I have a S parameter file in touchstone format (.s8p extension). I want to convert this into SpectreRF netlist such that I can use that for frequency as well as transient simulation. Can anyone help me regarding  conversion of .s8p into SpectreRF netlist. Thanks in advance.  :)

I have already checked but I have not found how to generate equivalent model so that it can be used for transient simulation.

There's also an application note on sourcelink.cadence.com - search for "nport" and restrict your search to application notes. You should find          "Using the nport Component from the analogLib Library". It's a good overview of using nport.

Regards,

Andrew.

This isn't true. Cadence haven't "denied" these things.

Convolution was supported in transient for years - way before rational in fact. The problem was supporting convolution in shooting in PSS; it's not that trivial, and the rational approach was created precisely to solve that problem. In practice, the rational method was not fully developed, and in the meantime we had done further work to come up with a way of supporting convolution in shooting PSS. That happened in around 2004.

Shooting methods are (and still are) excellent for solving strongly non-linear periodic steady-state. For many years harmonic balance methods in other simulators could not handle anything other than very small circuits and very linear circuits - they failed to converge, or ran out of memory. That changed as some of the numerical techniques first used in SpectreRF were also applied to harmonic balance in other simulators - so other simulators became able to handle larger circuit problems very effectively and robustly.

It became apparent that SpectreRF could also implement a harmonic balance engine using the same numerical techniques, building upon Cadence's experience of iterative Newton solvers, thus giving users the choice of algorithms - to use either shooting or harmonic balance as appropriate.

All tools take time to develop and evolve and take advantage of new techniques. It's not a matter of "denying" anything - it's just a matter of prioritizing resources and doing development work. Sure mistakes get made along the way as with any business, but hopefully in the long run the right thing gets done!

This app note is from 2005, and harmonic balance was added to SpectreRF nearly 4 years ago now and has had considerable development since then. So even if Cadence had "denied" anything, that's not exactly current information.

With harmonic balance, using s-parameter files is simpler, because you're simulating a frequency domain description and directly simulating in the frequency domain.

(yes, I work for Cadence, so this is probably a biased view).

Regards,

Andrew.

RFICDUDE wrote on Mar 28^th, 2009, 6:37pm:
It is very rare that "rational" gives good results compared to "convolution".
However we have no choice except for "rational" in Envelope Analysis in Cadence Spectre.

I don't use Cadence SpectreRF mainly for RF circuit.
But due to lack of Agilent licenses, I often have to use Cadence Spectre reluctantly.

When I run Envelope Analysis in Cadence Spectre using following S-parameter Library,
I often encounter simulation problems such as blow up or fake oscillation.
http://www.murata.co.jp/cgi-spara/search.pl?primary=lqg15hn&lang=en
http://www.murata.co.jp/cgi-spara/search.pl?primary=grm15&lang=en

When I can get Agilent licenses, I resimulate same circuit using Agilent Envelope Simulator such as GoldenGate.
Of course I can get reasonable results very quickly.

I'm always very honest because I don't have to defend or promote any specific vendor's tool.