This document provides an overview of a phase locked loop (PLL). It defines a PLL as an electronic circuit that uses feedback to generate an output signal whose phase is locked to the phase of an input signal. The key components of a PLL are described as a phase detector, filter, and voltage controlled oscillator. Examples applications of PLLs include frequency synthesizers, communication systems like GSM, and jitter reduction.

2. PHASE LOCKED LOOP
 Presented BY:
 Nasir Ihsan
 Presented To.
 Engr. Armaghan Zafar
 Communication System
 IET DEPT.
 GOMAL UNI PAKISTAN

3. OUTLINES
 History of PLL
 Definition of PLL
 Parts of PLL
 Applications
 Conclusion

5. DEFINITION OF PLL
 PLL is an Electronic Module (Circuit)
 A PLL is a negative feedback system

6. CONTROL SYSTEM REPRESENTATION

7. PARTS OF A PLL
 Phase Detector
 Filter
 Voltage Controlled Oscillator (VCO)
 Programmable Counter/Divider (OPTIONAL)

8. PARTS OF A PLL
 Phase Detector
 Produces a voltage
 Voltage becomes a control signal

9. PARTS OF A PLL
 Filter
 Determines dynamic characteristics of PLL
 Specify Capture Range (bandwidth)
 Specify Tracking Range
 Receives signal from Phase Detector and filters accordingly

10. PARTS OF A PLL
 Voltage Controlled Oscillator
 Changes a DC input voltage into a pulsed waveform.
 The output frequency is proportional to the magnitude of
input control voltage.

11. PARTS OF A PLL
 Voltage Controlled Oscillator (Cont.)
 The output frequency of a VCO is given by:
fout = fmin + KVCOVin
where fmin = output frequency when Vin=0
KVCO = VCO conversion gain, Hz/V

12. PARTS OF A PLL
 Programmable Counter (Divider)
 It is an optional part of PLL.

13. PRACTICAL APPLICATION:
 Digital wireless communication system
like GSM
 Cellular Handsets

14. OTHER APPLICATIONS OF PLLS:
 Control Systems
 Frequency Synthesizers
 Jitter reducers
 Zero Delay Buffers
 Demodulators (QPSK, QAM, FM, FSK, SSB)

15. Finally: If you would like to further enhance your
understanding of phase-locked loops, there is an excellent
YouTube video by different Professors. You can find it at:
http://www.youtube.com/watch?v=NeRdsWYqWFU