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Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 1 Quartz Crystal Oscillators and Phase Locked Loops Dominik Schneuwly Yves Schwab

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Page 1: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 1

Quartz Crystal Oscillators

and

Phase Locked Loops

Dominik Schneuwly

Yves Schwab

Page 2: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 2

Content

1. Quartz Crystal Resonator Technology

Quartz, crystal lattice and piezo-electric effect

Vibration modes and equivalent circuit

Cuts

Ageing mechanisms

2. Quartz Crystal Oscillator (XO) Technology

TCXO

MCXO

OCXO

DOCXO

3. XO Performance vs. Telecom Requirements

Frequency holdover

Phase holdover

4. Phase Locked Loops (PLL)

Page 3: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 3

1. Quartz Crystal Resonator Technology

Page 4: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 4

Quartz Crystal

Quartz = SiO2

Pink = silicon atoms

Blue = oxygen atoms

Quartz lattice

Page 5: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 5

Cuts

Small disks are cut out of the crystal at given angles.

z

y

x

z

y

x

Single rotated cut

(e.g. AT-cut)

Double rotated cut

(e.g. SC-cut)

X

Y

Z

Page 6: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 6

Cuts

Angle accuracy: + 10’’ (for SC-cut)

Page 7: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 7

Vibration Modes

Fundamental Mode

Thickness Shear

Third Overtone

Thickness Shear

Thickness Shear

Mode

Face Shear Mode Extensional Mode Flexure Mode

Page 8: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 8

Piezo-electric Effect

Piezo-electric effect:

Mechanical strain voltage

Voltage mechanical deformation

= Oxigen atom

= Silicon atom

Page 9: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 9

Piezo-electric Effect

x x x

y x y

z y

Field Axis & Mode Strain Axis

(A) (B) (C)

Page 10: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 10

Equivalent Circuit

C0

C3

C2

C1

R3

R2

L3

L2

L1

R1

Vibration mode 1

Vibration mode 2

Vibration mode 3

Page 11: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 11

Admittance Y(f)

Y(f) Arg ( Y(f) )

Frequency [MHz]

Arg

(Ad

mitta

nce

) [r

ad

]

1 102 5

2

1

0

- 1

- 2

/ 2

/ 2

Frequency [MHz]

1 102 5

1E-2

1E-3

1E-4

1E-5

1E-6

1E-7

Ad

mitta

nce

[

mh

o]

Note: Exaggerated resistance values R1, R2 and R3 for better readability

Page 12: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 12

Quartz Crystal Oscillator (XO)

CL R

UIN

= 0

IIN

G

UOUT

= G IIN

0 0

00

Open Loop Gain: 1

1 1If and then 1

resonance frequency2

GH G Y

j L Rj C

G HR L C

f

Page 13: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 13

Frequency Drift Due to Ageing

Time [day]

Fra

cti

on

al fr

eq

uen

cy d

evia

tio

n [1

]

41 3

3E-10

2E-10

1E-10

- 1E-10

- 2E-10

- 3E-10

2 50

0

Positive ageing

Negative ageing

Ageing reversal

Page 14: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 14

Ageing Mechanisms

Mass transfer due to contamination (e.g. electrode

metal atoms into the crystal

Stress relief in the resonator's mounting and bonding structure,

electrodes, and in the quartz

Other mechanisms:

Quartz outgassing

Diffusion effects

Chemical reaction effects

Pressure changes in resonator enclosure (leaks and

outgassing)

Oscillator circuit aging (load reactance and drive level changes)

Electric field changes (doubly rotated crystals only)

Oven-control circuitry aging

Page 15: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 15

BVA Resonator

Electrodes not in direct contact with the resonator body

contamination of the resonator body is stopped

Ageing improves by a factor of 10 or more

Other performance parameters improve also (Q, temperature

sensitivity, phase noise, etc.)

Courtesy Jean-Pierre Aubry

Page 16: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 16

AT-cut Resonator

AT-cut:

Θ = 35°

Φ = 0

Δf/f as a function of temperature

(parameter: ΔΘ = deviation from

reference angle)

Lower Turnover Point (LTP)

Inflection Point (IP)

Upper Turnover Point (UTP)

Page 17: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 17

SC-cut Resonator

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)

Page 18: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 18

Advantages of the SC-cut Thermal transient compensated (allows faster warm-up OCXO)

Static and dynamic f(T) allow higher stability OCXO

Planar stress compensated; lower f due to edge forces and bending

Better f(T) repeatability allows higher stability OCXO (less f for oscillator reactance changes)

Lower drive level sensitivity

Higher Q for fundamental mode resonators of similar geometry

Higher capacitance ratio (less f for oscillator reactance changes)

Less sensitive to plate geometry - can use wide range of contours

Far fewer activity dips

Lower sensitivity to radiation

Disadvantages of the SC-cut More difficult to manufacture

SC- versus AT-cut

Page 19: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 19

2. Quartz Crystal Oscillator (XO) Technology

Page 20: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 20

XO Categories rel. Temp. Control

XO, Crystal Oscillator:

LTP centered in the operation temperature range

> 1E-7 / °C

Page 21: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 21

XO Categories rel. Temp. Control

TCXO, Temperature Compensated XO:

Resonance frequency is modified by a varactor diode so as to compensate temperature sensitivity

5E-8 to 5E-7 over [-55°C to 85°C]

UCONTROL

Temp.

Control

Temp.

Sensor

Page 22: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 22

XO Categories rel. Temp. Control

MCXO, Microcomputer Compensated XO:

Dual mode oscillator generating fundamental (f1) and third overtone (f3).

Difference between f3 and 3 x f1 is used to measure temperature and compensate temperature sensitivity of f3.

f1

x 3

MixerTemp.

Control

Synthesizer

3 x f1

fOUT

fC = 3 x f

1 - f

3 ~ Temp. -1

f3

Page 23: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 23

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]

XO

Temp.

Sensor

Temp.

Control

Hea

ting

Oven

Page 24: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 24

XO Categories rel. Temp. Control

DOCXO, Double Oven Controlled XO:

Two temperature controlled ovens, one inside the other.

2E-10 to 5E-9 over [-30°C to 60°C]

BVA resonator: 1E-10 over [-30°C to 60°C], 5E-11 over [-15°C to 60°C]

XO

Temp.

Sensor

Temp.

Control

Heating

Temp.

Sensor

Heating

Temp.

Control

Outer Oven

Inner Oven

Page 25: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 25

Typical XOs

SOCXO:

DOCXO:

BVA-DOCXO: …mm

Page 26: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 26

3. XO Performance vs. Telecom

Requirements

Page 27: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 27

Frequency Holdover Autonomy

How long can the SSU stay in holdover mode until the MTIE hits

the Network Limit for PRC-traceable SSU outputs (G.823)?

Page 28: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 28

Frequency Holdover Autonomy

Notes: 1) OSA 8741 2) OSA 8663 3) OSA 8600 4) TNT RMO

Holdover autonomy for different oscillator types and for different temperature conditions (temp. change during holdover):

OCXO1 DOCXO2 BVA-

DOCXO3

Rb4

Const.

Temp.

9 h 21 h 51 h 9 days

2°C 1.4 h 17 h 46 h 5.5 days

5°C 30 min 13 h 39 h 67 h

10°C 15 min 8.3 h 31 h 33 h

Page 29: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 29

Holdover Autonomy T of cdma2000 Base Stations

Temperature variation: + 10°C

Criterion: phase-time accumulation < 7 microseconds

1.0E-11

1.0E-10

1.0E-09

1.0E-12 1.0E-11 1.0E-10 1.0E-09 1.0E-08

Frequency Drift Due to Ageing [1/day]

Fra

ctio

na

l F

req

ue

ncy D

evia

tio

n D

ue

to T

em

pe

ratu

re V

aria

tio

ns [1

]

T = 6 h T = 12 h T = 24 h T = 48 h T = 72 h

Phase Holdover Autonomy (e.g. 1PPS)

DOCXO

BVA-DOCXO

Rb

Page 30: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 30

4. Phase Locked Loops (PLL)

Page 31: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 31

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

PNO

M

IN

OU

T

u

K

x

x

( )C

P

ut

ut

gt

0

OU

T

C

V

uK

Page 32: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 32

Phase-time deviation x(t)

t1 t1 + x(t1)

nominal signal

actual signal

sin 2

sin 2

NO

NOM

M

t x t

t

x(t1)

t

Page 33: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 33

PLL: Transfert function

10- 5

0

- 20

- 40

- 60

- 80

20

10- 4

10- 3

10- 2

10- 1

10 0

10 1

20log 2 [dB]H j f

f [Hz]

where impulse response

transfer function Laplace

OUT IN

IN OUT

u t u t h t

U s U s H s

h t

H s h t

Red curve = PLL transfer

function

Blue curve = transfer function

for oscillator noise

Page 34: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 34

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

Page 35: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 35

PLL with Direct Digital Synthesis

Sine

Look-up

Table

Counts from

0 to 2N

-1 in

steps of M

Digital-to-

Analog

Converter

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

2OUT OSCN

M

Page 36: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 36

PLL with VCO and with DDS 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

Page 37: Quartz Crystal Oscillators and Phase Locked Loops · Quartz Crystal Resonator Technology Quartz, crystal lattice and piezo-electric effect Vibration modes and equivalent circuit Cuts

Ed. 2006-02 D. Schneuwly Oscilloquartz © 2006 Slide № 37

Thank you