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Electronic Devices - Transistor Bias Circuits - Discussion

Discussion Forum : Transistor Bias Circuits - General Questions (Q.No. 24)
Transistor Bias Circuits
24.
The input resistance of the base of a voltage-divider biased transistor can be neglected
at all times.
only if the base current is much smaller than the current through R2 (the lower bias resistor).
at no time.
only if the base current is much larger than the current through R2 (the lower bias resistor).
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
2 comments Page 1 of 1.
Millize said:   4 years ago
If Ri is much larger than resistance R2 where Ri = (β+1) RE, the current Ib will be much smaller than the current at R2, then the current at R2 would be approximately equal to the current at R1.

The Input resistance (β+1) RE can be neglected.
Tejas said:   1 decade ago
The input resistance can be neglected if the values of R1 and R2 are very very large. Therefore the base current becomes very very small.
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