More Related Content
Similar to Quartz Crystal Oscillators and Phase-Locked Loops (20)
Quartz Crystal Oscillators and Phase-Locked Loops
- 2. © 2015 ADVA Optical Networking. All rights reserved.2
Content
1. Quartz Crystal Oscillator (XO) Technology
• Quartz Crystal Overview
• Ageing and Temperature
• XO, TCXO, OCXO, DOCXO
2. Phase Locked Loops (PLL)
• PLL Overview
• Response To Injected Noise
3. PLL with 2 inputs
- 3. © 2015 ADVA Optical Networking. All rights reserved.3
1. Quartz Crystal Oscillator (XO) Technology
- 4. © 2015 ADVA Optical Networking. All rights reserved.4
Quartz = SiO2
Pink = silicon atoms
Blue = oxygen atoms
Quartz Crystal
Piezo-Electric Effect:
Mechanical strain voltage
Inverse Piezo-Electric Effect:
Voltage mechanical deformation
= Oxigen atom
= Silicon atom
Oxygen atom
- 5. © 2015 ADVA Optical Networking. All rights reserved.5
Vibration Modes, Resonance Frequency, High Q,
Cutting Orientation
Fundamental Mode
Thickness Shear
Third Overtone
Thickness
Shear
Thickness Shear
Mode
Face Shear
Mode
Extensional ModeFlexure Mode
- 6. © 2015 ADVA Optical Networking. All rights reserved.6
Frequency Drift Due to Ageing
Time [day]
Fractionalfrequencydeviation[1]
41 3
3E-10
2E-10
1E-10
- 1E-10
- 2E-10
- 3E-10
2 50
0
Positive Ageing
Negative Ageing
Ageing Reversal
Frequency vs. Temperature
SC-cut:
Θ = 34°
Φ = 22°
Δf/f as a Function of
Temperature
(Parameter: ΔΘ = Deviation From
Reference Angle)
Lower Turnover Point (LTP)
Inflection Point (IP)
Upper Turnover Point (UTP)
- 7. © 2015 ADVA Optical Networking. All rights reserved.7
XO Categories rel. Temp. Control
• XO, Crystal Oscillator:
• LTP centered in the operation
temperature range
• > 1E-7 / °C
• TCXO, Temperature
Compensated XO:
• Resonance frequency is
modified by a varactor diode so
as to compensate for
temperature sensitivity
• 5E-8 to 5E-7 over [-55°C to
85°C]
UCONTROL
Temp.
Control
Temp.
Sensor
- 8. © 2015 ADVA Optical Networking. All rights reserved.8
XO Categories rel. Temp. Control
• OCXO, Oven Controlled XO:
• A control loop maintains the
oven containing the XO at
(nearly) constant temperature.
• 5E-9 to 5E-8 over [-30°C to
60°C]
• DOCXO, Double Oven
Controlled XO:
• Two temperature controlled
ovens, one inside the other.
• 5E-11 to 5E-9 over [-30°C to
60°C]
XO
Temp.
Sensor
Temp.
Control
Heating
Oven
XO
Temp.
Sensor
Temp.
Control
Heating
Temp.
Sensor
Heating
Temp.
Control
Outer Oven
Inner Oven
- 9. © 2015 ADVA Optical Networking. All rights reserved.9
Summary
Oscillator Type Temperature Sensitivity
(Fractional Frequency vs. Temperature)
XO 1E-7 / °C
TCXO 5E-8 to 5E-7
[-55°C to 85°C]
SOCXO 5E-9 to 5E-8
[-30°C to 60°C]
DOCXO 5E-11 to 5E-9
[-30°C to 60°C
- 10. © 2015 ADVA Optical Networking. All rights reserved.10
2. Phase-Locked Loops (PLL)
- 11. © 2015 ADVA Optical Networking. All rights reserved.11
PLL: Working Principle
Phase
Comparator
Loop
Filter
Voltage
Controlled
Oscillator
( )INu t ( )OUTu t
0,
0,
( ) sin 2 sin 2
( ) sin 2 sin 2
IN NOM IN
OUT NOM
IN
OOU
IN
OT UT TU
u t A t A
u t A t A
t
t t
x
x
t
P
P
NOM
IN
OUT
u
K
x
x
( )
C
P
u
t
u
t
g
t
0
OUT
C
V
u
K
- 12. © 2015 ADVA Optical Networking. All rights reserved.12
Phase-Time Deviation x(t)
Note: Phase-time x = random component only
Time Error TE = random and deterministic components
t1 t1 + x(t1)
nominal signal
actual signal
sin 2
sin 2
NO
NOM
M
t x t
t
x(t1)
t
- 13. © 2015 ADVA Optical Networking. All rights reserved.13
Transfer Function «Input-to-Output»
20log 2 [dB]INH j f
where impulse response
transfer function Laplace
OUT IN IN
OUT IN IN
IN
IN IN
x t x t h t
X s X s H s
h t
H s h t
- 14. © 2015 ADVA Optical Networking. All rights reserved.14
Transfer Function «Oscillator-to-Output»
20log 2 [dB]OSCH j f
where impulse response
transfer function Laplace
OUT OSC OSC
OUT OSC OSC
OSC
OSC OSC
x t x t h t
X s X s H s
h t
H s h t
- 15. © 2015 ADVA Optical Networking. All rights reserved.15
Both Transfer Functions
20
20
lo
log 2 [dB]
g 2 [dB]
IN
OSC
H j
H j f
f
- 16. © 2015 ADVA Optical Networking. All rights reserved.16
PLL: Jitter Filtering
0
100 200
t [s]
xIN(t) [s]
xOUT(t) [s]
1 x 10 - 6
5 x 10 - 7
- 5 x 10 - 7
- 1 x 10 - 6
- 17. © 2015 ADVA Optical Networking. All rights reserved.17
PLL With Direct Digital Synthesis
Sine
Look-up
Table
Counts from
0 to 2
N
-1 in
steps of M
DAC
&
LPF
Free-running
Oscillator
Phase
Comparator
Loop
Filter
Replaces
the VCO!
M
νOSC
νOUT
where output of the digital loop filter (integer)
size of the counter in bits (integer)
frequency of output signal
free-run frequency of the oscilla
OUT OUT
OSC
M
N
u t
tor
2
OUT OSCN
M
DAC = Digital-to-Analog Converter
LPF = Low-pass Filter
- 18. © 2015 ADVA Optical Networking. All rights reserved.18
PLL With Digitally Controlled Oscillator
PFD – Phase & Frequency Detector
TDC – Time-to-Digital Converter
PFD
&
TDC
Digital
Loop
Filter
Digitally
Controlled
Oscillator
(DCO)
Divider
ref(t)
out(t)
Free-
running
Oscillator
18
- 19. © 2015 ADVA Optical Networking. All rights reserved.19
PLL With VCO, DDS, and DCO Compared
Pros Cons
PLL with VCO
•Very low phase noise •PLL’s pull-in range
depends on VCO’s pulling
range
•Requires VCO
PLL with DDS
•Configurable pull-in range
•Requires only free-running
oscillator
•Some quantization phase
noise
PLL with DCO
•Fully programmable
•Configurable pull-in range
•Configurable low pass filter
range
•Requires only free-running
oscillator
•Requires APLL to clean up
jitter
•Precision of TDC affects
close-in phase noise
19
- 20. © 2015 ADVA Optical Networking. All rights reserved.20
3. PLL with 2 Inputs
- 21. © 2015 ADVA Optical Networking. All rights reserved.21
Imagine the Following:
Sine
Look-up
Table
Counts from
0 to 2
N
-1 in
steps of M
DAC
&
LPF
Phase
Comparator
Loop
Filter
M
Input 1
Sine
Look-up
Table
Counts from
0 to 2
N
-1 in
steps of M
DAC
&
LPF
Free-running
oscillator
Phase
Comparator
Loop
Filter
M
Input 2
Output
- 22. © 2015 ADVA Optical Networking. All rights reserved.22
Imagine the Following:
│H2 (f)│ │HOSC (f)│
f [Hz]
(log-log scales)
│HINT (f)││H1 (f)│
f [Hz]
IN 1 OUT
INT
IN 2 INT
OSC
- 23. © 2015 ADVA Optical Networking. All rights reserved.23
What Do the Transfer Functions Look Like?
f [Hz]
log - log scales
│H1 (f)│ │H2 (f)│ │HOSC (f)│
OUTIN 1
IN 2
OSC
(Application: T-BC with support from SyncE physical layer according to G.8273.2)
- 24. © 2015 ADVA Optical Networking. All rights reserved.24
Imagine Three Spectral Densities (Phase-Time):
OSC
IN 1
IN 2
OUT
(log-log scales)
│SIN1 (f)│
f [Hz]
│SIN2 (f)│
│SOSC (f)│
- 25. © 2015 ADVA Optical Networking. All rights reserved.25
… Combined by the 2 Input PLL:
(log-log scales)
f [Hz]
│SOUT (f)│
OSC
IN 1
IN 2
OUT
- 26. © 2015 ADVA Optical Networking. All rights reserved.26
Physical Layer Support for T-BC and T-TSC
G.8273.2 calls for Telecom boundary clock (T-BC) and Telecom time
slave clock (T-TSC) to use the physical layer (SyncE) in combination
with PTP.
G.8273.2
- 27. © 2015 ADVA Optical Networking. All rights reserved.27
SyncE PTP Filtering in Combination
Transfer for SyncE Noise to Output:
OutDCOPTP
PLL 2
Osc
PTP
stack
SyncE
ToD
Counter
Loop
Filter
- 28. IMPORTANT NOTICE
The content of this presentation is strictly confidential. ADVA Optical Networking is the exclusive owner or licensee of the content, material, and information in this
presentation. Any reproduction, publication or reprint, in whole or in part, is strictly prohibited.
The information in this presentation may not be accurate, complete or up to date, and is provided without warranties or representations of any kind, either express or
implied. ADVA Optical Networking shall not be responsible for and disclaims any liability for any loss or damages, including without limitation, direct, indirect, incidental,
consequential and special damages,
alleged to have been caused by or in connection with using and/or relying on the information contained in this presentation.
Copyright © for the entire content of this presentation: ADVA Optical Networking.
Thank You