Your browser does not support JavaScript!
http://iet.metastore.ingenta.com
1887

access icon free Widely tunable low-pass gm  − C filter for biomedical applications

© The Institution of Engineering and Technology
Received 01/03/2018, Accepted 05/10/2018, Revised 11/09/2018, Published 24/10/2018

This study presents a fourth-order, low-pass Butterworth transconductor–capacitor filter with tunable bandwidth for biomedical signal processing front-ends. An architecture has been proposed for realising very low transconductance values with tunability. This transconductor architecture makes it possible to realise a fully differential filter without the need for explicit common-mode feedback circuit. The filter has two tuning schemes, a resistor-based tuning (R-tuning) and a switched transconductor-based tuning (D-tuning). With R-tuning, the bandwidth is adjustable between 1 and 70 Hz and with D-tuning, the tuning range is 30 mHz–100 Hz. The filter has been designed in united microelectronics corporation (UMC) 0.18 µm complementary metal–oxide–semiconductor process. In terms of figure-of-merit, the proposed filter is found to be on par with the filters reported in the literature.

Inspec keywords: low-power electronics; resistors; CMOS integrated circuits; medical signal processing; low-pass filters; operational amplifiers; Butterworth filters

Other keywords: resistor-based tuning; UMC complementary metal–oxide–semiconductor process; fourth-order Butterworth transconductor–capacitor; bandwidth 1.0 Hz to 70.0 Hz; differential filter; biomedical applications; switched transconductor-based tuning; transconductor architecture; frequency 30.0 mHz to 100.0 Hz; biomedical signal processing; size 0.18 mum; low-pass gm-C filter; low transconductance values; low-pass Butterworth transconductor–capacitor

Subjects: Digital signal processing; Electrical/electronic equipment (energy utilisation); Active filters and other active networks; CMOS integrated circuits; Signal processing and detection; Amplifiers

References

    1. 1)
      • 3. Solis-Bustos, S., Silva-Martinez, J., Maloberti, F., et al: ‘A 60 dB dynamic-range CMOS sixth-order 2.4 Hz low-pass filter for medical applications’, IEEE Trans. Circuits Syst. II, Analog Digit. Signal Process., 2000, 47, (12), pp. 1391–1398.
    2. 2)
      • 1. Harrison, R.R.: ‘A versatile integrated circuit for the acquisition of biopotentials’. Proc. Custom Integrated Circuits Conf., San Jose, CA, USA, September 2007, pp. 115–122.
    3. 3)
      • 16. Liu, Y.T., Lie, D.Y.C., Hu, W., et al: ‘An ultralow-power CMOS transconductor design with wide input linear range for biomedical applications’. Proc. IEEE Int. Symp. Circuits and Systems (ISCAS), Seoul, Korea (South), May 2012, pp. 2211–2214.
    4. 4)
      • 10. Schaumann, R., Valkenburg, M.E.V.: ‘Design of analog filters’ (Oxford University press, USA, 2001).
    5. 5)
      • 7. Alioto, M.: ‘Understanding DC behavior of subthreshold CMOS logic through closed-form analysis’, IEEE Trans. Circuits Syst. I, Regul. Pap., 2010, 57, (7), pp. 1597–1607.
    6. 6)
      • 8. Akbari, M., Hashemipour, O., Moradi, F.: ‘Input offset estimation of CMOS integrated circuits in weak inversion’, IEEE Trans. Very Large Scale Integr. (VLSI) Syst., 2018, 26, (9), pp. 1812–1816.
    7. 7)
      • 12. Veeravalli, A., Sanchez-Sinencio, E., Silva-Martinez, J.: ‘A CMOS transconductance amplifier architecture with wide tuning range for very low frequency applications’, IEEE J. Solid-State Circuits, 2002, 37, (6), pp. 776–781.
    8. 8)
      • 5. Zhou, L., Chakrabartty, S.: ‘Design of low-Gm transconductors using varactor-based degeneration and linearization technique’. Proc. IEEE Biomedical Circuits and Systems Conf. (BioCAS), Atlanta, USA, October 2015, pp. 1–4.
    9. 9)
      • 15. Lo, T.-Y., Hung, C.-C.: ‘A wide tuning range Gm–C continuous-time analog filter’, IEEE Trans. Circuits Syst. I, Regul.Pap., 2007, 54, (4), pp. 713–722.
    10. 10)
      • 19. Sun, C.-Y., Lee, S.-Y.: ‘A fifth-order Butterworth OTA-C LPF with multiple-output differential-input OTA for ECG applications’, IEEE Trans. Circuits Syst. II, Express Briefs, 2017, 65, (4), pp. 421–425.
    11. 11)
      • 2. Nagaraj, K.: ‘A parasitic-insensitive area-efficient approach to realizing very large time constants in switched-capacitor circuits’, IEEE Trans. Circuits Syst., 1989, 36, (9), pp. 1210–1216.
    12. 12)
      • 4. Veeravalli, A., Sanchez-Sinencio, E., Silva-Martinez, J.: ‘Transconductance amplifier structures with very small transconductances: a comparative design approach’, IEEE J. Solid-State Circuits, 2002, 37, (6), pp. 770–775.
    13. 13)
      • 11. Rodriguez-Villegas, E., Casson, A.J., Corbishley, P.: ‘A subhertz nanopower low-pass filter’, IEEE Trans. Circuits Syst. II, Express Briefs, 2011, 58, (6), pp. 351–355.
    14. 14)
      • 18. Richa, A., Oliveira, J.P.: ‘Gm−C biquad filter for low signal sensor applications’. Proc. MIXDES-23rd Int. Conf. Mixed Design of Integrated Circuits and Systems, Poland, 2016, pp. 207–210.
    15. 15)
      • 13. Lee, S.Y., Cheng, C.J.: ‘Systematic design and modeling of an OTA-C filter for portable ECG detection’, IEEE Trans. Biomed. Circuits Syst., 2009, 3, (1), pp. 53–64.
    16. 16)
      • 9. Chang, C.M.: ‘New multifunction OTA-C biquads’, IEEE Trans. Circuits Syst. II, Analog Digit. Signal Process., 1999, 46, (6), pp. 820–824.
    17. 17)
      • 6. Silva-Martinez, J., Salcedo-Suner, J.: ‘IC voltage to current transducers with very small transconductance’, Analog Integr. Circuits Signal Process., 1997, 13, (3), pp. 285–293.
    18. 18)
      • 17. Mahmoud, S., Bamakhramah, A., Al-Tunaiji, S.: ‘Low-noise low-pass filter for ECG portable detection systems with digitally programmable range’, Circuits Syst. Signal Process. J., 2013, 32, (9), pp. 2029–2045.
    19. 19)
      • 14. Bronzino, J.D.: ‘Medical devices and systems’ (CRC press, Boca Raton, Florida, USA., 2006, 3rd edn.).
http://iet.metastore.ingenta.com/content/journals/10.1049/iet-cds.2018.5002
Loading

Related content

content/journals/10.1049/iet-cds.2018.5002
pub_keyword,iet_inspecKeyword,pub_concept
6
6
Loading
Print this page
This is a required field
Please enter a valid email address