FET Miller Sweep - Transient Response

Discussion in 'Homework Help' started by chrispo86, Jan 30, 2009.

  1. chrispo86

    Thread Starter New Member

    Jan 28, 2009
    I've been given the attached circuit and been told to sketch the output from 0+ <= t <= ∞. I believe I'm correct in stating that the voltage across the cap at time 0+ is ecap = 9V, and the voltage at the output is eo(0+) = Vgs + 9V, and Vgs would be 0.7V so it would be 9.7V. At least, this is what it was in a similar problem which we did in class, so correct me if I'm wrong.

    This is where I get lost. I know the next step would be to find eo(∞). The capacitor would be replaced by an open once it reaches steady-state, so it can be taken out of the circuit, leaving the circuit in the second figure. What's confusing me is what do I do with the (gm Vgs)? Maybe it's just that I can't remember my classes where we covered transistors. It's been a couple years now.

    Thanks in advance for the help.