Designer’s Guide Community

loose-electron

Senior Fellow

Offline

Best Design Tool =
Capable Designers

Posts: 1638
San Diego California

Re: Poly resistor self heating
Reply #15 - Jan 04^th, 2012, 6:59am

RobG wrote on Jan 3^rd, 2012, 9:44am:

Actually, in my post I also did the calculation with the max current density that were in the rules that my friend gave me. The temp change was 100 C! I'm surprised they'd let it get that hot so the process guys probably put a lot of margin in that number.

However you are probably not accounting
for the max temp rules. Got to respect both.

If its an academic problem, it does not matter,

Back to top

Jerry Twomey
www.effectiveelectrons.com
Read My Electronic Design Column Here
Contract IC-PCB-System Design - Analog, Mixed Signal, RF & Medical

IP Logged

RobG

Community Fellow

Offline

Posts: 570
Bozeman, MT

Re: Poly resistor self heating
Reply #16 - Jan 4^th, 2012, 7:53am

vivkr wrote on Jan 4^th, 2012, 4:41am:

By the way, it might be better to use diffusion resistors rather the poly if current densities are high enough to make self-heating significant. The resistor is then embedded in a well and can dissipate more heat into the substrate directly, and any M1 cover on top of it can be placed much closer to the resistor (vertical clearance).

Yes, I believe that is the case.When you include the well and account for the spacings I'm not sure it isn't easier to make a wider poly. I guess it would depend.

Aaron, I know some models do account for self heating, but I don't know the details of how it is done.

rg

Back to top

IP Logged

Lex

Senior Member

Offline

Posts: 201
Eindhoven, Holland

Re: Poly resistor self heating
Reply #17 - Jan 5^th, 2012, 12:05am

aaron_do wrote on Jan 4^th, 2012, 1:45am:

P.S. that leads to a different question. Normally the resistance is temperature dependent and we set the temperature in the simulation options. So is this self-heating taken into account?

I think the VCR2 accounts for that (or at least for some of it), as it is the coefficient that is multiplied by V^2 (a power term).

Back to top

IP Logged