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Simulators >> RF Simulators >> Help on Spectre Tran. simulation for LC-VCO
https://designers-guide.org/forum/YaBB.pl?num=1181888175

Message started by trashbox on Jun 14^th, 2007, 11:16pm

Title: Help on Spectre Tran. simulation for LC-VCO
Post by trashbox on Jun 14^th, 2007, 11:16pm

Hi guys,
When I am running LC-VCO tran. simulation with spectre, I run into several problems:
1) what's the path and file name of netlist file which is used to be simulated? Even when I deleted the file "input.scs" and "netlist" at home/simulation/t_lcvco_test/spectre/schematic/netlist, then I press "run" on the Analog Design Environment, the simulation can run!! It seems that the file "input.scs" and "netlist" are not the files which is simulated directly. I want to modify my netlist file by hand, however, I don't know which file is the simulated-netlist.

2) During my simulation, there are several warnings, however, the spectre.out only shows five warnings and the others are suppressed. How can I let all warnings visible?

3) When I set a initial simulation condition at some node in my schematic, spectre warns:
Warning from spectre during IC analysis, during transient analysis `tran'.
Initial condition of 800 mV between nodes I0.net082 and 0 ignored because
there is no capacitive path to ground.
So I added a small capacitor between I0.net082 and vss, netstlist and run again, the spectre warns:
Notice from spectre during IC analysis, during transient analysis `tran'.
Initial condition computed for node I0.net082 is in error by 1.23307 mV
(154.134 m%).
To reduce error in computed initial conditions, decrease `rforce'.
However, setting rforce too small may result in convergence
difficulties or in the matrix becoming singular.
How to add initial conditions in spectre?
Thanks in advance.

Title: Re: Help on Spectre Tran. simulation for LC-VCO
Post by James Bond on Jun 16^th, 2007, 1:14am

Find your dc voltage of that node, and set initial value 10mv higher than that node voltage.