Dear all,

    These days I am doing the Gm-C LPF design, the spec is as following: center frequency=133KHz, BW=233KHz(0.5dB loss), @467KHz=-72dBc, 1dB ripple in passband, NF<=35dB, Gain<=10dB.
   
    I used 8-order ChebyshevI LPF and simulation results shows it met the above specs except NF. The NF of my circuit is about 60dB. I did not know how to reduce it.