about level shifter

Discussion in 'The Projects Forum' started by namratha28, Apr 10, 2009.

  1. namratha28

    Thread Starter New Member

    Apr 4, 2009
    We have a project where we have to convert a rectified AC signal which is sitting at 3.5V range to one which is sitting at 0V. So we basically need to have a gain of 1. What kind of circuit would be the best to get the desired result?

  2. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    Do you mean you want to remove the DC component of the rectified AC?
  3. namratha28

    Thread Starter New Member

    Apr 4, 2009
    yes, we need to do that.
  4. PRS

    Well-Known Member

    Aug 24, 2008
    I'll assume you're talking about an ac signal riding on 3.5 volts dc and you want to shift it to an ac signal riding on zero volts dc. You need a double ended supply for this so that the signal can swing between negative and positive voltages.

    If the ac signal is not high frequency, say it's an audio signal, then use an op amp. Depending on your need you can amplify the signal or simply shift it's dc voltage level. In the first case use a capacitively coupled inverting or non-inverting configuration; in the second case use a capacitive-coupled follower configuration.

    If the output needs to be exactly zero, then use a ten-turn pot as the (or part of the) feedback resistor or sampling resistor; or if you use unity gain, take advantage of the the op amp's offset input to null the output to zero.