Impedance Plot Data from S-Parameter File

Is it possible to get the impedance data from an s-parameter file?

In this example I'm using Part # GQM2195C2A100GB01

I'm using the s-data from SimSurf (http://ds.murata.co.jp/software/sims...us/index.html#
Click on Monolithic Ceramic Capacitors

The S-Data is attached.

The plot I'm looking for is:

In ADS, the normal way is import S2P file and simulate with Z parameter selected, then can plot with ADS data.
But your component is a Tan capacitor, it is nonsense to plot its impedance over frequency, say 1GHz.

It's a 'GQM*' Series. Those are High-Q (See http://psearch.en.murata.com/capacit...100GB01%23.pdf)



I did notice that plotting S11 is the same plot as |Z|. I'm just not sure why.

The two are related to one another, its the reason why smith charts were created. A neat way to display both complex reflection and impedance. Although the impedance contours aren't as easy to imagine / use as the X-Y plot you want.

S11 = (Zcap - Zo) / ( Zcap + Zo), assuming a 1 port measurement with the cap as the load of course.

Not sure if that helps,
Sami

if this is a capacitor, you have to realize that the impedance is a complex quantity. i.e. it has real ohms and imaginary reactance. it might be more useful to plot the real and imaginary part on different graphs.

what are you simulating, a series capacitor between two 50 ohm lines?

Note there is some sort of resonance around 4.5 GHz, either caused by the capacitance bulk dielectric acting like a waveguide, or the lead/parasitic inductance resonating with the capacitor.

I get this. But I need to get the Zcap from our VNA measurements.



No simulation, all VNA measurements in a series-thru configuration.

Yes, the 4.5 GHz is the parallel resonance frequency. From what I understand this is where the capacitor has maximum impedance (as opposed to the SRF which is minimum impedance.).

If the cap is in series between the two ports, the first step is to convert the 2-port data into the differential series element (1-port)

Z = stoz(S)
Zdiff = Z(1,1) – Z(1,2) – Z(2,1) + Z(2,2)

This Zdiff is the capacitor's impedance, similar to your plot.