Multiple choice

A PLL based feedback is applied to keep the amplitude of the Astable multivibrator, having output = 5 V at 1 KHz. It was found that if the VCC voltage of the vibrator is reduced to 10.5 volt, the output of the feedback system is also reduced to 4.3 volt. For correct operation, it should have remained at 5 volt. Which one of the options explains the reason correctly?

  1. Appropriate feedback has not been provided.

  2. VCO center frequency did not keep the same as vibrator frequency.

  3. PLL system keeps the frequency of the signal constant, it does not keep amplitude constant.

  4. Phase detector is not functioning properly.

  5. Both (1) and (3)

Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Both options (1) and (3) are correct.

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