Explanation of PLL functionality and related math

[haydaa]

Hi all,

I want to learn PLL functionality and related math. Pls, share with me if you have full conceptual understanding about PLL.

I know simple description as below but it is not sufficiently clear for me:

"Phase comparator" compares two signal, produces error voltage, "loop filter" eliminates unwanted parts, "VCO" produces reference signal.

Pls more if you have...

Best regards.

 

[electronics_kumar]

what does a pll do

it is a ALL-IN-ALL device as for communication domain is concerned..it can act as FM demodulator,frequency synthesiser and many more...


basically it is negative feedback mechanism

 

[Renjith]

what does pll do

Therez lots of info on this Board itself.
Search for "PLL" or Phase Lock in the Books upload/download or IEEE study papers.

 

[teteamigo]

what does a pll do?

PLL is a more other system that ideally follows the phase of input signal (with null DC error in output of phase comparator) .

Almost situations the input signal is a square wave then there isn't the phase concept. Unless the square wave is understanded by output of a hard limiter when the input of this block is a sinusoidal signal.


Then PLL is a system that ideally follows the transitions/slope of input signal. But nobody think that this system is memoryless, then take some time (delay, group delay) to reach this accomodation.

PLL is like a bandpass filter tracking to the fundamental&impulsive tone of input signal.

Frequency Synth-->Inut-Phase Comparator with loop Filter + VCO+Frequency Divider
FM demodulator--> we use the error signal that enters in VCO
FM modulator --> we add to the error our signal (that enters in VCO), then we use the output of VCO

 

[aelems]

what pll do i have

i have two books about PLL if you need tell me

Regards

 

[chin]

phase-locked loop fm modulator books

Hi..
Just check out this book " Phase Locked Loop - Design Simulation and Applications" by Ronald E Best..

regards

 

[xischaune]

loop filter + pll + fm modulator

Hi...
PLL is most widely used in FM modulation and de-modulation...
3 basic parts...
a. VCO: generates a frequency based on a center frequency and can give a (limited) shift in frequency
b. Phase Comparator: Compares the input signal phase with the VCO generated signal and thus in turn generates an error voltage
c. Loop Filter: It rejects unwanted components (noise) so that the error voltage does not go beyond a certain maximum due to noise. In a sense it averages out the error voltage.

Hopt it helps...