[SI-LIST] Re: simulation in Nexxim
- From: wfting@xxxxxxxxxxx
- To: agathon <hreidmarkailen@xxxxxxxxx>, Mohamad Haghtalab <mohaghtalab@xxxxxxxxx>, si-list@xxxxxxxxxxxxx
- Date: Wed, 10 Sep 2008 13:52:56 +0800 (CST)
I was told by one of the commercial tools vendor that it might be a problem to
assume the "ref" as the GND (0 node) in time domain simulator. As there might
be some unexpected current path between this "ref" node to the "GND" in your
additional spice block. It can be a workaround to put a resistor with high
resistance (such as 1 Mohm) between the "ref" and the global GND to limit the
unexpected current flow.
Regards,
Steve
=====Original Message=====
>寄件者:agathon <hreidmarkailen@xxxxxxxxx>;
>收件者:Mohamad Haghtalab <mohaghtalab@xxxxxxxxx>;
>副本:Saoer Sinaga <saoer.sinaga@xxxxxxxxx>; si-list@xxxxxxxxxxxxx;
>日期:Wed Sep 10 03:26:18 CST 2008
>主旨:[SI-LIST] Re: simulation in Nexxim
>
>I'm not sure exactly what the symptom is (what you mean by dc continuation)
>but I've seen a dc offset and strange "integration" or clean postive ramp
>component added to hspice results for a channel illustrated as:
> behavioral source -- sparam & hspice interconnect -- amplifier.
>HSpice 2004 or 2005 was used and Ansoft HFSS models w/ dc extrapolation. A
>colleague just refreshed my memory on it: The appearance was that hspice V
>sources and ABSV param had influence on simulator behavior. Workaround was
>to use a current source w/ 1ohm load and setting ABSI = 0.1nA (smaller than
>default I believe). Ie: more sim accuracy is needed for the responses.
>I don't suspect a noncausal issue since that would be characterized by
>response before stimulus or output signal presence w/ no input energy,
>although the "ramping" mentioned above mimics that. A passivity problem
>typically shows up as catastrophic oscillation.
>
>
>On Tue, Sep 9, 2008 at 12:50 AM, Mohamad Haghtalab
><mohaghtalab@xxxxxxxxx>wrote:
>
>> it's transient simulation,the s parameter model contain 0 Hz
>> data(matrix),but what's non-causal S-param?,what's the solution?
>>
>> regards
>> --- On Mon, 9/8/08, Saoer Sinaga <saoer.sinaga@xxxxxxxxx> wrote:
>>
>> From: Saoer Sinaga <saoer.sinaga@xxxxxxxxx>
>> Subject: [SI-LIST] Re: simulation in Nexxim
>> To: "'SI LIST'" <si-list@xxxxxxxxxxxxx>
>> Date: Monday, September 8, 2008, 10:39 PM
>>
>> Is it a frequency domain simulation or transient simulation. The causes
>> are likely to be non-causal S-par and/or no DC data in your S-par.
>>
>> saoer
>>
>> Mohamad Haghtalab wrote:
>> >
>> > Hi all
>> > I have a design in Nexxim(ansoft designer) in which there is both
>> S-parameter and Spice models blocks,s parameter blocks all have one port
>> named
>> 'ref ' ,I connect all these ports to ground in shematic,if all models
>> were S parameter when simulating the design we dont have any error ,but if
>> we
>> add a spice model (e.g. LNA model) we have error in simulation
>> > (DC continuation...),the problem seems to be the refrence of spice
>> model(?),can you help me about that?
>> >
>> > Regards
>> >
>> > Haghtalab
>> >
>> >
>> > ------------------------------------------------------------------
>>
>
>
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