Noise analysis of sensing circuit

Discussion in 'Homework Help' started by blackdeath320, Nov 25, 2012.

  1. blackdeath320

    Thread Starter New Member

    Nov 25, 2012
    Hey guys,

    I was hoping someone could help me out with the noise analysis for the following circuit:

    You can ignore the square blocks they're just behavioural models. Also the problem is that I don't have the input referred noise current or voltage for the opamps. I did a noise analysis on both high power opamps (HP: the upper two) and lower power amps (LP: the bottom three). The simulation results are shown below:

    Basically the square blocks are modulating a 2000Hz signal with a 90kHz carrier and the noise voltages at 90k for HP and LP are 32.74nV and 68nV respectively from the simulations shown above. The first opamp is just used as a non-inverting amplifier and the second one is being used to demodulate the signal. The three opamps at the bottom form the anti-aliasing filter.

    Any help would be appreciated.