CN206294152U - Frequency Synthesizer with Low Phase Noise - Google Patents
Frequency Synthesizer with Low Phase Noise Download PDFInfo
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- CN206294152U CN206294152U CN201720020194.0U CN201720020194U CN206294152U CN 206294152 U CN206294152 U CN 206294152U CN 201720020194 U CN201720020194 U CN 201720020194U CN 206294152 U CN206294152 U CN 206294152U
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- phaselocked loop
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Abstract
The utility model discloses a kind of Frequency Synthesizer with Low Phase Noise, including referring to crystal oscillator, for producing reference signal, the reference crystal oscillator connects power divider, the lock of power divider connection at least one is combined to the signal input part of unit, each described lock is sent to after for referenced signal to be distributed and is combined to unit, wherein, the lock is combined to unit includes the first phaselocked loop, for entering horizontal lock to the first crystal oscillator, second phaselocked loop, for entering horizontal lock to the second crystal oscillator, first crystal oscillator exports the first signal to the 4th phaselocked loop, second crystal oscillator exports secondary signal to the 3rd phaselocked loop, 3rd phaselocked loop is used to enter horizontal lock to the secondary signal；3rd phaselocked loop, the 4th phaselocked loop are exported after the signal of output is carried out into mixing combination.Scheme of the present utility model is made an uproar principle of stacking using irrelevant phase, can improve phase noise, circuit structure simple.
Description
Technical field
The utility model is related to frequency synthesis field, more particularly to a kind of Frequency Synthesizer with Low Phase Noise.
Background technology
With the development of electronic equipment, electronic system proposes requirement more and more high to frequency source, particularly in phase
It is even more so the key index such as noise, frequency hopping speed, spuious.
Modem frequency synthesizer mainly uses direct digital synthesizers and PHASE-LOCKED LOOP PLL TECHNIQUE.Wherein, most frequency synthesis
Device uses PHASE-LOCKED LOOP PLL TECHNIQUE.Using phaselocked loop（PLL）Frequency synthesizer composition frame chart it is as shown in Figure 1：Including phase discriminator
（PD）, loop filter（LF）, voltage controlled oscillator（VCO）, phase discriminator is reference-input signal（XTAL）Phase and VCO signal
Phase be compared, the phase error of the two input signals is converted into error voltage by PD, the voltage is by loop filtering
As the control voltage of VCO after device filtering, control voltage changes the output frequency of VCO, and after closed-loop system stabilization, VCO's is defeated
Go out frequency and reach required frequency, complete the locking of output frequency and reference frequency.When output frequency is higher than reference frequency
When, typically also need to increase frequency divider in feedback branch（N）So that the two paths of signals frequency for being input to PD is roughly equal.Equally,
Reference signal can also use a frequency divider（R）To obtain less phase demodulation frequency.
In actual applications, general emphasis considers the carrier wave near-end phase noise of output frequency, by the number to PLL frameworks
Learn and derive, the output near-end phase noise formula that can obtain whole system is：
PNtotal=PNREF+PN1Hz+ 10*log (fcomp)+20*log (N),
Wherein, PNref is the phase noise of reference frequency, and PN1Hz is the equivalent noise substrate of phase discriminator, when using numeral
During phase discriminator, the value be assess phase discriminator mutually make an uproar characteristic quality important parameter.Fcomp is phase demodulation frequency, fcomp=fout/N.
N is feedback frequency dividing ration.Because phaselocked loop is substantially the same as frequency multiplier, therefore output frequency relative to phase demodulation frequency or ginseng
The deterioration of mutually making an uproar of frequency is examined for 20*log（N）.
It is existing at present following several as can be seen that having the output frequency of more low phase noise in order to obtain from above formula
Method：
1st, using the reference frequency of more Low phase noise index, that is, PN is reducedREF.But the index made an uproar by system bottom influenceed without
Can infinitely reduce.
2nd, the equivalent noise substrate of phase discriminator is reduced, that is, reduces PN1HZ.Universal method is replaced using Sampling Phase Discriminator
Digital phase discriminator.If the applying date is 2003.11.14, S. Utility and the applying date of Application No. US71371703 are
1993.5.12, the S. Utility disclosure of Application No. US6075593 is to adopt in this way.
3rd, reduce phase demodulation frequency or reduce frequency dividing ratio, that is, reduce fcomp and N.But reducing fcomp will necessarily increase N, on the contrary
The deterioration mutually made an uproar can be brought.Therefore conventional method is to increase fcomp and cause that N reduces.But such harm is to obtain
Smaller frequency step.
4th, change on framework, be typically with the method for mixing in ring, first output frequency is mixed with a frequency f1 phase,
Obtain one and remove same reference frequency phase demodulation than relatively low feedback frequency.So, output frequency fout=f1+N2*fcomp=N1*
fref+N2*fcomp.Because f1 can be comprehensive using the frequency of a point source or big stepping, thus the output of f1 mutually make an uproar in formula can be with
Using above 3 kinds of method preferable phase noise specifications of relatively easy acquisition.So as to small frequency cannot be obtained in improving at the 3rd point
The problem of rate stepping, that is, taken into account and mutually made an uproar and small frequency step.If the applying date is 2008.9.5, Application No. US20563208
U.S. Utility Patent disclosed in scheme.
5th, using cancellation techniques of mutually making an uproar, such as feed-forward technique etc. is 2007.5.15, Application No. referring to the applying date
Scheme disclosed in the U.S. Utility Patent of US80360207.
6th, it is only the principle that linear power is superimposed using the superposition of incoherent phase noise, obtains 10*log（N）Phase
Make an uproar improvement.Referring specifically to《Phase Noise Improvement for Array Systems》, Shilei Hao,
Tongning Hu, Qun Jane Gu, P1 ~ 4,2016 IEEE MTT-S International Microwave
Symposium (IMS) with《A High Frequency Low Phase-Noise Signal Source Generated
Using a Self-Oscillating Mixer》, IET Microw. Antennas Propag., 2013, Vol. 7,
Iss. 2, pp. 123-130, disclosed scheme.
It can be seen to the analysis of existing such scheme, in foregoing method 2-4,20*log is not changed（N）'s
The dependent phase noise penalty factor, the phase noise of output frequency is according to 20*log（N）Coefficient deteriorate.Work as output frequency
During very high or N very big, the phase noise deterioration of output frequency is relatively more.Method 5 has bigger difficulty on technology is realized, special
Be not when frequency is higher, and be not a frequency in output frequency and when being the need for certain bandwidth, it is even more very difficult,
And it is also very limited to offset the lifting of mutually making an uproar for bringing.Method 6 based on irrelevant phase make an uproar superposition theory really be able to it is larger
Improve and export index of mutually making an uproar.But it uses the method for wave filter of mutually making an uproar to obtain irrelevant multiple signals, due to mutually making an uproar
Wave filter has certain bandwidth in itself, so distal end can only be improved（Such as 1M）Mutually make an uproar, and near-end is mutually made an uproar due to multiple signals
Between still have correlation, so near-end mutually can not be made an uproar improving.Simultaneously as wave filter is the device that frequency is fixed
Part, the method also only can be suitably used for point-frequency signal, and the frequency synthesizer for needing band frequency change bandwidth for output signal is believed
Number do not apply to yet.
In sum, existing scheme improves limited and circuit structure and answers to the phase noise of frequency synthesizer output signal
It is miscellaneous.
Utility model content
The utility model is the above-mentioned deficiency for overcoming prior art, there is provided one kind can be effectively improved phase noise, electricity
The simple Frequency Synthesizer with Low Phase Noise of line structure.
In order to realize above-mentioned utility model purpose, the technical solution adopted in the utility model is：
A kind of Frequency Synthesizer with Low Phase Noise, including crystal oscillator is referred to, for producing reference signal, the reference crystal oscillator connects
Power divider is connect, the lock of power divider connection at least one is combined to the signal input part of unit, for by referenced by
Each described lock is sent to after signal distribution and is combined to unit, wherein, the lock is combined to unit includes the first phaselocked loop, is used for
Enter horizontal lock, the second phaselocked loop, for entering horizontal lock, the first signal of the first crystal oscillator output to the second crystal oscillator to the first crystal oscillator
To the 4th phaselocked loop, second crystal oscillator exports secondary signal to the 3rd phaselocked loop, and the 3rd phaselocked loop is used for described the
Binary signal enters horizontal lock；3rd phaselocked loop, the 4th phaselocked loop are exported after the signal of output is carried out into mixing combination.
Further, the phaselocked loop includes the phase discriminator, loop filter, voltage controlled oscillator, the frequency divider that are sequentially connected.
Further, the phase discriminator is digital phase discriminator or analogue phase detection device.
Further, first phaselocked loop, the second phaselocked loop are narrow band phase lock loop.
Further, the narrow band phase lock loop loop bandwidth is less than 10Hz.
Compared with prior art, the beneficial effects of the utility model
Frequency Synthesizer with Low Phase Noise of the present utility model is made an uproar principle of stacking using irrelevant phase, and phase skill is locked using arrowband
Art obtains the uncorrelated frequency signal of multichannel, and these signals are carried out into group of frequencies by the architecture and method being mixed in ring
Close, to obtain the output frequency of needs.Made an uproar superposition as a result of irrelevant phase, the deterioration that output is mutually made an uproar is relative to reference signal
It is according to 10*log（N）Multiple deteriorate, rather than the 20*log of prior art（N）Multiple deteriorates, so relative to existing skill
Art can obtain 10*log（N）Lifting of mutually making an uproar, obtain extremely low phase noise, meanwhile, the utility model circuit structure is simple,
Easily realize.
Brief description of the drawings
Fig. 1 show Frequency Synthesizer with Low Phase Noise module frame chart of the present utility model.
Fig. 2 show the two-way Frequency Synthesizer with Low Phase Noise circuit in one embodiment.
Fig. 3 show the two-way Frequency Synthesizer with Low Phase Noise circuit in another embodiment.
Fig. 4 show four road Frequency Synthesizer with Low Phase Noise circuits.
Fig. 5 show multichannel Frequency Synthesizer with Low Phase Noise circuit.
Specific embodiment
The utility model is described in further detail with reference to specific embodiment.But this should not be interpreted as this
The scope of the above-mentioned theme of utility model is only limitted to following embodiment, and all technologies realized based on the utility model content are belonged to
In scope of the present utility model.
Fig. 1 show Frequency Synthesizer with Low Phase Noise module frame chart of the present utility model, including refers to crystal oscillator, for producing
Raw reference signal, the reference crystal oscillator connects power divider, and the lock of power divider connection at least one is combined to unit
Signal input part, for will referenced signal distribute after be sent to each it is described lock be combined to unit, wherein, the lock is harmonious
Include the first phaselocked loop into unit, for entering horizontal lock, the second phaselocked loop, for being locked to the second crystal oscillator to the first crystal oscillator
Phase, first crystal oscillator exports the first signal to the 4th phaselocked loop, and second crystal oscillator exports secondary signal to the 3rd phaselocked loop,
3rd phaselocked loop is used to enter horizontal lock to the secondary signal；The letter that 3rd phaselocked loop, the 4th phaselocked loop will be exported
Exported after number being mixed.
The phaselocked loop includes the phase discriminator, loop filter, voltage controlled oscillator, the frequency divider that are sequentially connected.
The phase discriminator is digital phase discriminator or analogue phase detection device.
First phaselocked loop, the second phaselocked loop are narrow band phase lock loop.
The narrow band phase lock loop bandwidth is less than 10Hz.
The principle that the utility model is linearly superimposed using the phase noise of multichannel unrelated signal combination.Locked by arrowband
Mutually first obtain the irrelevant signal of multichannel, and these signals carried out into combination of frequency by way of being mixed in ring, can obtain compared with
The lifting of mutually making an uproar of conventional Phase Lock Technique 10*logN, wherein N is incoherent frequency way.
Embodiment 1：
Fig. 2 show the frequency synthesizer circuit figure that unit is only combined to including one group of lock, wherein, X0 is to refer to crystal oscillator,
X1 and X2 are also crystal oscillator.V1 and V2 is voltage controlled oscillator（VCO）.PD is phase discriminator, can be that digital phase discriminator can also be mould
Intend phase discriminator.N is frequency divider.PS is power splitter.LPF is the loop filter of each loop.
With reference to crystal oscillator after power splitter is divided into two-way, X1 and X2 are locked respectively.Wherein PLL1 and PLL2 are exactly
The locked loop of X1 and X2.The two loops use arrowband Phase Lock Technique, that is, the loop bandwidth of PLL1 and PLL2 is transferred to
Very narrow, about within 10Hz, the present embodiment is calculated with 10Hz.The phase of so the output frequency f1 and f2 of the two loops is made an uproar
Sound is related only within frequency departure output frequency 10Hz, and is relevant to reference to crystal oscillator X0.Phase beyond 10Hz is deviateed
Position noise is phase noise of X1 and X2 itself, is incoherent between them.Therefore, output frequency f1 and f2 still have this
The characteristic of mutually making an uproar of body crystal oscillator, while their output frequency is exactly the same, i.e. f1=f2 due to the result of arrowband lock phase.
F2 obtains output frequency f3, f3=N3*f2 by PLL3 loops
PLL4 is major loop, by frequency divider and reference frequency f2 phase demodulations after output frequency f4 and f3 mixing, therefore has f4=
When f3+N4*f1=N3*f2+N4*f1, N3=N4=N, f1=f2, f4=N*f1+N*f2=2*N*f1.On mutually making an uproar, output frequency f4
The sum mutually made an uproar equal to N*f1 frequencies and mutually made an uproar with N*f2 frequencies of mutually making an uproar.Due in narrow band phase lock loop PLL1 and PLL2, having incited somebody to action
Phase noises of the f1 and f2 beyond off-center frequency 10Hz is incoherent.Therefore, according to the line of uncorrelated signal noise
Property principle of stacking, the phase noise beyond the off-center frequency 10Hz of output frequency f4 is：
PN（f4）=PN（N*f1）+PN（N*f2）=PN（N*f1）+10*log2.
Specifically, when there is multiple phase locked-loop units, final output frequency be by follow-up multichannel phase-locked loop frequency progressively
It is superimposed with what is come, penultimate phase-locked loop frequency is obtained by the frequency of last phaselocked loop, i.e. fn-1=2*fn.....,
By that analogy, the frequency f0=2*f1=2*....*2*fn of the first via for obtaining.
Embodiment 2：
Fig. 3 is another implementation method of the utility model, uses the principle of frequency addition.Still first adopted in this block diagram
The method for locking phase with arrowband obtains the incoherent reference frequency f1 and f2 of two-way, and not phase is obtained by the method for locking phase or frequency multiplication
Two-way the frequency f3 and f4 of pass.Therefore have：F5=f3+f4=N3*f2+N4*f1, its principle is obtained as the principle of embodiment 1
To phase noise to improve be also the same.
And the PN obtained using existing lock phase or frequency doubling technology（f4）= PN（N*f1）+ 20*log2, therefore the present embodiment
The phase noise of middle two paths of signals combination is improved as 20*log2-10*log2=10*log2=3dB.
The utility model gives the phase when output frequency is 13GHz of prior art and scheme in embodiment 1
Noise vs, the phase noise of prior art is respectively at 1K, 10K and 100K：- 112.5dBc/Hz, -117dBc/
Hz, -118.86dBc/Hz.
And the utility model is -115.1dBc/Hz, -119.4dBc/Hz, -120dBc/Hz.Comparatively speaking, this practicality is new
Phase noise of the scheme of type at 1K, 10K and 100K has the lifting of 2.6dB, 2.4dB and 1.14dB respectively.
Additionally, when lock be combined to unit for it is multiple when, as shown in Figure 4, Figure 5, with the increase of way, phase noise changes
It is kind to be consequently increased, e.g., when combining way is 4 or 8, the improvement of mutually making an uproar of 6dB and 9dB can be obtained in theory.
Specific embodiment of the present utility model has been described in detail above in conjunction with accompanying drawing, but the utility model is not
It is limited to above-mentioned implementation method, in the case of the spirit and scope for not departing from claims hereof, those skilled in the art
Member can be so that various modification can be adapted or remodeling.
Claims (5)
1. a kind of Frequency Synthesizer with Low Phase Noise, it is characterised in that described for producing reference signal including referring to crystal oscillator
Power divider is connected with reference to crystal oscillator, the lock of power divider connection at least one is combined to the signal input part of unit, uses
Each described lock is sent to after referenced signal is distributed and is combined to unit, wherein, the lock is combined to unit includes first
Phaselocked loop, for entering horizontal lock, the second phaselocked loop, for entering horizontal lock, first crystal oscillator to the second crystal oscillator to the first crystal oscillator
The first signal to the 4th phaselocked loop is exported, second crystal oscillator exports secondary signal to the 3rd phaselocked loop, the 3rd phaselocked loop
For entering horizontal lock to the secondary signal；The signal of output is carried out mixing combination by the 3rd phaselocked loop, the 4th phaselocked loop
After export.
2. Frequency Synthesizer with Low Phase Noise according to claim 1, it is characterised in that the phaselocked loop includes connecting successively
Phase discriminator, loop filter, voltage controlled oscillator, the frequency divider for connecing.
3. Frequency Synthesizer with Low Phase Noise according to claim 2, it is characterised in that the phase discriminator is digital phase detection
Device or analogue phase detection device.
4. Frequency Synthesizer with Low Phase Noise according to claim 1, it is characterised in that first phaselocked loop, second
Phaselocked loop is narrow band phase lock loop.
5. Frequency Synthesizer with Low Phase Noise according to claim 4, it is characterised in that the narrow band phase lock loop bandwidth is small
In 10Hz.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201720020194.0U CN206294152U (en) | 2017-01-09 | 2017-01-09 | Frequency Synthesizer with Low Phase Noise |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106533439A (en) * | 2017-01-09 | 2017-03-22 | 成都西蒙电子技术有限公司 | Low-phase noise frequency synthesizer |
| CN108055035A (en) * | 2017-12-26 | 2018-05-18 | 北京无线电计量测试研究所 | A kind of wideband frequency expanding unit of optical-electronic oscillator |
-
2017
- 2017-01-09 CN CN201720020194.0U patent/CN206294152U/en active Active
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106533439A (en) * | 2017-01-09 | 2017-03-22 | 成都西蒙电子技术有限公司 | Low-phase noise frequency synthesizer |
| WO2018126800A1 (en) * | 2017-01-09 | 2018-07-12 | 成都西蒙电子技术有限公司 | Low-phase-noise frequency synthesizer |
| CN108055035A (en) * | 2017-12-26 | 2018-05-18 | 北京无线电计量测试研究所 | A kind of wideband frequency expanding unit of optical-electronic oscillator |
| CN108055035B (en) * | 2017-12-26 | 2022-03-04 | 北京无线电计量测试研究所 | Broadband frequency extension device of photoelectric oscillator |
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