CN1705234A - Clock synthesizing method and system - Google Patents
Clock synthesizing method and system Download PDFInfo
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Abstract
A clock synthesizing method for realizing clock presetting and complex performance combined adjustment, which contains comparing the reference clock with feedback clock by phase discrimination/frequency discriminator to obtain the error between them, the microprocessor makes subtracting in said error with prospected clock error and loop filter treatment, using the treated result controlling digital controlled clock adjustment and outputting clock, said invention also discloses the system for realizing said method.
Description
Technical field
The present invention relates to the clock technology in the communication system, particularly a kind of clock synthetic method and system.
Background technology
Along with the development of thermometrically technology, more and more high for the requirement of test and excitation signal.It is controlled requiring the performance of the clock signal of input stimulus in a lot of test occasions, or can preset.As shown in Figure 1, the trend that the clock signal of input stimulus is described according to solid line changes, and the output response then need change according to the trend that dotted line is described.Just require signal is changed its time delay relation etc. on the existing fixed sequential relationship in the time of will verifying the sequential tolerance limit of Design of Digital System for another example.Therefore, performance signal generator adjustable, controlled and that can preset has become the important means and the measurement index of verification system tolerances in design fault freedom.
Can control the output clock with respect to the phase difference of input clock by traditional hardware simulation phase-locked loop circuit, input clock is carried out phase place draw inclined to one side function thereby reach.Figure 2 shows that traditional hardware simulation phase locked looped function block diagram, frame of broken lines shown in the figure is active proportional integral circuit, be used to realize the loop filtering function, wherein, by regulating the adjustable resistance R1 of the operational amplifier positive input in this active proportional integral circuit, can realize adjustment to the comparative voltage of operational amplifier, cooperate digital phase demodulation/frequency discriminator (PD/PF) and voltage controlled oscillator (VCO) again, can reach output clock tracing input clock thus and simultaneously to the phase place of output clock or the effect that frequency is regulated with phase demodulation or frequency discrimination function.But because traditional hardware simulation phase-locked loop circuit is subjected to the influence of discrete component and analog loop filter (being active proportional integral circuit), the bandwidth of loop is narrower, the restriction of suffered adjustable range is too big, and the degree of regulation of adjustable resistance is also relatively poor, can't realize that clock performance can preset the combination regulatory function with complicated performance.
Summary of the invention
The object of the present invention is to provide a kind of clock synthetic method and system, there is the relatively poor problem of restricted and degree of regulation of adjustable range in the hardware simulation phase-locked loop circuit because of being subjected to the influence of discrete component and analog loop filter in the prior art to solve.
For addressing the above problem, the invention provides with positive technical scheme:
A kind of clock synthetic method comprises the steps:
A, phase demodulation/frequency discriminator compare reference clock and feedback clock, obtain phase place between reference clock and the feedback clock or/and frequency error;
B, microprocessor subtract each other described error and the pairing ERROR CONTROL amount of expection clock performance, and carry out the loop filtering processing to subtracting each other the result;
C, the result who utilizes loop filtering to handle control digital controlled oscillator clock performance are regulated and clock signal.
According to said method:
Before steps A, also comprise step: the preset value that the expection clock performance is set by Man Machine Interface; By microprocessor described preset value is converted to ERROR CONTROL amount corresponding to phase place or frequency.
Among the step B, microprocessor carries out digital filtering to this error information earlier and handles, with the data of filtering mistake after the error information that reads phase demodulation/frequency discriminator output.
Described loop filtering is treated to ratio (P), proportional integral (PI), proportion differential (PD) or proportion integration differentiation (PID) and regulates.
The dateout mode that described microprocessor reads phase demodulation/frequency discriminator adopts to be provided with interrupts or inquiry mode regularly.
A kind of realization system for carrying out said process, this system comprises microprocessor, the phase demodulation/frequency discriminator and the digital controlled oscillator that are connected with this microprocessor; The phase place that described phase demodulation/frequency discriminator is used for the feedback clock that obtains to reference clock with from digital controlled oscillator obtains error information or/and frequency compares, and exports this error information to microprocessor; Described microprocessor is handled the related data of described sum of errors expection clock performance and is exported control data to digital controlled oscillator; Described digital controlled oscillator regulates and exports clock according to described control data to clock performance.
The present invention has following beneficial effect:
1,, can in frequency domain and time domain scope, realize control, thereby control flexibly to different performance according to different algorithms.
2, can preset owing to output clock performance, thereby can realize complicated Combination Control, synthesize such as the MTIE template of pressing setting etc.
3, because the present invention adopts microprocessor to calculate and controls, reduced the device parameters influence that separating component itself is brought, so Properties Control is accurate.
4, method of the present invention can be integrated into other occasion realizing specific demand, such as frequency deviation tolerance limit test of data link etc.
Description of drawings
Fig. 1 is clock signal input and output spectrum diagram;
Fig. 2 is traditional hardware simulation phase-locked loop circuit block diagram;
Fig. 3, Fig. 4 are the controlled clock synthesis system structured flowchart of the performance of the embodiment of the invention;
Fig. 5 presets the algorithm process flow chart for performance;
Fig. 6 is a flow chart of the present invention.
Embodiment
Consult shown in Figure 3ly, the controlled clock synthesis system of performance comprises microprocessor (CPU), digital phase demodulation/frequency discriminator (DPD/DPF) that is connected with CPU and digital controlled oscillator (DCO).
Numeral phase demodulation/frequency discriminator adopt the mode of digital counting finish the feedback clock that obtains to reference clock with from DCO frequency or/and the comparing function of phase place obtain the error numerical value of reference clock CLKi (n) and feedback clock CLKo (n) phase and offer CPU.
The function of the function of digital frequency discrimination/phase discriminator and the phase discriminator of conventional phase locked loops is consistent.Different is that traditional phase discriminator is by charge pump the error of phase demodulation/frequency discrimination to be changeed directly to change voltage signal into, this phase discriminator then is by direct the showing of quantizing of the form of binary data, as the initial data of software algorithm with the error between CLKi (n) and the CLKo (n).Numeral phase demodulation/frequency discriminator can realize that promptly digital phase demodulation/frequency discriminator can provide frequency and phase error data to CPU respectively or simultaneously by programmable logic chip as required.
Microprocessor loads and operation digital filtering algorithm, loop processed algorithm and performance preset algorithm, handles the phase data that digital phase demodulation/frequency discriminator differentiates out and exports control data.
Digital controlled oscillator receives the control data of microprocessor output, and finishes exporting the adjusting of clock according to these data.The different digital control amount of CPU output just can obtain different frequency or clock signals output from DCO, thereby reaches the purpose of change system output clock performance.
Adopt the digital controlled oscillator of different performance or form can satisfy the application that clock accuracy is required different occasions.Such as, if select the constant temperature VCXO (OCVCXO) of high stable for use, the clock stability of its output can reach the accuracy rating of 0.01ppm; If advanced synthetic (Direct Digtal synthesize DDS) is the frequency synthesis of core, and then the width of the frequency adjustment word FTW that provides of DDS can reach very high-precision adjusting step-length with Direct Digital and adopt.
Consult shown in Figure 4ly, digital controlled oscillator adopts that synthetic (Direct Digtal synthesize DDS) is the digital controlled oscillator of core, and is aided with low-pass filtering with Direct Digital.With the DDS device is the DCO that core constitutes, and its main feature is that the regulating frequency scope is big, and its frequency-tuning range can reach 1/2 of reference clock frequency; Adopt the reference clock REF of the constant temperature crystal of high stable as DDS, the clock accuracy of output can be accomplished very high, and such as the AD9850 device that ADI company provides, the width of its FTW is 32, and its degree of regulation just can reach
Degree of regulation.
Digital filtering algorithm is used for the phase demodulation of mistake or the filtering of frequency discrimination data are obtained available calculated data.It is to realize the controlled and adjustable key algorithm of performance of the present invention that performance presets algorithm, and the microprocessor adduction moves this algorithm and forms a personal-machine interactive interface, and the preset value of expection clock performance is set by this Man Machine Interface.Performance preset algorithm with this preset value change into the loop processed algorithm the parameter value that can accept and pass to the loop filtering algorithm, by this algorithm can realize to the frequency of output clock draw partially, phase place is drawn partially, the clock shaking setting and different performance is set by maximum time interval error (MTIE) template.
Frequency domain and data in time domain can be changed by the mode of Fourier Tranform, according to the needs of controllability, adopt phase difference or difference on the frequency to control as the ERROR CONTROL amount respectively.
The effect that performance presets algorithm be exactly can intuitivism apprehension the performance statement to convert the discernible data volume one of system to be same linear module with the systematic error amount that phase demodulation/frequency discriminator produces promptly.Just have only difference on the frequency and phase difference for the amount of setting that system can discern, measure just that performance presets two base quantitys that algorithm obtains for these two.Describe for single clock performance, draw partially etc. such as frequency shift (FS), phase place, the computing that just need simply superpose just can convert frequency difference or phase difference to the value with the same tolerance of systematic error amount.For the combination clock performance of complexity,, then need by different algorithms complicated clock performance to be described the performance requirement that is decomposed into single-frequency or phase place earlier, and then change according to the method for single performance such as the MTIE curve.
As shown in Figure 6, be that frequency shift (FS) is an example:, the relative deviation S of clock frequency is set at 5ppm by Man Machine Interface according to the clock performance of expection with the preset value; CPU obtains reference clock frequency F; Obtain the absolute value b of frequency departure according to F * S, promptly obtain the ERROR CONTROL amount.
Set dissimilar desired value S and adopt different performances to preset algorithm, setting is drawn partially, shaken to the function of clock input that just can adjusted generation different clocks performance and by the clock of different performances such as MTIE template such as phase place.
The effect of loop filtering algorithm is equivalent to analog phase-locked look intermediate ring road filter, and phase place or frequency data are compared, calculate and change, and converts the required control data of digital controlled oscillator at last to.The loop processed algorithm guarantees the closed loop of system, and control system is in stable state and no-self excitation.
The loop filtering algorithm generally also adopts ratio, the integral control of often using in the analog phase-locked look, realizes digitized ratio (P), proportional integral (PI), proportion differential (PD) or proportion integration differentiation (PID) algorithm.Wherein, scale parameter, integral parameter and differential parameter are fixed, and it is to determine according to the performance of necessary condition of system stability and system stability.
The output valve a that digital filtering is handled is the frequency/phase deviate of system's reality, and the difference of a and ERROR CONTROL amount b is the error e of system, the just controlled variable of loop filtering algorithm; By the loop filtering algorithm controlled variable e is calculated, obtain the output regulated quantity of system, promptly the adjusting word FTW of DDS controls the DDS output clock performance thereby reach.
Consulting (and consulting Fig. 4) shown in Figure 6, is example to regulate clock frequency, and after digital filtering algorithm, loop processed algorithm and performance were preset algorithm and be loaded into microprocessor, the synthetic performance process of control clock was:
Step 10:, will expect that the frequency relative deviation preset value of clock is set at 5ppm by Man Machine Interface.
Step 20:CPU execution performance presets algorithm preset value 5ppm is converted to the acceptable ERROR CONTROL amount of loop processed algorithm b.
Be in the description of example with the DDS device, it is skew 5ppm that Properties Control requires, if therefore use digital frequency discriminator, then can directly preset value be converted to corresponding frequency error controlled quentity controlled variable.
Step 30: digital phase demodulation/frequency discriminator compares reference clock and feedback clock, obtains the frequency error between reference clock and the feedback clock.
Step 40: microprocessor deposits this error information in buffer memory after reading the error information of described digital phase demodulation/frequency discriminator output, then the data in the buffer memory is carried out digital filtering and handles the data of filtering mistake.Data in the microprocessor after digital filtering is handled are the actual frequency deviate a of system.
Microprocessor reads the dateout mode of digital phase demodulation/frequency discriminator for interruption or regularly inquiry are set.
Step 50: microprocessor will subtract each other the frequency error value e of the system of obtaining through the ERROR CONTROL amount b that digital filtering is handled in back actual frequency deviation a and the step 20, and this frequency error value e carried out proportional integral (PI) computing, the output regulated quantity that obtains system is the adjusting word FTW of DDS.
Step 60:DDS draws partially the frequency of output clock according to the adjusting word FTW that obtains in the step 50, obtains the clock of estimated performance.
Loop filtering is handled and is not limited only to the PI adjusting, can also be that P, PD or PID regulate as required; Digital controlled oscillator also can adopt mould/number conversion to add VCXO and realize.
The present invention is by the numerical software PHASE-LOCKED LOOP PLL TECHNIQUE, utilize different algorithms realize clock performance controlled, can preset, Properties Control is accurate, has reduced the influence of the device parameters that discrete component itself brings.
The present invention can independently realize, also can be integrated into very easily in other special function, auxiliary some specific function that realizes.Such as the clock performance test that can realize data link layer, in serial link, the transmitting-receiving of serial data all needs send-receive clock, this moment is if regulate according to method provided by the invention its send-receive clock, the realization phase place that can be easily and effectively or the test of frequency tolerance, integrated this functional hardware only needs a spot of hardware such as DCO in holonomic system, and the logic chip that DPD/DFD can using system has is realized.
Claims (9)
1, a kind of clock synthetic method is characterized in that comprising the steps:
A, phase demodulation/frequency discriminator compare reference clock and feedback clock, obtain phase place between reference clock and the feedback clock or/and frequency error;
B, microprocessor subtract each other described error and the pairing ERROR CONTROL amount of expection clock performance, and carry out the loop filtering processing to subtracting each other the result;
C, the result who utilizes loop filtering to handle control digital controlled oscillator clock performance are regulated and clock signal.
2, the method for claim 1 is characterized in that: also comprised step before steps A:
The preset value of expection clock performance is set by Man Machine Interface;
By microprocessor described preset value is converted to ERROR CONTROL amount corresponding to phase place or frequency.
3, method as claimed in claim 1 or 2 is characterized in that: among the step B, microprocessor carries out digital filtering to this error information earlier and handles, with the data of filtering mistake after the error information that reads phase demodulation/frequency discriminator output.
4, method as claimed in claim 3 is characterized in that: described loop filtering is treated to ratio (P), proportional integral (PI), proportion differential (PD) or proportion integration differentiation (PID) and regulates.
5, method as claimed in claim 3 is characterized in that: the dateout mode that described microprocessor reads phase demodulation/frequency discriminator adopts to be provided with interrupts or inquiry mode regularly.
6, method as claimed in claim 3 is characterized in that, described phase demodulation/frequency discriminator adopts digital phase demodulation/frequency discriminator, and directly to microprocessor output digital signal.
7, a kind of system of method according to claim 1 that realizes, it is characterized in that: described system comprises microprocessor, the phase demodulation/frequency discriminator and the digital controlled oscillator that are connected with this microprocessor;
The phase place that described phase demodulation/frequency discriminator is used for the feedback clock that obtains to reference clock with from digital controlled oscillator obtains error information or/and frequency compares, and exports this error information to microprocessor;
Described microprocessor is handled the related data of described sum of errors expection clock performance and is exported control data to digital controlled oscillator;
Described digital controlled oscillator regulates and exports clock according to described control data to clock performance.
8, system as claimed in claim 7 is characterized in that: described digital controlled oscillator is that Direct Digital synthetic (DDS) is the digital controlled oscillator of core; Or add VCXO for D/A switch.
As claim 7 or 8 described systems, it is characterized in that 9, described phase demodulation/frequency discriminator is digital phase demodulation/frequency discriminator.
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Cited By (11)
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| CN1878054B (en) * | 2006-02-07 | 2010-05-12 | 华为技术有限公司 | Clock reference device and method for IP network transmission base station |
| CN1988426B (en) * | 2005-12-23 | 2010-09-01 | 中兴通讯股份有限公司 | Reference clock sending circuit and method for light repeat plate |
| CN101986569A (en) * | 2010-10-25 | 2011-03-16 | 北京科技大学 | Digital costas loop |
| CN101420294B (en) * | 2007-10-24 | 2011-06-15 | 大唐移动通信设备有限公司 | Time clock phase locking loop controlling method and apparatus |
| CN102768499A (en) * | 2012-07-23 | 2012-11-07 | 北京理工大学 | Method and system for improving control reliability of direct digital frequency synthesizer (DDS) signal source |
| CN104067520A (en) * | 2011-11-21 | 2014-09-24 | 沃福森微电子股份有限公司 | clock generator |
| CN104883186A (en) * | 2015-05-20 | 2015-09-02 | 中国电子科技集团公司第四十一研究所 | Phase-locked loop circuit used for frequency counter |
| CN106527577A (en) * | 2015-09-09 | 2017-03-22 | 华为技术有限公司 | Clock signal adjusting method and apparatus |
| US10003344B2 (en) | 2011-11-21 | 2018-06-19 | Cirrus Logic, Inc. | Clock generator |
| CN111490778A (en) * | 2020-04-03 | 2020-08-04 | 四川知微传感技术有限公司 | Delay phase-locked loop based on PD control and control method thereof |
| CN115372905A (en) * | 2022-08-31 | 2022-11-22 | 山东航天电子技术研究所 | Intelligent signal sorting method based on Monte Carlo tree search |
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| US4418318A (en) * | 1981-03-10 | 1983-11-29 | Frederick Electronics Corporation | Digital phase-locked loop circuit |
| FI965072L (en) * | 1996-12-17 | 1998-08-13 | Nokia Telecommunications Oy | Method for damping transients caused by equalization events in a desynchronizer |
| CN1464637A (en) * | 2002-06-28 | 2003-12-31 | 华为技术有限公司 | Clock phase locking method and phase-locked loop |
| CN1216456C (en) * | 2003-06-24 | 2005-08-24 | 深圳市东方汉华软件技术有限公司 | Method and circuit structure for carrying out temperature compensation and frequency correction on oscillation frequency source |
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| CN1988426B (en) * | 2005-12-23 | 2010-09-01 | 中兴通讯股份有限公司 | Reference clock sending circuit and method for light repeat plate |
| CN1878054B (en) * | 2006-02-07 | 2010-05-12 | 华为技术有限公司 | Clock reference device and method for IP network transmission base station |
| CN101420294B (en) * | 2007-10-24 | 2011-06-15 | 大唐移动通信设备有限公司 | Time clock phase locking loop controlling method and apparatus |
| CN101986569A (en) * | 2010-10-25 | 2011-03-16 | 北京科技大学 | Digital costas loop |
| CN101986569B (en) * | 2010-10-25 | 2013-04-03 | 北京科技大学 | Digital costas loop |
| US10361709B2 (en) | 2011-11-21 | 2019-07-23 | Cirrus Logic, Inc. | Clock generator |
| US11711086B2 (en) | 2011-11-21 | 2023-07-25 | Cirrus Logic, Inc. | Clock generator |
| CN104067520A (en) * | 2011-11-21 | 2014-09-24 | 沃福森微电子股份有限公司 | clock generator |
| US11146277B2 (en) | 2011-11-21 | 2021-10-12 | Cirrus Logic, Inc. | Clock generator |
| US10601430B2 (en) | 2011-11-21 | 2020-03-24 | Cirrus Logic, Inc. | Clock generator |
| CN104067520B (en) * | 2011-11-21 | 2017-09-05 | 思睿逻辑国际半导体有限公司 | clock generator |
| US10003344B2 (en) | 2011-11-21 | 2018-06-19 | Cirrus Logic, Inc. | Clock generator |
| CN102768499A (en) * | 2012-07-23 | 2012-11-07 | 北京理工大学 | Method and system for improving control reliability of direct digital frequency synthesizer (DDS) signal source |
| CN102768499B (en) * | 2012-07-23 | 2014-06-25 | 北京理工大学 | Method and system for improving control reliability of direct digital frequency synthesizer (DDS) signal source |
| CN104883186A (en) * | 2015-05-20 | 2015-09-02 | 中国电子科技集团公司第四十一研究所 | Phase-locked loop circuit used for frequency counter |
| CN106527577A (en) * | 2015-09-09 | 2017-03-22 | 华为技术有限公司 | Clock signal adjusting method and apparatus |
| CN111490778A (en) * | 2020-04-03 | 2020-08-04 | 四川知微传感技术有限公司 | Delay phase-locked loop based on PD control and control method thereof |
| CN115372905A (en) * | 2022-08-31 | 2022-11-22 | 山东航天电子技术研究所 | Intelligent signal sorting method based on Monte Carlo tree search |
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