lc resonator

Hi all,

Might be basic stuff, but I feel really tired these days.
And obviously, I am quite in a hurry !
I hope you could help me :)


Here's the problem.
I have an inductor, modelized by its S-parameters, imported from Momentum to ADS as a component.
I'd like to make this inductor resonate at a certain frequency, with a parallel capacitor.
Until here, everything's ok.
But now, I'd like to modelize this frequency resonance.
So, I connect all the things as it
- "Term" component to the capacitor, and ground
- The capacitor component in parallel of the "inductor"
- The LC parallel is connected to ground.

Guess you can imagine it :)

Now if I start a S simulation, I find S11 resonance at my frequency, identified by the notch... well, the valley... well, a gap... I can't find my words in english today :D

If I want to see a clear and perfect notch, I should put a source impedance quite high. The question is: why ?

And the bonus question is: if I want to drive this LC tank with something, should I show him a high impedance level ?

Thanks a lot in advance for your precious answer.
Regards

Ok, new day, new ideas.
I figured out most of the previous question: first, at resonance, the impedance is maximum. That explain why "Term" should show a high impedance.
Then, concerning the adaptation, smith abacus helped me a lot :)

Hi,

You must connect your LC-circuit with a very small capacitor 10-20 fF from i nput and output ports in order not to load the circuit. You can change the capacitor value to shift the peak level to about -30 dB or so, then the 50 ohm port loading does not load your circuit. You must have enough measurement points depending of course of the sweep etc. and you can easily measure the Q-value of your circuit by using banwidth_func.

Regards

Erno

If fact, I do not have any problem with theory.
But the simulator does, in a certain way, because I was looking for S parameters... and the reference was defined as "standardized", not "port(Z1)".