This ppt contains description of a PLL by razavi.

1. PRESENTED BY:- PRESENTED TO:-
Aman Jain (EC 08) Ravitesh Mishra
Gourav Gupta (EC 38) A.P,BCE Mandideep
Mohit Swarnkar ( EC 53)
Narendra Singh Rajput (EC 57)
Piyush Pal (EC66)
28/02/2013 Time taken: 24 mins AMAN JAIN Number of Slides : 19 1

2. Presentation Outline
 What is Phase Locked Loop (PLL)
 Parts of a PLL
 Locked Condition
 Dynamics of Simple PLL
 Transient Respone to PLL
 Application of PLL
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3. What is Phase Locked Loop (PLL)
PLL is an Electronic Module (Circuit) that locks the phase of the output to the input.
A PLL is a negative feedback system where an oscillator-generated signal is phase and frequency locked to a reference signal.
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4. Parts of a PLL
 Phase Detector
 Filter
 Voltage Controlled Oscillator
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5. Parts of a PLL
 Phase Detector
 Acts as comparator
 Produces a voltage proportional to the phase difference between input and output signal
 Voltage becomes a control signal
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6. Implementation of PD
 Phase Detector is an XOR gate.
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8. 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
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9. Parts of a PLL
 Voltage Controlled Oscillator
 Set tuning range
 Set noise margin
 Creates low noise clock oscillation
Wout = Wo+Kvco Vcont
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10. Locked Condition
 Locked Condition
d/dt(φin-φout)=0
This implies that
win = wout
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11. Vi and Vout has at the same
frequency W1
 The phase detector must
produce V1
 Hence, VCO is dynamically
changing and PD is creating
VControl to adjust for the phase
difference.
 The PLL is in the Locked state
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12. Dynamics of Simple PLL
 PLL is a feedback system
PD is a gain amplifier
LPF be first order filter
VCO is a unit step module
 The transfer function of the feedback system is given as:
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14. Transient Response to PLL
 The unit step response to second order system can be
Overdamped
Critically damped
Underdamped
 Problems with this PLL
Settling time Vs. ripple of Vcontor
Stability of the system
Lacks performance in ICs
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16. Application of PLL
 Frequency Multiplications
The feedback loop has frequency division.
Frequency division is implemented using a counter.
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17.  Jitter Reduction
 Clock Skew Reduction
Buffers are used to distribute the clock
Embed the buffer within the loop
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18. Other applications include:
 Demodulation of both FM and AM signals
 Recovery of small signals that otherwise would be lost in noise (lock-in amplifier)
 Recovery of clock timing information from a data stream such as from a disk drive
 Clock multipliers in microprocessors that allow internal processor elements to run faster than external connections, while
maintaining precise timing relationships
 DTMF decoders, modems, and other tone decoders, for remote control and telecommunications
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19. THANK YOU
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