floating node check with HSIM or ELDO

[gafsos]

floating node checking

Hi 2 all,
Can any one if u show me how to determinate if there is a floating node in my circuit ? is tehre an option used with eldo or hsim simulators.
What does mean 'no dc path to ground ??

THX

 

[Humungus]

how to detect floating nodes

No DC path is said when there is no resistor, inductor nor junction from the indicated node to ground. Tha is the node is floating or connected through capacitors to ground

 

[qslazio]

floating node find

I remember there is an option 'gshunt' means a large resistor to ground which may help you.

 

[gafsos]

floaring node check

Hi 2 all,

How does HSIM define a floating node? (I looked at Doc. it does not have there really a clear explanation, other simulators XSPICE like (HSPICE, PSIPICE.) defines a floating node as being ('No cd. path to ground) they will even go has to propose options which allow the addition of a resistance known as shunt which connects the node floating to gnd, of great value (several Kohm) .option rshunt=RSHUNT_VALUE, ELDO and HSIM do not propose such options (Good us one is interested rather has to include/understand km No these nodes are floating)

- is it possible that HSIM does not manage to detect the floating nodes, or this order does not go with the version which I use? To answer this question I used the last version of HSIM (Version 6.0 has) and it did not go no floating nodes If there are floating nodes is what HSIM does not converge??

Can one confirm that if HSIM finishes to simulate my design that there are no floating nodes?? In the docs of HSIM it is not mentioned the fact that when HSIM detects nodes floating it does not converge (I suppose only when one simulator detects nodes floating it does not converge or there are error messages or warning, is what it is not valid with HSIM??)

THX

 

[dipswitch]

finding floating nodes

Hi gafsos;

HSIM defines a floating node just like Hspice: anything that is not being driven through any device to a power source. These include any MOS transistors with the gate not connected, any capacitor with one side floating, or any stray wires that aren't tied somewhere.

I find with HSIM you must look very carefully at all output files, and look through ALL warning messages, to find instances of floating nodes or current sources with no DC path to ground. Simulations WILL simulate successfully even when they have floating nodes! HSIM automatically ties these floating nodes to ground. I like this because I can get the simulations running quickly; however it is dangerous if you don't check very carefully for connectivity problems. Check the ".out" and ".conn" files regularly.

You can also run CircuitCheck, an add-on to HSIM, which will give you plenty of options for connectivity checks.

Hope this helps,

-Bill

 

[gafsos]

find floating node with hspice

Hi Bill,

Thanks it's very very helpful, I use always HSIM for functionnality check and ELDO for others checks (leakage...)
I'm very interresting about theses two topics

SALAM
gafsos/