When $A$ is the internal stage gain of an amplifier and ${\rm{\beta }}$ is the feedback ratio, then the amplifier becomes as oscillator if

${\rm{\beta }}$ is positive and magnitude of ${\rm{\beta }} = 1/A$

${\rm{\beta }}$ is negative and magnitude of ${\rm{\beta }} = A/2$

${\rm{\beta }}$ is negative and magnitude of ${\rm{\beta }} = 1/A$

${\rm{\beta }}$ is negative and magnitude of ${\rm{\beta }} = A$

JEE PHYSICS MCQ: SEMI CONDUCTOR DEVICES

1 Medium

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Understanding +4 | -1

When

A

is the internal stage gain of an amplifier and

\mathrm{\beta }

is the feedback ratio, then the amplifier becomes as oscillator if

View answer and explanation

Correct option: D

\mathrm{\beta }

is positive and magnitude of

\mathrm{\beta } = 1/A

Option D (

\mathrm{\beta }

is positive and magnitude of

\mathrm{\beta } = 1/A

) is correct because the Barkhausen criterion for oscillation requires positive feedback and a loop gain of unity (Aβ = 1).