Analog and electronic circuits
Which circuit generates a clock at a frequency such as an integer multiple of a reference clock while locking its phase to the reference?
- APLL (phase-locked loop)
- BRectifier
- CSample-and-hold circuit
Show answer and explanation
Answer: A. PLL (phase-locked loop)
A PLL consists of a phase detector, a loop filter, a voltage-controlled oscillator (VCO) and a frequency divider, and controls the VCO so that its divided output matches the phase of the reference clock. With a division ratio of N, it produces a clock N times the reference frequency, used for CPU clock generation and wireless communication.