CN102801416B - Phase lock loop circuit - Google Patents
Phase lock loop circuit Download PDFInfo
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- CN102801416B CN102801416B CN201110139816.9A CN201110139816A CN102801416B CN 102801416 B CN102801416 B CN 102801416B CN 201110139816 A CN201110139816 A CN 201110139816A CN 102801416 B CN102801416 B CN 102801416B
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Abstract
The invention discloses a phase lock loop circuit, which comprises a phase frequency detector, a coarse tune low-pass filter module, a voltage control oscillator module and a feedback path, wherein the phase frequency detector is used for comparing the frequencies and phases of an input signal and a feedback signal; the coarse tune low-pass filter module is coupled with the phase frequency detector, and is used for performing low-pass filtering on a control signal with a gradually reduced frequency width to generate a filtered signal, and the control signal indicates a comparison result of the input signal and the feedback signal; the voltage control oscillator module has a first voltage control oscillation gain and a second voltage control oscillation gain, and generates an output signal according to the control signal and the filtered signal; and the feedback path provides a feedback signal for the phase frequency detector according to the output signal.
Description
Technical field
The present invention relates to a kind of phase-locked loop circuit, particularly relate to a kind of can fast and the phase-locked loop circuit of frequency and phase place needed for accurate lock.
Background technology
The evolution of phase-locked loop (Phase Lock Loop, PLL) circuit is long-standing, and wants angle so far still for Discussion on Technology, mainly because of its application very extensively and have high development potentiality.In brief, namely the basic mass action of phase-locked loop circuit is that oscillation source that frequency of utilization variation is extremely low is as reference, via the feedback effect of closed loop control system, drive the action of the element of variable frequency, fast and reach synchronous state with oscillation source sustainedly and stably, PGC demodulation (Phase Locked) can be.
In addition, the double loop design that current phase-locked loop circuit much adopts coarse adjustment loop (coarse tune loop) and fine setting loop (fine tune loop) to coexist.Phase-locked loop, typical simulated dual loop, under the considering of stability, can use large resistance and bulky capacitor to form its coarse adjustment loop, to produce the limit (pole) of very low frequency.In addition, for the stability of phase-locked loop, double loop when locking, then primary concern is designed to what finely tune loop.Traditional phase-locked loop, double loop its voltage controlled oscillator of framework (voltage control oscillator) has low frequency gain (frequencygain; And thus have low phase noise (Phase Noise) and splendid Power Supply Rejection Ratio (power supply rejection ratio, PSRR) Kvco).
But double loop of the prior art phase-locked loop circuit is fixing because of the frequency range of its coarse adjustment low pass filter and is exceedingly limited to, therefore the disadvantage of traditional double loop phase-locked loop circuit is that its locking reaction speed is very slow.
Summary of the invention
The invention provides a kind of can fast and the phase-locked loop circuit of frequency and phase place needed for accurate lock.
The present invention proposes a kind of phase-locked loop circuit, and it comprises phase-frequency detector, coarse adjustment low pass filter module, voltage controlled oscillator module and feedback path.Phase-frequency detector is in order to the frequency of comparator input signal and feedback signal and phase place.Coarse adjustment low pass filter module is used for the progressive frequency range reduced, and carries out low-pass filtering, and produce filtering signal to a control signal of the comparative result of the above-mentioned phase-frequency detector of instruction.Voltage controlled oscillator module is used for producing the first oscillator signal with the first VCO gain according to control signal, and for producing the second oscillator signal with the second VCO gain according to filtering signal, and produce according to the first oscillator signal and the second oscillator signal and output signal.Wherein the second VCO gain is higher than the first VCO gain.Feedback path is used for according to output signal and provides feedback signal to phase-frequency detector.
The present invention proposes a kind of phase-locked loop circuit, and it comprises phase-frequency detector, coarse adjustment low pass filter module, voltage controlled oscillator module and feedback path.Coarse adjustment low pass filter module is coupled to phase-frequency detector, and with the progressive frequency range running reduced.Voltage controlled oscillator module has the first voltage controlled oscillator being coupled to phase-frequency detector and the second voltage controlled oscillator being coupled to coarse adjustment low pass filter module.Feedback path is coupled between phase-frequency detector and coarse adjustment low pass filter module.
In one embodiment of this invention, above-mentioned voltage controlled oscillator module comprises the first voltage controlled oscillator, the second voltage controlled oscillator and blender.First voltage controlled oscillator has the first VCO gain, and is coupled to phase-frequency detector, in order to according to control signal to produce the first oscillator signal.Second voltage controlled oscillator has the second VCO gain, and is coupled to coarse adjustment low pass filter module, for according to filtering signal to produce the second oscillator signal.Blender is coupled to the first voltage controlled oscillator and the second voltage controlled oscillator, for mixing the first oscillator signal and the second oscillator signal outputs signal to produce.
In one embodiment of this invention, the frequency range of above-mentioned coarse adjustment low pass filter module reduces a set value every a predetermined period.
In one embodiment of this invention, above-mentioned coarse adjustment low pass filter module comprises the first low pass filter and frequency range controller.First low pass filter coupled, to voltage controlled oscillator module, for adjusting frequency range according to frequency range control signal, and is carried out low-pass filtering with the frequency range after adjustment to control signal, and is produced filtering signal.Frequency range controller for generation of and provide frequency range to control signal to the first low pass filter, to reduce above-mentioned frequency range progressively.
In one embodiment of this invention, above-mentioned frequency range controller comprises timer and the second low pass filter.Timer is for generation of triggering signal.Second low pass filter is used for producing frequency range control signal according to triggering signal.
In one embodiment of this invention, above-mentioned timer produces triggering signal every a predetermined period, produces frequency range control signal reduce above-mentioned frequency range to indicate the first low pass filter to make the second low pass filter every predetermined period.
In one embodiment of this invention, the first above-mentioned low pass filter comprises variable resistor and electric capacity.Variable resistor is coupled to phase-frequency detector, for changing its resistance value according to frequency range control signal.Electric capacity has the first end being coupled to system voltage, and is coupled to variable resistor with the second end of output filtering signal.
In one embodiment of this invention, above-mentioned phase-locked loop circuit, also comprises charge pump.Charge pump is coupled to phase-frequency detector, produces control signal with the comparative result according to phase-frequency detector
In one embodiment of this invention, above-mentioned phase-locked loop circuit also comprises loop filter.Loop filter is coupled to charge pump, and the control signal for exporting charge pump carries out filtering to be provided to coarse adjustment low pass filter module and voltage controlled oscillator module.
Based on above-mentioned, the frequency range of the coarse adjustment low pass filter module of phase-locked loop circuit of the present invention can be reduced progressively.Phase-locked loop circuit is when carrying out Frequency Locking, and the frequency range of its coarse adjustment low pass filter module is dynamic variation, and the Frequency Locking that phase-locked loop circuit can correctly be outputed signal rapidly is in specific frequency.
For above-mentioned feature and advantage of the present invention can be become apparent, special embodiment below, and coordinate accompanying drawing to be described in detail below.
Accompanying drawing explanation
Fig. 1 is the functional-block diagram of the phase-locked loop circuit of first embodiment of the invention.
Fig. 2 is the functional-block diagram of the frequency range controller of one embodiment of the invention.
Fig. 3 is the circuit diagram of first low pass filter of one embodiment of the invention.
Fig. 4 is the circuit diagram of first low pass filter of another embodiment of the present invention.
Fig. 5 is the circuit diagram of the loop filter of the phase-locked loop circuit of one embodiment of the invention.
Reference numeral:
100: phase-locked loop circuit
110: phase-frequency detector
120: coarse adjustment low pass filter module
122: frequency range controller
124: the first low pass filters
126: timer
128: the second low pass filters
130: VCO module
132: the first voltage controlled oscillators
134: the second voltage controlled oscillators
136: blender
140: feedback path
730: charge pump
740: loop filter
C: electric capacity
C1: the first electric capacity
C2: the second electric capacity
C
a~ C
n: electric capacity
R: variable resistor
Ra, R1: resistance
Fref: input signal
Fo: feedback signal
F
1: the first oscillator signal
F
2: the second oscillator signal
VDD: the first system voltage
VSS: second system voltage
K1: the first VCO gain
K2: the second VCO gain
S0 ~ SN: switch
S
c: control signal
S
f: filtering signal
St: triggering signal
S
w: frequency range control signal
S
w[0] ~ S
w[N]: bit
S
u: voltage up control signal
S
d: voltage down control signals
Fout: output signal
Embodiment
In following examples, enter the line-locked initial stage at phase-locked loop circuit, a central coarse adjustment low pass filter module is set to have larger frequency range, and the frequency of output signal therefore can be made to be adjusted to rapidly near desired frequency.In addition, enter line-locked latter stage at phase-locked loop circuit, this coarse adjustment low pass filter module is set to have less frequency range, and the frequency of output signal therefore can be made to be adjusted to desired frequency exactly.As a result, this phase-locked loop circuit Frequency Locking that can correctly be outputed signal again is rapidly in specific frequency.
Please refer to Fig. 1, Fig. 1 is the functional-block diagram of the phase-locked loop circuit 100 of first embodiment of the invention.Phase-frequency detector 110 (phase frequency detector, PFD) in order to the frequency of comparator input signal Fref and feedback signal Fo and phase place, and according to comparative result, produces voltage up control signal S
uand voltage down control signals S
d.
Charge pump 730 is coupled to phase-frequency detector 110, produces voltage up control signal S in order to receive
uand voltage down control signals S
d, to produce control signal S
c.In other words, control signal S
cthe frequency of input signal Fref and feedback signal Fo and the comparative result of phase place can be indicated.
In addition, according to designing requirement, phase-locked loop circuit 100 also optionally comprises primary Ioops filter 740.Loop filter 740 is coupled to charge pump 730, for the control signal S exported charge pump 730
ccarry out filtering.
Coarse adjustment low pass filter module 120 is coupled to phase-frequency detector 110, in order to receive the control signal S of the comparative result of instruction phase-frequency detector 110
c.As previously mentioned, in some embodiments, coarse adjustment low pass filter module 120 is coupled to phase-frequency detector 110 by charge pump 730, therefore control signal S
creceived by charge pump 730 and obtain.And in other embodiments, be then also coupled to phase-frequency detector 110 by loop filter 740, therefore control signal S
ccan be received by loop filter 740 and obtain.
Coarse adjustment low pass filter module 120 for a progressive frequency range reduced, to control signal S
ccarry out low-pass filtering, and produce filtering signal S
f.In other words, after phase-locked loop circuit 100 comes into operation, the frequency range of coarse adjustment low pass filter module 120 can be reduced progressively.
Fig. 1 also shows the embodiment of a thin portion structure of coarse adjustment low pass filter module 120.As shown in Figure 1, coarse adjustment low pass filter module 120 comprises the first low pass filter 124 and frequency range controller 122, wherein the frequency range of the first low pass filter 124 be above-mentioned coarse adjustment low pass filter module 120 by diminishing frequency range.First low pass filter 124 is coupled to frequency range controller 122, for receiving a frequency range control signal S by frequency range controller 122
wadjust its frequency range.In other words, at frequency range control signal S
wcontrol under, the frequency range (i.e. the frequency range of coarse adjustment low pass filter module 120) of the first low pass filter 124 can be little by little reduced.In addition, the first low pass filter 124 can reception control signal S
c, come control signal S with the frequency range after adjusting
ccarry out low-pass filtering, and produce filtering signal S
f, and by filtering signal S
fbe supplied to VCO module 130.
VCO module 130 is coupled to coarse adjustment low pass filter module 120 and charge pump 730 (by loop filter 740), for simultaneously according to control signal S
cwith filtering signal S
fproduce an output signal Fout.Carefully, VCO module 130 is according to control signal S
c, and produce the first oscillator signal F with the first VCO gain K1
1.In addition, VCO module 130 according to filtering signal S
f, and produce the second oscillator signal F with the second VCO gain K2
2.Preferably, the second VCO gain K2 is higher than the first VCO gain K1, and more preferably, the second VCO gain K2 is far above the first VCO gain K1.VCO module 130 is again according to the first oscillator signal F
1with the second oscillator signal F
2produce output signal Fout.
Fig. 1 also shows the embodiment of a thin portion structure of VCO module 130.As shown in Figure 1, VCO module 130 can comprise the first voltage controlled oscillator 132, second voltage controlled oscillator 134 and blender 136.First voltage controlled oscillator 132 has the first above-mentioned VCO gain K1, and is coupled to phase-frequency detector 110, in order to according to control signal S
cto produce the first oscillator signal F
1.Second voltage controlled oscillator 134 has the second VCO gain K2, and is coupled to coarse adjustment low pass filter module 120, for according to filtering signal S
fto produce the second oscillator signal F
2.Blender 136 is coupled to the first voltage controlled oscillator 132 and the second voltage controlled oscillator 134, for mixing the first oscillator signal F
1with the second oscillator signal F
2to produce output signal Fout.Wherein, the frequency outputing signal Fout equals the first oscillator signal F
1frequency and the second oscillator signal F
2the summation of frequency.
Voltage controlled oscillator module 130 is also coupled to phase-frequency detector 110 via a feedback path 140.Feedback path 140 can be coupled between voltage controlled oscillator module 130 and phase-frequency detector 110, for providing feedback signal Fo to this phase-frequency detector according to this output signal Fout.
It should be noted that in the embodiment shown in fig. 1, output signal Fout and feedback signal Fo is same signal.But the present invention is not as limit.Such as, in other embodiments, feedback path 140 includes one or more frequency eliminator, that is feedback signal Fo can be that output signal Fout produces after the frequency eliminator frequency elimination of feedback path 140.
Under above-mentioned configuration, when the frequency of the frequency of input signal Fref and phase place and feedback signal Fo and phase place different time, phase-frequency detector 110 can by change control signal S
ccurrent potential, adjusting the frequency of the feedback signal Fo that VCO module 130 produces and phase place Jin mono-Walk makes the frequency of feedback signal Fo and phase place level off to the frequency of input signal Fref and phase place, and finally make feedback signal Fo and the frequency both input signal Fref and phase place identical, and complete the locking of output signal Fout and feedback signal Fo.
Carefully, by phase-frequency detector 110 by compared with the frequency of input signal Fref and feedback signal Fo and phase place, control signal S can be changed according to comparative result
ccurrent potential, and and then utilize VCO module 130 to change the first oscillator signal F
1frequency.In addition, due to filtering signal S
fthat coarse adjustment low pass filter module 120 is by control signal S
ccarry out low-pass filtering and obtain, that is filtering signal S
fcurrent potential and control signal S
ccurrent potential between have the relevant of certain degree.Therefore, as control signal S
ccurrent potential when being adjusted, filtering signal S
fcurrent potential also change thereupon, and then the second oscillator signal F can be changed by VCO module 130
2frequency.As a result, by adjustment control signal S
ccurrent potential, the first oscillator signal F can be changed simultaneously
1with the second oscillator signal F
2frequency, and then change the frequency of feedback signal Fo and phase place.After repeating above-mentioned adjustment, the frequency of feedback signal Fo and phase place can level off to the frequency of input signal Fref and phase place, finally reach the locking of output signal Fout and feedback signal Fo
It must be appreciated, because coarse adjustment low pass filter module 120 has the progressive frequency range reduced, therefore feedback signal Fo correctly can be locked in specific frequency again rapidly by phase-locked loop circuit 100.Below will describe its principle in detail.
Lock in the frequency of feedback signal Fo and the process of phase place at phase-locked loop circuit 100, the reaction speed of its locking is relevant with the frequency range of coarse adjustment low pass filter module 120.When the frequency range of coarse adjustment low pass filter module 120 is larger, the locking reaction speed of phase-locked loop circuit 100 is slower, but the frequency accuracy of locking is then lower.Otherwise, when coarse adjustment low pass filter module 120 frequency range more hour, the locking reaction speed of phase-locked loop circuit 100 is faster, but has higher accuracy.
In the present embodiment, after phase-locked loop circuit 100 comes into operation, the frequency range of coarse adjustment low pass filter module 120 is set as reducing progressively.Thus, entering the line-locked initial stage at phase-locked loop circuit 100 to feedback signal Fo, because coarse adjustment low pass filter module 120 has larger frequency range, the frequency of feedback signal Fo can be first adjusted near the frequency of input signal Fref rapidly.Next, entering line-locked latter stage at phase-locked loop circuit 100 to feedback signal Fo, because coarse adjustment low pass filter module 120 has less frequency range, the frequency of feedback signal Fo can be adjusted to the frequency of input signal Fref exactly.As a result, feedback signal Fo correctly can be locked in specific frequency again rapidly by phase-locked loop circuit 100.
It should be noted that the thin portion structure shown in Fig. 1 only makes the purposes of an example explanation.Other all different circuit all can adopt to realize VCO module 130, as long as can according to control signal S
cwith filtering signal S
fand produce two oscillator signals, and produce output signal Fout according to these two oscillator signals again.
Please refer to Fig. 2, Fig. 2 is the functional-block diagram of the frequency range controller 122 of one embodiment of the invention.In the present embodiment, frequency range controller 122 comprises timer 126 and the second low pass filter 128.Timer 126 is for generation of triggering signal St.Second low pass filter 128 is coupled to timer 126, for producing above-mentioned frequency range control signal S according to triggering signal St
w.
Preferably, timer 126 can produce triggering signal St every a predetermined period (such as 50 milliseconds), controls the first low pass filter 124 reduce its frequency range to make the second low pass filter 128 every above-mentioned predetermined period.Thus, the frequency range of the first low pass filter 124 can successively be turned down.In addition, this turns down till frequency range that operation can be performed until the first low pass filter 124 is contracted to a minimum frequency range preset.It must be appreciated, above-mentioned predetermined period and minimum frequency range all according to actual demand, and can give different settings, and the present invention is not as limit.
For realizing above-mentioned mode of operation, in an embodiment, timer 126 can be configured to and produces triggering signal St every a predetermined period, produces frequency range control signal S to trigger the second low pass filter 128 every predetermined period
w.Whenever the first low pass filter 124 receives frequency range control signal S
wtime, its frequency range can reduce a set value.As a result, the frequency range (i.e. the frequency range of coarse adjustment low pass filter module 120) of the first low pass filter 124 can reduce a set value every a predetermined period.
It should be noted that timer 126 can be reset, restart to make phase-locked loop circuit 100 to lock input signal Fref and feedback signal Fo.For example, in one embodiment, when timer 126 receive reset signal Rst time, namely can send corresponding triggering signal St, produce corresponding frequency range control signal S to make the second low pass filter 128
w, and make the frequency range of the first low pass filter 124 revert to the state originally not yet reduced.After timer 126 is reset, again can trigger the second low pass filter 128, to reduce the frequency range of the first low pass filter 124.
Please refer to Fig. 3, Fig. 3 is the circuit diagram of first low pass filter 124 of one embodiment of the invention.First low pass filter 124 comprises variable resistor R and electric capacity C.Variable resistor R is coupled to phase-frequency detector 110.The first end of electric capacity C is coupled to the first system voltage VDD, and second end of electric capacity C is coupled to variable resistor R with output filtering signal S
f.Under this arrangement, frequency range controller 122 can transmit frequency range control signal S
wto the first low pass filter 124, to change the resistance value of variable resistor R, and then reduce the frequency range of the first low pass filter 124.In other words, variable resistor R is according to frequency range control signal S
wchange the resistance value of itself.
Please refer to Fig. 4, Fig. 4 is the circuit diagram of first low pass filter 124 of another embodiment of the present invention.In the present embodiment, the first low pass filter 124 comprises resistance Ra, multiple electric capacity C
a~ C
nand multiple switch S 0 ~ SN.Resistance Ra is coupled to phase-frequency detector 110.Each electric capacity C
a~ C
nfirst end be coupled to the first system voltage VDD, electric capacity C
athe second end be coupled to resistance Ra, and electric capacity C
b~ C
nthe second end be coupled to resistance Ra by switch S 0 ~ SN.In the present embodiment, above-mentioned frequency range control signal S
wfor the digital controlled signal of (N+1) bit, its each bit is in order to one of them switch in the middle of control switch S0 ~ SN.Such as: bit S
w[0] in order to control switch S0, bit S
w[1] in order to control switch S1, bit S
w[N] is in order to control switch SN.By the opening of control switch S0 ~ SN, electric capacity C can be changed
a~ C
noverall equivalent capacitance value, and then the frequency range changing the first low pass filter 124.
It must be appreciated, the first low pass filter 124 in Fig. 3 and Fig. 4 is only two kinds in spendable various first low pass filter of phase-locked loop circuit of the present invention, and the present invention is not as limit.For example Fig. 3 and Fig. 4 can in conjunction with enforcement.Those of ordinary skill in the art should understand that the first low pass filter can also utilize other circuit forms to implement.
Please refer to Fig. 5, Fig. 5 is the circuit diagram of the loop filter 740 of the phase-locked loop circuit of one embodiment of the invention.In the present embodiment, loop filter 740 has resistance R1, the first electric capacity C1 and the second electric capacity C2, to form resistance-capacitance (RC) loop.One end of first electric capacity C1 and the second electric capacity C2 is coupled to second system voltage VSS, and the other end of the first electric capacity C1 is coupled to one end of resistance R1, and the other end of resistance R1 is coupled to charge pump 730.The function of loop filter 740 be low-pass filtering charge pump 730 export control signal S
c, with filtering control signal S
cin high-frequency noise, and then promote the stability of VCO module 130 in time operating.It must be appreciated, the loop filter 740 in Fig. 5 is only the one in the spendable various low pass filter of phase-locked loop circuit of the present invention, and the present invention is not as limit.Those of ordinary skill in the art should understand that the low pass filter used in various embodiments of the present invention can be implemented with other circuit forms.
In sum, the phase-locked loop circuit of above-described embodiment is when carrying out Frequency Locking, the frequency range of its coarse adjustment low pass filter module is dynamic variation, and can by reduced progressively, and the Frequency Locking that therefore can correctly be outputed signal again is rapidly in specific frequency.
Although the present invention with embodiment disclose as above, so itself and be not used to limit the present invention, any person of an ordinary skill in the technical field, when doing a little change and retouching, and does not depart from the spirit and scope of the present invention.
Claims (17)
1. a phase-locked loop circuit, comprising:
One phase-frequency detector, in order to compare frequency and the phase place of an input signal and a feedback signal;
One coarse adjustment low pass filter module;
One voltage controlled oscillator module; And
One feedback path, for providing this feedback signal to this phase-frequency detector according to an output signal, is characterized in that:
This coarse adjustment low pass filter module is used for a progressive frequency range reduced, and carries out low-pass filtering, and produce a filtering signal to a control signal of the comparative result of this phase-frequency detector of instruction; And
This voltage controlled oscillator module is used for producing one first oscillator signal with one first VCO gain according to this control signal, and for producing one second oscillator signal with one second VCO gain according to this filtering signal, and produce this output signal according to this first oscillator signal and this second oscillator signal, wherein this second VCO gain is higher than this first VCO gain.
2. phase-locked loop circuit according to claim 1, wherein this voltage controlled oscillator module comprises:
One first voltage controlled oscillator, it has this first VCO gain, and is coupled to this phase-frequency detector, in order to according to this control signal to produce this first oscillator signal;
One second voltage controlled oscillator, it has this second VCO gain, and is coupled to this coarse adjustment low pass filter module, for according to this filtering signal to produce this second oscillator signal; And
One blender, is coupled to this first voltage controlled oscillator and this second voltage controlled oscillator, for mixing this first oscillator signal and this second oscillator signal to produce this output signal.
3. phase-locked loop circuit according to claim 1, wherein this frequency range of this coarse adjustment low pass filter module reduces a set value every a predetermined period.
4. phase-locked loop circuit according to claim 1, wherein this coarse adjustment low pass filter module comprises:
One first low pass filter, is coupled to this voltage controlled oscillator module, for adjusting this frequency range according to a frequency range control signal, and carries out low-pass filtering with this frequency range after adjustment to this control signal, and produces this filtering signal; And
One frequency range controller, for generation of and provide this frequency range to control signal to this first low pass filter, to reduce this frequency range progressively.
5. phase-locked loop circuit according to claim 4, wherein this frequency range controller comprises:
One timer, for generation of a triggering signal; And
One second low pass filter, for producing this frequency range control signal according to this triggering signal.
6. phase-locked loop circuit according to claim 5, wherein this timer produces this triggering signal every a predetermined period, produces this frequency range control signal reduce this frequency range to indicate this first low pass filter to make this second low pass filter every this predetermined period.
7. phase-locked loop circuit according to claim 4, wherein this first low pass filter comprises:
One variable resistor, is coupled to this phase-frequency detector, for changing its resistance value according to this frequency range control signal; And
One electric capacity, it has a first end and is coupled to a system voltage, and one second end is coupled to this variable resistor to export this filtering signal.
8. phase-locked loop circuit according to claim 1, wherein also comprises a charge pump, is coupled to this phase-frequency detector, produces this control signal with this comparative result according to this phase-frequency detector.
9. phase-locked loop circuit according to claim 8, wherein also comprise primary Ioops filter, be coupled to this charge pump, this control signal for exporting this charge pump carries out filtering to be provided to this coarse adjustment low pass filter module and this voltage controlled oscillator module.
10. a phase-locked loop circuit, comprising:
One phase-frequency detector, in order to compare frequency and the phase place of an input signal and a feedback signal;
One coarse adjustment low pass filter module, is coupled to this phase-frequency detector;
One voltage controlled oscillator module, it has one first voltage controlled oscillator being coupled to this phase-frequency detector; And
One feedback path, is coupled between this phase-frequency detector and this coarse adjustment low pass filter module, for providing this feedback signal to this phase-frequency detector according to an output signal, it is characterized in that:
This coarse adjustment low pass filter module, with a progressive frequency range running reduced, carries out low-pass filtering to a control signal of the comparative result of this phase-frequency detector of instruction, and produces a filtering signal; And
This voltage controlled oscillator module has more one second voltage controlled oscillator being coupled to this coarse adjustment low pass filter module, for producing one first oscillator signal according to this control signal, and for producing one second oscillator signal according to this filtering signal, and produce this output signal according to this first oscillator signal and this second oscillator signal.
11. phase-locked loop circuits according to claim 10, wherein this first voltage controlled oscillator has one first VCO gain, this second voltage controlled oscillator has one second VCO gain, and this second VCO gain is higher than this first VCO gain.
12. phase-locked loop circuits according to claim 10, wherein this voltage controlled oscillator module also comprises a blender, is coupled to this first voltage controlled oscillator and this second voltage controlled oscillator.
13. phase-locked loop circuits according to claim 10, wherein also comprise a charge pump, are coupled to this phase-frequency detector.
14. phase-locked loop circuits according to claim 13, wherein also comprise primary Ioops filter, are coupled between this charge pump and this coarse adjustment low pass filter module, and between this first voltage controlled oscillator being coupled to this charge pump and this voltage controlled oscillator module.
15. phase-locked loop circuits according to claim 10, wherein this frequency range of this coarse adjustment low pass filter module reduces a set value every a predetermined period.
16. phase-locked loop circuits according to claim 10, wherein this coarse adjustment low pass filter module comprises:
One first low pass filter, is coupled to this voltage controlled oscillator module, for adjusting this frequency range according to a frequency range control signal; And
One frequency range controller, for generation of and provide this frequency range to control signal to this first low pass filter.
17. phase-locked loop circuits according to claim 16, wherein this frequency range controller comprises:
One timer, for generation of a triggering signal; And
One second low pass filter, for producing this frequency range control signal according to this triggering signal.
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| US9467156B2 (en) * | 2014-12-02 | 2016-10-11 | Mediatek Inc. | Frequency synthesizing module and related frequency gain determining method |
| EP3425803B1 (en) * | 2017-07-07 | 2020-01-01 | Nxp B.V. | Chirp generating phase-locked loop |
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| US20060141963A1 (en) * | 2004-12-28 | 2006-06-29 | Adrian Maxim | Method and apparatus to reduce the jitter in wideband PLL frequency synthesizers using noise attenuation |
| US7098754B2 (en) * | 2005-01-31 | 2006-08-29 | Rf Micro Devices, Inc. | Fractional-N offset phase locked loop |
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