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Help on Spectre Tran. simulation for LC-VCO (Read 2251 times)
trashbox
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Help on Spectre Tran. simulation for LC-VCO
Jun 14th, 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.
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James Bond
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Re: Help on Spectre Tran. simulation for LC-VCO
Reply #1 - Jun 16th, 2007, 1:14am
 
Find your dc voltage of that node, and set initial value 10mv higher than that node voltage.
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