Help!I can't modeling capacitor using ADS

[qewqetw]

Hello everyone,I have a problem that I can't solve.
I have already use TRL calibration to my VNA.
And then I measure a chip-capacitor.The frequency is 1 to 8GHz.
And the capacitor is 2000pF.
I catch the S2P file and use ADS to modeling it.I use the equivalent circuit for high-frequency capacitor that I see in my book.
I use optimization to do it.But it always can't match my measurement.
Please help me.Thank you.

 

[ChaoFan]

Could you post your sch? you have to give a initial value for each component. And how close of your optimization now?

 

[Mazz]

The reason is probably that the component you are measuring is NOT a capacitor in the range you measured it.
2nF cap has first self resonance well below 1 GHz.

try with 2pF and you'll get some result, I guess.

Mazz