CN105933001A - Device and method for reducing electromagnetic interference in circuit - Google Patents
Device and method for reducing electromagnetic interference in circuit Download PDFInfo
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- CN105933001A CN105933001A CN201610244194.9A CN201610244194A CN105933001A CN 105933001 A CN105933001 A CN 105933001A CN 201610244194 A CN201610244194 A CN 201610244194A CN 105933001 A CN105933001 A CN 105933001A
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION, OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
- H03L7/00—Automatic control of frequency or phase; Synchronisation
- H03L7/06—Automatic control of frequency or phase; Synchronisation using a reference signal applied to a frequency- or phase-locked loop
- H03L7/08—Details of the phase-locked loop
- H03L7/099—Details of the phase-locked loop concerning mainly the controlled oscillator of the loop
Abstract
The present invention provides a device and method for reducing electromagnetic interference in a circuit. The device comprises a crystal oscillator, a jitter clock generation unit, a PLL circuit, a spectrum spreading direction and scope configuration unit, a clock random number generation unit, a configuration random number generation unit, a configuration information control unit, a random seed generation unit, a high precision temperature ADC sensor, a change period configuration storage unit, a random number switch unit, a configuration information storage unit, a PLL configuration storage unit, a PLL frequency calculation unit, a frequency judgment unit, and a storage unit of frequency points with unqualified EMI. According to the invention, a configurable PLL circuit is automatically adjusted through jitter, the frequency point can be automatically detected, then the upper jitter, lower jitter, or left and right jitter of the frequency is carried out on spectrum according to the configuration to adjust a clock jitter value, an EMI problem is avoided, and thus the EMC examination is passed.
Description
Technical field
The present invention relates to chip design field, reduce the dress of electromagnetic interference in circuit particularly to a kind of chip
Put and method.
Background technology
When the clock circuit on chip works, the extreme value (spike) of pulse can produce EMI, and (electromagnetism is done
Disturb), EMI (Electromagnetic Interference, electromagnetic interference), refer to pass through conducting medium
Signal on one electric network is coupled (interference) and arrives another electric network, affect other system or this is
The normal work of other subsystems in system.IC chip and circuit board all easily occur this feelings
Condition.And EMC is exactly emc testing, target is whether the EMI that test electronic system produces exists
Within certain safety range, otherwise it is assumed that the electromagnetic radiation of this electronic system exceeds standard.
PLL is the source of chip medium-high frequency clock, can produce stable clock signal for chip circuit
Use.But the clock signal frequency that generally high-performance PLL produces is highly stable, so easily causes work
As circuit, EMI problem occurs.Current technology cannot solve PLL and stablize the contradiction of frequency and EMI,
So the present invention proposes and a kind of reduces the device and method of electromagnetic interference in circuit, by jitter (clock
Shake) automatically adjust configurable PLL circuit, can automatically detect Frequency point, then according to being arranged in
On frequency spectrum, frequency is upwards shaken or shakes downwards or left and right shake adjusts clock jitter value,
To avoid EMI problem, thus checked by EMC.
PLL circuit is generally made up of phase discriminator, low pass filter and voltage controlled oscillator, and its signal moves towards
It is: input signal → phase discriminator → low pass filter → voltage controlled oscillator → output signal.Phase discriminator has two
Individual input, is the output signal of input signal and voltage controlled oscillator, at the two phase contrast and difference on the frequency respectively
Be not very big in the case of, the output of phase discriminator is directly proportional to the difference of two input signals, the output of phase discriminator
For analogue signal, it is considered except high frequency spurs by low pass filter, enters voltage controlled oscillator afterwards, voltage-controlled shakes
The output frequency swinging device changes with the change of its input voltage.Therefore to be actually one negative for PLL circuit
Feedback system, simply enters signal within normal range, and output signal can be caught up with in " in certain time ".
After input signal changes, output signal follows the tracks of the process referred to as capture of input signal；Output signal
Referred to as locking when following the tracks of complete；Input signal change too fast being referred to as when causing output signal to follow the tracks of, loses
Lock.N frequency multiplication can be conveniently realized by PLL.
Summary of the invention
The technical problem to be solved in the present invention, be to provide a kind of device reducing electromagnetic interference in circuit and
Method, is automatically adjusted configurable PLL circuit, can automatically detect frequency by jitter (clock jitter)
Rate point, then according to be arranged on frequency spectrum frequency is upwards shaken or downwards shake or left and right tremble
Move and adjust clock jitter value, to avoid EMI problem, thus checked by EMC.
Assembly of the invention is achieved in that and a kind of reduces the device of electromagnetic interference in circuit, including crystalline substance
Oscillation body device, jitter clock generating unit, PLL circuit, spread spectrum direction and scope dispensing unit, time
Clock random number generation unit, configuration random number generation unit, configuration information control unit, random seed produce
Raw unit, high-precision temperature ADC sensor, period of change configuration memory cell, random number switch are single
Unit, configuration information memory element, PLL configuration memory cell, PLL frequency computing unit, frequency judge
Unit and EMI underproof Frequency point memory element；
Described crystal oscillator, jitter clock generating unit, PLL circuit are sequentially connected with；
Described spread spectrum direction and scope dispensing unit connect described jitter clock generating unit, configuration respectively
Information control unit and frequency judging unit；
Described random seed generation unit connects described clock random number generation unit respectively and configuration is random
Number generation unit；
Described period of change configuration memory cell, random number switch element, clock random number generation unit depend on
Secondary it is connected to described jitter clock generating unit；
Described configuration information memory element, configuration information control unit are sequentially connected to described PLL circuit,
And configuration information control unit is also connected with described configuration random number generation unit；
Described PLL configuration memory cell, PLL frequency computing unit, frequency judging unit and EMI
Underproof Frequency point memory element.
Further, described PLL circuit is by phase discriminator, low pass filter, voltage controlled oscillator and feedback
Loop frequency divider is sequentially connected with composition one loop, and described jitter clock generating unit connects low pass filter,
Described feedback circuit frequency divider is also connected with described configuration information control unit.
The inventive method is achieved in that and a kind of reduces the method for electromagnetic interference in circuit, it is provided that this
The device of electromagnetic interference in bright described minimizing circuit, and comprise the steps:
(1) after described high-precision temperature ADC sensor carries out real-time sampling and will sample chip temperature
Current accurate temperature data be sent to described random seed generation unit；
After described random seed generation unit receives current accurate temperature data, through a high position block obtain with
Several sons of machine are also sent to described clock random number generation unit and described configuration random number generation unit；
(2) described period of change configuration memory cell according to configuration the random number Efficient Cycle cycle to institute
Stating random number switch element to be controlled, often after the reference clock cycle number of configuration, random number switchs
It is effective that unit arranges random number；
(3) described clock random number generation unit having according to the random number seed received and random number
Effect signal, produces clock extension compression random number, and the compression random number that extended by the clock of generation is sent to institute
State jitter clock generating unit；
(4) described PLL frequency computing unit configures according to the PLL of described PLL configuration memory cell
Value carries out PLL output frequency calculating, and result of calculation is sent to described frequency judging unit；By described frequency
Rate judging unit according in EMI defective Frequency point memory element storage the defective Frequency point of EMI and
Current PLL configuration frequency compares, when PLL configuration frequency Frequency point defective with EMI is consistent,
Start described spread spectrum direction and scope dispensing unit；
Described spread spectrum direction and scope dispensing unit control jitter clock and feedback circuit divide ratio time
Clock spread spectrum direction and scope, spread spectrum direction and scope are provided by EMI defective Frequency point memory element；
(5) described jitter clock generating unit is according to described clock extension compression random number and described clock
Spread spectrum direction and scope, produce with jitter shake reference clock after and be sent to PLL circuit；
Described configuration information memory element is responsible for storing the feedback circuit divide ratio of original PLL circuit,
And it is sent to configuration information control unit；
Described configuration information control unit according to the configuration configuration random number sent here of random number generation unit and
The control of described spread spectrum direction and scope dispensing unit carries out feedback circuit divide ratio control；
Wherein, described step (1), (2) do not limit precedence relationship and before step (3), described
Precedence relationship is not the most limited between step (4) and step (1), (2) or (3).
Further, described jitter clock generating unit produces the mistake of the reference clock with jitter shake
Journey is as follows:
First, the random value that original reference clock is sent here according to clock random number generation unit is carried out the cycle
Extending or squeeze operation, wherein, the clock cycle extends or compression depends on that described spread spectrum direction and scope are joined
Put the spread spectrum direction controlling information that unit is sent here:
If spread spectrum direction controlling information is to high frequency spread spectrum, then only reference clock is done cycle compression operation；
If spread spectrum direction controlling information is to low frequency spread spectrum, then only reference clock is done cycle extension operation；
If spread spectrum direction controlling information is the random spread spectrum of low-and high-frequency, then judge according to the lowest order of random number
Do cycle compression operation or cycle extension operation, owing to the lowest order of random number is random, i.e. realize
Spread spectrum direction random；
Then, the cycle compression of jitter clock or the time span scope of extension also depend on described spread spectrum side
To the scope control information sent here with scope dispensing unit.
Further, described configuration information control unit carries out the concrete mistake of feedback circuit divide ratio control
Cheng Wei:
First, original PLL feedback circuit divide ratio is sent here according to described configuration random number generation unit
Random value carries out divide ratio increase or reduces operation, and divide ratio increases or spread spectrum is depended in minimizing
The spread spectrum direction controlling information that direction and scope dispensing unit are sent here:
If spread spectrum direction controlling information is to high frequency spread spectrum, only divide ratio is done increase operation；
If spread spectrum direction controlling information is to low frequency spread spectrum, only divide ratio is done minimizing operation；
If spread spectrum direction controlling information is the random spread spectrum of low-and high-frequency, according to the lowest order judgement of random number it is
Do divide ratio increase and still reduce operation, owing to the lowest order of random number is random, i.e. achieve spread spectrum
Direction random；
Then, the scope that divide ratio increases or reduces also depends on spread spectrum direction and scope configuration is single
The scope control information that unit sends here, when the value of random number is more than range control value, only takes the scope of configuration
The value that controlling value increases as divide ratio or reduces.
Present invention have the advantage that
(1) use random offset to produce circuit and produce random offset configuration, frequency upwards can be shaken
Or shaking downwards or shake up and down, wherein random seed can configure, and downward shift can also be configured；
(2) Frequency point testing circuit can detect current expected frequency automatically, if Frequency point is served as reasons
During the frequency of emi problem, then automatically open up jitter and produce circuit to produce spread spectrum；
(3) random offset produces circuit is to configure in decimal mode, can skew be controlled positive and negative 5%
Within random value.
Accompanying drawing explanation
The present invention is further illustrated the most in conjunction with the embodiments.
Fig. 1 is that the present invention reduces the device of electromagnetic interference in circuit.
Detailed description of the invention
Referring to shown in Fig. 1, the device of electromagnetic interference in circuit that reduces of the present invention includes crystal oscillator
101, jitter clock generating unit 102, PLL circuit 103, spread spectrum direction and scope dispensing unit 104,
Clock random number generation unit 105, configuration random number generation unit 106, configuration information control unit 107,
The configuration storage of random seed generation unit 108, high-precision temperature ADC sensor 109, period of change
Unit 110, random number switch element 111, configuration information memory element 112, PLL configuration storage is single
Unit 113, PLL frequency computing unit 114, the underproof frequency of frequency judging unit 115 and EMI
Point memory element 116；
Described crystal oscillator 101, jitter clock generating unit 102, PLL circuit 103 are sequentially connected with；
Described spread spectrum direction and scope dispensing unit 104 connect described jitter clock generating unit respectively
102, configuration information control unit 107 and frequency judging unit；
Described random seed generation unit 108 connects described clock random number generation unit 105 respectively and joins
Put random number generation unit 106；
Described period of change configuration memory cell 110, random number switch element 111, clock random number produce
Raw unit 105 is sequentially connected to described jitter clock generating unit 102；
Described configuration information memory element 112, configuration information control unit 107 are sequentially connected to described
PLL circuit 103, and configuration information control unit 107 is also connected with described configuration random number generation unit
106；
Described PLL configuration memory cell 113, PLL frequency computing unit 114, frequency judging unit 115
And EMI underproof Frequency point memory element 116.
Wherein, described crystal oscillator 101 is responsible for producing the reference clock of PLL；
Described jitter clock generating unit 102 is responsible for producing according to described clock random number counting unit 105
Clock random number and the control of described spread spectrum direction and scope dispensing unit 104 carry out jitter clock product
Raw, after producing the reference clock with jitter shake and be sent to the phase discriminator unit of PLL circuit 103；
Described PLL circuit 103 is by phase discriminator 1031, low pass filter 1032, voltage controlled oscillator 1033
It is sequentially connected with composition one loop, wherein feedback circuit frequency divider 1034 with feedback circuit frequency divider 1034
The frequency dividing configuration accepting configuration information control unit 107 carries out feedback division process；Described jitter clock
Generation unit 102 connects low pass filter, and described feedback circuit frequency divider is also connected with described configuration information control
Unit 107 processed.
Described clock random number generation unit 105 be responsible for according to described random seed generation unit 108 with
Sub and the described period of change configuration memory cell 110 of machine period of change configuration control described at random
Number switch element 111 carries out the generation of clock extension compression random number and random number is sent to described jitter
Clock generating unit 102；Wherein, when the random switching signal of described random number switch element 111 is effective,
Producing random number, during invalidating signal, random number is 0, and reference clock is not the most cycle extension compression behaviour
Make；
Described period of change configuration memory cell 110 is responsible for the random number Efficient Cycle cycle according to configuration
Described random number switch element 111 is controlled, often after the reference clock cycle number of configuration, with
Machine number is effective, and in the reference clock cycle number of next configuration, random number is the most effective；
Described configuration random number generation unit 106 be responsible for according to described random seed generation unit 108 with
Machine carries out configuring the generation of random number and random number being sent to described configuration information control unit 107；
Described high-precision temperature ADC sensor 109 is responsible for chip temperature carrying out real-time sampling and adopting
Data after sample are sent to described random seed generation unit 108；
Described configuration information control unit 107 is responsible for sending here according to described configuration random number generation unit 106
Configuration random number and the control of described spread spectrum direction and scope dispensing unit 104 carry out feedback circuit and divide
Frequently coefficient controls；
Described configuration information memory element 112 is responsible for the PLL feedback circuit divide ratio that storage is original,
And it is sent to described configuration information control unit 107；
Described spread spectrum direction and scope dispensing unit 104 are responsible for controlling jitter clock and feedback circuit frequency dividing
The clock spread spectrum direction of coefficient and scope；
Described PLL configuration memory cell 113 is responsible for storage PLL and is produced all configurations of high frequency clock；
Described PLL frequency computing unit 114 is responsible for the PLL Configuration Values according to PLL configuration memory cell
Carry out PLL output frequency calculating, and result of calculation is sent to frequency judging unit；
Described frequency judging unit 115 is according to storage in EMI defective Frequency point memory element 116
The defective Frequency point of EMI and current PLL configuration frequency compare；As PLL configuration frequency and EMI
When defective Frequency point is consistent, start spread spectrum direction and scope dispensing unit 104, spread spectrum direction and scope
Thered is provided by EMI defective Frequency point memory element 116；
Described EMI defective Frequency point memory element 116 stores the defective Frequency point of EMI and this frequency
Spread spectrum direction and scope that corresponding EMI Resolving probiems needs configure.
It addition, before the described device work reducing electromagnetic interference in circuit, need based on reducing circuit
The device of middle electromagnetic interference does great many of experiments and obtains the Frequency point that EMI does not passes through, and tests the most again
To make this Frequency point by EMC detect corresponding to spread spectrum direction and scope, by defective for EMI frequency
Spread spectrum direction and scope configuration that the EMI Resolving probiems that point is corresponding with this frequency needs are stored in EMI and do not conform to
Lattice Frequency point memory element, and random number period of change value is stored in random number period of change memory element,
Then circuit work can be started.
After in the minimizing circuit of the present invention, the device of electromagnetic interference is started working, system CPU can be to PLL
Circuit 103 carries out configuration makes its work, by the computing of PLL frequency computing unit 114, sentences in frequency
Whether the PLL frequency that disconnected unit 115 judges configuration is the Frequency point having EMI problem, if it is not,
Then PLL circuit 103 normally works, and all reference clocks and configuration are operated according to original configuration.
If problem frequency, then control spread spectrum direction and scope dispensing unit 104 opened, to reference clock and
Feedback circuit divide ratio carries out spread spectrum control, to reach to solve the target of EMI.
The device of electromagnetic interference in minimizing circuit based on the present invention, in the minimizing circuit of the present invention, electromagnetism is done
The method disturbed, comprises the steps:
(1) described high-precision temperature ADC sensor 109 carries out real-time sampling and will adopt chip temperature
Current accurate temperature data after sample are sent to described random seed generation unit 108；
After described random seed generation unit 108 receives current accurate temperature data, block through a high position
To random number seed and be sent to described clock random number generation unit 105 and described configuration random number and produce
Unit 106；
(2) described period of change configuration memory cell 110 is according to the random number Efficient Cycle cycle of configuration
Described random number switch element 111 is controlled, often after the reference clock cycle number of configuration, with
It is effective that machine number switch element 111 arranges random number；
(3) described clock random number generation unit 105 is according to the random number seed received and random number
Useful signal, produce clock and extend compression random number, and the compression random number that the clock of generation extended send
Toward described jitter clock generating unit 102；
(4) described PLL frequency computing unit configures according to the PLL of described PLL configuration memory cell
Value carries out PLL output frequency calculating, and result of calculation is sent to described frequency judging unit；By described frequency
Rate judging unit according in EMI defective Frequency point memory element storage the defective Frequency point of EMI and
Current PLL configuration frequency compares, when PLL configuration frequency Frequency point defective with EMI is consistent,
Start described spread spectrum direction and scope dispensing unit；
Described spread spectrum direction and scope dispensing unit control jitter clock and feedback circuit divide ratio time
Clock spread spectrum direction and scope, spread spectrum direction and scope are provided by EMI defective Frequency point memory element；
(5) described jitter clock generating unit 102 extends compression random number and described according to described clock
Clock spread spectrum direction and scope, produce with jitter shake reference clock after and be sent to PLL circuit
103；
Described configuration information memory element 112 is responsible for the feedback circuit of the original PLL circuit 103 of storage
Divide ratio, and it is sent to configuration information control unit 107；
Described configuration information control unit 107 according to the configuration configuration sent here of random number generation unit 106 with
The control of machine number and described spread spectrum direction and scope dispensing unit 104 carries out feedback circuit divide ratio control
System；
Wherein, described step (1), (2) do not limit precedence relationship and before step (3), i.e.
Produce to described clock random number through random number switch element 111 from period of change configuration memory cell 110
The process of unit 105 and described high-precision temperature ADC sensor 109 are through random seed generation unit 108
Extremely the process of described clock random number generation unit 105 is in no particular order, but all collects to described clock random
Number generation unit 105.Elder generation is not the most limited between described step (4) and step (1), (2) or (3)
Rear relation, the most described EMI monitoring unit 113 is by described spread spectrum direction and scope dispensing unit 104
Arrive the process of described jitter clock generating unit 102 with during via described after step (1) (2)
Clock random number generation unit 105 arrives the process of described jitter clock generating unit 102 in no particular order.
Wherein, described jitter clock generating unit 102 produces the mistake of the reference clock with jitter shake
Journey is as follows:
First, the original reference clock produced by crystal oscillator 101 is according to clock random number generation unit
105 random values sent here carry out cycle extension or squeeze operation, and wherein, the clock cycle extends or compression is depended on
The spread spectrum direction controlling information sent here in described spread spectrum direction and scope dispensing unit 102:
If spread spectrum direction controlling information is to high frequency spread spectrum, then only reference clock is done cycle compression operation；
If spread spectrum direction controlling information is to low frequency spread spectrum, then only reference clock is done cycle extension operation；
If spread spectrum direction controlling information is the random spread spectrum of low-and high-frequency, then judge according to the lowest order of random number
Do cycle compression operation or cycle extension operation, owing to the lowest order of random number is random, i.e. realize
Spread spectrum direction random；
Then, the cycle compression of jitter clock or the time span scope of extension also depend on described spread spectrum side
To the scope control information sent here with scope dispensing unit 104.
Wherein, described configuration information control unit 107 carries out the detailed process of feedback circuit divide ratio control
For:
First, original PLL feedback circuit divide ratio is sent according to described configuration random number generation unit 106
The random value come carries out divide ratio increase or reduces operation, and divide ratio increase still reduces to be depended on
The spread spectrum direction controlling information that spread spectrum direction and scope dispensing unit 104 are sent here:
If spread spectrum direction controlling information is to high frequency spread spectrum, only divide ratio is done increase operation；
If spread spectrum direction controlling information is to low frequency spread spectrum, only divide ratio is done minimizing operation；
If spread spectrum direction controlling information is the random spread spectrum of low-and high-frequency, according to the lowest order judgement of random number it is
Do divide ratio increase and still reduce operation, owing to the lowest order of random number is random, i.e. achieve spread spectrum
Direction random；
Then, the scope that divide ratio increases or reduces also depends on spread spectrum direction and scope configuration is single
The scope control information that unit sends here, when the value of random number is more than range control value, only takes the scope of configuration
The value that controlling value increases as divide ratio or reduces.
Although the foregoing describing the detailed description of the invention of the present invention, but it is familiar with the technology people of the art
Member should be appreciated that our described specific embodiment is merely exemplary rather than for this
The restriction of bright scope, those of ordinary skill in the art are in the equivalence made according to the spirit of the present invention
Modify and change, all should contain in the scope of the claimed protection of the present invention.
Claims (5)
1. one kind is reduced the device of electromagnetic interference in circuit, it is characterised in that: include crystal oscillator,
Jitter clock generating unit, PLL circuit, spread spectrum direction and scope dispensing unit, clock random number produce
Raw unit, configuration random number generation unit, configuration information control unit, random seed generation unit, height
Accurate temperature ADC sensor, period of change configuration memory cell, random number switch element, configuration letter
Breath memory element, PLL configuration memory cell, PLL frequency computing unit, frequency judging unit and
EMI underproof Frequency point memory element；
Described crystal oscillator, jitter clock generating unit, PLL circuit are sequentially connected with；
Described spread spectrum direction and scope dispensing unit connect described jitter clock generating unit, configuration respectively
Information control unit and frequency judging unit；
Described random seed generation unit connects described clock random number generation unit respectively and configuration is random
Number generation unit；
Described period of change configuration memory cell, random number switch element, clock random number generation unit depend on
Secondary it is connected to described jitter clock generating unit；
Described configuration information memory element, configuration information control unit are sequentially connected to described PLL circuit,
And configuration information control unit is also connected with described configuration random number generation unit；
Described PLL configuration memory cell, PLL frequency computing unit, frequency judging unit and EMI
Underproof Frequency point memory element.
The most according to claim 1 a kind of reducing the device of electromagnetic interference in circuit, its feature exists
In: described PLL circuit is by phase discriminator, low pass filter, voltage controlled oscillator and feedback circuit frequency divider
Being sequentially connected with composition one loop, described jitter clock generating unit connects low pass filter, described feedback
Loop frequency divider is also connected with described configuration information control unit.
3. one kind is reduced the method for electromagnetic interference in circuit, it is characterised in that: provide such as claim 1
Described EMI automatic regulating apparatus, and comprise the steps:
(1) after described high-precision temperature ADC sensor carries out real-time sampling and will sample chip temperature
Current accurate temperature data be sent to described random seed generation unit；
After described random seed generation unit receives current accurate temperature data, through a high position block obtain with
Several sons of machine are also sent to described clock random number generation unit and described configuration random number generation unit；
(2) described period of change configuration memory cell according to configuration the random number Efficient Cycle cycle to institute
Stating random number switch element to be controlled, often after the reference clock cycle number of configuration, random number switchs
It is effective that unit arranges random number；
(3) described clock random number generation unit having according to the random number seed received and random number
Effect signal, produces clock extension compression random number, and the compression random number that extended by the clock of generation is sent to institute
State jitter clock generating unit；
(4) described PLL frequency computing unit configures according to the PLL of described PLL configuration memory cell
Value carries out PLL output frequency calculating, and result of calculation is sent to described frequency judging unit；By described frequency
Rate judging unit according in EMI defective Frequency point memory element storage the defective Frequency point of EMI and
Current PLL configuration frequency compares, when PLL configuration frequency Frequency point defective with EMI is consistent,
Start described spread spectrum direction and scope dispensing unit；
Described spread spectrum direction and scope dispensing unit control jitter clock and feedback circuit divide ratio time
Clock spread spectrum direction and scope, spread spectrum direction and scope are provided by EMI defective Frequency point memory element；
(5) described jitter clock generating unit is according to described clock extension compression random number and described clock
Spread spectrum direction and scope, produce with jitter shake reference clock after and be sent to PLL circuit；
Described configuration information memory element is responsible for storing the feedback circuit divide ratio of original PLL circuit,
And it is sent to configuration information control unit；
Described configuration information control unit according to the configuration configuration random number sent here of random number generation unit and
The control of described spread spectrum direction and scope dispensing unit carries out feedback circuit divide ratio control；
Wherein, described step (1), (2) do not limit precedence relationship and before step (3), described
Precedence relationship is not the most limited between step (4) and step (1), (2) or (3).
The most as claimed in claim 3 a kind of reduce the method for electromagnetic interference in circuit, it is characterised in that:
The process that described jitter clock generating unit produces the reference clock with jitter shake is as follows:
First, the random value that original reference clock is sent here according to clock random number generation unit is carried out the cycle
Extending or squeeze operation, wherein, the clock cycle extends or compression depends on that described spread spectrum direction and scope are joined
Put the spread spectrum direction controlling information that unit is sent here:
If spread spectrum direction controlling information is to high frequency spread spectrum, then only reference clock is done cycle compression operation；
If spread spectrum direction controlling information is to low frequency spread spectrum, then only reference clock is done cycle extension operation；
If spread spectrum direction controlling information is the random spread spectrum of low-and high-frequency, then judge according to the lowest order of random number
Do cycle compression operation or cycle extension operation, owing to the lowest order of random number is random, i.e. realize
Spread spectrum direction random；
Then, the cycle compression of jitter clock or the time span scope of extension also depend on described spread spectrum side
To the scope control information sent here with scope dispensing unit.
The most as claimed in claim 3 a kind of reduce the method for electromagnetic interference in circuit, it is characterised in that:
Described configuration information control unit carries out the detailed process of feedback circuit divide ratio control:
First, original PLL feedback circuit divide ratio is sent here according to described configuration random number generation unit
Random value carries out divide ratio increase or reduces operation, and divide ratio increases or spread spectrum is depended in minimizing
The spread spectrum direction controlling information that direction and scope dispensing unit are sent here:
If spread spectrum direction controlling information is to high frequency spread spectrum, only divide ratio is done increase operation；
If spread spectrum direction controlling information is to low frequency spread spectrum, only divide ratio is done minimizing operation；
If spread spectrum direction controlling information is the random spread spectrum of low-and high-frequency, according to the lowest order judgement of random number it is
Do divide ratio increase and still reduce operation, owing to the lowest order of random number is random, i.e. achieve spread spectrum
Direction random；
Then, the scope that divide ratio increases or reduces also depends on spread spectrum direction and scope configuration is single
The scope control information that unit sends here, when the value of random number is more than range control value, only takes the scope of configuration
The value that controlling value increases as divide ratio or reduces.
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| WO2018113254A1 (en) * | 2016-12-22 | 2018-06-28 | 惠科股份有限公司 | Spread-spectrum decoding method for transmitted signal and display apparatus |
| CN109462397A (en) * | 2018-11-08 | 2019-03-12 | 苏州裕太车通电子科技有限公司 | A kind of reduction electromagnetic interference method |
| CN110214418A (en) * | 2019-04-23 | 2019-09-06 | 京东方科技集团股份有限公司 | Parameter determination method and device, the clock spread spectrum method and device of spread spectrum circuit |
| CN115065232A (en) * | 2022-05-17 | 2022-09-16 | 致瞻科技(上海)有限公司 | Frequency invariant spread spectrum method and spread spectrum system |
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| CN101404569A (en) * | 2007-11-23 | 2009-04-08 | 硅谷数模半导体（北京）有限公司 | Apparatus and method for frequency expansion of reference clock signal |
| US8433024B2 (en) * | 2009-07-27 | 2013-04-30 | National Taiwan University | Spread spectrum clock generator and method for adjusting spread amount |
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| CN101404569A (en) * | 2007-11-23 | 2009-04-08 | 硅谷数模半导体（北京）有限公司 | Apparatus and method for frequency expansion of reference clock signal |
| US8433024B2 (en) * | 2009-07-27 | 2013-04-30 | National Taiwan University | Spread spectrum clock generator and method for adjusting spread amount |
| WO2015172372A1 (en) * | 2014-05-16 | 2015-11-19 | Lattice Semiconductor Corporation | Fractional-n phase locked loop circuit |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2018113254A1 (en) * | 2016-12-22 | 2018-06-28 | 惠科股份有限公司 | Spread-spectrum decoding method for transmitted signal and display apparatus |
| CN109462397A (en) * | 2018-11-08 | 2019-03-12 | 苏州裕太车通电子科技有限公司 | A kind of reduction electromagnetic interference method |
| CN109462397B (en) * | 2018-11-08 | 2023-01-24 | 裕太微电子股份有限公司 | Method for reducing electromagnetic interference |
| CN110214418A (en) * | 2019-04-23 | 2019-09-06 | 京东方科技集团股份有限公司 | Parameter determination method and device, the clock spread spectrum method and device of spread spectrum circuit |
| CN110214418B (en) * | 2019-04-23 | 2022-12-27 | 京东方科技集团股份有限公司 | Parameter determination method and device of spread spectrum circuit and clock spread spectrum method and device |
| CN115065232A (en) * | 2022-05-17 | 2022-09-16 | 致瞻科技(上海)有限公司 | Frequency invariant spread spectrum method and spread spectrum system |
| CN115065232B (en) * | 2022-05-17 | 2023-07-07 | 致瞻新能源(浙江)有限公司 | Frequency-invariant spread spectrum method and spread spectrum system |
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| CN105933001B (en) | 2018-11-20 |
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