CN101136630A - Frequency synthesizer - Google Patents
Frequency synthesizer Download PDFInfo
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- CN101136630A CN101136630A CNA2006100305607A CN200610030560A CN101136630A CN 101136630 A CN101136630 A CN 101136630A CN A2006100305607 A CNA2006100305607 A CN A2006100305607A CN 200610030560 A CN200610030560 A CN 200610030560A CN 101136630 A CN101136630 A CN 101136630A
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Abstract
This invention discloses a frequency synthesizer including: a loop filter and a voltage-controlled oscillator, in which, the voltage-controlled oscillator is composed of a voltage-current converter and a current controlled ring oscillator, and the frequency synthesizer also includes a band automatic switch circuit parallel in the voltage-current converter composed of an automatic switch circuit and a set of switch control current source generating one or many bias currents, and the automatic switch circuit generates one or many digital logic signals to control the off/on of one or many bias currents generated by the switch controlled current source circuit so as to realize automatic switch among frequency bands.
Description
Technical field
The present invention relates to a kind of frequency synthesizer, relate in particular to a kind of frequency output area and can reach tens even the frequency synthesizer of hundreds and thousands of times output frequency excursion.
Background technology
General frequency synthesizer mainly comprises following a few part: phase demodulation/frequency device, charge pump, loop filter, voltage controlled oscillator (VCO) and loop divider.In order to make frequency synthesizer can reach tens even hundreds and thousands of times output frequency excursion, realize by following four kinds of methods basically at present:
(1) by improving the output center frequency of voltage controlled oscillator, utilize programmable output frequency divider to realize the output of various frequencies then.
As shown in Figure 1, when Vc=Vdd/2, the pairing output frequency of voltage controlled oscillator is centre frequency f0, and wherein Vdd is the supply voltage of frequency synthesizer work, and Vc is the control voltage of VCO.The output frequency of frequency synthesizer is represented with fout M is the divide ratio of output frequency divider, then fout=f0/M.The shortcoming of this method is: though the output frequency that actual frequency synthesizer requires is not high, but f0 need do very highly usually, therefore well-known high-frequency signal power supply noise rejection ratio very poor when high frequency be easy to be subjected to power supply noise effect on the ground; Its second shortcoming is that technology itself has limited the size of accessible centre frequency, and the operating rate of the digital circuit of ordinary construction is with originally not reaching so high frequency simultaneously.Therefore the digital circuit of this frequency synthesizer part no longer can use common structure to realize, and will adopt some structures at a high speed.
(2) utilize the high-gain of single ring oscillator to realize, will utilize the VCO control voltage that to use this moment as far as possible.
As shown in Figure 2, owing to will realize the output of very wide frequency, the output frequency of 2 ~ 200MHz for example, promptly output frequency has changed 100 times.Because output frequency is along with VCO control voltage linear changes, so the control voltage of VCO also is necessary for 100 times variation.As everyone knows, along with the application of large scale integrated circuit, supply voltage is more and more littler.General technology (not considering high-pressure process) supply voltage at 0.25um is generally 2.5/3.3V; and threshold voltage is generally 0.5V; promptly at most also can only realize 5 ~ 6 times variation; so can not there be 100 times Vc to change basically; therefore in this method, also used Vc to equal the subthreshold value zone of Vsth ~ Vth usually; wherein the VsthNMOS pipe begins to enter the voltage of sub-threshold region, and Vth is the threshold voltage of NMOS pipe.And the gain meeting of VCO significantly descends in this zone of Vsth ~ Vth, thereby causes the instability of loop.This method all is used in a lot of circuit, and the voltage-frequency curve of its VCO structure and VCO correspondence as shown in Figure 3 and Figure 4.
(3) transfer wide reference frequency output by the number that changes delay-level in the ring oscillator.
The shortcoming of this method is: because the number of delay-level can be from influencing the loop phase noise, so usually in order to optimize this performance, can take 3 ~ 5 grades delay-level to a great extent.Thereby reference frequency output is considering that noiseproof feature can not be very wide under limiting.
(4) the required frequency range of VCO is divided into several frequency bands, utilizes digital signal (control signal in the external pin input or the synthesizer external register of adjusting frequency) to control selecting for use of frequency range.
Said method (3) and (4) all are to utilize external pin input or adjust the frequency output that control signal in the register reaches wide region.These have all inevitably increased the complexity of circuit; And can in the regional adjustment loop that the VCO gain significantly descends, each parameter make loop reach stable in the method (2), thereby also need the circuit of some automatic regulation loop ballasts.
Summary of the invention
The technical problem to be solved in the present invention provides a kind of frequency synthesizer, it is identical and have a frequency band of high Linearity reference frequency output can be divided into a plurality of gains, and automatically switch between these a plurality of frequency bands, thereby realization has the characteristics of low jitter, wide frequency ranges output.
For solving the problems of the technologies described above, the present invention is achieved by the following technical solutions: include loop filter and voltage controlled oscillator, wherein said voltage controlled oscillator is made up of voltage-current converter and Current Control annular oscillator, described frequency synthesizer also includes a frequency band automatic switch-over circuit, this circuit is connected in parallel in the described voltage-current converter, is made up of an automatic switch-over circuit and a switch Control current source circuit; Wherein, described switch Control current source circuit is used to produce one or more bias currents (I0, I1 ... In); Described automatic switch-over circuit is used to produce one or more digital logic signals (C0, C1 ... Cn), make the work tail current of described Current Control annular oscillator satisfy following formula: Itail1=Itail0+C0*I0+C1*I1+ ... + Cn*In; Wherein, Itail1 represents to introduce the work tail current of frequency band automatic switch-over circuit after-current control ring oscillator, the work tail current of Current Control annular oscillator when Itial0 represents not introduce the frequency band automatic switch-over circuit; Described digital logic signal (C0, C1 ... Cn) by described automatic switch-over circuit can realize different logical combinations (C0: C1: ...: Cn), described one or more bias currents (I0, I1 that difference control switch Control current source circuit produces ... turning on and off In) automaticallyed switch thereby be implemented between each frequency band.
Described switch Control current source circuit is formed in parallel by one or more current source.
Described automatic switch-over circuit is mainly by being formed by connecting before and after one or more voltage comparators, one or more status latch and the decoding circuit; Wherein said voltage comparator is used to discern the frequency range of needs; Status latch is used for filtering because the caused misoperation of the undesired upset of voltage comparator; Decoding circuit be used to produce the digital logic signal that satisfies Different Logic combination (C0: C1: ...: Cn).
The present invention has adopted technique scheme, has following beneficial effect, it is identical and have a frequency band of high linearity to have realized that promptly reference frequency output is divided into a plurality of gains, and between these a plurality of frequency bands, automatically switch, thereby the frequency synthesizer of realized having low jitter, wide frequency ranges being exported, and need not to increase the pin of any outside or unnecessary external control signal, more do not need complicated loop parameter regulating circuit, have simple in structure, easy realization, high-performance, characteristics cheaply.
Description of drawings
The present invention is further detailed explanation below in conjunction with accompanying drawing and embodiment:
Fig. 1 is to use the voltage-frequency curve chart of realizing the output of frequency synthesizer wideband by the method that improves centre frequency;
Fig. 2 utilizes the high-gain of single ring oscillator to realize the voltage-frequency curve chart that the frequency synthesizer wideband is exported;
Fig. 3 utilizes the high-gain of single ring oscillator to realize the exemplary circuit configuration figure that the frequency synthesizer wideband is exported;
Fig. 4 utilizes virtual voltage-frequency test curve that the high-gain of single ring oscillator realizes the output of frequency synthesizer wideband figure as a result;
Fig. 5 is the frequency range distribution schematic diagram when according to the present invention reference frequency output being divided into two frequency bands;
Fig. 6 is an exemplary circuit configuration figure of the automatic switch-over circuit when according to the present invention reference frequency output being divided into two frequency bands;
Sequential chart when Fig. 7 is the work of the described automatic switch-over circuit of Fig. 6;
Fig. 8 is of the present invention for realizing the exemplary circuit configuration figure that high Linearity adopted of each frequency band;
Fig. 9 is the structured flowchart that has added the frequency synthesizer behind the frequency band automatic switch-over circuit according to the present invention;
Figure 10 is the exemplary block diagram of the frequency synthesis apparatus when according to the present invention reference frequency output being divided into two frequency ranges;
Figure 11 is the frequency range distribution schematic diagram when according to the present invention reference frequency output being divided into three frequency ranges;
Figure 12 is the exemplary block diagram of the frequency synthesis apparatus when according to the present invention reference frequency output being divided into three frequency ranges.
Embodiment
What be well known to those skilled in the art is, the output frequency fout of existing frequency synthesizer is proportional to Itail/ (Vout*C), wherein Itail is the work tail current of Current Control annular oscillator, Vout is the high level of ring oscillator output signal, and C is the parasitic capacitance of single delay-level output.Because the variation of Vout generally generally designs lessly, think that output frequency fout is proportional to the work tail current Itail of Current Control annular oscillator so can be similar to.Therefore, based on above-mentioned principle, frequency synthesizer of the present invention is a frequency band automatic switch-over circuit in parallel in original voltage-current converter, this circuit is made up of a frequency band automatic switch-over circuit and one group of switch Control current source circuit, can make the work tail current satisfy formula: Itail1=Itail0+C0*I0+C1*I1+ ... + Cn*In, the work tail current of Current Control annular oscillator when wherein Itail0 represents not introduce the frequency band automatic switch-over circuit; Itail1 represents to introduce the work tail current of frequency band automatic switch-over circuit after-current control ring oscillator; I0, I1 ... In represents the output current of each road current source in the switch Control current source circuit respectively; C0, C1 ... Cn represents to be used for the digital logic signal that each road electric current of switch Control current source circuit control opens and closes respectively.Like this, with regard to being equivalent to required reference frequency output a plurality of frequency bands have been divided into, and the slope between each frequency band (being proportional to the slope of Itail0) equates, the VCO approximately equal that gain is that original frequency (is proportional to C0*I0+C1*I1+ ... + Cn*In) difference.An advantage of doing like this is to reduce the gain of VCO, and the ripple on the then onesize control voltage is just little for the output frequency influence of VCO.As Fig. 5 and shown in Figure 11, exemplary output frequency when respectively reference frequency output being divided into two frequency bands and three frequency bands is cut apart schematic diagram, wherein Vmin represents that VCO enters the minimum voltage value in linear work district, and Vmax represents the maximum voltage value that VCO can linear work.Just can make up C0: C1 then by choosing different digital logic signals: ...: Cn can be implemented between each frequency band and switch.
Described switch Control current source circuit is used to produce one or more bias current I0, I1 ... In, it is formed in parallel by one or more current source, the selection of its concrete way can be cut apart according to concrete frequency hop count optimization and obtains, the output current of voltage-current converter (directly related with the input voltage of voltage controlled oscillator) is superimposed with the total bias current of the output current of described switch Control current source circuit as Current Control annular oscillator, the deviation of the intersegmental original frequency of each side frequency that will realize is depended in the selection of the output current of each road current source in the wherein said switch Control current source circuit, should guarantee in each adjacent frequency band in a plurality of frequency bands that this deviation should guarantee to be divided into that the HFS of low-frequency range and the low frequency part of high band have sufficient overlapping frequency part, thereby guarantee can not exist the frequency range of disappearance.
Described frequency band automatic switch-over circuit and switch Control current source circuit are combined, the input control voltage that is used to monitor ring oscillator produces digital logic signal with the opening and closing of Control current source circuit, and automaticallyes switch thereby be implemented between each frequency band.Described automatic switch-over circuit is mainly by being formed by connecting before and after one or more voltage comparators, one or more status latch and the decoding circuit.Wherein, described voltage comparator, be used to discern the frequency range of needs, the optional input ceiling voltage of control voltage of voltage-controlled oscillator, voltage controlled oscillator or the input minimum voltage of voltage controlled oscillator got of its both-end input voltage, the actual selection situation of positive and negative terminal input voltage then depends primarily on the logical signal combination of decoding circuit output, when input voltage is the input ceiling voltage of voltage controlled oscillator or input during minimum voltage, these two voltages can be provided by voltage source independently (as band-gap voltage source etc.); Described status latch is used for filtering because the caused misoperation of the undesired upset of voltage comparator; Described decoding circuit is used for producing the digital logic signal C0 that satisfies the Different Logic combination: C1 according to actual conditions: ...: Cn.As shown in Figure 6, the exemplary block diagram of automatic switch-over circuit when output frequency being divided into two frequency bands.Voltage comparator is a pair of voltage comparator among the figure, and its input voltage is got VCO control voltage Vc respectively and switched reference voltage Vmax, the maximum voltage value when wherein switching reference voltage Vmax and being set to each frequency band work.Decoding circuit shown in passing through like this can be realized when controlling voltage Vc greater than Vmax, this pair voltage comparator is with output signal " 1 ", at this moment the digital logic signal Ctrl of automatic switch-over circuit is output as " 0 ", thereby has realized utilizing power-down signal and ctrl signal 2 the automatic switchover from frequency band 1 to frequency band (power-down=' 0 ' time circuit enter closed condition).Be illustrated in figure 7 as the sequential chart of this embodiment, after energising, frequency band 1 has just been started working as can be known.After control voltage Vc surpasses reference voltage Vref, the comparator upset, thus cutting off frequency band 1, frequency band 2 is started working.
In order to guarantee that each frequency band has high linearity, work tail current Itail0 when promptly being equivalent to will guarantee not introduce automatic switch-over circuit and current source circuit has high linearity, as shown in Figure 8, in current/charge-voltage convertor, introduce an operational amplifier and a resistance R b, the negative input end of described operational amplifier links to each other with the control voltage of VCO, positive input terminal is connected with resistance R b, the other end ground connection of resistance R b.At this moment according to " empty short " characteristic of operational amplifier, can make work tail current Itail0=Vc/Rb, promptly its slope is 1/Rb, therefore can guarantee that output frequency has the good linearity.When add above-mentioned current source circuit and automatic switch-over circuit in current/charge-voltage convertor after, the slope of its each section work tail current also is 1/Rb, so the slope of each frequency band also can keep the good linearity like this.This is an exemplary example, and one of ordinary skill in the art should be known and also can adopt additive method to make frequency band keep high linearity.
Be the structured flowchart that has added frequency synthesizer behind the frequency band automatic switch-over circuit according to of the present invention as shown in Figure 9, come below by two specific embodiments that the invention will be further described.
Be an exemplary circuit configuration figure of the frequency synthesizer when utilizing said method that reference frequency output is divided into two frequency ranges shown in Figure 5 as shown in figure 10.Wherein, switch symbols are used for representing the output control figure logical signal Ctrl of automatic switch-over circuit, are used to turn on and off the output current I0 of current source.In this embodiment, a frequency band automatic switch-over circuit in parallel in the voltage-current converter of VCO includes only a current source in the switch Control current source circuit in this frequency band automatic switch-over circuit.And automatic switch-over circuit mainly is made up of a voltage comparator, a d type flip flop and a decoding circuit is formed.In this embodiment, the anode input of described voltage comparator is held with the LP in the loop filter and is connected, this is because in actual applications, because the shake on the control voltage Vc can cause the variation of the frequency of output immediately, so directly do not use control voltage Vc to carry out voltage ratio usually; And because the C1 in the loop filter is bigger usually, so the shake meeting at LP end place is more much smaller than control voltage Vc, so the voltage with LP end place in the time of is here imported as the anode of voltage comparator, because the voltage of LP end is proportional to control voltage Vc, therefore can not have influence on the direct ratio of frequency and work tail current again.The negative terminal of described voltage comparator is input as reference voltage Vmax, this can guarantee that the switching of frequency band is not misoperation, but the frequency range of working can't provide needed frequency output, so the closed loop of loop is corresponding smoother, and tangible damped oscillation phenomenon can not be arranged.This frequency synthesizer mainly is to open or the cut-off current source by the high-low level of digital logic signal Ctrl in course of normal operation.Therefore, the tail current Itail1 that at this moment works satisfies following formula: Itail1=Vc/Rb+I0*Ctrl, wherein I0 is corresponding to the current value of current source.Therefore can make the operation principle of frequency synthesizer described in the present embodiment as follows by decoding circuit again: if Ctrl=' 0 ', Itail1=Vc/Rb then, then output frequency fout is fully by control voltage Vc control; If Ctrl=' 1 ', then work tail current Itail1=I0 when control voltage Vc=0 represents that promptly the initial frequency of frequency band 2 is non-vanishing.In the circuit diagram of this embodiment, only can realize automatic switchover, and, then must re-power if will revert to low frequency section 1 from high-frequency section 2 from low frequency section 1 to high-frequency section 2.During Vc minimum value that in fact we can consider to arrive less than this frequency band as LP in side circuit design, then switch to next low-frequency range, its design philosophy is followed and switched to high band is the same.Be example with Fig. 6 and Fig. 7 still, when circuit one powers on, when frequency synthesizer can automatically operate in frequency band 2, the switch Ctrl that promptly controls I0 opened, and the tail current of working this moment is Itail1=Itail0+I0; When Vc＜Vmin, voltage comparator output 0, close the switch Ctrl of Control current 10 this moment, is operating current Itail1=Itail0, carries out work thereby frequency synthesizer has switched to frequency band 1 from frequency band 2.
Figure 12 is an exemplary block diagram of the frequency synthesis apparatus when reference frequency output is divided into as shown in figure 11 three frequency ranges.Wherein, two switch symbols are used for representing respectively the output control figure logical signal C0 and the C1 of automatic switch-over circuit, are respectively applied for the output current I0 and the I1 that turn on and off described two current sources.A frequency band automatic switch-over circuit in parallel in the voltage-current converter of this frequency synthesizer, described automatic switch-over circuit in this frequency band automatic switch-over circuit mainly comprises two voltage comparators, two d type flip flops and a decoding circuit, the input voltage of wherein said two voltage comparator positive input terminals is VCO control voltage Vc, also is connected with LP end in the loop filter in order to reduce to shake this positive input terminal; The reference voltage of two voltage comparator negative input end inputs is respectively Vmax and Vmin; Here selected voltage comparator all is the hysteresis voltage comparator, and its hysteresis voltage must remain within certain reasonable range, to realize reaching the purpose that ignorance Vc holds some voltage glitch that may occur.And use the clock signal clk of exporting by VCO to sample and keep the output result of described voltage comparator.Switch Control current source circuit in the described frequency band automatic switch-over circuit is that first current source of I0 and second current source that output current is I1 are formed in parallel by output current then.The break-make of the output current I0 that is respectively applied for control first current source by the control logic signal C0 and the C1 of automatic switch-over circuit output and the output current I1 of second current source, the tail current Itail1 that therefore at this moment works satisfies following formula: Itail1=Vc/Rb+I0*C0+I1*C1.Therefore can make the course of work of the frequency synthesizer in the present embodiment as follows by decoding circuit again: after circuit powered on, this frequency synthesizer at first was operated in frequency band 2, as Vmin＜Vc＜Vmax, promptly can operate as normal in the frequency range of this frequency range.This moment switch Control current source control end C0=1, C1=0, the work tail current of current control oscillator is equivalent to the stack of Itail0 and I0.As Vc＜Vmin, then need to switch to low-frequency range, promptly frequency band 1, and this moment, comparator was output as D0=0, D1=0.The control signal C1=0 in switch Control current source, C0=0, then the two-way additional bias current is all closed, then Itail1=Itail0.Work as Vc〉Vmax, then need to switch to high band, promptly frequency band 3, and this moment, comparator was output as D0=1, D1=1.The control signal C1=1 in switch Control current source, C0=1, then the two-way additional bias current is all opened, then Itail1=Itail0+I0+I1.
By the description of the above-described embodiment and examples, the general designer in this area can realize reference frequency output is divided into three with super band easily, and realizes the concrete application of automatic switchover.
The experiment proved that frequency synthesizer of the present invention utilizes cutting automatically of two frequency bands can realize the frequency output that 24M ~ 220MHz scope is interior, and the representative value of the 1 σ shake (one sigmajitter) of output clock is 25ps.
Claims (9)
1. frequency synthesizer, include loop filter and voltage controlled oscillator, wherein said voltage controlled oscillator is made up of voltage-current converter and Current Control annular oscillator, it is characterized in that, described frequency synthesizer also includes a frequency band automatic switch-over circuit, this circuit is connected in parallel in the described voltage-current converter, is made up of an automatic switch-over circuit and a switch Control current source circuit; Wherein, described switch Control current source circuit is used to produce one or more bias currents (I0, I1 ... In); Described automatic switch-over circuit is used to produce one or more digital logic signals (C0, C1 ... Cn), make the work tail current of described Current Control annular oscillator satisfy following formula: Itail1=Itail0+C0*I0+C1*I1+ ... + Cn*In; Wherein, Itail1 represents to introduce the work tail current of frequency band automatic switch-over circuit after-current control ring oscillator, the work tail current of Current Control annular oscillator when Itial0 represents not introduce the frequency band automatic switch-over circuit; Described digital logic signal (C0, C1 ... Cn) by described automatic switch-over circuit can realize different logical combinations (C0:C1: ...: Cn), described one or more bias currents (I0, I1 that difference control switch Control current source circuit produces ... turning on and off In) is to automatically switch between each frequency band.
2. frequency synthesizer according to claim 1 is characterized in that, described switch Control current source circuit is formed in parallel by one or more current source.
3. frequency synthesizer according to claim 1 is characterized in that, described automatic switch-over circuit is mainly by being formed by connecting before and after one or more voltage comparators, one or more status latch and the decoding circuit; Wherein said voltage comparator is used to discern the frequency range of needs; Status latch is used for filtering because the caused misoperation of the undesired upset of voltage comparator; Decoding circuit be used to produce the digital logic signal that satisfies Different Logic combination (C0:C1: ...: Cn).
4. frequency synthesizer according to claim 1 and 2, it is characterized in that, the deviation of the intersegmental original frequency of each side frequency that will realize is depended in the selection of each road current source output current size in the described switch Control current source circuit, should guarantee in each adjacent frequency band in a plurality of frequency bands that this deviation should guarantee to be divided into that the HFS of low-frequency range and the low frequency part of high band have sufficient overlapping frequency part.
5. according to claim 1 or 3 described frequency synthesizers, it is characterized in that, the optional input ceiling voltage of control voltage of voltage-controlled oscillator, voltage controlled oscillator or the input minimum voltage of voltage controlled oscillator got of the both-end input voltage of described voltage comparator, the actual selection situation of positive and negative terminal input voltage then depend primarily on the logical signal combination of decoding circuit output.
6. frequency synthesizer according to claim 5 is characterized in that, the input ceiling voltage of described voltage controlled oscillator and input minimum voltage are provided by voltage source independently.
7. frequency synthesizer according to claim 5 is characterized in that, in order to reduce shake, control voltage of voltage-controlled oscillator can be replaced the input voltage as described voltage comparator by the voltage that main capacitance anode from loop filter is drawn.
8. according to claim 1 or 3 described frequency synthesizers, it is characterized in that described voltage comparator is the hysteresis voltage comparator.
9. frequency synthesizer according to claim 1 is characterized in that, introduces an operational amplifier and a resistance in described voltage-current converter, is used to guarantee the linearity of described each frequency band.
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102299707A (en) * | 2011-04-27 | 2011-12-28 | 广州润芯信息技术有限公司 | Secondary frequency divider with quadrature phase error correction |
| CN102522984A (en) * | 2011-12-31 | 2012-06-27 | 杭州士兰微电子股份有限公司 | Phase-locked loop and voltage-controlled oscillating circuit thereof |
| CN102571084A (en) * | 2011-12-20 | 2012-07-11 | 上海贝岭股份有限公司 | Low-noise phase-locked loop circuit |
| US8433266B2 (en) | 2009-09-30 | 2013-04-30 | Huawei Technologies Co., Ltd. | Power supply method, apparatus, and system for a radio frequency power amplifier |
| CN106130544A (en) * | 2016-06-15 | 2016-11-16 | 上海兆芯集成电路有限公司 | Automatically band calibration method and system |
| CN108566199A (en) * | 2018-04-24 | 2018-09-21 | 上海玮舟微电子科技有限公司 | A kind of phaselocked loop and control method for frequency |
| CN108768389A (en) * | 2018-04-26 | 2018-11-06 | 清华大学 | A kind of multiband two-stage annular voltage controlled oscillator in phaselocked loop |
| CN110471038A (en) * | 2019-08-16 | 2019-11-19 | 上海英恒电子有限公司 | A kind of Waveform generating method and device of millimetre-wave radar |
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Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8433266B2 (en) | 2009-09-30 | 2013-04-30 | Huawei Technologies Co., Ltd. | Power supply method, apparatus, and system for a radio frequency power amplifier |
| CN102035480B (en) * | 2009-09-30 | 2013-11-06 | 华为技术有限公司 | Power supply method and device and system for radio frequency power amplifier |
| CN102299707A (en) * | 2011-04-27 | 2011-12-28 | 广州润芯信息技术有限公司 | Secondary frequency divider with quadrature phase error correction |
| CN102571084A (en) * | 2011-12-20 | 2012-07-11 | 上海贝岭股份有限公司 | Low-noise phase-locked loop circuit |
| CN102522984A (en) * | 2011-12-31 | 2012-06-27 | 杭州士兰微电子股份有限公司 | Phase-locked loop and voltage-controlled oscillating circuit thereof |
| CN106130544A (en) * | 2016-06-15 | 2016-11-16 | 上海兆芯集成电路有限公司 | Automatically band calibration method and system |
| CN106130544B (en) * | 2016-06-15 | 2021-10-29 | 上海兆芯集成电路有限公司 | Automatic frequency band calibration method and system |
| CN108566199A (en) * | 2018-04-24 | 2018-09-21 | 上海玮舟微电子科技有限公司 | A kind of phaselocked loop and control method for frequency |
| CN108566199B (en) * | 2018-04-24 | 2024-02-20 | 张家港康得新光电材料有限公司 | Phase-locked loop and frequency control method |
| CN108768389A (en) * | 2018-04-26 | 2018-11-06 | 清华大学 | A kind of multiband two-stage annular voltage controlled oscillator in phaselocked loop |
| CN108768389B (en) * | 2018-04-26 | 2020-06-05 | 清华大学 | Multi-band two-stage annular voltage-controlled oscillator for phase-locked loop |
| CN110471038A (en) * | 2019-08-16 | 2019-11-19 | 上海英恒电子有限公司 | A kind of Waveform generating method and device of millimetre-wave radar |
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