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Think of Frequency
Think of
Introduction to Crystal
TXC Confidential & Proprietary | 1
Quartz Crystal Basic: Structure
Z
Constitutes :
Silicon Dioxide, SiO2
Crystal System :
Trigonal 32
X
Melting Point :
~ 1,750 degree C
@ 1 atm
Y
Hardness :
Domain
Wall
00
Silicon
Oxygen
~ 7.2 Mohs
@ 1 atm
79
21
88
88
33 45
67 55
67
12
79
79
00
00
21
21
88
33 45 67
45
Synthetic Quartz
Nature Quartz
TXC Confidential & Proprietary | 2
Quartz Crystal Basic: Piezoelectricity
- Piezoelectric Effect
- -Si
Si4+
O2-
O2-
++
4+
Electric neutral
O2-
Si4+
O2-
++
When a pulling-outward force
is applied on O2-, a positive
electric field is induced.
2-
O
When a pushing-inward force
O2-
is applied on O2-, a negative
electric field is induced.
- Reverse Piezoelectric Effect
-+ +- +- +- +- +-
++++++
Si4+
- - - -Si - -
Si4+
4+
O2-
O2-
Electric neutral
O2-
++++++
------
O2-
When an electric field is applied,
the induced electric filed is generated,
and force the O2- moving outward.
O2-
O2-
-+ -+ -+ +- +- +-
When an electric field is applied,
the induced electric filed is generated,
and force the O2- moving inward.
TXC Confidential & Proprietary | 3
Quartz Crystal Basic: Natural vs. Synthetic
Natural Quartz
Synthetic Quartz
TXC Confidential & Proprietary | 4
Quartz Crystal Basic: Synthetic Quartz
AUTOCLAVE
HYDROTHERMAL METHOD
RAW MATERIAL： Silica
HIGH TEMPERATURE： ~ 350 ~ 400 ℃
Crystal Growth
Region (~300 ℃)
HIGH PRESSURE： ~ 900 ~ 1,000 Kg / cm2
HIGH TEMP. STABILITY ： ± 3 ℃
LONG GROWTH TIME： 1 ~ 6 Month
HIGH PURITY
Dissolving
Region (~400 ℃)
Infra-Red Absorption (IRA)： 3585 CM-1
TXC Confidential & Proprietary | 5
Quartz Crystal Basic: Synthetic Quartz
Moving new autoclave to the factory
Grown quartz bars from autoclave
TXC Confidential & Proprietary | 6
Manufacturing Process: From Bar to Blank
Processing time: <10 days
Wire Sawing
Quartz Bar
Wafer Frequency
Lapping
22.1372
1 2 3
4 5 6
7 8 9
0 EN
A
B
C
D
TXC Confidential & Proprietary | 7
Cutting Angle
 Many cutting angles for
various applications.
High Frequency
Low Frequency
AT : +35012’
BT : -490
0
CT : +38
DT : -520
ET : +660
FT : -570
Z
CT
AT
BT
 AT cutting is one of the
most popular and
applicable angles.
DT
+50X
R
+500
Z
r
NT
m
X
+50
0
GT
+5
0
+2 X
r
m
R
+20
X
Y
m
r
X
TXC Confidential & Proprietary | 8
Cutting Angle: FT Characteristic of Different Cuts
40
GT
Frequency Change in ppm
20
AT
0
- 20
AT
GT
- 40
- 60
DT
DT
- 80
- 100
- 120
XY
XY
- 140
CT
CT
- 160
- 40
- 20
0
20
40
60
80
Temperature ( ºC )
TXC Confidential & Proprietary | 9
Cutting Angle: AT-Cut FT Characteristic
25

(ppm)
BT-cut
49o
35¼o
R
20
Z
AT-cut
r
8’
R
m
15
7’
10
6’
r
0’
Z
Y-bar quartz
5’
5
Y
R -1’
m
R
1’
4’
0
2’
f
f
3’
-5
3’
2’
4’
1’
-10
0’
-15
-1’
 = 35o 12.5’+ ,  = 0 for
fundamental mode plano-plano AT-cut
6’
 = 35o 20’ + ,  = 0
for 5th overtone AT-cut
-20
-25
5’
7’
8’
-45 -40
-35
-30 -25
-20
-15
-10
-5
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
Temperature (oC)
TXC Confidential & Proprietary | 10
Thickness of Blank: Determines Frequency
A
l
Frequency
 AT Cut Crystal
- Resonance frequency is determined by thickness of blank.
- For a 20 MHz crystal, the thickness is around 83um.
(The diameter of human hair is around 50~80um)
- The thinner the blank, the higher the frequency is.
F(Hz) 
1650 ~ 1670
l (m)
Note : The constant of 1670 is not the exact number for AT cutting. This number ranges from 1650 ~ 1685 depends on
the dimension and thickness of the AT quartz plate.
TXC Confidential & Proprietary | 11
Structure and Manufacturing Process
Processing time: <10 days
Crystal
IC Die Bonding
Oscillator
Wire Bonding
Blank Cleaning
Metal
Lid
Frequency Adj.
Seam Sealing
Mechanical Testing
Final Testing
Marking
Crystal
Blank AutoMounting
Oscillator
Base Plating
Plated
Blank
Oscillation IC
Ceramic
Package
(Top)
Ceramic
Package
(Bottom)
Taping
TXC Confidential & Proprietary | 12
Specification
Ex: 8Z Series (2.5x2.0 mm)
Tips of Defining the Specification of a Crystal:
1. Determine the Nominal Frequency
2. Choose the Load Capacitance
3. Define the Frequency Tolerance and Stability
4. Define the Drivel Level, Effective Resistance, and Shunt capacitance C0
TXC Confidential & Proprietary | 13
Load Capacitance Choosing : CL vs. Trim Sensitivity
Trim Sensitivity Pullabilty =
∆ 𝐹𝑟𝑒𝑞𝑢𝑒𝑛𝑐𝑦
∆ 𝐿𝑜𝑎𝑑 𝐶𝑎𝑝𝑎𝑐𝑖𝑡𝑎𝑛𝑐𝑒
Ex. 3.2 x 2.5mm, 12.0 MHz, CL=8.0 pF
Load Capacitance: 06~10 pF, high trim sensitivity: unstable, but tunable
Load Capacitance: 16~30 pF, low trim sensitivity: stable, but hardly tunable
TXC Confidential & Proprietary | 14
Package Size vs Drive Level & Resistance
Ex: 25MHz Crystal
Typ. Value of Drive Level (uW)
300 uW
Typ. Value of Effective Resistacne (Ω)
200 uW
150 uW
100 uW
𝒍
𝑹=𝝆
𝑨
10 Ω
HC-49
(9B/9C)
80 uW
25 Ω
30 Ω
3.2mmx2.5mm
(7M)
2.5mmx2.0mm
(8Z)
40 Ω
2.0x1.6mm
(8Y)
50 Ω
1.6x1.2mm
(8Q)
TXC Confidential & Proprietary | 15
Worldwide Lab Facilities
Ningbo, China
San Jose, USA
Taoyuan, Taiwan
 Three FAE locations with RD level testing equipment for Oscillation Circuit/Oscillator
 When the assistance is needed, please contact account manager to arrange the test
in different locations
TXC Confidential & Proprietary | 16
Services
 Unit Analysis




Crystal & Tuning Fork Electrical Testing (S&A 250B)
SPICE Model (RLC Model)
Oscillator Electrical Testing
Testing Temperature：-73˚C ~175 ˚C
 Board Evaluation and Circuit Matching





Accuracy of Frequency
Drive Level
Negative Resistance
Start-up Time
Operating Temperature Testing (Stability)
 Failure Part Analysis
 Initial FA report
TXC Confidential & Proprietary | 17
Measuring Instruments and Test Equipment
TXC Confidential & Proprietary | 18
Purpose of Matching

Mismatched Circuit:
Х None or inconsistent oscillation
Х Long startup time
Х Bad temperature performance
Х Crystal resonator damaging
Х Bad jitter and frequency error
Х Others

Measurements:
 Accuracy of Frequency
 Drive Level
 Negative Resistance
 Startup time
 Operating Temperature Test (Stability)
TXC Confidential & Proprietary | 19
www.txccorp.com
Think of Frequency
Think of
Introduction to Crystal Oscillators
TXC Confidential & Proprietary | 20
Crystal Oscillators

Simple Packaged Crystal Oscillator (XO)
VDD
Amplifier
Fout
Buffer
Crystal
1. Least integrated circuitry inside IC
2.
Best noise performance in LSI-based
crystal oscillator
3. ±15 PPM level temperature stability
Cg
Cd
GND
4.
±10 PPM level frequency accuracy based
on physical tuning capability
No Voltage Tunable Capability
TXC Confidential & Proprietary | 21
Crystal Oscillators

Voltage-Controlled Crystal Oscillator (VCXO)
VDD
Amplifier
1.
Buffer
2.
(CMOS/Differenial)
Crystal
VC
Fout
3.
Varactor
Cg
Cd
GND
4.
Integrated varactor inside IC
The tunable range of varactor and the load
sensitivity of X'tal resonator influences the
tunable range of VCXO
±15 PPM level temperature stability
±10 PPM level frequency accuracy based
on physical tuning capability
VC-plus
VC
Tunable Range over Temp.
VC-minus
TXC Confidential & Proprietary | 22
Crystal Oscillators

Temperature-Compensated Crystal Oscillator (TCXO)
Temperature
Sensor and
Compensation
Circuitry
VDD
F
Crystal
Cg
Integrated varactor & compensation circuit
inside IC
2.
The tunable range of varactor and the load
sensitivity of X'tal resonator influences the
tunable range of VCXO
3.
<±2.5 to ±0.28 (S3-TCXO)PPM level
IC Compensated
temperature stability
4.
<±2.5 PPM level frequency accuracy based on
physical tuning capability
Fout
Buffer
Crystal
VC
Varactor
Amplifier
1.
Cd
GND
Result
T
25 ̊C
≦2.5 ppm
≦0.3 ppm (Stratum 3 TCXO)
Tunable Range over Temp.
TXC Confidential & Proprietary | 23
Crystal Oscillators

Oven-Controlled Crystal Oscillator (OCXO)
Vdd
Temperature
Sensor
Oven Control
Circuit
Fout
Amplifier
Crystal
Buffer
Vc
Varactor
Cg
Oven
1.
Discrete electrical components & oven
controlled circuit
2.
The tunable range of varactor and the
load sensitivity of X'tal resonator
influences the tunable range of VCXO
3.
<±0.1 PPM level temperature stability
4.
<±0.1 PPM level frequency accuracy
based on physical tuning capability
Cd
Tunable Range over Temp.
(Depends on crystal cut)
TXC Confidential & Proprietary | 24
Differential Output
CMOS: Single-ended
Differential*: Dual-ended (same frequency)
 Advantage of Differential Output
 Low voltage swing
 Better noise rejection

Less than
1/3 of
CMOS
voltage
swing
Less than
1/6 of
CMOS
voltage
swing
*: 3 kinds of differential output that TXC is using:
LVPECL, LVDS, HCSL
CMOS (Single-ended)
Differential
TXC Confidential & Proprietary | 25
Thank you
TXC Confidential & Proprietary | 26