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
    1
    0
    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

    Expert

    Nov 30, 2010
    16,246
    6,738
    Not a chance of helping you without a schematic. Can you post a drawing?
     
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