Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Different results in Hspice and Spectre

Status
Not open for further replies.

wjlzhx

Member level 5
Joined
Apr 14, 2005
Messages
82
Helped
4
Reputation
8
Reaction score
1
Trophy points
1,288
Activity points
1,785
which will i trust hspice or spectre?
I simulate a circuit--osc

using spectre i get the rusult ,frequcy is 22k
but using hspiec i can not get the rusult ,it can not osc .

when i simulate with hspice, there are no error.

so which i can trust??
 

Ruritania

Member level 5
Joined
Nov 18, 2004
Messages
93
Helped
4
Reputation
8
Reaction score
3
Trophy points
1,288
Activity points
856
Re: hspice vs spectre

Hi,

I think you should make sure that all the settings are the same in both the Spectre simulator and Hspice simulator... and, maybe you need to set some initial conditions to make the circuit oscillate in Hspice.

Anyway, Hspice is always the golden standard in the IC industry ...

Hope this helps.

Ruri
 

xirix

Full Member level 2
Joined
Jun 26, 2001
Messages
123
Helped
3
Reputation
6
Reaction score
1
Trophy points
1,298
Location
Romania
Activity points
939
Re: hspice vs spectre

HSpice - good for analog simulations
Spectre - good enough; used for big digital circuits (very fast vs. HSpice)
 

bigpop

Junior Member level 3
Joined
Nov 24, 2004
Messages
30
Helped
7
Reputation
14
Reaction score
5
Trophy points
1,288
Activity points
179
Re: hspice vs spectre

You should add some initial condition in hspice to let it oscillate.
If your circuit is not large, hspice and spectre will get same results.
 

sunny153

Member level 2
Joined
Mar 29, 2005
Messages
46
Helped
1
Reputation
2
Reaction score
0
Trophy points
1,286
Activity points
1,603
Re: hspice vs spectre

certainly Hspice is the king of analog simulators. As mention by other folks u need to check out the settings..
 

vbhupendra

Full Member level 4
Joined
May 11, 2005
Messages
235
Helped
15
Reputation
30
Reaction score
8
Trophy points
1,298
Location
GOA, INDIA
Activity points
3,219
Re: hspice vs spectre

hspice is very accurate. and as others have mentioned you have to give initial conditions. or you can just give a pwl to VDD from 0 to VDD in a small time.
 

wjlzhx

Member level 5
Joined
Apr 14, 2005
Messages
82
Helped
4
Reputation
8
Reaction score
1
Trophy points
1,288
Activity points
1,785
hspice vs spectre

thank you for your helps

I set the initial condition like this
.ic v(net108)=0.5v v(net137)=0.5v v(net110)=0.5v
net108,net110,net137 they connect cap to gnd!

but i got nothing.

and i also add the pwl ,but got nothing .

now sometime i got the wrong rusult ,it said "no convegence",is this the modle's problem or the circuit's problem???
 

Fom

Advanced Member level 2
Joined
Mar 10, 2004
Messages
633
Helped
84
Reputation
168
Reaction score
32
Trophy points
1,308
Location
Taiwan
Activity points
4,456
Re: hspice vs spectre

Hspice or Spectre? It looks like religions.
Hspice believer or Spectre believer.
Why some people consider Hspice is more accurate than other simulators? Any proof except declaration?
May be it was during before BSIM3 era. When Hspice used level 28 MOS model. But today if simulator use BSIM3 models it has the same accuracy as other simulator that use the same model.
If simulator use the same differential equations accuracy is defined by options like reltol, abstol, etc.
Another thing is an algorithm used to find solution. But it affects only on simulation time not accuracy.
BTW, I was very surprised when I didn't find voltage nonlinearity for resistor model in Hspice.
 

yibinhsieh

Full Member level 4
Joined
Apr 25, 2005
Messages
194
Helped
19
Reputation
38
Reaction score
4
Trophy points
1,298
Activity points
2,845
Re: hspice vs spectre

I think this two simulator are good for us. The convergence in spectre is better than the one in hspice. But the waveform view in hspice is more friendly than the one in spectre.

Yibin,
 

Fom

Advanced Member level 2
Joined
Mar 10, 2004
Messages
633
Helped
84
Reputation
168
Reaction score
32
Trophy points
1,308
Location
Taiwan
Activity points
4,456
Re: hspice vs spectre

yibinhsieh it is just your opinion. I am absolutely disagree with you. If to consider Analog Artist it has the most frendly interface.
Just an example.
For Hspice you have to care about what kind of sophisticated waveform you will plot after simulation and put it in simulation netlist as MEASURE statement. If you forget to do that or you need to plot something else you cannot plot it.
For Spectre (Analog Artist) you don't care about that because you can plot every expression AFTER simulation.
 

Analog_starter

Advanced Member level 4
Joined
Nov 15, 2004
Messages
113
Helped
1
Reputation
2
Reaction score
0
Trophy points
1,296
Activity points
1,111
Re: hspice vs spectre

xirix Posted: 12 May 2005 9:05 Post subject: Re: hspice vs spectre

--------------------------------------------------------------------------------

HSpice - good for analog simulations
Spectre - good enough; used for big digital circuits (very fast vs. HSpice)


But I found spectre is not faster enough than hspice.

Best Regards
Analog_starter
 

dendrite

Junior Member level 1
Joined
Nov 29, 2004
Messages
15
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
121
Re: hspice vs spectre

If you use the large mixed signal circuit. you'll feel the speed.
The third choice is ultrasim. Maybe it's the best.

Analog_starter said:
xirix Posted: 12 May 2005 9:05 Post subject: Re: hspice vs spectre

--------------------------------------------------------------------------------

HSpice - good for analog simulations
Spectre - good enough; used for big digital circuits (very fast vs. HSpice)


But I found spectre is not faster enough than hspice.

Best Regards
Analog_starter
 

layes2

Full Member level 4
Joined
Dec 3, 2004
Messages
230
Helped
10
Reputation
20
Reaction score
6
Trophy points
1,298
Activity points
1,410
Re: hspice vs spectre

you should add
option
.ic
to hspice
hspice is better
 

simov

Member level 1
Joined
Sep 3, 2003
Messages
33
Helped
2
Reputation
4
Reaction score
2
Trophy points
1,288
Activity points
244
hspice vs spectre

in your case, low frequency oscillator is autonomy circuit, so the simulation result depend on the arithmetic of simulator about autonomy circuit. From my experience, simulate low frequency autonomy oscillator not only in time domain but also in frequency domain, and base on some theoretics calculation and real chip test result
 

selvaraja

Full Member level 4
Joined
Jun 1, 2004
Messages
190
Helped
6
Reputation
12
Reaction score
3
Trophy points
1,298
Activity points
1,416
Re: hspice vs spectre

Hi,

It is trade off if want accuracy go for Hspice .... Spectre for fast & complex circuits
 

hrkhari

Full Member level 4
Joined
Mar 4, 2004
Messages
224
Helped
6
Reputation
12
Reaction score
3
Trophy points
1,298
Activity points
2,250
Re: hspice vs spectre

I think Spectre and HSPICE carries the same acurracy rate due to the common model used. Spectre are much user friendly and has good waveform display. The only thing distinguish both of the simulator is the cost of purchasing it.

Rgds
 

piao

Full Member level 4
Joined
Feb 12, 2003
Messages
221
Helped
12
Reputation
24
Reaction score
8
Trophy points
1,298
Activity points
1,517
hspice vs spectre

I think it is up to the accuracy options and all other options you used in your design.

But Hspice works as a standard in the IC design field.
 

uncle_urfi

Full Member level 2
Joined
Mar 15, 2004
Messages
146
Helped
10
Reputation
20
Reaction score
6
Trophy points
1,298
Activity points
2,004
hspice vs spectre

The supply voltage goes from 0 to Vdd in a short time, as someone mentioned is the solution to the convergence problem.

This works for me when i simulate LC oscillators in spectreRF, but the frequency is too low, and i don't know a direct solution for this in Hspice, if it is indeed a frequency-related problem.

One can also put an initial condition on the currents and check the biasing circuits at start-up. May be there is not enough current to establish DC conditions that will be used for the rest of the simulation.
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top