How to Find the BJT Power Dissipation in NI Multisim?

Updated Mar 30, 2023

Reported In

Software

  • Multisim

Issue Details

I want to know the power dissipation for a BJT.  In Multisim, there is a wattmeter but how do I connect this instrument to the BJT? 

Solution

You cannot use the wattmeter to find the BJT power dissipation, you should use the transient analysis instead.  To find power dissipation for a BJT, follow the steps below:

1) Select Simulate»Analyses»Transient Analysis
2) Select the Output tab
3) Under the Variables in circuit select P(Qx), the Qx corresponds to your BJT reference ID
4) Select Add 
5) Select Simulate

The SPICE engine calculates the BJT power dissipation by using the following expression:
P(Qx)=(Ic*Vc)+(Ib*Vb)+(Ie*Ve)

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