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Design Languages >> Verilog-AMS >> VerilogA laplace_zp element convergency issue
https://designers-guide.org/forum/YaBB.pl?num=1239163769

Message started by neoflash on Apr 7^th, 2009, 9:09pm

Title: VerilogA laplace_zp element convergency issue
Post by neoflash on Apr 7^th, 2009, 9:09pm

I have come up with convergency difficulty in hspice simulation with laplace_zp element.

It is an peaking amplifier and the simulation results looks good in AC simulation. However, in transient simulation it reports "internal time step too small".

Already tried method=gear option and still can't get it to work.

Please advice if you have better solutions.

Title: Re: VerilogA laplace_zp element convergency issue
Post by Peruzzi on Apr 8^th, 2009, 7:32am

Without knowing more details I can only take a guess, and suggest you look for step functions in voltages or currents. Make sure you set initial conditions, or know and approve of their defaults.

Good luck.

Bob P.
www.RPeruzzi.com

Title: Re: VerilogA laplace_zp element convergency issue
Post by patrick on Apr 8^th, 2009, 8:38am

If you are not using the 2009.03 release you should upgrade to it if possible. Also if you can post the circuit & va module we can take a look.

Patrick

Title: Re: VerilogA laplace_zp element convergency issue
Post by neoflash on Apr 8^th, 2009, 10:47am

I know it now. I screw up the polarity of the zero and poles.

AC looks right but transient is a mess.