Phase shift with N-Mosfet oscillator

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Samantha Groves

Joined Nov 25, 2023
62
I am trying to build up a phase shift oscillator using a N Mosfet.

The circuit diagram of such oscillator is:

DrawIO29_12_23_01_49.png
The AC equivalent of this circuit will be:

1703808430234.png

By writing KCL for every node of the circuit we end up with these equations:

\[ g_{m}V\pi+\frac{V_{B}}{R_{d}}+\frac{V_{C}}{R_{1}}+\frac{V_{D}}{R_{1}}+\frac{V_{E}}{R_{1}} =0 \]

\[ g_{m}V\pi-sC_{1}(V_{C}-V_{B})+\frac{V_{B}}{R_{d}}=0 \]

\[ sC_{1}(V_{C}-V_{B})+\frac{V_{C}}{R_{1}}-sC_{1}(V_{D}-V_{C})=0 \]

\[ sC_{1}(V_{D}-V_{C})+\frac{V_{D}}{R_{1}}-sC_{1}(V_{E}-V_{D})=0 \]

\[ \frac{V_{E}}{R_{1}}+sC_{1}(V_{E}-V_{D})=0 \]

From the above set of equations we get:

Vc=0

So now what do I have to do to find the resonant frequency and the feedback gain?
 
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