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  1. A diode detector has a load of 1kΩ shunted by a 10000 pF capacitor. The diode has a forward resistance of 1Ω. The maximum permissible depth of modulation, so as to avoid diagonal clipping, with modulating signal frequency of 10kHz will be—
    1. 0.847

    2. 0.628
    3. 0.734
    4. None of these
Correct Option: A

We know that

RC ≤
1
1 − μ2
ωmμ2

given that R = 1 kΩ = 1000Ω
C = 10000 pf = 10–8 f
ωm = 2π fm = 2π × 10 × 103 radian/sec
μ =? (neglecting diode forward resistance i.e.1Ω)
1000 × 10−8
1
1 − μ2
2π × 10 ×103μ2

or
0.628 ≤
1 − μ2
μ2

or
0.394 ≤
1 − μ2
μ2

or
0.394 μ2 ≤ 1 − μ2
or
1.394 μ2 ≤ 1
or
μ2
1
1.394

or
μ ≤ 0.8469
or
μmax ≤ 0.847
Hence alternative (A) is the correct choice.



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