How to choose the right opamp?

Discussion in 'The Projects Forum' started by sreejuviswan, Mar 11, 2014.

  1. sreejuviswan

    Thread Starter New Member

    Mar 11, 2014
    For one of my projects I am using 2 stage amplification. the first stage of amplification is done by a LMV324 opamp under the difference input configuration. for The second stage i need a programmable gain amplifier hence i tried using MCP6s21 PGA. this PGA has amplification gain setting of +1, +2, +4,+5,+8,+10,+16 or +32. However when i analyse the output signal the amplification does not happen as expected for a gain set at +8 the amplification is only twice the input signal and for +16 and +32 setting there is only noise in the output.

    My signal frequencies are not more than 2 KHz and the datasheet claims that this PGA could handle upto 18 MHz.

    Why is the opamp performing so poorly? is it because the opamp has poor performance or because i have not chosen the right opamp for my application? what are the opamp parameters i should look into for choosing the right amplifier?
  2. #12


    Nov 30, 2010
    Not a chance of helping you without a schematic. Can you post a drawing?