bias Current Ic in PNP

Determine the quiescent collector current of the pnp transistor

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Thread Starter

freeze777

Joined Apr 1, 2015
3
I was asked to find the quiescent collector current of the pnp transistor Q2.
I got stuck in between a point where the base of pnp connected to the collector of npn.
The npn transistor has bias current Ic=2 mA. which cause a Vc=4.3 V. But this will cause a drop of 1.4 V at the Base emitter of pnp...!! and i felt i am goin wrong somwhere
 

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DickCappels

Joined Aug 21, 2008
10,153
But the base-emitter voltage of the PNP is given as 0.7V. Consider the likely purpose of connecting the collector of the PNP to the emitter of the NPN.
 

JDT

Joined Feb 12, 2009
657
As beta is infinity, the base current of both transistors is zero. Makes the calculation easy.
In fact, no calculator needed!

Start by considering the resistors biasing the base of Q1. What is the current in these resistors? What is Q1 base voltage?
 

Thread Starter

freeze777

Joined Apr 1, 2015
3
Well... found my mistake.... i considered the sum of pnp collector current and npn emitter current as the emitter current of npn.
Finally the answer is 1 mA :)
 
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