+1 vote
in Linear Integrated Circuits by (38.2k points)
In the circuit shown, find the overall current gain?

(a) 456218

(b) 444878

(c) 444210

(d) 455734

I have been asked this question by my school teacher while I was bunking the class.

This intriguing question originated from Operational Amplifier Internal Circuit in section Operational Amplifier of Linear Integrated Circuits

1 Answer

0 votes
by (39.8k points)
Right option is (b) 444878

Explore the finest explanation: From the circuit given, IB= IB1 = 5.6µA.

IE1= IB1+ IC1 = 1.43mA + 5.6µA = 1.435mA.

IE1= IB2 = 1.435mA.

The individual current gain values,

β1=IC1/ IB1

=> β1 = 1.43mA/5.6µA= 255.36.

Similarly,β2=IC2/ IB2

=> β2 = 2.5A / 1.435mA =1742.16

Therefore, the overall current gain, β = β1 × β2 = 255.36 × 1742.16 = 444878.

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