CN201976070U - High-frequency crystal oscillator with function of digital temperature compensation - Google Patents
High-frequency crystal oscillator with function of digital temperature compensation Download PDFInfo
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- CN201976070U CN201976070U CN201120014104XU CN201120014104U CN201976070U CN 201976070 U CN201976070 U CN 201976070U CN 201120014104X U CN201120014104X U CN 201120014104XU CN 201120014104 U CN201120014104 U CN 201120014104U CN 201976070 U CN201976070 U CN 201976070U
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Abstract
The utility model relates to a crystal oscillator of communication equipment, in particular to a high-frequency crystal oscillator with a function of digital temperature compensation, which belongs to the technical field of communication equipment. The high-frequency crystal oscillator mainly comprises a temperature sensor with a 12-bit A/D (analog-to-digital) converter, a crystal oscillator body, a microprocessor with a 12-bit A/D converter and a 12-bit D/A (digital-to-analog) converter and a frequency synthesizer, a digital signal output by the temperature sensor is directly input to the microprocessor, a D/A output end of the microprocessor is connected with an input end of a voltage control crystal oscillator, and a frequency signal output by the voltage control crystal oscillator is output after passing the frequency synthesizer. The high-frequency crystal oscillator can compensate temperature within a full temperature range, is high in accuracy and wide in work frequency range, and overcomes the defects in size and accuracy of a conventional micro-computer compensation crystal oscillator.
Description
Technical field
The utility model relates to the crystal oscillator in a kind of communication equipment, and especially a kind of high-frequency, crystal oscillator with digital temperature compensate function belongs to the communication equipment technical field.
Background technology
Generally all have crystal oscillator in the communication equipment, because the frequency of oscillation of crystal can change with variation of temperature, thereby, being the frequency of oscillation of stable crystal, people have designed the temperature compensating crystal oscillator with temperature compensation function.
Present temperature compensating crystal oscillator is generally crystal oscillator of analog temperature compensation (TCXO), it comprises temperature sensor and crystal oscillator, and it requires than higher crystal, the crystal of cutting for AT, require temperature frequency difference to be controlled at about 70, very unfavorable to crystal production; And adopt the segmented compensation mode, and its precision is not high, and particularly extreme two of temperature, change curve is very big, and it is impossible adopting the analogy method full remuneration; Produce very difficulty on the other hand, selection to thermistor and fixed resistance is relatively more difficult, will be through adjustment repeatedly, particularly under the inconsistent situation of crystal, it is just very low to produce qualification rate in batches, therefore just to be used for temperature range narrow for crystal oscillator of analog temperature compensation, and the temperature compensating crystal oscillator that ratio of precision is lower refers generally to be designated as :+/-1～2PPM (0 ℃～50 ℃)
In addition, crystal oscillator of analog temperature compensation generally is made up of the amplification or the output stage of a master-oscillator and a buffer action.The operating frequency of crystal oscillator is drawn by crystal resonator, and its frequency stability is suitable with the resonant frequency of a crystal temperature characterisitic.At present, said temperature compensated crystal oscillator, general work frequency all are below 40MHz, can't reach the frequency requirement (the Modern High-Speed data communication network requires more than 100M reaches) of Modern High-Speed data communication.
Therefore, can design a kind of novel crystal oscillator,, become the technical barrier that those skilled in the art need to be resolved hurrily to overcome above-mentioned defective.
The utility model content
In order to solve the problems of the technologies described above, the utility model aims to provide a kind of high-frequency digital temperature compensation crystal oscillistor, and it can realize that the high frequency of crystal oscillator and wide temperature compensation repay, and volume is little, precision is high.Its technical scheme that adopts is as follows:
This high-frequency digital temperature compensation crystal oscillistor mainly comprises: crystal oscillator, temperature sensor, microprocessor and frequency synthesizer, wherein said temperature sensor has the A/D converting unit, described microprocessor has arithmetic element and the D/A converting unit that connects in turn, and described temperature sensor is arranged near the position of described crystal oscillator; The input of described microprocessor is connected with described temperature sensor, and its output is connected with the input of described crystal oscillator, and the output of described crystal oscillator is connected with described frequency synthesizer.
Preferably, described crystal oscillator is a VCXO.
Preferably, the A/D converting unit in the described temperature sensor is 12, and described D/A converting unit is 12.
Preferably, described temperature sensor is surveyed the working temperature of described crystal oscillator by thermocouple.
Compared with prior art, the utlity model has following advantage:
1, temperature compensation range is wide, can reach-40～+ 85 degrees centigrade;
2, the operating frequency range of crystal oscillator is wide, from hundreds of KHz to all can more than the 100MHz;
3, because temperature sensor carries the A/D transfer capability, make overall volume reduce;
4, precision height can reach 0.1ppm;
5, compensation is level and smooth, does not have frequency jitter;
6, reduce the requirement of quartz crystal device, reduce production costs, it is easier to produce in batches.
Description of drawings
Fig. 1: the structural representation of high-frequency digital temperature compensation crystal oscillistor of the present utility model;
Fig. 2: the program flow diagram of high-frequency digital temperature compensation crystal oscillistor of the present utility model;
Fig. 3: the AT of not compensated cuts crystal resonator frequency-temperature characteristics;
Fig. 4: frequency shift (FS) and the corresponding curve of voltage-controlled voltage relationship;
Fig. 5: voltage-controlled voltage and the corresponding curve of the relation of temperature sensor count value.
Among the figure: 1, crystal oscillator; 2, temperature sensor; 3, microprocessor; 4, frequency synthesizer; 5, arithmetic element; 6, D/A converting unit.
Embodiment
The utility model is described in further detail below in conjunction with accompanying drawing and example:
An embodiment of the present utility model as shown in Figure 1, this high-frequency digital temperature compensation crystal oscillistor mainly comprises: crystal oscillator 1, temperature sensor 2, microprocessor 3 and frequency synthesizer 4, wherein temperature sensor 2 has the A/D converting unit, microprocessor 3 has arithmetic element 5 and the D/A converting unit 6 that connects in turn, and temperature sensor 2 is arranged near crystal oscillator 1 position; The input of microprocessor 3 is connected with temperature sensor 2, and output is connected with the input of crystal oscillator 1, and the output of crystal oscillator 1 is connected with frequency synthesizer 4.
Microprocessor 3 adopts C8051F007, and its encapsulation little (LQFP32) can be satisfied the requirement of compact package; By program, make D/A be converted to 12, the precision of temperature control is provided.
What present embodiment used aspect circuit is that digital temperature sensor 2 and microprocessor 3 combine, temperature sensor 2 can directly convert temperature signal to voltage digital signal output, produce the function of a digital bucking-out system based on microprocessor 3, utilize 12 the A/D functions that carry of temperature sensor 2, this digital signal directly is defeated by microprocessor 3, carry out computing by arithmetic element 5, by microprocessor 3 operation result is exported analog voltage signal after D/A converting unit 6, regulate by microprocessor is outside, the pulling frequency makes it to reach needed value, it is stored, obtain the bucking voltage amount corresponding with it, on the other hand can be by program to microprocessor, the quantizing noise that produces when control is moved by microprocessor, and optimized calculation method, make the better grade of reaching of frequency stabilization.
The compensation precision of temperature-compensating of the present utility model is relevant with the design of program in the arithmetic element 5 to a great extent.What the utility model compensation operation adopted is seven order polynomials.The coefficient of seven order polynomials exists in the microprocessor with the form of constant.The work that microprocessor will carry out will be coordinated the operate as normal of each several part circuit exactly.It mainly finishes the work of following 3 aspects: read the temperature sensing value, calculate seven multinomial, output signals.Program circuit as shown in Figure 2.
Because aspect in the past is difficult to accomplish that operating frequency is more than 100MHz, in order to overcome this difficulty, the utility model has also adopted the low noise frequency synthesis technique that has commonly used now, the frequency Fin that oscillator produces enters frequency synthesizer, by internal frequency synthetic back output, make phase noise can reach following index then:
100MHz@100Hz -125db/Hz
100MHz@1KHz -135db/Hz
100MHz@10KHz -140db/Hz
Below concise and to the point analysis temperature compensation principle of the present utility model:
The utility model adopts the temperature of temperature sensor measurement crystal resonator internal wafer, the crystal resonator of its use is generally the quartz-crystal resonator that AT cuts, its frequency-temperature characterisitic is an approximate cubic curve (as shown in Figure 3) in wide temperature range, therefore the available digital technology is come the treatment temperature transducing signal and is formed control voltage, control variable capacitance diode in the crystal oscillator by control voltage, thereby the frequency of oscillation of pulling crystal oscillator reaches the final purpose of compensation.
Cut crystal resonator for AT, promptly to specific crystal, present embodiment obtains the frequency-temperature characteristics of not compensated, as shown in Figure 3.
Curve among Fig. 3 can be represented with the functional relation G between frequency f and the temperature t, is designated as
F＝G(T) (1)
It is exactly to want the output frequency of crystal oscillator with the variation of temperature amount that crystal oscillator is carried out temperature-compensating, improves the frequency-temperature characterisitic of crystal, makes its frequency shift (FS) in whole temperature range reach minimum, promptly exports a stable frequency signal.For this routine described MCXO is to make it export the signal of stable 100MHz in-40～+ 85 ℃ temperature range.Can get the frequency offset of crystal by formula (4)
Δf＝f-fo＝G(T)-fo＝H(T) (2)
Be to represent with functional relation H that fo is the nominal frequency of crystal resonator between the frequency offset of crystal and the T.
The change of crystal oscillator frequency is to be called voltage-controlled voltage V by the voltage that change is added on the variable capacitance diode that links to each other with crystal one end, has the relation of approximately linear between the crystal output frequency variable quantity that voltage-controlled voltage V and its cause, as shown in Figure 4.Be designated as
Δf＝L(T) (3)
Hence one can see that, and the voltage-controlled voltage V under a certain temperature has just represented the frequency offset Δ f of crystal under this temperature.
Therefore can obtain the relation of voltage-controlled voltage V and temperature T, be designated as F.Promptly
V＝L
-1(Δf)＝L
-1[H(T)]＝F＝G(T) (4)
This curve shape is the mirror image of axis with the horizontal coordinate just like the curve among Fig. 3, this has also just in time illustrated the rightabout effect that the voltage-controlled voltage that is added on the crystal oscillator plays with variation of temperature crystal oscillation frequency, promptly when temperature changes, the frequency of oscillation of crystal changes towards the direction that increases or reduce, and the variation balance of power of voltage-controlled voltage is opposite with the crystal oscillation frequency variation tendency, so just spur the frequency of crystal oscillation, it is changed in the opposite direction, and the frequency of oscillation of crystal just can't change according to original trend like this.When temperature and two kinds of effects of voltage-controlled voltage are added on the crystal simultaneously, and two kinds of effects, are stabilized on the nominal frequency with regard to the frequency of oscillation that makes crystal suitable the time the influence of crystal oscillation frequency.
In design system, temperature signal embodies by count value, because of cycle of the signal of crystal temperature effect transducer output varies with temperature the character of approximately linear,, be designated as so have relation one to one between count value N that obtains by the transducer modulate circuit and the temperature T:
N＝p(T) (5)
Therefore count value N has just represented the residing environment T of temperature sensor, and the numerical value of N of using tricks of the T in the formula (5) is replaced, and so just obtains the relation of voltage-controlled voltage V and count value N, is designated as B, then:
T＝F(T)＝F[p
-1(N)]＝B(N) (6)
Its curve as shown in Figure 5.
As long as the curve among Fig. 5 is come out by match with computer, promptly determine the functional relation between voltage-controlled voltage and the count value, just can obtain arbitrary temp point and go up required voltage-controlled voltage.
This high-frequency digital temperature compensation crystal oscillistor is simple in structure, volume is little, precision is high, power consumption is little, cost is low, and start is short warm-up time, has good development prospect, in field such as military, commercial, that the people have market is widely arranged all.
With way of example the utility model is illustrated above, but the utility model is not limited to above-mentioned specific embodiment, all any change or modification of doing based on the utility model all belong to the claimed scope of the utility model.
Claims (4)
1. high-frequency digital temperature compensation crystal oscillistor, it is characterized in that, comprise: crystal oscillator (1), temperature sensor (2), microprocessor (3) and frequency synthesizer (4), wherein said temperature sensor (2) has the A/D converting unit, described microprocessor (3) has arithmetic element (5) and the D/A converting unit (6) that connects in turn, and described temperature sensor (2) is arranged near the position of described crystal oscillator (1); The input of described microprocessor (3) is connected with described temperature sensor (2), and its output is connected with the input of described crystal oscillator (1), and the output of described crystal oscillator (1) is connected with described frequency synthesizer (4).
2. high-frequency digital temperature compensation crystal oscillistor according to claim 1 is characterized in that, described crystal oscillator (1) is a VCXO.
3. high-frequency digital temperature compensation crystal oscillistor according to claim 1 is characterized in that, the A/D converting unit in the described temperature sensor (2) is 12, and described D/A converting unit (6) is 12.
4. high-frequency digital temperature compensation crystal oscillistor according to claim 1 is characterized in that, described temperature sensor (2) is surveyed the working temperature of described crystal oscillator (1) by thermocouple.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201120014104XU CN201976070U (en) | 2011-01-17 | 2011-01-17 | High-frequency crystal oscillator with function of digital temperature compensation |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201120014104XU CN201976070U (en) | 2011-01-17 | 2011-01-17 | High-frequency crystal oscillator with function of digital temperature compensation |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102931916A (en) * | 2012-11-15 | 2013-02-13 | 清华大学 | Analog-digital mixed temperature compensation crystal oscillating circuit |
| CN110198155A (en) * | 2019-06-07 | 2019-09-03 | 晶科芯(苏州)集成电路设计有限公司 | A kind of digital temperature compensation crystal oscillator |
| CN112422084A (en) * | 2019-08-20 | 2021-02-26 | Oppo广东移动通信有限公司 | Temperature compensation method and device for crystal oscillator, electronic device and storage medium |
-
2011
- 2011-01-17 CN CN201120014104XU patent/CN201976070U/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102931916A (en) * | 2012-11-15 | 2013-02-13 | 清华大学 | Analog-digital mixed temperature compensation crystal oscillating circuit |
| CN110198155A (en) * | 2019-06-07 | 2019-09-03 | 晶科芯(苏州)集成电路设计有限公司 | A kind of digital temperature compensation crystal oscillator |
| CN112422084A (en) * | 2019-08-20 | 2021-02-26 | Oppo广东移动通信有限公司 | Temperature compensation method and device for crystal oscillator, electronic device and storage medium |
| CN112422084B (en) * | 2019-08-20 | 2024-04-19 | Oppo广东移动通信有限公司 | Temperature compensation method and device for crystal oscillator, electronic equipment and storage medium |
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