simple question about a resonance frequency

I have a big circuit and a little part of circuit showed in this figure
I want to know how I can calculate the resonance frequency?
How can I use 1/(L18*C18 )=w^2

Is the C20 effected in the resonance freq or not?

Hi laperla, the seond tank circuit (right-hand) has no influence on the output voltage without any load impedance . It only provides a frequency-dependent output impedance.

thanks for reply

when I want to calculate the W I have to consider half of the circuit becouse my circuit is double side
I want to know if c20 is effected in the w or not?

A complex LC circuit can't be described by a single resonance frequency. You can calculate resonance frequencies of individual LC tanks, or the frequency characteristic of the full circuit, which also requires a source and load impedance specification. The latter will be affected by all component parameters, also C20.

thanks for reply

Can I help from frequncy responce of output?

I don't know what you want to achieve. The overall frequency response of the filter can't be determined without specifying source and load impedance. But we can say, that the real zeros in overall response would be effectively identical to the resonance frequencies of the two individual tanks for this filter.

thanks for answer
I found that I can't calculate this parameter in the paper
now how can I amount of resonance frequency with depict in ADS? How can I show in the schematic?

Just set S-params to sweep the freq and check the S21.

thanks for reply
I did it but S21 curve don't hormonic and is vague
I am working on the mixer in ADS and I chage the RF input and replace P_tone with Z term , Is it tru?
first input is RF freq.
second input is LO freq.
last port is output
I think that I measure S31 Is it ok?
Can u guide me to simulate S21?

I want to attach image of curves but I can't