Hi,
SInce the stop time if my TRAN analysis is long, tens of micro seconds, it takes a long time. Any idea of decrease the time consuming on the simulation? No difference if a big time step is used.
Thank you.
Eh? How can that be? Simulation speed is circuit-content dependent.
...Jim Thompson
-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et |
Thank you for your reply.
SPICE3 is the spice program for unix. WHat does 'ecipsTL' mean?
Hello, Jim
Is there anything I can do to increase the speed? My circuit is a ring VCO.
Thank you.
Which flavor of Spice?
Oscillators always need a small max timestep
Use a .IC statement, or a starting current pulse
...Jim Thompson
-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et |
"vivian" schrieb im Newsbeitrag news: snipped-for-privacy@g44g2000cwa.googlegroups.com...
Hello Vivian,
maybe your PC is too slow.
A ".tran 100us" takes exactly 1.2345sec on my PC.
What exactly means SPICE3 in your case?
I recommend to try your circuit with some other SPICE-programs. My secret tip is 'ecipsTL'. Just read this '' backward.
Best regards, Helmut
Hello Jim,
I am using Spice3 under unix. Actually, I have used .IC statement in my spice file. Does that help?
The .IC statement usually improves start-up time dramatically, but generally won't have any effect on the length of time the total simulation takes.
...Jim Thompson
-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et |
"vivian" schrieb im Newsbeitrag news: snipped-for-privacy@g43g2000cwa.googlegroups.com...
Hello Vivian,
This 'ecipsTL' is LTspice. It's written for WIN-98,ME,2K,XP. You can use it with WINE under Linux as well, but
99.99% of the users run LTspice under the native OS WIN-xx. Please use it with WIN-xx to avoid any unnecessary problems. It can be used with netlists or with schematics.Best regards, Helmut
Thank you all for your kind help!
vivian
You still get slapped wristies for......
A ".tran 100us" takes exactly 1.2345sec on my PC.
Fortunately your name sounds like you are German so, other than no sense of humour, we might assume you have a different one.
I think the origin of Germans having no sense of humour arises because the language is at least 84.607E3% longer than the rest of the stuff we grunt with and the audience goes to sleep long before the punchline.
OK..... I'm an asshole.
DNA
Thank you for your kind help.
"Genome" a écrit dans le message de news:1ObYe.20117$ snipped-for-privacy@newsfe6-win.ntli.net...
of
How can you think that people insisting on saying 21 "one and twenty" lack sense of humor?
-- Thanks, Fred.
Hmmm. Getting rid of any un-needed capacitances,or lowering their values may help. Also, look into a faster machine with more memory? Reading the replies from the (V-E-R-Y elite) S.E.C. social club probably won't help, because it seems they are mostly a bunch of self-absorbed assholes.
[snip]
I may be "self-absorbed", but I'm not clueless, as you appear to be.
...Jim Thompson
-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et |
In principle, there is a technique "model reduction" that allows us to reduce the dimension of the original circuit. You can have a look at
R. W. Freund, Reduced-Order Modeling Techniques Based on Krylov Subspaces and Their Use in Circuit Simulation
Unfortunately, in order to use this you need to have special software.
Best wishes,
Evgenii Rudnyi
--
I just pulled out a 7-stage BIPOLAR ring oscillator from my files, simulated for a total of 1us with max timestep set to 1ps (*).
Simulation time 915 seconds, 1.09ns per second of simulation, oscillator frequency 2.7GHz.
(*) To get good resolution for the Spectral/Fourier that was also performed.
With no max timestep restriction, 101.86 seconds of simulation time,
9.82ns per second of simulation, but seriously degraded spectral view.A CMOS circuit would likely run faster, since there are far fewer elements.
...Jim Thompson
-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et |
Hello Brett,
The first message from Vivian contained no information about the simulated circuit. How could somebody give any useful advice except running it on the fastest PC?
After the second posting from Vivian we have got informed that it is a ring oscillator. I expect now that it's an odd number of inverters in a loop. There is still no detailed information about the circuit, e.g. the number of stages. It makes a big difference whether you use 3 or 31 inverters. In the ladder case the simulation time will be 10 times longer.
After the third message we know it's any SPICE-3 simulator under Unix. Something self compiled? Who can give any advice for an unknown program?
-- Hello Vivian, I have tried now with an 11 stage ring oscillator which oscillates
And recommending getting RID of capacitance ranks Brett as the most clueless one of the year... SHEEEESH ;-)
...Jim Thompson
-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et |
Brett, you just elected yourself to the asshole status IMNSHO. Some of these people are very helpful SPICE experts. They can also get distracted talking to past and around each other and not answer OP. If you really want them to help, post your netlist or if it is large put it on a web page or some other publicly accessable place. And help you will normally get.
-- JosephKK
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