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https://designers-guide.org/forum/YaBB.pl Simulators >> RF Simulators >> IIP3 analysis on a netlist with nport statement https://designers-guide.org/forum/YaBB.pl?num=1076097546 Message started by amitava on Feb 6th, 2004, 11:59am |
Title: IIP3 analysis on a netlist with nport statement Post by amitava on Feb 6th, 2004, 11:59am Hi, I am facing a problem when doing Cadence Spectre simulation for IIP3 analysis on a netlist that has "nport" statements modeling the interconnects of a circuit. As an example I am giving the nport statement of a 2 port network that I have in my netlist below: -------------------------------------------- simulator lang=spectre model sp_data1 nport file="spNport1.data" //Components X1 (a1 a2 b1 b2 )sp_data1 ------------------------------------------- The file "spNport1.data" contains the s-parameters (2x2 matrix) of the interconnects (a1 to a2 and b1 to b2) as a 2-port network. The netlist has other elements like resistors, transistors, inductors and capacitors connected to each other to form an LNA topology. There are other "nport" statements too for other connectivities but I have given an instace with 2 nets connecting a few of the components. When I simulate the entire netlist for doing the IIP3 analysis I get an error like this: ************************************ Error found by spectre during periodic steady state analysis `pss1'. Distributed components and components with hidden state are not allowed with this analysis -- analysis skipped. nport Analysis `pss1' terminated prematurely due to error. ************************************** As pss and pac analysis are essential to do the IIP3 analysis, I am not sure how to avoid this error from happening and to determine IIP3 of a netlist that has "nport" statements describing the interconnects. (I went thru the designers guide on how to avoid "hidden-state" errors in spectre but am clueless on how to avoid the error in this case) Can anyone of you help me on this. Thanks and Regards, Amitava |
Title: Re: IIP3 analysis on a netlist with nport statemen Post by Andrew Beckett on Mar 5th, 2004, 1:52am You will need to set "interp=rational" on the nport ("Interpolation Method" on the edit parameters form in the schematic), together with either ratorder (to indicate the "order" it should use for the rational approximation when producing a time domain representation. Alternatively you can use relerr/abserr to control the accuracy (see "spectre -h nport" for more info). Currently only this approach for generating a time-domain representation will work with spectreRF, because spline and linear interpolation methods have hidden states (as you've seen). In IC5141, all modes will work with SpectreRF though (due out in June). Andrew. |
Title: Re: IIP3 analysis on a netlist with nport statemen Post by CDR on Mar 24th, 2004, 6:44pm What should be the format of spNport1.data?Could you give examples? |
Title: Re: IIP3 analysis on a netlist with nport statemen Post by Andrew Beckett on Mar 28th, 2004, 11:36am The format can be spectre's own format (I think this is covered in the documentation), touchstone or citifile format. From IC5033 this can be selected on the instance of nport itself, but there's also a translator "sptr" which can be used to do the conversion (translator also available in older versions). Andrew. |
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