This document discusses various applications of phase-locked loops (PLLs). It describes how PLLs can be used for tracking band-pass filters, carrier recovery in coherent receivers, amplifying angle-modulated signals, and frequency synthesis. For tracking filters, a PLL tracks the varying carrier frequency of an angle-modulated signal. In carrier recovery, a PLL is used to retrieve the carrier signal from a noisy input in a coherent receiver. PLLs can also amplify angle-modulated signals. Additionally, PLLs are widely used for frequency synthesis to generate spectrally pure signals with adjustable frequencies.

1. PLL APPLICATIONS
BY;
S.NALADHARMA KAVASKAR
B.TECH (ECE) 2ND YEAR
115012013895
TECHNICALCOMMUNICATION
XTC407

2. CONTENTS
 INTRODUCTION
 TRACKING BAND-FILTER
 CW CARRIER RECOVERY
 PLL AMPLIFIER FOR ANGLE MODULATED SIGNAL
 FREQUENCY SYNTHESIS

3. INTRODUCTION
the pll is one of the most
commonly used circuit
in electrical engineering
1
obtained either as the
voltage singal
corresponding to the
error voltage in the
loop
2
(or) as a frequency
singal at VCO output
terminal
3

4. TRACKING BAND –PASS FILTER
Because of their temperature dependence, narrowband band
pass filters cannot be implemented by conventional analog filter
1
The carrier frequency of angle –modulated signal to be
selected varies.2
If a PLL tracking the carrier is used as a band pass filter.
3
The relationship between the input and output phase
modulation is determined by the close-loop transfer function.4

5. CW CARRIER RECOVERY
In every coherent receiver , the
carrier has to be recovered from the
recovered from the noisy input
singal
1
2
It is assumed that the carrier is
present all the time in the
received spectrum
The recovery of a suppressed
carrier will be considered later
3
4 The aim of cw carrier recovery is
to retrieve the carrier and to
suppress as much noise ,
modulation.

6. PLL AMPLIFIER FOR ANGLE MODULATED
SIGNAL

7. FREQUENCY SYNTHESIS
4
If necessary ,to operate as an analog or
phase modulator
3
the PLL is widely used in frequency
synthesis to generate spectrally pure
signal
2
In many application ,the frequency of
generated signal must be varied
1
Signal with high frequency stability and
spectral purity are often

8. Thank you