What is free running frequency?
[¦frē ‚rən·iŋ ‚frē·kwən·sē] (electronics) Frequency at which a normally driven oscillator operates in the absence of a driving signal.
How many phase comparators are there in the PLL IC CD 4046b?
The PLL structure consists of a low-power, linear VCO and two different phase comparators, having a common signal-input amplifier and a common comparator input.
What is PLL and its applications?
A phase-locked loop or phase lock loop (PLL) is a control system that generates an output signal whose phase is related to the phase of an input signal. Phase-locked loops are widely employed in radio, telecommunications, computers and other electronic applications.
What is free running frequency and how it is controlled?
This PLL free running frequency is determined by its internal frequency determining components. As explained in fig. 1 when frequency changes, phase detector and LPF will produce new DC voltage. This voltage force VCO frequency to change and adopt to the new input frequency.
What is free running frequency of a VCO?
Without connecting any input signal, apply power and use an oscilloscope or frequency counter to measure the free- running frequency at VCO out. It should be close to f0 = 1.2/4RTCT ≈ 1360 Hz. Set your function generator to output a sine wave at the measured value of f0.
What happens when VCO output is 90 degree out of phase with respect to input signal?
What happens when VCO output is 90o out of phase with respect to input signal? Explanation: The error voltage is zero when the phase shift between the two inputs is 90o.
At what range the PLL can maintain the lock in the circuit?
7. At what range the PLL can maintain the lock in the circuit? Explanation: The change in frequency of the incoming signal can be tracked when the PLL is locked. So, the range of frequencies over which PLL maintains the lock with the incoming signal is called as the lock in range.
What happens when VCO output is 90?
What happens when VCO output is 90o out of phase with respect to input signal? Explanation: The error voltage is zero when the phase shift between the two inputs is 90o. So, for the perfect lock, the VCO output should be 90o out of phase with respect to the input signal.
What is the basic principle of PLL?
The input signal is directly proportional to the output frequency of the VCO (fo). The input and output frequencies are compared and adjusted through the feedback loop until the output frequency is equal to the input frequency. Hence, the PLL works like free running, capture, and phase lock.
What are the different stages of PLL?
Thus, a PLL goes through three stages (i) free running, (ii) capture and (iii) locked or tracking. Capture range: the range of frequencies over which the PLL can acquire lock with an input signal is called the capture range.