This document discusses applications of phase-locked loops (PLLs), including FM demodulation and FSK demodulation. It describes the internal block diagram of the LM565 PLL integrated circuit and introduces common PLL ICs. Applications of PLLs mentioned include frequency multiplication/division, frequency translation, AM detection, FM detection, and FSK demodulation. Circuit diagrams and operating principles are provided for FM demodulation and FSK demodulation using a PLL. Advantages of using a PLL for FM demodulation include high linearity and the ability to handle wider bandwidth signals.

1. SARVAJANIK COLLEGE
OF
ENGINEEING & TECNOLOGY
SUB NAME :- ANALOG ELECTRONICS
TOPIC
APPLICTIONS OF PLL
 FM DEMODULATION
 FSK DEMODULATOR
NAME ENROLLMENTNO
JARIWALA SIDDHARTH R. 140423109005
VASAVA CHIRAG M. 140423109014

2. Internal Block Diagram of IC 565
 The LM565 is a general purpose
phase locked loop(PLL) containing a
stable, highly linear voltage controlled
oscillator(VCO) and a double balanced
phase detector with good carrier
suppression.

3. INRODUCTION OF PLL
• PLL – Phase Locked Loops
• It is two type – linear and Nonlinear
• It is use in TV , FM Demodulation , FSK Demodulation Motor speed control
, etc.
• PLL ICS :- 560,561,562,564,565 & 567

4. APPLICATION OF PLL
1. Frequency multiplication/division.
2. Frequency translation
3. AM detection
4. FM detection
5. FSK demodulation

5. FM DEMODULATION USING PLL
Circuit Diagram
of
FM Demodulation

6. The operation of FM demodulation using PLL
 The FM signal is applied to PLL.
 As the PLL is locked to the FM signal, the VCO start tracking instantaneous frequency in
the input FM signal.
 The error voltage produced at the output of the error amplifier is directly proportional to
the frequency deviation.
 Thus the ac component of the error voltage represents the modulating signal.
 Demodulation FM output is obtained at the output of the error amplifier.

7. Advantage of using PLL for FM demodulation
 PLL ensures a high degree of linearity between the
instantaneous input frequency and VCO control
voltage which is the output of error amplifier.
 The bandwidth of the incoming FM signal can be
much wider than that of the low-pass which is
restricted to the baseband.
 The control voltage signal of the VCO has bandwidth
of the modulating signal.

8. FSK DEMODULATOR USING PLL

9. OPRATION OF FSK DEMODULATOR USING PLL
 The capacitor coupling at the i/p is used for removing the dc level in the i/p FSK signal.
 As we apply the FSK signal at the i/p, the loop gets locked to the i/p frequency and the VCO
tracks the i/p frequency between the two frequencies Fh and Fl. A corresponding dc shift will be
produced at the o/p.
 The three stage RC low pass filter is used for removing the carrier component from the o/p.
 R1 & C1 are decide the free running frequency of VCO .
 VOC Control voltage is produced which is given by:
Vc1 = Fh – F0
K
Where, F0 = Free running VCO frequency &
K = V to f transfer coefficient of VCO.
 When the i/p frequency is FL the control voltage is given by:
Vc2 = F0 – FL
K
 Where, Vc2 is i/p side capacitor
 These voltages are compared whit the reference voltage by the external comparator to produce a
digital signal.

10. ?
ANY QUESTION

11. THE END
Thank..u