CN202978895U - Low phase noise frequency synthesizer - Google Patents
Low phase noise frequency synthesizer Download PDFInfo
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- CN202978895U CN202978895U CN 201220734093 CN201220734093U CN202978895U CN 202978895 U CN202978895 U CN 202978895U CN 201220734093 CN201220734093 CN 201220734093 CN 201220734093 U CN201220734093 U CN 201220734093U CN 202978895 U CN202978895 U CN 202978895U
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Abstract
The utility model discloses a low phase noise frequency synthesizer, and relates to a low phase noise frequency synthesizer product covering the C frequency band in the communication countermeasure field. The low phase noise frequency synthesizer comprises a constant-temperature crystal oscillator, a phase discriminator, a frequency divider, switches, filters, a voltage-controlled oscillator, a control unit and the like. The variable loop bandwidth technology is adopted, and in the C frequency band (4GHz to 7GHz), multiple groups of optimized loop filters are used respectively corresponding to different frequency bands of the broadband voltage-controlled oscillator, so as to prevent the output signal phase noise from getting worse due to the fact that tuning sensitivity of the voltage controlled oscillator changes greatly along with the frequency, and the purposes that the loop bandwidth is matched with the tuning sensitivity of the voltage-controlled oscillator, and the phase-locked loop phase noise is reduced can be achieved. In an experiment, after the technology is adopted, in the condition that the phase-locked loop changes little, the phase noise can be improved by 5dB to 9dB. The low phase noise frequency synthesizer has the advantages of simple structure, low phase noise, low power consumption, small volume and like, and particularly applied to situations where the phase noise of the output signals are low, the volume is small, and the cost is low.
Description
Technical field
The utility model relates to the frequency synthesizer in the communication countermeasures field, is specially adapted to C frequency range low phase noise frequency synthesizer in the communication countermeasures field.
Technical background
The frequency synthesizer that uses in the receiver that uses in wireless communication field at present, transmitter is all that the proportion synthesis mode is realized.The spectral purity of frequency synthesizer signal is directly connected to the dynamic range of receiver and the spectral purity of transmitter.And along with the increase of communication system working band, the working band of required frequency synthesizer is also in corresponding increase.
Conventional frequency synthesis mode is respectively: direct modeling synthetic method, phase-locked loop synthetic method and Direct Digital synthetic method.Direct modeling synthetic method frequency switching time is fast, phase noise good, but volume, power consumption are larger.
The phase-locked loop synthetic method by phase-locked loop complete the adding of frequency, subtract, the multiplication and division computing.The method designs simplification, volume are little.The contradiction that solves between high-resolution and fast conversion speed can the adjustment loop bandwidth, and the time of the larger locking of bandwidth is shorter, but the spuious deterioration of loop is larger; In addition, the phase noise of phase-locked loop synthetic method is except the impact that is subject to reference signal, and is also relevant with phase discriminator and frequency dividing ratio, and final phase noise is compared weaker with the direct modeling synthetic method.
Method conversion speed with Direct Digital frequency synthesis (DDS) is very fast, and still, Direct Digital frequency synthesis (DDS) is subject to the restriction of the operating frequency of digital to analog converter (DAC), and its output frequency also is restricted.In addition, Direct Digital frequency synthesis mode output signal is spuious sometimes larger.
Consider phase noise, spuious, frequency range, the complexity of realization, volume/factors such as power consumption size, the phase-locked loop synthetic method has comparative advantages, in the situation that volume, power consumption are smaller, can in the frequency range of relative narrower, can reach phase noise and spuious index preferably.
In the phase-locked loop synthesis mode, generally include phase discriminator, loop filter, voltage controlled oscillator and frequency divider.In the phase-locked loop frequency synthesis mode of widely applying at present, there is following problem: limited by the voltage controlled oscillator output frequency, cause frequency range narrow; Along with the increase of voltage controlled oscillator reference frequency output, the voltage controlled oscillator tuning change of sensitivity increases, and causes loop filter and voltage controlled oscillator inadaptable, finally causes the phase of output signal noise sharply to worsen.When being 4GHz～7GHz as the voltage controlled oscillator reference frequency output, in the output signal frequency scope was 5.1GHz～5.3GHz, phase noise can reach-90dBc/Hz@10kHz; And high-end at output frequency, in 6.9GHz～7.0GHz scope, phase noise can only reach-85dBc/Hz@10kHz.
Along with the development of the communication technology, more and more wider to the reference frequency output of frequency synthesizer signal, the requirement of phase noise is more and more higher, and conventional phase-locked loop frequency synthesis mode can not meet the demands in some cases.
The utility model content
For solving the problem in the above-mentioned background technology, the utility model provides a kind of low low phase noise frequency synthesizer of making an uproar mutually and requiring in broadband that satisfies, and output frequency is 4GHz～7GHz, and frequency step is 10MHz, and phase noise reaches-94dBc/Hz@10kHz.
Technical solution adopted in the utility model is:
A kind of low phase noise frequency synthesizer is characterized in that: comprise constant-temperature crystal oscillator 1, variable division phase discriminator 2, loop filter group 3, voltage controlled oscillator 4 and control unit 5;
The signal of constant-temperature crystal oscillator output is as the reference signal; One road signal of voltage controlled oscillator output enters the variable division phase discriminator, in the variable division phase discriminator, the signal that obtains after the variable frequency divider frequency division, reference signal with constant-temperature crystal oscillator output, carry out frequency and bit comparison mutually in phase discriminator in the variable division phase discriminator, phase discriminator output frequency or phase error signal are after the loop filter group is carried out filtering, enter the control end of voltage controlled oscillator, control the output frequency of voltage controlled oscillator; Variable division phase discriminator, loop filter group are controlled by control unit.
Wherein, described loop filter group comprises: the first switch 6, first ring path filter 7, the second loop filter 8 and second switch 9; From the signal of variable division phase discriminator, enter the input of the first switch 6, control the first switch 6 according to control strategy; Signal after the first switch 6 carries out gating after carrying out filtering by one in first ring path filter 7 or the second loop filter 8, enters the input of second switch 9, and exports at the output of second switch 9, as the control signal of voltage controlled oscillator.
Wherein, the first ring path filter comprises: capacitor C 1, resistance R 1, capacitor C 2 and the first amplifier; The input of capacitor C 1, resistance R 1 is connected in the inverting input of the first amplifier in parallel, and be connected with an output of the first switch, corresponding reference voltage is connected to the in-phase input end of the first amplifier, the output of resistance R 1, capacitor C 1 is connected to the input of capacitor C 2, and the output of capacitor C 2 is connected with the output of the first amplifier and an input of second switch.
Wherein, the second loop filter comprises capacitor C 3, resistance R 2, capacitor C 4 and the second amplifier; The input of capacitor C 3, resistance R 2 is connected in the inverting input of the second amplifier in parallel, and is connected with another output of the first switch.Corresponding reference voltage is connected to the in-phase input end of the second amplifier, and the output of capacitor C 3, resistance R 2 is connected to the input of capacitor C 4, and the output of capacitor C 4 is connected with the output of the second amplifier and another input of second switch.
Wherein, described crystal oscillator adopts constant-temperature crystal oscillator; Described phase discriminator, frequency divider adopt ADF4106; Described voltage controlled oscillator adopts the broadband Integrated VCO; Described switch adopts high voltage, the low noise electronic switch; Described loop filter adopts three rank active loop filters; Described control unit adopts FPGA to control, and output adds photoelectrical coupler and isolates.
The utility model compared with prior art, obtained beneficial effect is:
Adopt low phase noise frequency synthesizer described in the utility model, be significantly improved on the phase noise index, in 4GHz～7GHz scope, in frequency step 10MHz situation, in the full frequency band scope, the phase noise worst-case value can reach-94dBc/Hz@10kHz, more than optimizing 4dB～9dB than conventional scheme.
Description of drawings
Fig. 1 is the electric theory diagram of phase-lock frequency synthesizer of the present utility model;
Fig. 2 is the electric functional-block diagram of loop filter group.
Embodiment
In conjunction with Fig. 1 and Fig. 2, low phase noise frequency synthesizer described in the utility model is further described in detail.
The technical solution of the utility model is to adopt variable loop bandwidth technology, at C frequency range (4GHz～7GHz), by using the loop filter of many groups through optimizing, realize low frequency synthesizer of making an uproar mutually.
Specifically comprise with reference to Fig. 1 the utility model: constant-temperature crystal oscillator 1, variable division phase discriminator 2, the loop filter groups 3, voltage controlled oscillator 4, control unit 5.
The signal of constant-temperature crystal oscillator output is as the reference signal; One road signal of voltage controlled oscillator output enters the variable division phase discriminator, in the variable division phase discriminator, the signal that obtains after the variable frequency divider frequency division, with the reference signal of constant-temperature crystal oscillator output, carry out frequency and bit comparison mutually in the phase discriminator in the variable division phase discriminator, phase discriminator output frequency or phase error signal, after the loop filter group is carried out filtering, enter the control end of voltage controlled oscillator, control the output frequency of voltage controlled oscillator, thereby make phase-locked loop enter lock-out state.Variable division phase discriminator, loop filter group are controlled by control unit.
In Fig. 2, the loop filter group comprises: the first switch 6, first ring path filter 7, the second loop filter 8 and second switch 9.
From the signal of variable division phase discriminator, enter the input of the first switch 6, control the first switch 6 according to control strategy; Signal after the first switch 6 carries out gating after carrying out filtering by one in first ring path filter 7 or the second loop filter 8, enters the input of second switch 9, and exports at the output of second switch 9, as the control signal of voltage controlled oscillator.
In the first ring path filter, comprising: capacitor C 1, resistance R 1, capacitor C 2 and the first amplifier; In the second loop filter, comprising: capacitor C 3, resistance R 2, capacitor C 4 and the second amplifier.
In the first ring path filter, the input of capacitor C 1, resistance R 1 is connected to the inverting input of the first amplifier, and is connected with an output of the first switch.Corresponding reference voltage is connected to the in-phase input end of the first amplifier, and the output of resistance R 1, capacitor C 1 is connected to the input of capacitor C 2, and the output of capacitor C 2 is connected with the output of the first amplifier and an input of second switch.In the second loop filter, the input of capacitor C 3, resistance R 2 is connected to the inverting input of the second amplifier, and is connected with another output of the first switch.Corresponding reference voltage is connected to the in-phase input end of the second amplifier, and the output of capacitor C 3, resistance R 2 is connected to the input of capacitor C 4, and the output of capacitor C 4 is connected with the output of the second amplifier and another input of second switch.
Can compare by test data.Table 1 is that conventional monocycle common solution and scheme test data described in the utility model compare.
Table 1
Test condition
Frequency spectrograph: Agilent E4440A
Reference source: the 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 the phase noise index.At offset carrier 10kHz and 100kHz place phase noise lower than conventional monocycle scheme 9dB.
Adopt the frequency synthesizer of this utility model alternatives formulation to realize that finally index is as follows.
Operating frequency: f
o=4000MHz～7000MHz;
Phase noise :≤-94dBc/Hz@10kHz;
≤-94dBc/Hz@100kHz；
Spuious inhibition: be better than 75dBc;
It is the constant-temperature crystal oscillator of OX204D-S-JT-R@100M that constant-temperature crystal oscillator is selected 13 models, the variable division phase discriminator is selected the ADF4106 of ADI company, the loop filter group is designed to three order active filter, and the first amplifier and the second amplifier are the AD820 of ADI company, and capacitor C 1 is 120pF, capacitor C 2 is 2nF, capacitor C 3 is 820pF, and capacitor C 4 is 0.01 μ F, and resistance R 1 is 1.3k Ω, resistance R 2 is 620 Ω, and the integrated broadband voltage controlled oscillator is selected 13 HEM102.
Adopt certain radio frequency software analysis, operating frequency is 4000MHz～7000MHz, and loop bandwidth is respectively 80kHz, 180kHz, and the element of the loop filter group in whole phase-locked loop as shown in Figure 2.Phase noise emulated data and experimental test data see Table 2.
Need to prove that the result that records in table 2 is whole frequency range 4000MHz～the most not good enough f of 7000MHz
oThe test value of other points in the test data of=7000MHz, this band limits all is better than test result in table 2.
Table 2
As can be seen from Table 2, phase noise index and spuious index all are better than adopting the index of conventional monocycle alternatives formulation frequency synthesizer, show that the method for the frequency synthesizer ground phase noise that the utility model proposes is effective.
Claims (5)
1. a low phase noise frequency synthesizer, is characterized in that: comprise constant-temperature crystal oscillator (1), variable division phase discriminator (2), loop filter group (3), voltage controlled oscillator (4) and control unit (5);
The signal of constant-temperature crystal oscillator output is as the reference signal; One road signal of voltage controlled oscillator output enters the variable division phase discriminator, in the variable division phase discriminator, the signal that obtains after the variable frequency divider frequency division, reference signal with constant-temperature crystal oscillator output, carry out frequency and bit comparison mutually in phase discriminator in the variable division phase discriminator, phase discriminator output frequency or phase error signal are after the loop filter group is carried out filtering, enter the control end of voltage controlled oscillator, control the output frequency of voltage controlled oscillator; Variable division phase discriminator, loop filter group are controlled by control unit.
2. a kind of low phase noise frequency synthesizer according to claim 1, it is characterized in that: described loop filter group comprises: the first switch (6), first ring path filter (7), the second loop filter (8) and second switch (9);
From the signal of variable division phase discriminator, enter the input of the first switch (6), control the first switch (6) according to control strategy; Signal after the first switch (6) carries out gating, after carrying out filtering by one in first ring path filter (7) or the second loop filter (8), enter the input of second switch (9), and export at the output of second switch (9), as the control signal of voltage controlled oscillator.
3. a kind of low phase noise frequency synthesizer according to claim 2, it is characterized in that: the first ring path filter comprises: capacitor C 1, resistance R 1, capacitor C 2 and the first amplifier; The input of capacitor C 1, resistance R 1 is connected in the inverting input of the first amplifier in parallel, and be connected with an output of the first switch, corresponding reference voltage is connected to the in-phase input end of the first amplifier, the output of resistance R 1, capacitor C 1 is connected to the input of capacitor C 2, and the output of capacitor C 2 is connected with the output of the first amplifier and an input of second switch.
4. a kind of low phase noise frequency synthesizer according to claim 2, it is characterized in that: the second loop filter comprises capacitor C 3, resistance R 2, capacitor C 4 and the second amplifier; The input of capacitor C 3, resistance R 2 is connected in the inverting input of the second amplifier in parallel, and be connected with another output of the first switch, corresponding reference voltage is connected to the in-phase input end of the second amplifier, the output of capacitor C 3, resistance R 2 is connected to the input of capacitor C 4, and the output of capacitor C 4 is connected with the output of the second amplifier and another input of second switch.
5. low phase noise frequency synthesizer as claimed in claim 1, is characterized in that: described crystal oscillator, employing constant-temperature crystal oscillator; Described phase discriminator, frequency divider adopt ADF4106; Described voltage controlled oscillator adopts the broadband Integrated VCO; Described switch adopts high voltage, the low noise electronic switch; Described loop filter adopts three rank active loop filters; Described control unit adopts FPGA to control, and output adds photoelectrical coupler and isolates.
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| CN 201220734093 CN202978895U (en) | 2012-12-28 | 2012-12-28 | Low phase noise frequency synthesizer |
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| CN 201220734093 CN202978895U (en) | 2012-12-28 | 2012-12-28 | Low phase noise frequency synthesizer |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2016112719A1 (en) * | 2015-01-13 | 2016-07-21 | 合肥工业大学 | Temperature sensor integrated in rfid label |
| CN105959002A (en) * | 2016-05-18 | 2016-09-21 | 成都福兰特电子技术股份有限公司 | Wireless signal emission system of aviation communication |
| CN106549665A (en) * | 2015-09-16 | 2017-03-29 | 华为技术有限公司 | The control method of phase-locked loop circuit, data recovery circuit and phase-locked loop circuit |
| CN109450445A (en) * | 2018-10-26 | 2019-03-08 | 中国电子科技集团公司第四十研究所 | A kind of variable loop bandwidth frequency synthesizer, system and method |
-
2012
- 2012-12-28 CN CN 201220734093 patent/CN202978895U/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2016112719A1 (en) * | 2015-01-13 | 2016-07-21 | 合肥工业大学 | Temperature sensor integrated in rfid label |
| CN106549665A (en) * | 2015-09-16 | 2017-03-29 | 华为技术有限公司 | The control method of phase-locked loop circuit, data recovery circuit and phase-locked loop circuit |
| CN106549665B (en) * | 2015-09-16 | 2019-09-03 | 华为技术有限公司 | The control method of phase-locked loop circuit, data recovery circuit and phase-locked loop circuit |
| CN105959002A (en) * | 2016-05-18 | 2016-09-21 | 成都福兰特电子技术股份有限公司 | Wireless signal emission system of aviation communication |
| CN109450445A (en) * | 2018-10-26 | 2019-03-08 | 中国电子科技集团公司第四十研究所 | A kind of variable loop bandwidth frequency synthesizer, system and method |
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