02-26-2009 11:51 PM
How does the capacitor value change with the operating temperature in Multisim? Is there a way to include the temperature coefficient for the capacitors when I run the analysis at a different operating temperature (say at -40C, +125C)..
03-01-2009 07:59 PM
You can use temperature coefficients with capacitors, however, the standard capacitor component does not have a way to specify this parameter. I believe you will need to use the Arbitrary SPICE block.
For example, the following creates a 0.001 F capacitor with some temperature coefficients.
C1 0.001 0 1 cmod
.model cmod c(TC1=0.01 TC2=0.001 TNOM=100)
The capacitor obeys the equation <value> * C * (1 + VC1 * V + VC2 * V^2) * ( 1 + TC1 * (T - Tnom) + TC2 * (T - Tnom)^2). T is the operating temperature specified in the analysis options (ANALYSIS > Analysis Options > Use Custom Settings > Customize > Global > Operating Temperature).
In the latest update (10.1.1), you can also use PSpice-style temperature parameters. The equation isn't there, but you can have a look at all supported parameters in the Multisim User Manual (Chapter 7 Multisim SPICE Reference > Analog Devices > Capacitor)