Colpitts oscillator and transconductance value

Discussion in 'Homework Help' started by Iza Soliwoda, Feb 17, 2016.

  1. Iza Soliwoda

    Thread Starter New Member

    Sep 2, 2015
    Hello! Can you give me a hint to answer this question? This is part of an exam task. The first part was to identify input impedance, which I did.
    "For what values of parameters (gm, I1) circuit can (regardless of the small changes of voltage and current supply and the temperature) generate periodic output voltage signal?" I searched for this whole night and failed to answer it. What I found is that:
    Magnitude criterion for steady-state oscillation at the oscillation frequency f is given by
    |T (f)| = 1
    In order for the oscillations to start and grow, the magnitude of the loop gain T must be greater than unity.
    (I had to translate it from Polish to English, so I hope everything is understandable and sorry for any mistakes :). )
  2. Jony130

    AAC Fanatic!

    Feb 17, 2009
    Try to watch this
    Iza Soliwoda likes this.