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
    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


    Dec 20, 2007
    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
    "Love is wise, hatred is foolish, schematics are essential." -Ron H