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Simulators >> RF Simulators >> N2PORT DC problem
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Message started by uncle_ezra on Oct 12^th, 2006, 1:58am

Title: N2PORT DC problem
Post by uncle_ezra on Oct 12^th, 2006, 1:58am

Hi,

I have s-parameter data of a balun and tried importing into spectre using N2PORT. However when I run simulation it cannot give me the correct DC value. I have ran the s-parameter data down to 0 Hz but the problem persists. Is there a way around this problem, other than use another tool such as ADS?

Thanks

Title: Re: N2PORT DC problem
Post by vara on Oct 12^th, 2006, 4:39am

Uncle,
Try 'rational' for the interpolation method in the 'n2port' instance.
I had to import from an other tool like you did and it works for me
in ac analysis.
However, for Transient analysis, 'rational' does not work and i read
somewhere (don't remember where) that 'spline' should be used.
Vara

Title: Re: N2PORT DC problem
Post by vara on Oct 12^th, 2006, 4:44am

See attachement

Title: Re: N2PORT DC problem
Post by uncle_ezra on Oct 12^th, 2006, 5:49pm

Thanks, I tried using 'rational' but it did not work. Basically what I have is a balun where in the primary one port is connected to VDD and the other to the signal and the secondary is a differential output. So when I run transient or DC analysis I get garbage since there are no DC voltage or current flowing from VDD to the main circuit.

Title: Re: N2PORT DC problem
Post by madengr on Oct 13^th, 2006, 2:04pm

I noticed you are using Sonnet. It will export a lumped element equivalent circuit that may work, assuimg it generates a low-pass structure.

Title: Re: N2PORT DC problem
Post by Andrew Beckett on Jan 15^th, 2007, 2:32am

Bit late in replying, but probably I would suggest using spline or linear as the interpolation method. I'd also recommend setting "Use smooth data windowing" to "yes" - this is nearly always the right thing to do; failure to do this often leads to an error in the DC value (but is more accurate if you have signals close to the maximum frequency in the s-parameter data).

There is an application note on sourcelink (search for "nport application note") which covers the parameters well.

Regards,

Andrew.