A CMOS "Soft-Switched" transconductor and its application in gain control and filters

Clemens Mensink, Clemens H.J. Mensink, Bram Nauta, Hans Wallinga

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    47 Citations (Scopus)
    270 Downloads (Pure)


    This paper presents a transconductor suitable for implementation in submicron CMOS technology. The transconductor is nearly insensitive for the second-order effects of the MOS transistors, which become more and more prevalent in today's submicron processes. The transconductor relies on a differential pair with variable degeneration resistance, while the degeneration resistors are “soft-switched” by means of MOS transistors. The transconductance is continuously tunable. A transconductor, using a device in which the degeneration resistors and “soft switches” are merged, is optimized for a maximum tuning range and can be used in variable gain stages like in an automatic gain control (AGC) circuit. Besides, a third-order 5.5 MHz low-pass filter has been realized in a 0.5-μm CMOS process using the “soft-switched” transconductor. At a 3.3 V supply voltage the filter dissipates 12 mW and the dynamic range equals 62 dB where the total harmonic distortion (THD) is -48 dB for an input voltage of 1 Vpp.
    Original languageEnglish
    Pages (from-to)989-997
    JournalIEEE journal of solid-state circuits
    Issue number7
    Publication statusPublished - 1997


    • METIS-111605
    • IR-14438
    • circuit theory and design
    • continuous-time filters
    • transconductors
    • tuning
    • integrators
    • Amplifiers
    • CMOS devices
    • CMOS integrated circuits


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