How can I simulate a big circuit with paracitic resistors

• Oct 11, 2004

• #1

Q

Question

Member level 5

Joined

Aug 11, 2004

Messages

89

Helped

5

Reputation

10

Reaction score

4

Trophy points

1,288

Activity points

758

I have designed a DAC with bandgap. After finished the layout design, I can not run post layout simulation.

There are more than 300000 instances in my extranted view. It is too slow to simulate it by spectre or Hspice. I also use StarSim to do this job. But the result has big distortion, enev I use high accurate mode.

Pls give me some advice of how can I simulate this big circuit.

 

• Oct 12, 2004

• #2

C

codec

Junior Member level 3

Joined

Sep 11, 2004

Messages

26

Helped

1

Reputation

2

Reaction score

0

Trophy points

1,281

Activity points

221

Re: How can I simulate a big circuit with paracitic resistor

Ultrasim is the best choice I think.

As for starsim, you should set high accuracy to the critical blocks.
However, in my oppion, fast spice is to confirm the total function rather than exactly accurate performance. You my run spectre with simplified netlist.

 

• Oct 12, 2004

• #3

H

HCM_bucat

Guest

Re: How can I simulate a big circuit with paracitic resistor

It's imposible for Hspice to handle a circuit more than 10,000 transtors. Star-simXT and Hsim can handle that. read their manual to learn the technique how to use the tools. I saw some simulations 100 times bigger than your design went through.

 

• Oct 15, 2004

• #4

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: How can I simulate a big circuit with paracitic resistor

you can simplify your netlist by writing subcircuits in hspice......but carefull with
nonconverging nets.....

 

• Oct 19, 2004

• #5

T

thcm

Member level 2

Joined

Jun 13, 2004

Messages

52

Helped

4

Reputation

8

Reaction score

0

Trophy points

1,286

Activity points

379

For large scale analog simulation, abstratction is necessary and important.I think it's not appropriate to put everything into simulator.

 

• Oct 20, 2004

• #6

D

dumeHCM

Advanced Member level 4

Joined

Sep 30, 2004

Messages

106

Helped

2

Reputation

4

Reaction score

2

Trophy points

1,298

Activity points

587

Re: How can I simulate a big circuit with paracitic resistor

with StarSim you can set the accuracy mode in each block. By doing this you can simulate a big circuit very fast and maintain a reasonable accuracy

 

• Oct 20, 2004

• #7

K

kyrandia

Member level 1

Joined

Jun 23, 2004

Messages

33

Helped

0

Reputation

0

Reaction score

0

Trophy points

1,286

Activity points

286

Re: How can I simulate a big circuit with paracitic resistor

You can do rc reduction before simulating

 

• Oct 20, 2004

• #8

J

jordan76

Full Member level 3

Joined

Mar 25, 2004

Messages

170

Helped

4

Reputation

8

Reaction score

1

Trophy points

1,298

Activity points

1,852

Re: How can I simulate a big circuit with paracitic resistor

For your design-a DAC with bandgap, it doesn't quite make sense to me that "there are more than 300000 instances in my extracted view".
Suppose you are using RC extraction tools like Xcalibre or StarRC or LPE to get your extracted view, you had better check the manual to make sure you set the appropriate options/settings so that you can get a manageable netlist and still maintain reasonable accuracy.

Hope it will of some help to you.

regards,
jordan76

 

• Oct 26, 2004

• #9

T

toka

Newbie level 6

Joined

Oct 25, 2004

Messages

13

Helped

0

Reputation

0

Reaction score

0

Trophy points

1,281

Activity points

120

Re: How can I simulate a big circuit with paracitic resistor

I think you need add RC reduction options or some filters option to your extracted tools. One DAC of 300000 instances are too slow even for ultrasim. Most of time, you can reduce most of parasitic R&Cs with enough accuracy.

 

• Oct 26, 2004

• #10

I

itaifrenkel

Full Member level 2

Joined

Oct 9, 2004

Messages

147

Helped

36

Reputation

72

Reaction score

17

Trophy points

1,298

Location

Israel

Activity points

1,859

Re: How can I simulate a big circuit with paracitic resistor

Have you tried Nexxim ?

This new solver is HSPICE compatible and is capable of solving much larger netlists and faster

**broken link removed**
**broken link removed**

Itai

 

• Oct 26, 2004

• #11

D

devrimaksin

Member level 5

Joined

Oct 13, 2004

Messages

90

Helped

11

Reputation

22

Reaction score

2

Trophy points

1,288

Location

Dallas, Texas, USA

Activity points

1,062

It dont make sense to simulate this many
component, you have to filter out the component
that are insignificant (say resistors less than 1 Ohm)

 

• Oct 28, 2004

• #12

Y

yakyao

Newbie level 5

Joined

Oct 12, 2004

Messages

8

Helped

0

Reputation

0

Reaction score

0

Trophy points

1,281

Activity points

54

I do not think starsim is a good tool. The speed is slow when simulate the mixed circuit.