GATE Electronics and Communications (EC) 2020 Solved Papers

Question : 34 of 65

Marks: +1, -0

The components in the circuit shown below are ideal.

If the Op-amp is in positive feedback and the input voltage

V_{i}

is a sine wave of amplitude

1 V, V_{0}=?

Solution:

V_{N}=V_{i} \;{1 k}/{2 k}+V_{0} \;{1 k}/{2 k}

{V}_{ {N}}=\;{ {V}_{ {i}}+ {V}_{0}}/{2}

{V}_{ {N}}>0 ⇒ {V}_{0}=+ {V}_{ {sat}}

Where

V_{N}=\;{V_{i}+V_{0}}/{2}

V_{0}=+V

sat

⇒ V_{N}=\;{1+5}/{2}=3 V

V_{i}=1 V

peak

V_{N}=\;{-1+5}/{2}=2 V

V_{i}=-1 V

peak
If

V_{0}=-V_{\;\text "sat "\;} ⇒ V_{N}=\;{1-5}/{2}=-2

V_{i}=+1 V

peak

⇒ {V}_{ {N}}=\;{-1-5}/{2}=-3

{V}_{ {i}}=-1 {V}

peak
So the output is either

+ {V}_{\;\text "sat "\;}

- {V}_{\;\text "satas "\;} {V}_{ {N}}

is not crossing '

0^{'}

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