I need to extract s parameters of a differential linear equalizer (high pass filter) using spectre.
I do not have spectre RF. How do I do four port analysis?
Assuming you want basic differential and not mixed-mode S-parameters, then you can attach a "balun" component (from the "rfLib" library) to both the differential input and output of your amplifer. One would then attach a "port" component (from the "analogLib") library to single-ended terminals of the balun. The port should configured with the correct impedance (e.g 50Ohms) and assigned a port number (1 and 2). Depending on your design you may also need to add DC blocking and biasing to the amplifier inputs, etc.
The "rfLib " library is available in the cadence installation directory: $CDS_INSTALL_DIR/tools/dfII/samples/artist/rfLib
You should now be ready to simulate the design in spectre using ADE. Setup an "sp" analysis and sweep over the desired frequencies. After the simulation completes, select "Results->Direct Plot->Main Form..." You can also use the calculator to plot S12.
You may also want to check the RF Design Forum for addition help and suggestions.
In reply to Jim McMahon:
Thank you for pointing to right direction. The challenge is that I do not have rfLib.
So I tried to create balun using two xfmr elements. But cant define rout and rin of balun.
I am not sure what port impedance to use. Considering the ckt as blakcbox, how do I select
In reply to aaamin:
You should also be able to get it to work using the xfrm. The port impedance can be set by changing the port resistance parameter. The default is 50Ohms.
For the ideal balun, take a look at http://www.designers-guide.org/Analysis/diff.pdf.