A wide tuning range Gm-C continuous-time analog filter

Tien Yu Lo*, Chung-Chih Hung

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

33 Scopus citations


A CMOS operational transconductance amplifier (OTA) for low-power and wide tuning range filter application is proposed in this paper. The OTA can work from the weak inversion region to the strong inversion region to maximize the transconductance tuning range. The transconductance can be tuned by changing its bias current. A fifth-order Elliptic low-pass filter implemented with the OTAs was integrated by TSMC 0.18-μm CMOS process. The filter can operate with the cutoff frequency of 250 Hz to 1 MHz. The wide tuning range filter would be suitable for multi-mode applications, especially under the consideration of saving chip areas. The third-order inter-modulation (IM3) of -40 dB was measured over the tuning range with two tone input signals. The power consumption is 0.8 mW at 1-MHz cutoff frequency and 1.8-V supply voltage with the active area less than 0.3 mm2.

Original languageEnglish
Pages (from-to)713-722
Number of pages10
JournalIEEE Transactions on Circuits and Systems I: Regular Papers
Issue number4
StatePublished - 1 Apr 2007


  • G-C filters
  • Low power
  • Operational transconductance amplifier (OTA)
  • Strong inversion region
  • Tuning
  • Weak inversion region

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