# Finding resonant frequency question

#### The_Cook

Joined May 29, 2014
48
Does anyone know how to find the resonant frequency for the attached circuit in terms of C's and L's?

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#### shteii01

Joined Feb 19, 2010
4,644

#### The_Cook

Joined May 29, 2014
48
Is the formula on the page same as resonant frequency?

Would you be able to show me how to derive that?

#### DerStrom8

Joined Feb 20, 2011
2,390
This sounds an awful lot like a homework question. Why don't you attempt it yourself first, and then we can look at it and see what you might need touching up on?

Regards,
Matt

#### The_Cook

Joined May 29, 2014
48
This sounds an awful lot like a homework question. Why don't you attempt it yourself first, and then we can look at it and see what you might need touching up on?

Regards,
Matt
Hey Matt, we never went over this in class and I couldn't find any example in our book, or online. So could you tell me how to derive it, I have no idea where to start with this. And I am also confused how the small signal circuit is supposed to help me with the question either.

#### The_Cook

Joined May 29, 2014
48

#### shteii01

Joined Feb 19, 2010
4,644
That's a colpitts oscillator. Is that the same thing as the question?

Also I couldn't really find anything in the notes where the resonant frequency is derived, it's kind of just given there. Could you explain how that works?
That is the point of the homework. You have the start and you have the end, it is your job to connect the two.

From googling, Clapp Oscillator is a Colpitts type oscillator.

#### The_Cook

Joined May 29, 2014
48
That is the point of the homework. You have the start and you have the end, it is your job to connect the two.

From googling, Clapp Oscillator is a Colpitts type oscillator.
Yeah I can't figure out how to make that connection. Could you tell me how to?

#### Jony130

Joined Feb 17, 2009
5,241
Yeah I can't figure out how to make that connection. Could you tell me how to?
Here you have. Now all you need to do is to w rite the transfer function for feedback and solve for ωo to make the imaginary part of the denominator = 0

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#### The_Cook

Joined May 29, 2014
48
Here you have. Now all you need to do is to w rite the transfer function for feedback and solve for ωo to make the imaginary part of the denominator = 0
Is there an example I could look at to see the steps to find the resonant frequency

#### Jony130

Joined Feb 17, 2009
5,241