Think of Frequency Think of Introduction to Crystal TXC Confidential & Proprietary | 1.

Think of FrequencyThink of

Introduction to Crystal

www.txccorp.com

TXC Confidential & Proprietary | 1


Quartz Crystal Basic: Structure

33 4567

21 2100

79

6745

12

21

4567

3388

55

7900

88

7900

88

SiliconOxygen

Domain Wall

X

Y

ZConstitutes : Silicon Dioxide, SiO2

Crystal System : Trigonal 32

Melting Point : ~ 1,750 degree C @ 1 atm

Hardness : ~ 7.2 Mohs @ 1 atm

Nature QuartzSynthetic Quartz


Si4+

O2- O2-

Si4+

O2- O2-

- -

+ +

Si4+

O2- O2-

+ +

- -

- Piezoelectric Effect

- Reverse Piezoelectric Effect

Si4+

O2- O2-

Electric neutral When a pulling-outward forceis applied on O2-, a positive electric field is induced.

When a pushing-inward forceis applied on O2-, a negative electric field is induced.

Electric neutral - - - - - -

Si4+

O2- O2-

+ + + + + +

+ + + + + +

- - - - - -

- - - - - -

- - - - - -

+ + + + + +

+ + + + + +Si4+

O2- O2-

When an electric field is applied, the induced electric filed is generated,and force the O2- moving outward.

When an electric field is applied, the induced electric filed is generated,and force the O2- moving inward.

Quartz Crystal Basic: Piezoelectricity


Natural Quartz

Synthetic Quartz

Quartz Crystal Basic: Natural vs. Synthetic


AUTOCLAVE

HYDROTHERMAL METHOD

RAW MATERIAL ： Silica

HIGH TEMPERATURE ： ~ 350 ~ 400 ℃

HIGH PRESSURE ： ~ 900 ~ 1,000 Kg / cm2

HIGH TEMP. STABILITY ： ± 3 ℃

LONG GROWTH TIME ： 1 ~ 6 Month

HIGH PURITY

Infra-Red Absorption (IRA) ： 3585 CM-1

Crystal GrowthRegion (~300 ℃)

DissolvingRegion (~400 ℃)

Quartz Crystal Basic: Synthetic Quartz


Quartz Crystal Basic: Synthetic Quartz

Grown quartz bars from autoclaveMoving new autoclave to the factory


Wire Sawing

Quartz Bar

A1 2 34 5 67 8 90 EN

BCD

Lapping

22.1372

Wafer Frequency

Processing time: <10 days

Manufacturing Process: From Bar to Blank


Low Frequency

CT : +380

DT : -520

ET : +660

FT : -570

High Frequency

AT : +35012’BT : -490

Many cutting angles for various applications.

AT cutting is one of the most popular and applicable angles.

Xm

r

R

m

Z

r

R

m

X

r

Z

X

NT

GT

DTBTATCT

+20

+50X

+50

+50

+500

+20X

Y

Cutting Angle


Cutting Angle: FT Characteristic of Different Cuts

20

40

0

- 20

- 40

- 60

- 80

- 100

- 160

- 120

- 140

- 40 - 20 0 20 40 60 80

Freq

uenc

y Ch

ange

in p

pm

Temperature ( ºC )

AT

AT

GT

GT

DT

DT

XYXY

CTCT


Cutting Angle: AT-Cut FT Characteristic

rm

R

R

R

Rr

m Y

ZAT-cut BT-cut

49o35¼o

-1’

0’

1’

2’

3’

4’

5’

6’

7’

8’

-1’

0’

1’

2’

3’

4’

5’

6’

7’

8’

Y-bar quartzZ

25

20

15

10

5

0

-5

-10

-15

-20

-25-45 -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

f f(p

pm)

Temperature (oC)

= 35o 12.5’+ , = 0 forfundamental mode plano-plano AT-cut

= 35o 20’ + , = 0for 5th overtone AT-cut


Thickness of Blank: Determines Frequency

A l

(m)(Hz)

1670~1650F

l

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.

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.

Frequency


Structure and Manufacturing Process

IC Die Bonding

Wire Bonding

Blank Cleaning

Base Plating

Frequency Adj.

Final Testing

Marking

Taping

Seam Sealing

Mechanical Testing

Blank Auto-Mounting

Crys

tal

Osc

illat

or

Oscillator

■ 40.000

TXC CM211 ■ 24.576

TXC CN001

Crystal

Metal Lid

Plated Blank

Ceramic Package (Bottom)

Ceramic Package

(Top)

Oscillation IC

Processing time: <10 days


Specification

Tips of Defining the Specification of a Crystal:1. Determine the Nominal Frequency

Ex: 8Z Series (2.5x2.0 mm)

2. Choose the Load Capacitance3. Define the Frequency Tolerance and Stability4. Define the Drivel Level, Effective Resistance, and Shunt capacitance C0


Load Capacitance Choosing : CL vs. Trim Sensitivity

Load Capacitance: 06~10 pF, high trim sensitivity: unstable, but tunableLoad Capacitance: 16~30 pF, low trim sensitivity: stable, but hardly tunable

Trim Sensitivity ( Pullabilty )= ∆𝐹𝑟𝑒𝑞𝑢𝑒𝑛𝑐𝑦∆ 𝐿𝑜𝑎𝑑𝐶𝑎𝑝𝑎𝑐𝑖𝑡𝑎𝑛𝑐𝑒

Ex. 3.2 x 2.5mm, 12.0 MHz, CL=8.0 pF


Package Size vs Drive Level & Resistance

HC-49(9B/9C)

3.2mmx2.5mm (7M)

2.5mmx2.0mm (8Z)

2.0x1.6mm (8Y)

1.6x1.2mm (8Q)

10 Ω25 Ω 30 Ω 40 Ω 50 Ω

300 uW

200 uW

100 uW80 uW

Typ. Value of Drive Level (uW)

Typ. Value of Effective Resistacne (Ω)

150 uW

Ex: 25MHz Crystal

𝑹=𝝆 𝒍𝑨

❑


Worldwide Lab Facilities

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

Ningbo, China

Taoyuan, Taiwan

San Jose, USA


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


Measuring Instruments and Test Equipment


Purpose of Matching

Mismatched Circuit:Х None or inconsistent oscillationХ Long startup timeХ Bad temperature performanceХ Crystal resonator damagingХ Bad jitter and frequency errorХ Others

Measurements: Accuracy of Frequency Drive Level Negative Resistance Startup time Operating Temperature Test (Stability)

Think of FrequencyThink of

Introduction to Crystal Oscillators

www.txccorp.com



Crystal Oscillators

1. Least integrated circuitry inside IC

2.Best noise performance in LSI-based crystal oscillator

3. ±15 PPM level temperature stability

4.±10 PPM level frequency accuracy based on physical tuning capability

Amplifier

BufferCrystal

CdCg

GND

Fout

VDD

Simple Packaged Crystal Oscillator (XO)

No Voltage Tunable Capability


1. Integrated varactor inside IC

2.The tunable range of varactor and the load sensitivity of X'tal resonator influences the tunable range of VCXO

3. ±15 PPM level temperature stability

4.±10 PPM level frequency accuracy based on physical tuning capability

Tunable Range over Temp.

VC

VC-plus

VC-minus

Amplifier

Buffer(CMOS/Differenial)

Fout

VDD

Crystal

CdCgVaractor

VC

GND

Voltage-Controlled Crystal Oscillator (VCXO)

Crystal Oscillators

Tunable Range over Temp.


Amplifier

Buffer

Fout

VDD

Crystal

CdCgVaractor

VC

Temperature Sensor and

Compensation Circuitry

GND

1.Integrated varactor & compensation circuit inside IC


3.<±2.5 to ±0.28 (S3-TCXO)PPM level temperature stability

4.<±2.5 PPM level frequency accuracy based on physical tuning capability

Temperature-Compensated Crystal Oscillator (TCXO)

Crystal Oscillators

25 C � T

F

Crystal IC Compensated

Result

≦2.5 ppm ≦0.3 ppm (Stratum 3 TCXO)


Oven

Amplifier

Buffer

Fout

Vdd

Crystal

CdCgVaractor

Vc

Temperature Sensor

Oven Control Circuit

1.Discrete electrical components & oven controlled circuit


3. <±0.1 PPM level temperature stability

4.<±0.1 PPM level frequency accuracy based on physical tuning capability

Tunable Range over Temp.(Depends on crystal cut)

Oven-Controlled Crystal Oscillator (OCXO)

Crystal Oscillators

Less than 1/3 of CMOS

voltage swing

Less than 1/6 of CMOS

voltage swing


Differential Output

CMOS (Single-ended)

Differential

CMOS: Single-endedDifferential*: Dual-ended (same frequency)

Advantage of Differential Output Low voltage swing Better noise rejection

*: 3 kinds of differential output that TXC is using: LVPECL, LVDS, HCSL


Thank you

Think of Frequency Think of Introduction to Crystal TXC Confidential & Proprietary | 1.

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