3. INTRODUCTION
What is a PLL?
Block Diagram of PLL
Parts of a PLL
PLL Design in Simulink
• PLL Without divider design
• Waveform
• PLL With divider design
• Waveform
4. What is a PLL?
A phase lock loop (PLL) is a control
system that generates an output signal
whose phase is related to the phase of an
input signal
6. Parts of a PLL
Phase Detector
Filter
Voltage Controlled Oscillator
Programmable Counter/Divider
7. 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
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
9. Parts of a PLL
Voltage Controlled Oscillator
Set tuning range
Set noise margin
Creates low noise clock oscillation
10. Divider
Divides the VCO output by the degree of the open loop gain
Feedback loop allows phase comparison
Parts of a PLL
24. INTRODUCTION
What is a DLL?
Block Diagram of DLL
Parts of a DLL
DLL Design in Simulink
• DLL design
• Waveform
25. What is DLL?
A delay-locked loop (DLL) is a digital circuit similar to
a Phase-Locked Loop (PLL), with the main difference
being the absence of an internal voltage-controlled
oscillator(VCO), replaced by a voltage-controlled delay
line (VCDL).
27. Parts of a PLL
Phase Detector(PD)
Charge pump(CP)
Loop Filter(LF)
Voltage Controlled Delay Line(VCDL)
28. Parts of a DLL
Phase Detector(PD)
Acts as comparator
Produces a voltage proportional to the phase difference
between input and output signal
Voltage becomes a control signal
29. Parts of a DLL
Charge Pump(CP)
• The outputs of the PD are directly connected to the
inputs of CP, and CP prepares the input of LF which is
proportional to the width of the PD output signals
(inputs of CP).
• In Matlab Simulink, a simple adder can be used to
model CP
30. Parts of a DLL
Loop Filter(LF)
• Loop filter is a simple integrator that performs integral
of the output signals from CP.
• In the other word the loop filter’s capacitor gets
charged or discharged if there is a time lead or time
lag between the reference signal and the output of the
delay line.
31. Parts of a DLL
Voltage Controlled Delay Line(VCDL)
• Voltage controlled delay line (VCDL) includes a chain of
delay cells.
• Usually all of the delay cells have the same structure.
• In locked condition, the output of the last delay stage is
exactly one cycle lagged from the reference clock (Vin).
