Two stage OTA

Discussion in 'Homework Help' started by maybeejune, Apr 23, 2015.

  1. maybeejune

    Thread Starter New Member

    Apr 23, 2015
    Hey guys, I'm doing a simple simulation project for class and need some help.
    I've uploaded the circuit diagram. I'm having problems with the frequency compensation for sufficient phase margin.
    No matter what I change in the RC network the frequency in which the dB gain goes to 0 does not change, which I need to bring down for phase margin. The RC feedback network induces a pole and a zero which gives the Bode plot profile that I have uploaded. I can see that there's a second pole between 10MHz and 100MHz that is not affected by the feedback network.
    How do I have to set the circuit to have sufficient phase margin? The load cap value is set so I can't change that.
  2. rfenergyharvester

    New Member

    Apr 23, 2015
    have you designed the circuit such that the first non-dominant pole is at least thrice the GBW?