Question

What is the approximate hybrid parameter input resistance of a CB amplifier?

(a) hfe / 1 – hfe

(b) hfe / 1 + hfe

(c) hie / 1 – hfe

(d) hie / 1 + hfe

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Query is from Approximate Hybrid Model and its use in CE, CB, CC in section Small-Signal Low-Frequency AC models of Transistors of Electronic Devices & Circuits

Answer 1

The correct choice is (d) hie / 1 + hfe

Explanation: The input resistance of a common base (CB) amplifier can be expressed in terms of approximate hybrid parameters. The input resistance is hie / 1 + hfe where, hie and hfe are the input resistance and current gain of CE amplifier respectively.