Crystal oscillator, it is to point to from a quartz it is certain to be pressed on crystal azimuthal cut next chip (abbreviation is chip) , quartz crystal resonator, abbreviation is quartz crystal or crystal, brilliant brace up; And crystal oscillator is called in the crystal cell that encloses interior to add IC to comprise oscillating circuit. Its product is enclosed with metallic crust commonly, case of useful also glass, pottery and porcelain or plastic enclose. The crystal oscillator of article introduction has 4 kinds as follows: Oscillator of constant temperature crystal (OCXO) , oscillator of temperature compensation crystal (oscillator of TCXO) , common crystal (SPXO) , pressure accuse crystal oscillator (VCXO) .

 

 

This type brilliant brace up used technology of constant temperature chamfer to the solution of temperature stability, chamfer of crystal park constant temperature inside, through installing constant temperature the job is nodded, make cell body holds constant temperature position, do not suffer external temperature effect inside certain limits, achieve stability to output the effect of frequency. This kind of brilliant brace up the communication device that basically is used at all sorts of types, include switching equipment, SDH to transmit equipment, mobile to put the domain such as TV of receiver of machine, GPS, broadcasting station, number and war industry equipment continuously. According to user need, this type brilliant brace up can belt pressing accuses to cite a base. Following plan institute show the working principle of OCXO:

 

Block diagram of principle of oscillator of constant temperature crystal

 

The main good point of OCXO is, because used technology of constant temperature chamfer, frequency temperature character is in all type brilliant brace up in it is best, because circuit designs nicety, its are short mix firmly phasic noise is better. Main drawback is power comsumption volume is big, large, need the left and right sides 5 minutes heat time ability works normally etc. This kind of any crystalline substance that my company produces brace up typical target is as follows:

 

 

 

TCXO lukewarm Bu Jingzhen is to pass its additional temperature compensation circuit makes all round a kind of quartz that the amount of oscillation frequency change that temperature change produces cuts down crystal oscillator. Its temperature compensatory principle the laden capacitance in passing change oscillation loop namely, the frequency drift that makes because place of environmental temperature change arises,its compensate resonator along with temperature change.

 

Brilliant brace up action is to be a system to provide basic clock signal. Normally altogether of a department uses an any crystalline substance brace up, facilitate departmental cent keeps synchronous. The fundamental frequency of some communication system and radio frequency use different any crystalline substance brace up, and the method that adjusts frequency through the electron keeps synchronous.

 

 

Brilliant brace up with Suo Xianghuan normally circuit cooperates to use, in order to offer the clock frequency that systematic place requires. If different subsystem needs the clock signal of different frequency, can use with same a brilliant brace up conjoint different Suo Xianghuan will offer.

 

Its used a few temperature to compensate a method to the solution of temperature stability, main principle is to pass inductive environment temperature, brilliant is controlled after making temperature news proper shift brace up output frequency, achieve stability to output the effect of frequency. Traditional TCXO is to use imitate parts of an apparatus to undertake compensating, as the development that compensates a technology, a lot of digitlization compensate big TCXO to begin to appear, TCXO of compensatory of this kind of digitlization calls DTCXO again, with odd when undertaking compensating, we weigh a chance for MCXO, because used digitlization technology, the brilliant of this one type brace up very tall precision was achieved on temperature character again, and can get used to wider working temperature range, basically apply at war industry domain and the circumstance with use harsh environment. Below the joint efforts of personnel of extensive research and development, my company opens the MCXO that gave out high accuracy independently, its design principle and alive bound range is banner, deserve to test a system with the production of high automation, its are produced per month can achieve 5000, its design a principle to pursue as follows.

 

 

Block diagram of principle of MCXO number lukewarm Bu Jingzhen

 

This type brilliant brace up typical applied target is as follows:

 

 

 

 

 

This is a kind of simple crystal oscillator, call Zhong Zhen normally, its job principle is a graph 3 in purify “ is pressed accuse temperature of ” , “ to amend ” and “AGC” part, the free oscillation that is You Jing body completely is finished. This kind of brilliant brace up main application asks at stability not tall circumstance.

 

 

This is a basis brilliant brace up whether belt pressing accuses a function to classify, a kind of brilliant that belt pressing accuses an input to cite a base brace up call VCXO, above the brilliant of 3 kinds of types brace up OK belt pressing accuses port.

 

 

Total frequency difference: Inside formulary time, the job as a result of the regulation and the crystal oscillator frequency that are not the job to parameter is combined entirely and be caused and give nominal the biggest error of frequency.

 

Explain: The character of voltage of the deviation that total frequency difference includes rate of ageing of frequency temperature stability, frequency to cause, frequency and frequency load performance the biggest frequency difference that creates jointly. Caring to short-term frequency stability only commonly, and the circumstance of not strict to index of other frequency stability requirement is used. For example: Radar of accurate control and guide.

 

Frequency stability: Any brilliant brace up, it is absolutely that frequency is not stabilized, level is different just. A brilliant brace up if the curve that output frequency changes along with time pursues 2. 3 kinds of elements with not stable frequency show in the graph: Ageing, drift and short firm.

 

Brilliant brace up the sketch map that output frequency changes along with time

 

Curve 1 it is the situation that measures with 0.1 seconds, behaved brilliant brace up short firm; Curve 3 it is the situation that measures with 100 seconds, behaved brilliant brace up drift; Curve 4 it is the situation that measures with 1 day. Behaved brilliant brace up ageing.
 

Frequency temperature stability: Be in nominal below power source and load, the job inside formulary temperature limits what do not take implicit and fiducial temperature or take implicit and fiducial temperature is the biggest allow frequency to slant.

 

Ft=±(fmax-fmin)/(fmax+fmin)

｜ of ±MAX[of Ftref ＝ (Fmax-fref)/fref ｜ , ｜ (Fmin-fref)/fref ｜ ]

Ft: Frequency temperature stability (do not take implicit and fiducial temperature)

Ftref: Frequency temperature stability (take implicit and fiducial temperature)

Fmax: The regulation measures gotten highest frequency inside temperature limits

Fmin: Set the lowermost frequency that measures inside temperature limits

Fref: Stipulate fiducial temperature measures gotten frequency

 

Explain: Its produce the crystal oscillator that uses Ftref index the crystal oscillator that difficulty wants prep above to use Ft index, the crystal oscillator price of reason Ftref index is higher.

 

Switch on the mobile phone characteristic (frequency stabilizes warm-up time) : Point to the period of time after switching on the mobile phone (like 5 minutes) frequency arrives another paragraph of time after switching on the mobile phone (like 1 hour) the metabolic ratio of frequency. Represented any crystalline substance brace up the rate that achieves stability. This index is right often the instrument of switch is like frequency meter to wait very useful.

 

Explain: In majority application, crystal oscillator appends report for a long time, switch on the mobile phone often in need of oscillator of the crystal in certain applying however and close machine, at this moment need of index of time of frequency stability warm-up is considered (the broadcasting station of communication of for military use that uses in harsh to be in environment especially, when ～ of ℃ of ≤±0.3ppm(-45 of stability of requirement frequency temperature 85 ℃ ) , use OCXO to regard as this brace up, frequency stabilizes warm-up time will not less than 5 minutes, and use MCXO to need) ten seconds only.

 

Frequency ageing leads: When oscillator frequency is measured below constant ambient conditions, the relation between oscillator frequency and time. The slow change of component of You Jing body and oscillator circuit element causes drift of this kind of long-term frequency, accordingly, the rate of its frequency deflection makes ageing rate, the biggest change after usable specified time limits is led (like ±10ppb/ day, after appending report 72 hours) , or the biggest total frequency inside formulary time limit changes (be like: ±1ppm/ (the first year) with ±5ppm/ (10 years) ) will express.

 

Because be put in blemish of craft of gas of stress, contaminant, remain, structure to wait for a problem when producing crystal,crystal ageing is. The metabolic gift that stress should pass for some time is stable, a kind of crystal cut method that calls “ stress compensation ” (SC patterning method) the character with make crystal has better.

 

The element of contaminant and rudimental gas will be deposit in crystal piece go up or make crystal electrode oxidizes, oscillation frequency is taller, uses crystal piece thinner, this kind of influence is fiercer. This kind of influence should pass a paragraph of longer time ability to be stabilized gradually, and this kind of stability can have as the change of temperature or working status repeatedly —— makes contaminant is in crystal surface is centered once more or disperse. Accordingly, the brilliant with low frequency brace up taller than frequency brilliant brace up, the brilliant with long working hours brace up shorter than working hours brilliant brace up, the brilliant of successive job brace up than intermittent working brilliant brace up ageing rate is close friends.

 

Explain: The frequency ageing rate of TCXO is: ±0.2ppm ～ ±2ppm (the first year) with ±1ppm ～ ±5ppm (10 years) (divide special situation, TCXO is used rarely everyday the index that frequency ageing leads, because although be in,the condition of the lab falls, the frequency change that temperature change causes also will exceed temperature to compensate crystal oscillator greatly everyday frequency ageing, because this index lost real sense) . The frequency ageing rate of OCXO is: Day of ±0.5ppb ～ ±10ppb/ (after appending report 72 hours) , ±30ppb ～ ±2ppm (the first year) , ±0.3ppm ～ ±3ppm (10 years) .

 

Short firm: Short-term stability, the time of observation is 1 millisecond, 10 millisecond, 100 millisecond, 1 second, 10 seconds.

 

Brilliant brace up output frequency gets the influence of in-house circuit (the Q value of crystal, yuan status of the stability of the noise of parts of an apparatus, circuit, job) and generation spectrum is very broad not stable. After measuring a chain of frequency to be worth, with Alan equation is calculated. Phasic noise can be mirrorred as much short firm circumstance (should special apparatus measures) .

 

Reappearance: Definition: Brilliant brace up after be being stabilized via working for long, close machine, stop machine T1(of period of time is like 24 hours of) , switch on the mobile phone for some time T2(is like 4 hours of) , measure frequency F1, stop again opportunity is same paragraph of time T1, reopen machine is the same as T2 of period of time, measure frequency F2. Reappearance =(f2-f1)/f2.

 

Frequency pressing accuses limits: frequency control voltage moves terminal voltage of the regulation from fiducial voltage, the least peak value of crystal oscillator frequency changes a volume.

 

Explain: Fiducial voltage is ＋ 2.5V, stipulate terminal voltage is ＋ 0.5V and ＋ 4.5V, press the frequency when accusing crystal oscillator to control voltage in ＋ 0.5V frequency to change a quantity to be – 2ppm, when ＋ 4.5V frequency controls voltage frequency change measures the 2.1ppm that it is ＋ , criterion VCXO voltage controls frequency pressing to accuse limits to express to be: ≥±2ppm(2.5V±2V) , slope is, linear is + 2.4% .

 

Pressure accuse frequency to answer limits: When modulation frequency changes, peak value frequency slants with the relation between modulation frequency. The modulation that compares a regulation with modulation frequency of the regulation normally is fiducial frequency is low a certain number of DB express.

 

Explain: VCXO frequency is pressed accuse limits frequency to answer for 0 ～ 10kHz.

 

Frequency pressing accuses linear: With ideal (linear) the output frequency that function photograph compares – a kind of measurement that inputs control voltage to transmit character, the admissibility that it expresses to whole range frequency slants with percentage is nonlinear degree.

 

Explain: Frequency pressing accuses typical VCXO linear is: ≤±10% , ≤±20% . Frequency pressing accuses simple VCXO linear calculation method is (accuse the) when polarity is positive electrode sex when frequency pressing:

 

Frequency pressing accuses linear ＝ ±((fmax-fmin)/ F0)×100%

Fmax: VCXO is in the biggest press the output frequency when accusing voltage

Fmin: VCXO is in the smallest press the output frequency when accusing voltage

F0: Pressure accuse central voltage frequency

 

Unilateral takes phasic noise ￡ (F) : F of deviate carrier wave is in, of the power density of webbing of a phasic modulation and carrier wave power than.

 

Output is undee: From kinds big for, output weaveform can be divided for square wave and sine wave two kinds.

 

Square wave basically is used on clock of digital communication system, wave of the other side basically has output n, occupy sky comparing, rise / the requirement of a few index such as ability of decay time, drive.

 

As the swift and violent development of science and technology, in the similar system such as communication, radar and high speed data transmission, the signal source that needs high quality regards complex with each passing day base band as the carrier wave of information. Because one contains the carrier wave signal of parasitism amplitude modulation and phase modulation (sordid signal) after be being carried to have the modulation of base band signal of information, the spectrum component that existence does not answer below these good position (the parasitism modulation in carrier wave) the signal quality that can bring about place to transmit and data transmission are piled up by accident lead apparent addle. Transmit the carrier of signal as place so, the clean degree of carrier wave signal (spectrum purity) having immediate effect to communication quality. To sine wave, normally need is offerred for example the index such as harmonic, noise and output power.