CN102045061B - Loop bandwidth control device and method of phase locked loop - Google Patents
Loop bandwidth control device and method of phase locked loop Download PDFInfo
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- CN102045061B CN102045061B CN 200910178329 CN200910178329A CN102045061B CN 102045061 B CN102045061 B CN 102045061B CN 200910178329 CN200910178329 CN 200910178329 CN 200910178329 A CN200910178329 A CN 200910178329A CN 102045061 B CN102045061 B CN 102045061B
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Abstract
The invention discloses loop bandwidth control device and method of a phase locked loop, which can greatly shorten the time required for controlling the voltage of a correction voltage-controlled oscillator. The loop bandwidth control device comprises a first loop filtering module, a second loop filtering module, a control module, a first switching module and a second switching module, wherein the first loop filtering module and the second loop filtering module respectively output a first voltage and a second voltage; the bandwidth of the second loop filtering module is different from the bandwidth of the first loop filtering module; the control module generates a bandwidth control signal according to the first voltage or the second voltage; the first switching module ensures that a charge pump and the first loop filtering module or the second loop filtering module form a passage according to a bandwidth control signal; and the second switching module ensures that the voltage-controlled oscillator and the first loop filtering module or the second loop filtering module form a passage according to the bandwidth control signal.
Description
Technical field
The present invention relates to the phase-locked loop, especially, about a kind of loop frequency width control device and loop method for controlling bandwidth that is applied to the phase-locked loop.
Background technology
Generally speaking, phase-locked loop (Phase Locked Loop, PLL) can be regarded as the feedback circuit system of a kind of output phase and input phase, in order to inputting low-frequency periodicity signal and to export high-frequency periodicity signal, and input with export between have certain constant phase relation.The phase-locked loop mainly comprises phase frequency detector, charge pump, loop filter and voltage controlled oscillator.In fact, the phase-locked loop has been widely used in electronics and the communication field, in the devices such as internal memory, microprocessor, hard disk drive, wireless radiofrequency transceiver and fiber optical transceiver.
Please refer to Fig. 1, Fig. 1 is the functional block diagram of traditional phase-locked loop.As shown in Figure 1, phase-locked loop 1 comprises phase frequency detector 10, charge pump 12, loop filter 14, voltage controlled oscillator 16 and frequency eliminator 18.Wherein, charge pump 12 is to be coupled between phase frequency detector 10 and the loop filter 14; Loop filter 14 is to be coupled to voltage controlled oscillator 16; Frequency eliminator 18 is to be coupled between phase frequency detector 10 and the voltage controlled oscillator 16.
When phase frequency detector 10 received reference frequency CKR and feedback frequency CKV, phase frequency detector 10 will compare reference frequency CKR and feedback frequency CKV, to produce phase difference ΔΦ between the two and to be sent to charge pump 12.Wherein, the output frequency f that feedback frequency CKV system is exported voltage controlled oscillator 16 with predetermined divisor by frequency eliminator 18
OutCarry out frequency elimination and get; Reference frequency CKR system carries out frequency elimination according to a preset multiple to a reference frequency with reference to frequency eliminator (not being shown among the figure) by one and is produced.Then, charge pump 12 namely produces corresponding charge pump electric current I and exports loop filter 14 to according to the phase difference ΔΦ that receives.When loop filter 14 received the charge pump electric current I, loop filter 14 namely saw through its impedance the charge pump electric current I is converted to control voltage V and exports voltage controlled oscillator 16 to.Afterwards, voltage controlled oscillator 16 produces corresponding output frequency f according to control voltage V again
Out
In phase-locked loop 1, loop filter 14 is one of considerable assembly, and based on the consideration of cost and benefit, the second-order low-pass filter that is made of resistance and electric capacity is adopted in phase-locked loop 1 usually system.Generally speaking, loop filter 14 has several important parameters, parameters such as phase margin (phase margin), loop frequency range (loop bandwidth) and loop filter configuration (loop filter topology), wherein important with the loop frequency range size that can determine noise filtering and locking time again.
When the loop of loop filter 14 frequency range hour, though loop filter 14 effectively filtering input reference frequency and charge pump 12 switches the noise that causes and reduces the acute non-ideal effects that (jitter) causes of jumping, but because the size of the length of locking time system and loop frequency range is inversely proportional to, so its shortcoming namely is that locking time of cost is long.On the contrary, if the loop frequency range of loop filter 14 is increased, though can shorten locking time by this, also may cause the facts that loop filter 14 can't the establishment noise to occur.
Therefore, main category of the present invention is to provide a kind of loop frequency width control device and loop method for controlling bandwidth that is applied to the phase-locked loop, to address the above problem.
Summary of the invention
Technical problem to be solved by this invention provides a kind of loop frequency width control device and loop method for controlling bandwidth of phase-locked loop, can significantly shorten proofread and correct voltage controlled oscillator the required time of control voltage.
In order to solve above technical problem, the invention provides following technical scheme:
The invention provides a kind of loop frequency width control device, this loop frequency width control device system is applied to a phase-locked loop.This phase-locked loop comprises a phase frequency detector, a charge pump and a voltage controlled oscillator.This loop frequency width control device comprises one first loop filter module, a second servo loop filtration module, a control module, one first handover module and one second handover module.This first loop filter module and second servo loop filtration module system are in order to export respectively one first voltage and a second voltage, and wherein the frequency range of this second servo loop filtration module is different from the frequency range of this first loop filter module.This control module system in order to according to this first voltage or this second voltage one of them, produce frequency range control signal.This first handover module system is in order to according to this frequency range control signal, makes this charge pump and this first loop filter module or this second servo loop filtration module form path between one of them.This second handover module system is in order to according to this frequency range control signal, makes this voltage controlled oscillator and this first loop filter module or this second servo loop filtration module form path between one of them.
The present invention also provides a kind of loop method for controlling bandwidth, and this loop method for controlling bandwidth system is applied to a phase-locked loop, and this phase-locked loop comprises a loop frequency width control device, a phase frequency detector, a charge pump and a voltage controlled oscillator.This loop frequency width control device comprises one first loop filter module and a second servo loop filtration module, and the frequency range of this second servo loop filtration module is different from the frequency range of this first loop filter module.At first, the second voltage that one first voltage that the method is exported according to this first loop filter module or this second servo loop filtration module are exported one of them, produce frequency range control signal; Then, the method is according to this frequency range control signal, so that see through this first loop filter module or this second servo loop filtration module formation path between this charge pump and this voltage controlled oscillator.
At last, the invention provides a kind of phase-locked loop, this phase-locked loop comprises a phase frequency detector, a charge pump, a voltage controlled oscillator, a frequency eliminator and a loop frequency width control device.This loop frequency width control device comprises one first loop filter module, a second servo loop filtration module, a control module, one first handover module and one second handover module.This phase frequency detector system is in order to produce a phase difference according to a reference frequency and a feedback frequency; This charge pump is in order to produce an output current according to this phase difference; This voltage controlled oscillator system is in order to produce an output frequency according to a control voltage; This frequency eliminator system is in order to produce this feedback frequency according to this output frequency.This first loop filter module and this second servo loop filtration module system are in order to produce one first voltage and a second voltage according to this output current respectively, and wherein the frequency range of this second servo loop filtration module system is greater than the frequency range of this first loop filter module.This control module system is in order to monitor this first voltage and this second voltage and to produce according to this frequency range control signal.This first handover module system is according to this frequency range control signal, and one of them forms path to make this charge pump and this first loop filter module or this second servo loop filtration module.This second handover module system is according to this frequency range control signal, makes this voltage controlled oscillator and this first loop filter module or this second servo loop filtration module form path between one of them.
In sum, the loop frequency width control device of the phase-locked loop that the present invention adopts and loop method for controlling bandwidth see through the mode of switching the loop filter module with different frequency ranges, so that the phase-locked loop that operates under the voltage controlled oscillator correction mode has larger loop frequency range, so can significantly shorten the required time of control voltage of proofreading and correct voltage controlled oscillator, use the disappearance of improving prior art.In addition, when this phase-locked loop operates on normal operation pattern lower time, the loop frequency range of this phase-locked loop also can return back to normal size, and is unlikely to because the frequency range excessive noise filtering ability of its loop filter module that causes in loop reduces.
Can be by following detailed Description Of The Invention and appended graphic being further understood about the advantages and spirit of the present invention.
Description of drawings
Fig. 1 is the functional block diagram of traditional phase-locked loop.
Fig. 2 is the functional block diagram according to the phase-locked loop of the first specific embodiment of the present invention.
Fig. 3 is a kind of pattern of the phase-locked loop among Fig. 2.
Fig. 4 is a kind of pattern of the second servo loop filtration module among Fig. 3.
Fig. 5 is phase frequency detector among Fig. 3 and the detailed operation situation of charge pump.
The variable locking time of Fig. 6 for when voltage controlled oscillator forms path from the loop filter module with different frequency ranges, producing.
Fig. 7 is the flow chart according to the loop method for controlling bandwidth of the second specific embodiment of the present invention.
[primary clustering symbol description]
S10～S20: process step
1,2: phase-locked loop 12,22: charge pump
10,20: phase frequency detector 16,26: voltage controlled oscillator
18, frequency eliminator 24: the loop frequency width control device
240: the first loop filter modules 244: buffer module
242: second servo loop filtration module 248: control module
246: the second handover modules of 245: the first handover modules
CKR: reference frequency CKV: feedback frequency
I, I
p: charge pump electric current V, V
c: control voltage
f
Out: output frequency ΔΦ: phase difference
S
BC: frequency range control signal S
VCO: voltage controlled oscillator control signal
V
1: the first voltage V
2: second voltage
R: variable resistor assembly C1, C2: variable capacitance component
Q
A, Q
B: output signal f
1, f
2: the frequency range of loop filter module
t
S1, t
S2: locking time V
C1: reference voltage
S
c: setting signal
Embodiment
The first specific embodiment according to the present invention is a kind of phase-locked loop.Please refer to Fig. 2, Fig. 2 is the functional block diagram of this phase-locked loop.As shown in Figure 2, phase-locked loop 2 mainly comprises phase frequency detector 20, charge pump 22, loop frequency width control device 24, voltage controlled oscillator 26 and frequency eliminator 28.Loop frequency width control device 24 comprises the first loop filter module 240, second servo loop filtration module 242, buffer module 244, the first handover module 245, the second handover module 246 and control module 248.
Wherein, phase frequency detector 20 is to be coupled to charge pump 22; The first handover module 245 is input and the charge pump 22 that is coupled to the first loop filter module 240 and second servo loop filtration module 242; Buffer module 244 is the output that is coupled to the first loop filter module 240 and second servo loop filtration module 242; Control module 248 is to be coupled to charge pump 22, the first handover module 245, the second handover module 246, buffer module 244 and voltage controlled oscillator 26; The second handover module 246 is output and the voltage controlled oscillator 26 that is coupled to the first loop filter module 240 and second servo loop filtration module 242; Frequency eliminator 28 is to be coupled to phase frequency detector 20 and voltage controlled oscillator 26.
In this embodiment, when phase frequency detector 20 received reference frequency CKR and feedback frequency CKV, phase frequency detector 20 will compare reference frequency CKR and feedback frequency CKV, to produce phase difference ΔΦ between the two and to be sent to charge pump 22.Wherein, the output frequency f that feedback frequency CKV system is exported voltage controlled oscillator 26 with predetermined divisor by frequency eliminator 28
OutCarry out frequency elimination and get; Reference frequency CKR then carries out frequency elimination to a reference frequency and gets according to a preset multiple with reference to frequency eliminator (not being shown among the figure) by one.Then, charge pump 12 namely produces corresponding charge pump electric current I according to the phase difference ΔΦ that receives
pAnd see through the first handover module 245 and export the first loop filter module 240 or second servo loop filtration module 242 to.Then, the first loop filter module 240 or second servo loop filtration module 242 are according to the charge pump electric current I
pProduce the first voltage V
1Or second voltage V
2Then, control module 248 monitoring the first voltage V
1Or second voltage V
2And produce according to this frequency range control signal.In more detail, control module 248 is comparison one reference voltage and the first voltage V
1Or second voltage V
2, and judge this reference voltage and the first voltage V
1Or second voltage V
2The absolute value of difference whether less than a default value, if the determination result is NO for control module 248, the output frequency that represents voltage controlled oscillator 26 not yet is corrected to be finished, so control module 248 namely produces voltage controlled oscillator control signal SVCO, is used for adjusting the frequency of operation curve of voltage controlled oscillator; If the judged result of control module 248 is yes, the output frequency correction that represents voltage controlled oscillator 26 is finished, so control module 248 produces frequency ranges control signal SBC, is used for the switching circuit module and adjusts the charge pump electric current I
pIn fact, this reference voltage system is relevant with the frequency of operation curve of voltage controlled oscillator 26, and for example, this reference voltage can be the Vc1 between Vc1 (max) and Vc1 (min) among Fig. 6, but not as limit.
It should be noted that in loop frequency width control device 24 frequency range of second servo loop filtration module 242 will be greater than the frequency range of the first loop filter module 240.In order to eliminate the charge share effect (charge sharing effect) between the first loop filter module 240 and the second servo loop filtration module 242, buffer module 244 will drive the first voltage V that the first less loop filter module 240 of frequency range is exported it
1The second voltage V that can be as far as possible exports with the larger second servo loop filtration module 242 of frequency range
2About equally.
In practical application, control module 248 is not limited in according to monitoring the first voltage V
1Or second voltage V
2Output control the first handover module 245 and the second handover module 246 switch to simultaneously the first loop filter module 240 or second servo loop filtration module 242, control module 248 also can receive a setting signal S
cAnd according to this setting signal S
cControl the first handover module 245 and the second handover module 246 switches to the first loop filter module 240 or second servo loop filtration module 242 simultaneously, with the different purposes corresponding to phase-locked loop 2.
For example, when phase-locked loop 2 was applied to transmission end (Tx), control module 248 can control the first handover module 245 and the second handover module 246 switches to the first loop filter module 240 simultaneously; When phase-locked loop 2 was applied to receiving terminal (Rx), control module 248 can control the first handover module 245 and the second handover module 246 switches to second servo loop filtration module 242 simultaneously.Another example is that when phase-locked loop 2 was applied to bluetooth (bluetooth) radio transmitting device, control module 248 can control the first handover module 245 and the second handover module 246 switches to the first loop filter module 240 simultaneously; When phase-locked loop 2 was applied to the WiFi radio transmitting device, control module 248 can control the first handover module 245 and the second handover module 246 switches to second servo loop filtration module 242 simultaneously, but is not limited with above-mentioned example.
Please refer to Fig. 3, Fig. 3 is a kind of preferred embodiment of the phase-locked loop 2 among Fig. 2.As shown in Figure 3, in this preferred embodiment, buffer module 244 can be used a negative feedback operational amplifier, and its output is connected with negative input end, and the first voltage V that the first loop filter module 240 is exported
1Be coupled to the output of this operational amplifier, the second voltage V that second servo loop filtration module 242 is exported
2Be coupled to the positive input terminal of this operational amplifier, to keep the first voltage V
1With second voltage V
2Equate.Then, control module 248 comparison reference voltages and the first voltage V
1Or second voltage V
2The absolute value of difference whether less than default value, and produce according to this frequency range control signal S
BCAnd voltage controlled oscillator control signal S
VCO
Wherein, control module 248 is to see through frequency range control signal S
BC Control charge pump 22 is adjusted the size of its output current; Control module 248 also sees through frequency range control signal S
BCControl the first handover module 245 and the second handover module 246 switches to the first loop filter module 240 or second servo loop filtration module 242 simultaneously, so that see through the first loop filter module 240 between charge pump 22 and the voltage controlled oscillator 26 or second servo loop filtration module 242 forms paths.In addition, control module 248 also can see through voltage controlled oscillator control signal S
VCOControl voltage controlled oscillator 26 is adjusted its frequency of operation curve.
When being when seeing through the first loop filter module 240 and forming path between charge pump 22 and the voltage controlled oscillator 26, the control voltage V that voltage controlled oscillator 26 is received
cBe the first voltage V that the first loop filter module 240 is exported
1When being when seeing through second servo loop filtration module 242 and forming path between charge pump 22 and the voltage controlled oscillator 26, the control voltage V that voltage controlled oscillator 26 is received
cBe the second voltage V that second servo loop filtration module 242 is exported
2
See through above-mentioned switching mode, when phase-locked loop 2 is in the voltage controlled oscillator correction mode, can see through the larger second servo loop filtration module of frequency range 242 between charge pump 22 and the voltage controlled oscillator 26 and form path, so that the loop frequency range of phase-locked loop 2 can increase, use when shorten proofreading and correct voltage controlled oscillator 26 frequency of operation curve length locking time that phase-locked loop 2 is required.After voltage controlled oscillator 26 frequency of operation curvature corrections are complete, its control voltage V
cCan level off to reference voltage, judge thus whether voltage controlled oscillator 26 is proofreaied and correct complete.In fact, this reference voltage can be system default value or is set according to actual demand by the user, there is no specific restriction.
At this moment, because the excessive loop frequency range that the larger second servo loop filtration module 242 of frequency range has will cause the ability variation of its filtering noise, that is be in the loop frequency range that phase-locked loop 2 under the normal operation pattern only need have normal size and get final product, so the first handover module 245 and the second handover module 246 namely can switch to the first less loop filter module 240 of frequency range simultaneously, phase-locked loop 2 forms path so that see through the first loop filter module 240 between charge pump 22 and the voltage controlled oscillator 26, so can have good noise filtering ability under the normal operation pattern.
In addition, as shown in Figure 3, charge pump 22 also is coupled to control module 248, and can control signal S according to the frequency range that control module 248 is exported
BCAdjust the charge pump electric current I of its output
PSize, but not as limit.
In practical application, the first loop filter module 240 and second servo loop filtration module 242 can be the second-order low-pass filter circuit all, and include variable resistor assembly and variable capacitance component.Please refer to Fig. 4, Fig. 4 is a kind of pattern of second servo loop filtration module 242.As shown in Figure 4, second servo loop filtration module 242 comprises variable resistor R and variable capacitance C1 and C2, and is in parallel with variable capacitance C2 with formation second-order low-pass filter circuit again after wherein variable resistor R system is one another in series with variable capacitance C1, but not as limit.Also can be adjusted to according to actual demand different patterns as for the first loop filter module 240, not give unnecessary details separately in this.
Fig. 5 is the detailed operation situation of phase frequency detector 20 and charge pump 22 among Fig. 3.In phase-locked loop 2, the main function of charge pump 22 is action that the first loop filter module 240 of back or second servo loop filtration module 242 are carried out charge injection and remove.As shown in Figure 5, phase frequency detector 20 is to see through two output signal Q
AAnd Q
BControl respectively the charge and discharge switch S of charge pump 22
1And S
2Open and close.Work as Q
ABe ON and Q
BDuring for OFF, charge pump 22 will to the first loop filter module 240 or 242 chargings of second servo loop filtration module, be used the control voltage V that promotes voltage controlled oscillator 26
cWork as Q
ABe OFF and Q
BDuring for ON, charge pump 22 will to the first loop filter module 240 or 242 discharges of second servo loop filtration module, be used the control voltage V that reduces voltage controlled oscillator 26
cSuppose I
1=I
2=I and charge and discharge switch S
1And S
2Open simultaneously, the electric charge that injects of charge pump 22 electric charge that will equal to remove then so do not have charge storage in the first loop filter module 240 or second servo loop filtration module 242, can effectively reduce the non-ideal effects of phase frequency detector 20 and charge pump 22.
Fig. 6 is for working as voltage controlled oscillator 26 and having different frequency range f
1And f
2The variable locking time t that produces when forming path with second servo loop filtration module 242 of the first loop filter module 240
S1And t
S2As shown in Figure 6, when phase-locked loop 2 be under the normal operation pattern and charge pump 22 and voltage controlled oscillator 26 between be when seeing through the first less loop filter module 240 of frequency range and forming path, phase-locked loop 2 has the loop frequency range of normal size, and its required length locking time of control voltage of proofreading and correct voltage controlled oscillator 26 is t
S1, that is need cost t
S1Time could be so that the control voltage V of voltage controlled oscillator 26
cLevel off to reference voltage V
C1Be to see through to have larger frequency range f when phase-locked loop 2 is between voltage controlled oscillator correction mode and charge pump 22 and the voltage controlled oscillator 26
2Second servo loop filtration module 242 when forming path, the loop frequency range of phase-locked loop 2 is larger, so proofread and correct the control voltage V of voltage controlled oscillator 26
C1Required length t locking time
S2Be shorter than t
S1
The second specific embodiment according to the present invention is a kind of loop method for controlling bandwidth.In this embodiment, this loop method for controlling bandwidth system is applied to a phase-locked loop, and this phase-locked loop comprises a loop frequency width control device, a phase frequency detector, a charge pump and a voltage controlled oscillator.This loop frequency width control device comprises one first loop filter module and a second servo loop filtration module, and the frequency range system of this second servo loop filtration module is greater than the frequency range of this first loop filter module.Please refer to Fig. 7, Fig. 7 is the flow chart of this loop method for controlling bandwidth.
When this phase-locked loop is under the voltage controlled oscillator frequency of operation curvature correction pattern, between this voltage controlled oscillator and this charge pump be to see through this second servo loop filtration module to form path.As shown in Figure 7, the method execution in step S10 at first, the second voltage that comparison reference voltage and second servo loop filtration module are exported.Then, the method execution in step S12 judges that whether the absolute value of the difference between reference voltage and the second voltage is less than a default value.In fact, this default value can be system default value or be set according to actual demand by the user, there is no specific restriction.If the judged result of step S12 for whether, represents the output frequency of voltage controlled oscillator and not yet proofreaies and correct and finish, then execution in step S15 produces voltage controlled oscillator control signal S
VCO, follow execution in step S20, voltage controlled oscillator 26 is according to voltage controlled oscillator control signal S
VCOAdjust its frequency of operation curve, repeat above-mentioned action, if until the judged result of step S12 is yes, the output frequency that represents voltage controlled oscillator has been proofreaied and correct and has been finished, and execution in step S14 produces frequency range control signal S
BC, make under the changeable time normal operation state in this phase-locked loop.Then execution in step S16 switches to the first less loop filter module of frequency range according to this frequency range control signal from the larger second servo loop filtration module of frequency range, forms path so that see through the first loop filter module between this charge pump and this voltage controlled oscillator.In more detail, under the voltage controlled oscillator correction mode, be to see through this larger second servo loop filtration module of frequency range to form path between this charge pump and this voltage controlled oscillator, use the loop frequency range that increases this phase-locked loop, proofread and correct required time to shorten this voltage controlled oscillator of correction.When this control voltage of this voltage controlled oscillator levels off to a reference voltage, represent this voltage controlled oscillator correction and finish, the switching circuit module makes and sees through this less the first loop filter module formation path of frequency range between this charge pump and this voltage controlled oscillator.At this moment, the normal operation pattern is got back in this phase-locked loop, has the loop frequency range of normal size.
In addition, but also execution in step S18 of the method adjusts the size of the output current of this charge pump according to this frequency range control signal.Then please refer to the relevant narration of aforementioned the first specific embodiment and graphic as for the detailed operation situation of this loop method for controlling bandwidth, do not give unnecessary details separately in this.
Compared to prior art, see through the mode of switching the loop filter module with different frequency ranges according to loop of the present invention frequency width control device and method system, so that the phase-locked loop that operates under the voltage controlled oscillator correction mode has larger loop frequency range, proofread and correct the required time of voltage controlled oscillator so can significantly shorten, use the disappearance of improving prior art.In addition, when this phase-locked loop operates on normal operation pattern lower time, the loop frequency range of this phase-locked loop also can return back to normal size, and is unlikely to because the frequency range excessive noise filtering ability of its loop filter module that causes in loop reduces.
By the above detailed description of preferred embodiments, be that hope can be known description feature of the present invention and spirit more, and be not to come category of the present invention is limited with above-mentioned disclosed preferred embodiment.On the contrary, its objective is that hope can contain in the category of claim of being arranged in of various changes and tool equality institute of the present invention wish application.
Claims (12)
1. a loop frequency width control device is applied to a phase-locked loop, and this phase-locked loop comprises a phase frequency detector, a charge pump and a voltage controlled oscillator, it is characterized in that, this loop frequency width control device comprises:
One first loop filter module is coupled to this charge pump, in order to export one first voltage;
One second servo loop filtration module is coupled to this charge pump, and in order to export a second voltage, the frequency range of this second servo loop filtration module is different from the frequency range of this first loop filter module;
One buffer module, be coupled to this first loop filter module and this second servo loop filtration module, with so that this first voltage of this first loop filter module output equate with this second voltage of this second servo loop filtration module output, use the charge share effect between this first loop filter module of elimination and this second servo loop filtration module;
One control module, be coupled to this first loop filter module and this second servo loop filtration module, this control module is a reference voltage and this first voltage or this second voltage relatively, when the absolute value of the difference of this reference voltage and this first voltage or this second voltage less than a default value, produce frequency range control signal, this control module also is coupled to this charge pump, and this charge pump system adjusts its output current according to this frequency range control signal;
One first handover module is coupled to this control module and this charge pump, in order to according to this frequency range control signal, makes this charge pump and this first loop filter module or this second servo loop filtration module form path between one of them; And
One second handover module is coupled to this control module and this voltage controlled oscillator, in order to according to this frequency range control signal, makes this voltage controlled oscillator and this first loop filter module or this second servo loop filtration module form path between one of them.
2. loop as claimed in claim 1 frequency width control device, it is characterized in that, this control module more according to this first voltage and this second voltage one of them, produce voltage controlled oscillator control signal, and this VCO controller is according to this voltage controlled oscillator control signal, adjusting operation frequency curve.
3. loop as claimed in claim 1 frequency width control device, it is characterized in that, this buffer module is an operational amplifier, comprise an output, a positive input terminal and a negative input end, this negative input end links to each other with this output, positive input terminal is connected to the output of this second servo loop filtration module, and this output is connected to the output of this first loop filter module.
4. loop as claimed in claim 1 frequency width control device, it is characterized in that, when this phase-locked loop is under the voltage controlled oscillator frequency of operation curvature correction pattern, be to see through the loop filter module that frequency range is larger in this first loop filter module and this second servo loop filtration module to form path between this voltage controlled oscillator and this charge pump, use the loop frequency range that increases this phase-locked loop, shorten and proofread and correct this voltage controlled oscillator required locking time.
5. loop as claimed in claim 1 frequency width control device is characterized in that, this control module in order to according to a setting signal, produces frequency range control signal.
6. loop as claimed in claim 1 frequency width control device is characterized in that this first loop filter module and this second servo loop filtration module all are low-pass filter circuit, and include variable resistor assembly and variable capacitance component.
7. loop method for controlling bandwidth, be applied to a phase-locked loop, this phase-locked loop comprises a loop frequency width control device, a phase frequency detector, a charge pump and a voltage controlled oscillator, this loop frequency width control device comprises one first loop filter module and a second servo loop filtration module, the frequency range of this second servo loop filtration module is different from the frequency range of this first loop filter module, it is characterized in that the method comprises the following step:
Relatively a reference voltage and one first voltage or a second voltage, when the absolute value of the difference of this reference voltage and this first voltage or this second voltage less than a default value, produce a frequency range and control signal;
The second voltage that one first voltage of exporting according to this first loop filter module or this second servo loop filtration module are exported one of them, produce frequency range control signal; And
According to this frequency range control signal, so that see through this first loop filter module or this second servo loop filtration module formation path between this charge pump and this voltage controlled oscillator;
This first voltage of this first loop filter module output is equated with this second voltage of this second servo loop filtration module output, use the charge share effect of eliminating between this first loop filter module and this second servo loop filtration module; And
According to this frequency range control signal, adjust the output current of this charge pump.
8. method as claimed in claim 7 is characterized in that, more comprises the following step:
Monitor this first voltage or this second voltage one of them, produce voltage controlled oscillator control signal; And
According to this voltage controlled oscillator control signal, adjust the frequency of operation curve of this voltage controlled oscillator control.
9. method as claimed in claim 7, it is characterized in that, when this phase-locked loop is under the voltage controlled oscillator frequency of operation curvature correction pattern, be to see through the loop filter module that frequency range is larger in this second servo loop filtration module and this first loop filter module to form path between this charge pump and this voltage controlled oscillator, use the loop frequency range that increases this phase-locked loop and shorten a required locking time of a control voltage of proofreading and correct this voltage controlled oscillator.
10. a phase-locked loop is characterized in that, comprises:
One phase frequency detector produces a phase difference according to a reference frequency and a feedback frequency;
One charge pump is coupled to this phase frequency detector, in order to produce an output current according to this phase difference;
One voltage controlled oscillator is in order to produce an output frequency according to a control voltage;
One frequency eliminator produces this feedback frequency according to this output frequency; And
One loop frequency width control device comprises:
One first loop filter module is coupled to this charge pump, in order to produce one first voltage according to this output current;
One second servo loop filtration module is coupled to this charge pump, and in order to produce a second voltage according to this output current, the frequency range system of this second servo loop filtration module is greater than the frequency range of this first loop filter module;
One control module, be coupled to this first loop filter module and this second servo loop filtration module, in order to compare a reference voltage and this first voltage or this second voltage, when the absolute value of the difference of this reference voltage and this first voltage or this second voltage less than a default value, produce this frequency range control signal, this control module also is coupled to this charge pump, and this charge pump system adjusts its output current according to this frequency range control signal;
One first handover module is coupled to this control module and this charge pump, in order to according to this frequency range control signal, makes this charge pump and this first loop filter module or this second servo loop filtration module form path between one of them; And
One second handover module is coupled to this control module and this voltage controlled oscillator, in order to according to this frequency range control signal, makes this voltage controlled oscillator and this first loop filter module or this second servo loop filtration module form path between one of them;
One buffer module, be coupled to this first loop filter module and this second servo loop filtration module, with so that this first voltage of this first loop filter module output equate with this second voltage of this second servo loop filtration module output, use the charge share effect between this first loop filter module of elimination and this second servo loop filtration module.
11. phase-locked loop as claimed in claim 10, it is characterized in that, this control module more according to this first voltage or this second voltage one of them, produce voltage controlled oscillator control signal, and this VCO controller is according to this voltage controlled oscillator control signal, adjusting operation frequency curve.
12. phase-locked loop as claimed in claim 10, it is characterized in that, this buffer module is an operational amplifier, comprise an output, a positive input terminal and a negative input end, this negative input end links to each other with this output, this positive input terminal is coupled to the output of this second servo loop filtration module, and this output is coupled to the output of this first loop filter module.
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| US4789996A (en) * | 1988-01-28 | 1988-12-06 | Siemens Transmission Systems, Inc. | Center frequency high resolution digital phase-lock loop circuit |
| CN1129369A (en) * | 1994-11-03 | 1996-08-21 | 摩托罗拉公司 | Circuit and method for reducing a gate voltage of a transmission gate within a charge pump circuit |
| CN1815892A (en) * | 2005-01-31 | 2006-08-09 | 瑞昱半导体股份有限公司 | Circuit for detecting phase-error and generating control signal |
| EP1693967A1 (en) * | 2003-12-10 | 2006-08-23 | Matsushita Electric Industrial Co., Ltd. | Delta-sigma type fraction division pll synthesizer |
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| US4789996A (en) * | 1988-01-28 | 1988-12-06 | Siemens Transmission Systems, Inc. | Center frequency high resolution digital phase-lock loop circuit |
| CN1129369A (en) * | 1994-11-03 | 1996-08-21 | 摩托罗拉公司 | Circuit and method for reducing a gate voltage of a transmission gate within a charge pump circuit |
| EP1693967A1 (en) * | 2003-12-10 | 2006-08-23 | Matsushita Electric Industrial Co., Ltd. | Delta-sigma type fraction division pll synthesizer |
| CN1815892A (en) * | 2005-01-31 | 2006-08-09 | 瑞昱半导体股份有限公司 | Circuit for detecting phase-error and generating control signal |
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