CN203596813U - Low-phase-noise frequency synthesizer - Google Patents
Low-phase-noise frequency synthesizer Download PDFInfo
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- CN203596813U CN203596813U CN201320835510.1U CN201320835510U CN203596813U CN 203596813 U CN203596813 U CN 203596813U CN 201320835510 U CN201320835510 U CN 201320835510U CN 203596813 U CN203596813 U CN 203596813U
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Abstract
The utility model discloses a low-phase-noise frequency synthesizer which relates to a frequency synthesizer product covering a C-frequency-band in the field of communication and measurement. The low-phase-noise frequency synthesizer is composed of a constant-temperature crystal oscillator, a phase discriminator, a variable frequency divider, a loop filter, a voltage controlled oscillator set, a radio frequency switch, a demultiplexer, a controller, etc. The low-phase-noise frequency synthesizer adopts the technology of using the voltage controlled oscillator switching work, and in a C-frequency-band (5.8 GHz to 8 GHz) application frequency range, a phase-locked loop adopts two narrow-band voltage controlled oscillators to control the work modes of gate operation, replace a conventional full-frequency-band coverage work mode with a single wide-band voltage controlled oscillator. During operation, the phase-locked loop makes full use advantages of the narrow-band voltage controlled oscillators, such as good consistency in high-end and low-end tune sensitivity and high phase noise index. Through test verification, with the adoption of the low-phase-noise frequency synthesizer, the phase noise can ban be improved by 6 dB to 8 dB than the adoption of a conventional narrow-band voltage controlled oscillator frequency synthesizer. The low-phase-noise frequency synthesizer is applicable to situations of relatively low phase noise of output signals, small size, simple structure and low cost.
Description
Technical field
The utility model relates to the C frequency range low phase noise frequency synthesizer in the communications field, fields of measurement.
Technical background
The various receivers that use in modern communications field, electronic measurements field at present, communication equipment, instrument, instrument etc., all will be applied to frequency synthesizer.Frequency synthesizer index height is the key equipment that determines electronic system performance quality.Along with frequency synthesizer having been proposed to more and more higher requirement, the development of low phase noise synthesizer is also more and more rapider, and is widely used.
The frequency synthesis technique that current design frequency synthesizer adopts is respectively: Direct Digital Frequency Synthesizer Technology (DS), frequency synthesis technique (being PHASE-LOCKED LOOP PLL TECHNIQUE PLL), Direct Digital frequency synthesis technique (DDS) and hybrid frequency synthesis technique indirectly.The hybrid frequency synthetic method in addition several technology being mutually combined in addition.
Direct Digital Frequency Synthesizer Technology is one or more reference frequencies to be passed through to the measures such as frequency multiplication, frequency division, mixing, realizes the arithmetical operation of frequency, finally synthetic required frequency.Its advantage is: frequency switch speed is fast, phase noise can do finely.Shortcoming is circuit structure complexity, volume is large, cost is higher, development debugging is more difficult.
The synthetic phase feedback control principle that utilized of frequency synthesis technique (PLL) indirectly, its advantage is: the far-end that can effectively suppress output signal is spuious, there is good selectivity, thresholding performance is good, less demanding to frequency switch speed, shortcoming is that the frequency converting time loop bandwidth of indirect frequency synthesis technique restricts mutually, but is difficult to take into account many-sided overall targets such as the spuious inhibition, frequency converting time, frequency resolution of output signal.
Direct Digital frequency synthesis technique (DDS) is utilized sampling thheorem, produces the waveform needing by look-up table.Its advantage is to have high frequency resolution, and frequency switch speed is fast, and volume is little and cost is low; Major defect is to be subject to the restriction output frequency of clock frequency limited, and the basic principle producing due to DDS signal, produces the relatively another two kinds of technology of spuious index of signal also poor.
Consider technology and realize the factors such as phase noise, spuious inhibition, frequency range, volume/structure complexity, phase-locked loop synthetic method has comparative advantages, in the situation that volume, power consumption are smaller, can be in the frequency range that realizes relative narrower, can reach good phase noise and spuious index.
In the phase-locked loop frequency synthesis mode of widely applying at present, due to the basic functional principle of PHASE-LOCKED LOOP PLL TECHNIQUE, there is following problem: limited by voltage controlled oscillator device manufacturing process, along with the increase of voltage controlled oscillator covering frequence scope, its height frequency end tuning sensitivity changes excessive, causes loop filter and voltage controlled oscillator inadaptable.While being 5.8GHz～8GHz as voltage controlled oscillator reference frequency output, high-end at output frequency, within the scope of 7.9GHz～8.0GHz, can only reach-85dBc/Hz of phase noise@10kHz.Wideband voltage controlled oscillator phase noise index also can worsen than arrowband voltage controlled oscillator simultaneously, as arrowband voltage controlled oscillator 5.8GHz～6.6GHz, reach-80dBc/Hz of phase noise@10kHz when output frequency 6.6GHz, and wideband voltage controlled oscillator 5.8GHz～8GHz, when output frequency 6.6GHz, phase noise is-75dBc/Hz@10kHz, and both differ 5dB.The higher noise of voltage controlled oscillator finally can have influence on the final index of phase-locked loop.
Along with modern communications field and modern surveying field have proposed more and more higher requirement to frequency synthesizer, conventional phase-locked loop frequency synthesis mode can not meet the demands in some cases.
Utility model content
For solving the problem in above-mentioned background technology, the utility model provides one to meet the low requirement of making an uproar mutually in broadband, and output frequency is 5.8GHz～8GHz, and frequency step is 10MHz, reach-100dBc/Hz of phase noise@10kHz.
The technical solution of the utility model is as follows:
A kind of low phase noise frequency synthesizer, is characterized in that comprising:
Constant-temperature crystal oscillator 1, for generating reference signal;
Phase discriminator 2, the frequency division signal after treatment of exporting for reference signal that constant-temperature crystal oscillator 1 is exported and variable frequency divider 3 carries out frequency or phase bit comparison, output frequency or phase error signal;
Loop filter 4, for carrying out loop filter to frequency or the phase error signal of phase discriminator output;
Vco bank 5, under the control for the signal exported at loop filter 4, produces radiofrequency signal;
Radio-frequency (RF) switch 6, under the control of control unit 8, selects to switch for the radiofrequency signal that vco bank 5 is exported;
Wherein, described constant-temperature crystal oscillator, adopts constant-temperature crystal oscillator; Described phase discriminator, variable frequency divider, adopt HMC703LP4E; Described voltage controlled oscillator, adopts 2 arrowband Integrated VCOs; Described radio-frequency (RF) switch, adopts the low differential loss switch of microwave broadband; Described control unit, adopt FPGA to control, and output adds photoelectrical coupler and isolates.
Compared with prior art, obtained beneficial effect is the utility model:
The utility model adopts voltage controlled oscillator switch operating technology, within the scope of C frequency range (5.8GHz～8GHz) applying frequency, phase-locked loop adopts the mode of operation of two arrowband voltage controlled oscillator switching gate work, replaces the covering full frequency band mode of operation of single wideband voltage controlled oscillator in the past.When phase-locked loop operation, give full play to the advantage such as high low side tuning sensitivity high conformity, phase noise index height that arrowband voltage controlled oscillator device has.By verification experimental verification, adopt after the technical solution of the utility model, more conventional use wideband voltage controlled oscillator frequency synthesizer, phase noise can improve 6dB～8dB.This utility model is applicable to being applied to phase of output signal noise compared with situation low, that volume is little, simple in structure, cost is low.
Accompanying drawing explanation
Fig. 1 is electric theory diagram of the present utility model.
Embodiment
In conjunction with Fig. 1, the utility model is further described in detail.
A kind of low phase noise frequency synthesizer, comprising: constant-temperature crystal oscillator 1, phase discriminator 2, variable frequency divider 3, loop filter 4, vco bank 5 and radio-frequency (RF) switch 6, splitter 7 and control unit 8.Fig. 1 is electric theory diagram of the present utility model, and embodiment carries out connection line by Fig. 1.
Constant-temperature crystal oscillator 1, for generating reference signal; Phase discriminator 2, the frequency division signal after treatment of exporting for reference signal that constant-temperature crystal oscillator 1 is exported and variable frequency divider 3 carries out frequency or phase bit comparison, output frequency or phase error signal; Loop filter 4, for carrying out loop filter to frequency or the phase error signal of phase discriminator output; Vco bank 5, under the control for the signal exported at loop filter 4, produces radiofrequency signal; Radio-frequency (RF) switch 6, under the control of control unit 8, selects to switch for the radiofrequency signal that vco bank 5 is exported; Splitter 7, carries out shunt for the signal of radio-frequency (RF) switch 6 being selected to output, and externally export on a road, and another road exports variable frequency divider 3 to; Variable frequency divider 3, under the control of control unit 8, carries out frequency division processing for the radiofrequency signal that splitter 7 is exported; Control unit 8, for controlling variable frequency divider 3, loop filter 4, vco bank 5 and radio-frequency (RF) switch 6.
The technical solution of the utility model is to adopt voltage controlled oscillator switch operating technology, and embodiment, by using 2 arrowband high target voltage controlled oscillator gating work to cover the method for full frequency band, realizes C frequency range (5.8GHz～8GHz) low phase noise frequency synthesizer.
As shown in Figure 1, constant-temperature crystal oscillator output signal phase discriminator Yi road reference signal, vco bank is through radio-frequency (RF) switch gating and splitter output signal along separate routes as another road feedback signal, and two paths of signals carries out phase/frequency comparison through variable frequency divider and phase discriminator.The error voltage signal of output enters the control end of the corresponding voltage controlled oscillator of mains switch gating after loop filter, controls the output frequency of this voltage controlled oscillator, thereby makes phase-locked loop enter lock-out state.
Can compare by test data.Table 1 is conventional monocycle common solution and scheme test data described in the utility model comparison.
Table 1
Test condition
Frequency spectrograph: AgilentE4440A
Reference source: 100MHz constant-temperature crystal oscillator (≤-155dBc/Hz@10kHz)
By above-mentioned Data Comparison, to find out very clearly, scheme described in the utility model has clear improvement in phase noise index.Be better than conventional monocycle scheme 5dB at offset carrier 10kHz and 100kHz place phase noise.
Adopt the frequency synthesizer of this utility model alternatives formulation finally to realize index as follows.
Operating frequency: f
0=5.8GHz～8GHz;
Phase noise :≤-100dBc/Hz@10kHz;
≤-100dBc/Hz@100kHz；
Spuious inhibition: be better than 70dBc;
It is the constant-temperature crystal oscillator of OX204D-S-JT-R@100M that constant-temperature crystal oscillator is selected 13 models, variable division phase discriminator is selected the HMC703LP4E of HITTITE company, loop filter group is designed to three order active filter, and integrated arrowband vco bank is selected 13 HEV0710N, HEV-750N.Mains switch is chosen the SI3861DV of VISHAY company, and radio-frequency (RF) switch is selected the HMC345 of HITTITE company.
Control unit control radio-frequency (RF) switch is operated in corresponding modes, makes vco bank be operated in corresponding frequency band.Constant-temperature crystal oscillator produces high stability, and the 100MHz reference signal of low phase noise, sends into variable division phase discriminator chip HMC703LP4E and carry out R frequency division.The signal that voltage controlled oscillator signal produces by the prescalar in HMC703LP4E and Fractional-N frequency device, compares with the signal after reference signal R frequency division, produces an error signal that is proportional to phase difference, controls the electric current of charge pump.By suppressing noise and high fdrequency component after loop filter, obtain an approximate direct-current control voltage and enter the control end of voltage controlled oscillator.This voltage draws the output frequency of voltage controlled oscillator to the direction of track reference frequency, finally reaches locking.The frequency of frequency synthesizer, pump electric current and frequency step can be set by counter and frequency divider etc. in the control of correspondent program phase discriminator chip in control unit.
Frequency synthesizer operating frequency is 5.8GHz～8GHz, loop bandwidth 300kHz, and the element of the mains switch in phase-locked loop is as shown in Figure 2.Phase noise emulated data and experimental test data are in table 2.
Table 2
As can be seen from Table 2, phase noise index and spuious index are all better than adopting the index of conventional monocycle alternatives formulation frequency synthesizer, show that the frequency synthesizer optimization phase noise the utility model proposes refers to that calibration method is effective.
Claims (2)
1. a low phase noise frequency synthesizer, is characterized in that comprising:
Constant-temperature crystal oscillator (1), for generating reference signal;
Phase discriminator (2), for carrying out frequency or phase bit comparison, output frequency or phase error signal by the frequency division signal after treatment of the reference signal of constant-temperature crystal oscillator (1) output and variable frequency divider (3) output;
Loop filter (4), for carrying out loop filter to frequency or the phase error signal of phase discriminator output;
Vco bank (5), under the control for the signal in loop filter (4) output, produces radiofrequency signal;
Radio-frequency (RF) switch (6), under the control of control unit (8), for the radiofrequency signal of vco bank (5) output is selected to switch;
Splitter (7), for selecting the signal of output to carry out shunt radio-frequency (RF) switch (6), externally export on a road, and another road exports variable frequency divider (1) to;
Variable frequency divider (3), under the control of control unit (8), for the radiofrequency signal of splitter (7) output is carried out to frequency division processing;
Control unit (8), for controlling variable frequency divider (3), loop filter (4), vco bank (5) and radio-frequency (RF) switch (6).
2. low phase noise frequency synthesizer according to claim 1, is characterized in that:
Described phase discriminator, variable frequency divider, adopt HMC703LP4E;
Described voltage controlled oscillator, adopts two arrowband Integrated VCOs;
Described radio-frequency (RF) switch, adopts the low differential loss switch of microwave broadband;
Described control unit, adopt FPGA to control, and output adds photoelectrical coupler and isolates.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201320835510.1U CN203596813U (en) | 2013-12-18 | 2013-12-18 | Low-phase-noise frequency synthesizer |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105406862A (en) * | 2015-12-07 | 2016-03-16 | 扬州海科电子科技有限公司 | Low stray broadband 10-20GHz phase lock loop device |
| CN107968651A (en) * | 2017-11-20 | 2018-04-27 | 北京中创锐科信息技术有限公司 | Broadband signal generator |
-
2013
- 2013-12-18 CN CN201320835510.1U patent/CN203596813U/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105406862A (en) * | 2015-12-07 | 2016-03-16 | 扬州海科电子科技有限公司 | Low stray broadband 10-20GHz phase lock loop device |
| CN105406862B (en) * | 2015-12-07 | 2019-01-08 | 扬州海科电子科技有限公司 | A kind of low spurious broadband 10~20GHz phase-locked loop apparatus |
| CN107968651A (en) * | 2017-11-20 | 2018-04-27 | 北京中创锐科信息技术有限公司 | Broadband signal generator |
| CN107968651B (en) * | 2017-11-20 | 2021-12-17 | 成都中创锐科信息技术有限公司 | Broadband signal generator |
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| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20140514 Termination date: 20211218 |