Adjustable Single Supply High Pass Filter

Discussion in 'General Electronics Chat' started by Robert.Adams, Oct 16, 2012.

  1. Robert.Adams

    Thread Starter Active Member

    Feb 16, 2010
    112
    5
    I'm trying to come up with a single supply high pass filter that is adjustable from very low (as close to DC as possible) to 5kHz.

    I'm trying to use a gyrator-based filter with a 2.5V virtual ground and using a transistor to vary the resistance to the virtual ground and adjust the gain. The problem is that the output resistance of the previous stage of my circuit and the on-resistance of the transistor are creating a voltage divider that kills my signal. I'd prefer to not add more amplification stages since I'm trying to fit the design with a quad op-amp package.

    Any ideas?
     
  2. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    Where is your schematic?
    Gyrator based high-pass filter, virtual ground and transistor on-resistance are just a bunch of words, not a circuit.
     
    Ron H likes this.
  3. Ron H

    AAC Fanatic!

    Apr 14, 2005
    7,050
    657
    "Love is wise, hatred is foolish, schematics are essential." -Ron H
     
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