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Ceramic Resontors Technical Seminalposition: Home > Tech Info > Ceramic Resontors Technical Seminal

INTRODUCTION OF CERAMIC RESONATORS
Ceramic Resonators are made of high stability piezoceramic ceramics that fountion as a mechanical resonator. This device has been developed to function as a reference. signal generator and frequency is primarily adjusted by the size and thickness of ceramic element.
CHARACTERS OF CERAMIC RESONATORS
I. The high stability of oscillation freqeuency
The frequency stability of Ceramic Resonators is between that of Quartz Crystals and LC or RC oscillation circuits. The temperature coefficient of Quartz Crystals is
10 -5/℃ maximum and approximately 10 -3 /℃ to 10 -4/℃ for LC or RC oscillation
Circuits. Compared with these, it is 10-5 /℃ at the the temperature range of -20 ℃
to +80℃.
II. Miniature Size and Light Weight.The size of the Ceramic Resonators is only half of popular Quartz Crystal. III. Low power consumption.
IV. Comply with European and USA ROHS regulations regarding hazardous substances.
V. Low price, no adjustment is necessary for oscillation circuit.Ceramic wafer is mass produced, resulting in low cost and high stablility. Unlike RC or LC circuits, ceramic resonators use mechanical resonators, it means it is not basically affected by external circuits or by fluctuation of the supply voltage.High stable oscillation circuits can therefor be made without the need of adjustment.

PROCESS OF CERAMIC WAFER
First grinding  -----grinding on thickness of ceramic wafer
Second griding ----grinding on frequency of ceramic wafer against  thickness
Surface griding  -----ceramic wafer out size shaping
Wafer Cleaning      -----   wash the surface of ceramic wafer
Drying, Sputtering   -----  equipment for ceramic surface electrode
Polarization        -----  Make piezoelectric effect on ceramic resonators
Anti-erode printing  -----  Printing electrode graph of  ceramic resonator

Anti-erode cleaning----- Move electrode graph of resonator and cover ink
Sort Frequency----- Assorting and adjusting frequency of ceramic wafer
Cutting----- cut the ceramic wafer into the needed resonator unit
Testing----- sort and confirm the electronic performance

PROCESS OF SMD CERAMIC RESONATORS

Assembling----fit resonator on the baseboard, connecting them with epoxy, sealed by cover
             board
Cutting----- cut large wafer into small unit resonator
Metallizing on the side -----Metallizing on the side of resonator, leading to electrode
Electroplatiing-----Electroplate the outer of electrode which will increase its solderability and heat resistance
Assorting on electrical performance-----rountine test on finished products
Mark-----a symbol that can identify the features of a product.
Packing-----package refers to a product
Final Testing-----Testing before delivery

BASIC PARAMETERS OF CERAMIC RESONATORS
The Ceramic Resonators are devided into two types: CRA (with built-in capacitance)and CRT (without built-in capacitance), the equivalent circuit are as follows:

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C0: shunt capacitance;
C1: dynamic capacitance;
L1: dynamic inductance;
R1: dynamic impedance; CL1、CL2 inner load capacitance
R0: resonator impedance,nearly asR1;

CERAMIC RESONATORS IN TYPICAL OSCILLATION CIRCUIT

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Basic oscillation circuit that using C-MOS invertor
It is becoming more common to configure the oscillation circuit with a digitalLC, and the simplest way to use an inverter gate.Last page shows the configuration of a basic oscillation cicuit with a C-MOS inverter.INV.1 works as an inverter amplifier of the oscillation circuit. INV.2 acts to shape the waveform ans also acts as a buffer for the connection of a frequency counter.
The feedback resistance Rf provides negative feedback around the inverter in order to put it in the linear region, so the oscillation will start, when power is applied.If the Rf is too large, and if the input of the insulating resistance of input inverter is accidentally decreased, oscillation will stop due to the loss of loop gain.Also, if the RF is too large, the noises from the other circuits will be introduced into the oscillation circuit. Obviously, if the Rf is too small, the loss gain will be low. An Rf of 1MΩis generally used with a ceramic resonator.Damping resistor Rd provides loose coupling between the inverter and feedback Circuit and decreases the loading on the inverter, thus saving energy..In addition, the damping resistor stabilizes the phase of feedback circuit and provides.A mens of reducing ghe gain in the high frequency area, thus preventing the possibility of spurious oscillation.Load capacitance CL1 and CL2 provide the phase lag of 180°. The proper selected value depends on the application, the IC used, and frequency. If CL1 and CL2 values .Are low, loop gain in the high frequency is increased, which in turn increases the probability of spurious oscillation.

FOSC in circuit can be presented as follows:
FOSC=Fr√1+C1/(C0+CL
This clearly shows that the oscillation frequancy is influenced by load capacitance. An caution shoud be paid when a tight of frequency tolerence is required.

CERAMIC RESONATORS APPLICATION IN VARIOUS OSCILLATION CIRCUIT
Application to C-MOS Inverter
For the C-MOS inverting amplifier, the one-stage 4069C-MOS group is best suited. The C-MOS 4049 type is not used, because the three-stage buffer type has excessive gain, which causes RC oscillation and ringing.Recently, high speed C-MOS (H-CMOS) have been used more frequently for oscillation circuits allowing high speed and energy saving control for the microprocessor.There are two types of H-CMOS inverters: the un-buffered 74HCU series and the 74HC series with buffers.The 74HCU system is optimum for the ceramic oscillation circuit.Since H-CMOS has high gain, especially in the high frequency area, greater loading capacitor (CL) and damping resistor (Rd) should be employed to stabilize oscillation performance. As a standard circuit, we recommend Toshiba's TC74CU04,but any 74HCU04 inverter from other manufacturers may be used。

MAJOR SMD PRODUCTS

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NOTICE FOR STORAGE AND OPERATING
I. Product Storage Condition
Please store the products in room where the temperature/humidity is stable. And avoid such places where there are large temperature changes. Please store the products under the following conditions: Temperature: -10 to + 40 degree C Humidity: 15 to 85% R.H.
II. Expire Date on Storage
Expire date (Shelf life) of the products is six months after delivery under the conditions of a sealed and an unopened package. Please use the products within six months after delivery. If you store the products for a long time (more than six months), use carefully because the products may be degraded in the solderability and/or rusty.Please confirm solderability and characteristics for the products regularly.
III. Notice on Product Storage
(i)Please do not store the products in a chemical atmosphere (Acids, Alkali, Bases, Organic gas, Sulfides and so on), because the characteristics may be reduced in quality, and/or be degraded in the solderability due to the storage in a chemical atmosphere.
(ii) Please do not put the products directly on the floor without anything under them to avoid damp places and/or dusty places.
(iii) Please do not store the products in the places such as: in a damp heated place, in a place where direct sunlight comes in, in place applying vibrations.
(iv) Please use the products immediately after the package is opened, because the characteristics may be reduced in quality, and/or be degraded in the solderability due to storage under the poor condition.
(v) Please do not drop the products to avoid cracking of ceramic element.
IV. Others
Conformal coating or washing of the component is not acceptable because it is not hermetically sealed.Please be sure to consult with our sales representative or engineer whenever and prior to using the products.The component may be damaged if excess mechanical stress is applied. Ceramic resonators may stop oscillating or oscillateirregularly under improper circuit conditions.

APPLICATIONS
I.      Clock oscillators for microprocessors.
II.  Small electronic equipment such as hand held phone, digital viedo camcorder
(DVC), ditital still camera (DSC), protable audio player, etc.
III. Storage media and memory
(HDD, Optical storage device, FDD, Flash memory, card, etc.)
IV. Office automation equipment
( Mobile PC, Mouse, Keyboard, etc.)
V. Audio-visual applications
(TV, DVD-HDD recorder, Audio equipment, remote, controller, etc.)
VI. Home applicances
(Air conditioner, Microwave oven, refrigerator, washing machine, etc.)

TENDENCY OF CERAMIC RESONATORS
With the fast development of eletronic industry, especially the quickly growing and vast use of digital technique in various areas, high integration, microminiature、 multifunction and high speed are the tendency of Ceramic Resonators. The electric system is developing in the direction of meshwork、high speed processing and transmission. So they have the same requirement of light, thin, short, high frequancy and chip like on the piezoelectricity components .Recently we pushed out a SMD series of 4.5*2.0mm、2.5*2.0mm、3.2*1.3mm with high frequency in small size. 2.0*1.3 and 2.0*1.6mm series will also enter into the market in the very near furture.