What is the function of VCO in PLL?

The VCO generates the output signal. It is maintained at the setpoint frequency by the PLL and locked to the reference frequency. The reference frequency is typically supplied by a very accurate quartz oscillator.

How does phase locked loop work?

The underlying mechanism of a PLL operates based on the phase difference between two signals. This “feedback signal” is then applied back to the voltage-controlled oscillator to control its frequency. A simplified look at how a phase-locked loop works constantly to adjust voltage to match input signal frequency.

What is the basic principle of VCO?

Basic Working principle of Sawtooth waveform generator VCO The input is given in form a voltage that can be controlled. This voltage is converted to a current signal and is applied to the capacitor. As the current passes through the capacitor, it starts charging and a voltage starts building across it.

Is PLL used in CPU?

PLLs can be used to multiply and divide frequencies. CPUs that have PLLs to generate their clocks are highly reconfigurable. The clock speed can be varied relative to the external reference clock over a wide range, and it’s the PLL that makes this possible.

What are the advantages of using PLL?

The advantage of phase-lock loops is that they receive an input signal, compare this to the feedback of their internal clock generated by a voltage-controlled oscillator (VCO), and adjust the VCO by way of the charge pump to match the new input frequency and synchronize the internal and external clocks.

What is PLL loop bandwidth?

• PLL acts as a high-pass filter with respect to VCO jitter. • “Bandwidth” is the modulation frequency at which the PLL. begins to lose lock with the changing reference (-3dB) log(frequency) BW.

How is frequency stability obtained in a PLL by use of a VCO?

To understand the basic idea of a VCO let us consider a RC oscillator. Hence in this case the frequency of oscillation is inversely proportional to the value of capacitance used in the circuit. As the input voltage (control voltage) is increased the output frequency increases and the vice versa is also possible.

How is PLL set?

Procedure for determining PLL Settings

1. Choose the desired system frequency (CCLK).
2. Select the input frequency for the crystal oscillator (FOSC).
3. Calculate the value of Multiplier (M) and configure the MSEL bits.
4. Calculate the value of Divider (P) and configure the PSEL bits.

What are 3 running conditions in PLL?

Thus, a PLL goes through three stages (i) free running, (ii) capture and (iii) locked or tracking.