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GATE 2026 IN – Question 61

Analog Electronics · Oscillators and phase-locked loops · 2 marks · Numerical answer

In the phase-locked-loop circuit shown below, the output of the VCO is a digital square wave. If the input is a square wave at 10 kHz, the steady-state frequency of the output is ________ kHz. (Rounded off to the nearest integer.)

Diagram for GATE 2026 IN question 61

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Correct answer: 512 to 512

Explanation

At lock, the two phase-detector input frequencies are equal. The input divider supplies $f_{in}/20=10/20=0.5\ \mathrm{kHz}$. The feedback divider supplies $f_{out}/1024$.

Equating them gives $f_{out}=1024\times0.5=$ **512 kHz**.