology with a total chip area of 330 µm × 600 µm. The performance of the fabricated circuit was evaluated by pairing it with a micromechanical variable capacitor. Experimental results demonstrated the capability of the circuit to resolve 160 aF of differential capacitance with a total power consumption of 720 µW while remaining insensitive to common-mode parasitic capacitances.

References

1. 1)
  - 24. Sameoto, D., Hubbard, T., Kujath, M.: ‘Operation of electrothermal and electrostatic MUMPs microactuators underwater’, J. Micromech. Microeng., 2004, 14, (10), p. 1359 (doi: 10.1088/0960-1317/14/10/010).
2. 2)
  - 2. Selvakumar, A., Najafi, K.: ‘A high-sensitivity z-axis capacitive silicon microaccelerometer with a torsional suspension’, J. Microelectromech. Syst., 1998, 7, (2), pp. 192–200 (doi: 10.1109/84.679356).
3. 3)
  - 19. Scotti, G., Pennisi, S., Monsurro, P., et al: ‘88-μA 1-MHz stray-insensitive CMOS current-mode interface IC for differential capacitive sensors’, IEEE Trans. Circuits Syst. Regul. Pap., 2014, 61, (7), pp. 1905–1916 (doi: 10.1109/TCSI.2014.2298275).
4. 4)
  - 16. Omran, H., Arsalan, M., Salama, K.N.: ‘An integrated energy-efficient capacitive sensor digital interface circuit’, Sens. Actuators Phys., 2014, 216, pp. 43–51 (doi: 10.1016/j.sna.2014.04.035).
5. 5)
  - 7. Lee, J.-I., Huang, X., Chu, P.B.: ‘Nanoprecision MEMS capacitive sensor for linear and rotational positioning’, J. Microelectromech. Syst., 2009, 18, (3), pp. 660–670 (doi: 10.1109/JMEMS.2009.2016275).
6. 6)
  - 10. Peng, S.-Y., Qureshi, M.S., Hasler, P.E., et al: ‘A charge-based low-power high-SNR capacitive sensing interface circuit’, IEEE Trans. Circuits Syst. Regul. Pap., 2008, 55, (7), pp. 1863–1872 (doi: 10.1109/TCSI.2008.918006).
7. 7)
  - 3. Ayazi, F., Najafi, K.: ‘A HARPSS polysilicon vibrating ring gyroscope’, IEEE J. Microelectromech. Syst., 2001, 10, (2), pp. 169–179 (doi: 10.1109/84.925732).
8. 8)
  - 11. ‘FDC1004 Capacitance to digital converter’. [Online]. Available at: http://www.ti.com/product/fdc1004, accessed: 13-Feb-2015.
9. 9)
  - 9. Aezinia, F., Bahreyni, B.: ‘An interface circuit with wide dynamic range for differential capacitive sensing applications’, IEEE Trans. Circuits Syst. II Express Briefs, 2013, 60, (11), pp. 766–770 (doi: 10.1109/TCSII.2013.2281891).
10. 10)
  - 1. Haider, M.R., Mahfouz, M.R., Islam, S.K., et al: ‘A low-power capacitance measurement circuit with high resolution and high degree of linearity’. Fifty-First Midwest Symp. on Circuits and Systems, 2008, MWSCAS 2008, 2008, pp. 261–264.
11. 11)
  - 8. Shin, D.-Y., Lee, H., Kim, S.: ‘A delta-sigma interface circuit for capacitive sensors with an automatically calibrated zero point’, IEEE Trans. Circuits Syst. II Express Briefs, 2011, 58, (2), pp. 90–94 (doi: 10.1109/TCSII.2010.2104015).
12. 12)
  - 5. Furuichi, H., Fearing, R.S.: ‘A planar capacitive micro positioning sensor’. Proc. of the Seventh Int. Symp. Micro Machine and Human Science, 1996, 1996, pp. 85–90.
13. 13)
  - 23. Nizza, N., Dei, M., Butti, F., et al: ‘A low-power interface for capacitive sensors with PWM output and intrinsic low pass characteristic’, IEEE Trans. Circuits Syst. Regul. Pap., 2013, 60, (6), pp. 1419–1431 (doi: 10.1109/TCSI.2012.2220461).
14. 14)
  - 23. Bruschi, P., Nizza, N., Piotto, M.: ‘A current-mode, dual slope, integrated capacitance-to-pulse duration converter’, IEEE J. Solid-State Circuits, 2007, 42, pp. 1884–1891 (doi: 10.1109/JSSC.2007.903102).
15. 15)
  - 13. Mason, A., Yazdi, N., Chavan, A.V., et al: ‘A generic multielement microsystem for portable wireless applications’, Proc. IEEE, 1998, 86, (8), pp. 1733–1746 (doi: 10.1109/5.704279).
16. 16)
  - 4. Lee, Y.S., Wise, K.D.: ‘A batch-fabricated silicon capacitive pressure transducer with low temperature sensitivity’, IEEE Trans. Electron. Devices, 1982, 29, (1), pp. 42–48 (doi: 10.1109/T-ED.1982.20656).
17. 17)
  - 15. van der Goes, F.M.L., Meijer, G.C.M.: ‘A novel low-cost and accurate multiple-purpose sensor interface with continuous autocalibration’. IEEE Instrumentation and Measurement Technology Conf., 1996, IMTC-96. Conf. Proc.. Quality Measurements: The Indispensable Bridge between Theory and Reality, 1996, vol. 2, pp. 782–787.
18. 18)
  - 17. Zhang, X., Liu, M., Wang, B., et al: ‘A wide measurement range and fast update rate integrated interface for capacitive sensors array’, IEEE Trans. Circuits Syst. Regul. Pap., 2014, 61, (1), pp. 2–11 (doi: 10.1109/TCSI.2013.2264696).
19. 19)
  - 12. ‘AD7143 Capacitance to digital converters’. [Online]. Available at: http://www.analog.com/en/analog-to-digital-converters/capacitance-to-digital-converters/ad7143/products/product.html, accessed: 13-Feb-2015.
20. 20)
  - 20. Heidary, A., Heidary Shalmany, S., Meijer, G.: ‘A flexible low-power high-resolution integrated interface for capacitive sensors’. 2010 IEEE Int. Symp. on Industrial Electronics (ISIE), 2010, pp. 3347–3350.
21. 21)
  - 21. Lu, T.C., Huang, Y.J., Chou, H.P.: ‘A novel interface circuit for capacitive sensors using correlated double sampling demodulation technique’. Second Int. Conf. on Sensor Technologies and Applications, 2008, SENSORCOMM‘08, 2008, pp. 396–400.
22. 22)
  - 18. Singh, T., Saether, T., Ytterdal, T.: ‘Current-mode capacitive sensor interface circuit with single-ended to differential output capability’, IEEE Trans. Instrum. Meas., 2009, 58, (11), pp. 3914–3920 (doi: 10.1109/TIM.2009.2021241).
23. 23)
  - 6. Aezinia, F.: ‘Design of interface circuits for capacitive sensing applications’. Thesis, Applied Sciences, School of Mechatronic Systems Engineering, 2014.
24. 24)
  - 14. Yazdi, N., Mason, A., Najafi, K., et al: ‘A generic interface chip for capacitive sensors in low-power multi-parameter microsystems’, Sens. Actuators Phys., 2000, 84, (3), pp. 351–361 (doi: 10.1016/S0924-4247(00)00307-1).

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Low-power, parasitic-insensitive interface circuit for capacitive microsensors

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