CN202004638U - Frequency jittering circuit for switching power supply - Google Patents
Frequency jittering circuit for switching power supply Download PDFInfo
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- CN202004638U CN202004638U CN2010206083679U CN201020608367U CN202004638U CN 202004638 U CN202004638 U CN 202004638U CN 2010206083679 U CN2010206083679 U CN 2010206083679U CN 201020608367 U CN201020608367 U CN 201020608367U CN 202004638 U CN202004638 U CN 202004638U
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Abstract
The utility model relates to a frequency jittering circuit for a switching power supply, which can conveniently change the continuation degree of a difference triangular wave by adjusting the proportion of the sampling capacitance and the integrating capacitance of a full-differential switch capacitance integrator and an input reference voltage value. On the other hand, by the difference triangular wave production circuit, the deviation of the frequency jittering cycle, caused by nonideal effect of the switch, can be eliminated, and the consistence in reduction of chip electromagnetic interference can be improved. Finally, by a system feedback voltage processing circuit, the load condition can be automatically detected, the output frequency and the frequency jittering quantity of the frequency jittering circuit can be adjusted in a self-adaption way, and the very good balance between reduction in the chip electromagnetic interference and maintenance in the stable system can be ensured. The frequency jittering circuit for the switching power supply, disclosed by the utility model has good system stability and high frequency jittering precision.
Description
Technical field
The utility model relates to a kind of frequency jitter circuit that is used for Switching Power Supply.
Background technology
Along with the day of the energy is becoming tight, how the energy is carried out reasonable use more and more put on schedule.Switching Power Supply is with its efficient height, and the advantage that hear rate is little has obtained using widely.Most of electric equipments such as household electrical appliances, hand-hold electronic equipments, industrial control equipment all adopt switching power converters as its power solution.As switch power supply system, a problem of escaping to be unable to do without is its means that adopt clock to move as energy, so electromagnetic interference is the problem that switch power supply system need be paid close attention to.Usually, most of concentration of energy of switching power converters is at the fundamental frequency and the low-order harmonic frequency place of switching frequency, and forms the radiation peak at these frequency places.In order to reduce the outer electromagnetic interference Filter Design difficulty of switching power source chip sheet, reduce electromagnetic interference in the inner method for designing of being correlated with that adopts of switching power source chip usually.
The method of the relatively more normal reduction electromagnetic interference that adopts is frequency jitter at present.The core concept of frequency jitter is that the energy with radiation expands to a relative continuum of states from discrete state, thereby reduces the energy emission peak value.The clock spectrum that does not adopt the frequency jitter method is shown among Fig. 1 101, and the clock spectrum that adopts the frequency jitter method is shown among Fig. 2 102.
The normal at present frequency jitter circuit that adopts is divided into digital control and simulation control.Fig. 3 is a kind of existing numerically controlled frequency jitter circuit.This circuit comprises counter 201, digital to analog converter 202, oscillator 203.Oscillator provides the rolling counters forward pulse.Counter is from 000 ... 00 to 111 ... 11 then to 000 ... 00 cycle count.The output of counter offers digital to analog converter, and the triangular wave that produces one-period produces.The output control generator of digital to analog converter produces the frequency output of shake.The shortcoming of this frequency jitter circuit is that counter quantity is more, and adopts digital to analog converter, need take very big chip area.Have continuity preferably if wish chattering frequency, need to adopt the counter of bigger meter digital number, this has further increased chip area.
The frequency jitter circuit of simulation control often adopts the switching capacity mode to produce the triangular wave of a low frequency.Produce the low frequency triangular wave for 301 modes shown in Figure 4.Because electric capacity 306 discharges and recharges into logarithmic relationship with electric capacity 307, the triangular wave that is produced is an approximate triangular wave.In order to realize the triangular wave of more continuous low frequency, need bigger capacity ratio usually.For 302 modes shown in Figure 5, in order to realize the low frequency triangular wave, need to realize burst pulse that the burst pulse control switch discharges and recharges electric capacity, the frequency accuracy of triangular wave can be affected.For above-mentioned dual mode, all can't avoid switch 303,304,305 channel charge is to the influence of triangular wave frequency accuracy.
The frequency jitter scope of traditional frequency jitter circuit is a fixed value.Under the heavier situation of load, the frequency of Switching Power Supply is higher, and the ratio of the frequency of frequency jitter scope and Switching Power Supply is less at this moment, and the effect of spread spectrum is not so good.Under the lighter situation of load, the frequency of Switching Power Supply is lower, and the ratio of the frequency of frequency jitter scope and Switching Power Supply is bigger at this moment, and the stability of a system is affected.
Therefore, in order to improve the deficiency of legacy frequencies dither circuit.Be necessary to design a kind of frequency jitter circuit of more optimizing to address the above problem.
The utility model content
A kind of frequency jitter circuit that is used for Switching Power Supply that the utility model provides, the stability of a system is good, frequency jitter precision height.
In order to achieve the above object, the utility model provides a kind of frequency jitter circuit that is used for Switching Power Supply, comprises feedback voltage treatment circuit, difference circuit for generating triangular wave, difference commentaries on classics single-end circuit, voltage controlled oscillator that circuit connects.
The input termination feedback voltage of described feedback voltage treatment circuit, output connect the difference circuit for generating triangular wave, difference is changeed single-end circuit, voltage controlled oscillator; The output of described difference circuit for generating triangular wave connects difference changes single-end circuit; The output that described difference is changeed single-end circuit connects voltage controlled oscillator; The output of described voltage controlled oscillator connects the difference circuit for generating triangular wave, and the output clock signal of voltage controlled oscillator.
Described feedback voltage treatment circuit is judged the load condition of Switching Power Supply by detecting feedback voltage, thereby regulates the frequency jitter scope of difference triangular wave.Described difference circuit for generating triangular wave produces the insensitive difference triangular wave output of the non-ideal effects to technogenic influence, switch.Described difference is changeed the voltage output that single-end circuit converts the difference triangular wave to the one-period shake.Described voltage controlled oscillator produces a frequency and the proportional square wave output of input, and the output of voltage controlled oscillator simultaneously drives the difference circuit for generating triangular wave.
Described feedback voltage treatment circuit comprises first comparator, second comparator, first NOR gate, second NOR gate, first switch, second switch, the 3rd switch and the inverter that circuit connects.The input of described feedback voltage treatment circuit comprises system feedback voltage, threshold value 5 and threshold value 6.
When system feedback voltage during greater than threshold value 5 voltages, first switch closure, second switch, the 3rd switch disconnect, and the output of feedback voltage treatment circuit equals the voltage of threshold value 5; When system feedback voltage less than threshold value 5 voltages, and system feedback voltage is during greater than threshold value 6 voltages, the second switch closure, first switch, the 3rd switch disconnect, the output of feedback voltage treatment circuit equals system feedback voltage; When system feedback voltage during less than threshold value 6 voltages, the 3rd switch closure, first switch, second switch disconnect, and the output of feedback voltage treatment circuit equals the voltage of threshold value 6.
First comparator in the described feedback voltage treatment circuit all comprises current source, the first transistor, transistor seconds, the 3rd transistor, the 4th transistor, the 5th transistor, the 6th transistor that circuit is connected with second comparator.
Described the first transistor and transistor seconds are the differential pair tube of common source, its source electrode links to each other with current source, the drain electrode of the first transistor links to each other with the 4th transistor drain with the 3rd transistor, and the drain electrode of transistor seconds links to each other with the 6th transistor drain with the 5th transistor.The 3rd transistor is connected the drain electrode of the first transistor with the 5th transistorized grid.The 4th transistor and the drain electrode of transistor seconds in succession of the 6th transistorized grid.
Described difference circuit for generating triangular wave comprises the four mutually non-overlapping clock generation circuits that circuit connects, fully differential switched-capacitor integrator and integration upset logical circuit.
Four mutually non-overlapping clock generation circuits produce four and have four not overlapping mutually clocks of frequency and phase relation with input clock.The fully differential switched-capacitor integrator is four mutually under the driving of not overlapping clocks and the first upset control clock, the second upset control clock, carries out forward, reverse integral with certain cycle.Integration upset logical circuit produces the first upset control clock, the second upset control clock according to the end output of fully differential switched-capacitor integrator.
Described fully differential switched-capacitor integrator comprises first switch, second switch, the 3rd switch, the 4th switch, the 5th switch, the 6th switch, minion pass, octavo pass, the 9th switch, the tenth switch, the 11 switch, twelvemo pass, first electric capacity, second electric capacity, the 3rd electric capacity, the 4th electric capacity and the fully differential operational amplifier that circuit connects.
First non-overlapping clock control the 5th switch and the 6th switch, the second non-overlapping clock control minion is closed and octavo is closed, the 3rd non-overlapping clock control the 9th switch and the tenth switch, the 4th non-overlapping clock control the 11 switch and twelvemo are closed.When non-overlapping clock is high level, the corresponding switch closure of being controlled.When non-overlapping clock was low level, the corresponding switch of being controlled disconnected.
Described integration upset logical circuit comprises first comparator, second comparator, rest-set flip-flop, first inverter, second inverter that circuit connects.
The negative input end of the positive input terminal of described first comparator and second comparator is connected the triangle wave voltage signal from the fully differential switched-capacitor integrator.The negative input end of first comparator connects voltage VF+K*VF, and the positive input terminal of second comparator connects voltage VF-K*VF.The output of first comparator connects the R end of rest-set flip-flop, and the output of second comparator connects the S end of rest-set flip-flop.The output of rest-set flip-flop connects the input of first inverter, and the output of first inverter connects the input of second inverter.First inverter is output as the first upset control clock, and second inverter is output as the second upset control clock.Voltage VF+K*VF and voltage VF-K*VF are the upper limit of integral and the lower limit of integral of fully differential switched-capacitor integrator.Fully differential switched-capacitor integrator and integration upset logical circuit are formed closed feedback loop.By the adjusting of feedback loop, fully differential switched-capacitor integrator cycle between forward integration and reverse integral switches.In the reverse integral link, the voltage linear of the input of integration upset logical circuit increases, when reaching in limited time, the upset of triggering rest-set flip-flop, the first upset control clock becomes high level from low level, and the second upset control clock becomes low level from high level, enters forward integral element.In forward integral element, the voltage linear of the input of integration upset logical circuit reduces, when reaching down in limited time, the upset of triggering rest-set flip-flop, the first upset control clock becomes low level from high level, and the second upset control clock becomes high level from low level, enters the reverse integral link.
Described difference is changeed single-end circuit and is comprised first resistance, second resistance, the 3rd resistance, the 4th resistance and the operational amplifier that circuit connects.
One end of first resistance, second resistance connects the positive and negative input that difference is changeed single-end circuit.One termination operational amplifier of the other end of first resistance and the 3rd resistance negative input end.The other end of the 3rd resistance links to each other with the output of operational amplifier.The anode of one termination operational amplifier of the other end of second resistance and the 4th resistance.The other end of the 4th resistance connects the output from the feedback voltage treatment circuit.
Described voltage controlled oscillator comprises voltage-controlled current source, first switch that circuit connects, second switch, the 3rd switch, the 4th switch, first electric capacity, second electric capacity, first comparator, second comparator, first inverter, second inverter and rest-set flip-flop.Described voltage-controlled current source produces two proportional electric currents of exporting with difference commentaries on classics single-end circuit of control voltage VC.
First electric current links to each other with the first electric capacity anode through first switch in the voltage controlled oscillator.The negativing ending grounding of first electric capacity.The anode of first electric capacity is through the 3rd switch ground connection.Second electric current links to each other with the second electric capacity anode through second switch in the voltage controlled oscillator.The negativing ending grounding of second electric capacity.The anode of second electric capacity is through the 4th switch ground connection.The anode of first electric capacity and second electric capacity connects the anode of first comparator and second comparator respectively.The negative terminal of first comparator and second comparator fetches the output of self feed back voltage treatment circuit.The output of first comparator and second comparator connects R end, the S end of rest-set flip-flop.The output of rest-set flip-flop connects the input of first inverter.The output of first inverter connects the input of second inverter.First inverter is output as first control signal.Second inverter is output as second control signal.When first control signal is high level, second switch, the 3rd switch closure.When first control signal is low level, second switch, the 3rd switch disconnects.When second control signal is high level, first switch, the 4th switch closure.When second control signal was low level, first switch, the 4th switch disconnected.
Advantage of the present utility model shows: on the one hand, do not need up-down counter and digital to analog converter, saved the chip layout area, by the sampling capacitance of adjusting fully differential switched-capacitor integrator and the ratio and the input reference voltage value of integrating capacitor, can change the continuous degree of difference triangular wave easily.On the other hand, by design difference circuit for generating triangular wave, eliminated because the deviation in the frequency jitter cycle that the switch non-ideal effects is brought has improved the consistency aspect reduction chip electromagnetic interference.At last, by system feedback voltage treatment circuit, detect load state automatically, the output frequency of self adaptation regulating frequency dither circuit and frequency jitter amount are reducing the chip electromagnetic interference and are keeping well compromise of system stability maintenance.
Description of drawings
Fig. 1 is the clock spectrum that does not adopt the frequency jitter method in the background technology;
Fig. 2 is the clock spectrum after the employing frequency jitter method in the background technology;
Fig. 3 is the frequency jitter circuit system of digital control approach in the background technology;
Fig. 4 and Fig. 5 are the frequency jitter circuit systems of analog control mode in the background technology;
Fig. 6 is the frequency jitter circuit structural representation that is used for Switching Power Supply of the present utility model;
Fig. 7 is the circuit diagram of feedback voltage treatment circuit of the present utility model;
Fig. 8 is feedback voltage treatment circuit output waveform of the present utility model and load condition relation curve;
Fig. 9 is the structural representation of difference circuit for generating triangular wave of the present utility model;
Figure 10 is of the present utility model four mutually non-overlapping clock output waveform figures;
Figure 11 is the circuit diagram of fully differential switched-capacitor integrator of the present utility model;
Figure 12 is the circuit diagram of integration upset logical circuit of the present utility model;
Figure 13 is the circuit diagram of of the present utility model four mutually non-overlapping clock generation circuits with Figure 14;
Figure 15 is the circuit diagram that difference of the present utility model is changeed single-end circuit;
Figure 16 is the circuit diagram of voltage controlled oscillator of the present utility model;
Figure 17 is the oscillogram of voltage controlled oscillator V1 of the present utility model, V2, Q3 and Q4;
Figure 18 is the circuit diagram of comparator of the present utility model;
Figure 19 is average frequency and the load condition relation curve that is used for the frequency jitter circuit clock output of Switching Power Supply of the present utility model;
Figure 20 is the ratio and the load condition relation curve of the average frequency of the frequency jitter scope of the frequency jitter circuit that is used for Switching Power Supply of the present utility model and clock output.
Embodiment
Following according to Fig. 6～Figure 20, specify preferred embodiment of the present utility model:
As shown in Figure 6, be the frequency jitter circuit structural representation that is used for Switching Power Supply of the present utility model, this frequency jitter circuit comprises feedback voltage treatment circuit 401, difference circuit for generating triangular wave 402, difference commentaries on classics single-end circuit 403, the voltage controlled oscillator 404 that circuit connects.
The input termination feedback voltage of described feedback voltage treatment circuit 401, output connect difference circuit for generating triangular wave 402, difference is changeed single-end circuit 403, voltage controlled oscillator 404; The output of described difference circuit for generating triangular wave 402 connects difference changes single-end circuit 403; The output that described difference is changeed single-end circuit 403 connects voltage controlled oscillator 404; The output of described voltage controlled oscillator 404 connects difference circuit for generating triangular wave 402, and the output clock signal of voltage controlled oscillator 404.
Described feedback voltage treatment circuit 401 is judged the load condition of Switching Power Supply by detecting feedback voltage, thereby regulates the frequency jitter scope of difference triangular wave.Described difference circuit for generating triangular wave 402 produces the insensitive difference triangular wave output of the non-ideal effects to technogenic influence, switch.Described difference is changeed the voltage output that single-end circuit 403 converts the difference triangular wave to the one-period shake.Described voltage controlled oscillator 404 produces a frequency and the proportional square wave output of input, and the output of voltage controlled oscillator 404 simultaneously drives difference circuit for generating triangular wave 402.
As shown in Figure 7, described feedback voltage treatment circuit 401 comprises first comparator 1101, second comparator 1102, first NOR gate 1104, second NOR gate 1105, first switch 1106, second switch 1107, the 3rd switch 1108 and the inverter 1103 that circuit connects.The input of described feedback voltage treatment circuit comprises system feedback voltage VFB, threshold value 5 vth5 and threshold value 6 vth6.
As system feedback voltage VFB during greater than threshold value 5 voltage vth5, first switch, 1106 closures, second switch 1107, the 3rd switch 1108 disconnect, and the output VF of feedback voltage treatment circuit 401 equals the voltage vth5 of threshold value 5; When system feedback voltage VFB less than threshold value 5 voltage vth5, and system feedback voltage VFB is during greater than threshold value 6 voltage vth6, second switch 1107 closures, first switch 1106, the 3rd switch 1108 disconnect, and the output VF of feedback voltage treatment circuit 401 equals system feedback voltage VFB; As system feedback voltage VFB during less than threshold value 6 voltage vth6, the 3rd switch 1108 closures, first switch 1106, second switch 1107 disconnect, and the output VF of feedback voltage treatment circuit 401 equals the voltage vth6 of threshold value 6.The waveform of output VF waveform under the different loads situation of feedback voltage treatment circuit 401 as shown in Figure 8.
As shown in figure 18, first comparator 1101 in the described feedback voltage treatment circuit 401 all comprises current source 1301, the first transistor 1302, transistor seconds 1303, the 3rd transistor 1304, the 4th transistor 1305, the 5th transistor 1306, the 6th transistor 1307 that circuit is connected with second comparator 1102.
Described the first transistor 1302 and transistor seconds 1303 are the differential pair tube of common source, its source electrode links to each other with current source 1301, the drain electrode of the first transistor 1302 links to each other with the drain electrode of the 3rd transistor 1304 and the 4th transistor 1305, and the drain electrode of transistor seconds 1303 links to each other with the drain electrode of the 5th transistor 1306 and the 6th transistor 1307.The 3rd transistor 1304 is connected the drain electrode of the first transistor 1302 with the grid of the 5th transistor 1306.The drain electrode of transistor seconds 1303 in succession of the grid of the 4th transistor 1305 and the 6th transistor 1307.
As shown in Figure 9, described difference circuit for generating triangular wave comprises the four mutually non-overlapping clock generation circuits 501 that circuit connects, fully differential switched-capacitor integrator 502 and integration upset logical circuit 503.
Four mutually non-overlapping clock generation circuits 501 produce four and have four not overlapping mutually clock P1, P2, P3 and the P4 of frequency and phase relation with input clock.Fully differential switched-capacitor integrator 502 is four mutually under the driving of not overlapping clock P1, P2, P3, P4 and the first upset control clock Q1, the second upset control clock Q2, carries out forward, reverse integral with certain cycle.Integration upset logical circuit 503 produces the first upset control clock Q1, the second upset control clock Q2 according to the end output of fully differential switched-capacitor integrator 502.
Four mutually not the phase relation of overlapping clock as shown in figure 10, the trailing edge Δ T1 time of second phase clock of leading first beat of trailing edge of first phase clock of first beat of output.The third phase rising edge clock Δ T2 time of leading first beat of trailing edge of second phase clock of first beat.The 4th phase clock rising edge Δ T3 time of leading first beat of trailing edge of second phase clock of first beat.The 4th phase clock trailing edge Δ T4 time of leading first beat of third phase clock trailing edge of first beat.The first phase clock Δ T5 time of leading second beat of the 4th phase clock trailing edge of first beat.The second phase clock Δ T6 time of leading second beat of the 4th phase clock trailing edge of first beat.
As shown in figure 13, be first embodiment of four mutually non-overlapping clock generation circuits 501, this four mutually non-overlapping clock generation circuit 501 comprises inverter 1401, first NOR gate 1402, second NOR gate 1403, first delay cell 1404, second delay cell 1405, the 3rd delay cell 1406 and the 4th delay cell 1407 that circuit connects.Input clock is CLK, and the not overlapping clock of four phases of output is the not overlapping clock P1 of the one or four phase, the two or four not overlapping clock P2, the not overlapping clock P3 of the three or four phase, the not overlapping clock P4 of the four or four phase mutually.
As shown in figure 14, be second embodiment of four mutually non-overlapping clock generation circuits 501, this four mutually non-overlapping clock generation circuit 501 comprises frequency divider 1501, inverter 1502, first NOR gate 1503, second NOR gate 1504, first delay cell 1505, second delay cell 1506, the 3rd delay cell 1507, the 4th delay cell 1508, the 5th delay cell 1509, the 6th delay cell 1510 that circuit connects.Input clock is CLK, and the not overlapping clock of four phases of output is the not overlapping clock P1 of the one or four phase, the two or four not overlapping clock P2, the not overlapping clock P3 of the three or four phase, the not overlapping clock P4 of the four or four phase mutually.
As shown in figure 11, described fully differential switched-capacitor integrator 502 comprises first switch 701, second switch 702, the 3rd switch 703, the 4th switch 704, the 5th switch 705, the 6th switch 706, minion pass 707, octavo pass the 708, the 9th switch 709, the tenth switch the 710, the 11 switch 711, twelvemo pass 712, first electric capacity 713, second electric capacity 714, the 3rd electric capacity 715, the 4th electric capacity 716 and the fully differential operational amplifier 717 that circuit connects.The first input voltage V1, the second input voltage V2, the 3rd input voltage V3 three's pass is: V3-V1=V1-V2.
The first non-overlapping clock P1 controls the 5th switch 705 and the 6th switch 706, the second non-overlapping clock P2 controls minion pass 707 and octavo closes 708, the 3rd non-overlapping clock P3 controls the 9th switch 709 and the tenth switch 710, the four non-overlapping clock P4 control the 11 switch 711 and twelvemo closes 712.When non-overlapping clock is high level, the corresponding switch closure of being controlled.When non-overlapping clock was low level, the corresponding switch of being controlled disconnected.When clock P1 and clock P2 are high level, the the 5th, the 6th, the 7th, octavo close closed, to first, second electric capacity charging.Next under clock P3 and clock P4 control, the 9th switch, the tenth switch, the 11 switch, twelvemo are closed closed, and the electric charge that is stored in first, second electric capacity is transferred to the 3rd, the 4th electric capacity.The leading clock P2 of clock P1 closes, and has only the channel charge of the 5th switch 705 and the 6th switch 706 that there is the electric charge contribution in first and second electric capacity.According to the characteristic of fully-differential amplifier, under negative feedback, the voltage of node A and Node B is V1.Because the 5th switch 705 and the 6th switch 706 are switches of symmetry, therefore the 5th switch 705 and the 6th switch 706 are the common mode influences to the influence of first and second electric capacity.In like manner, the 9th switch 709 and the tenth switch 710 also are the common mode influences to the influence of third and fourth electric capacity.According to the characteristic of fully-differential amplifier, the common mode influence can not bring influence to the output of difference triangular wave.
As shown in figure 12, described integration upset logical circuit 503 comprises first comparator 801, second comparator 802, rest-set flip-flop 803, first inverter 804, second inverter 805 that circuit connects.
The negative input end of the positive input terminal of described first comparator 801 and second comparator 802 is connected the triangle wave voltage signal from fully differential switched-capacitor integrator 502.The negative input end of first comparator 801 connects voltage VF+K*VF, and the positive input terminal of second comparator 802 connects voltage VF-K*VF.The output of first comparator 801 connects the R end of rest-set flip-flop 803, and the output of second comparator 802 connects the S end of rest-set flip-flop 803.The output of rest-set flip-flop 803 connects the input of first inverter 804, and the output of first inverter 804 connects the input of second inverter 805.First inverter 804 is output as the first upset control clock Q1, and second inverter 805 is output as the second upset control clock Q2.Voltage VF+K*VF and voltage VF-K*VF are the upper limit of integral and the lower limit of integral of fully differential switched-capacitor integrator.Fully differential switched-capacitor integrator 502 and integration upset logical circuit 503 are formed closed feedback loop.By the adjusting of feedback loop, fully differential switched-capacitor integrator 502 cycle between forward integration and reverse integral switches.In the reverse integral link, the voltage linear of the input of integration upset logical circuit 503 increases, when reaching in limited time, trigger rest-set flip-flop 803 upsets, the first upset control clock Q1 becomes high level from low level, the second upset control clock Q2 becomes low level from high level, enters forward integral element.In forward integral element, the voltage linear of the input of integration upset logical circuit 503 reduces, when reaching down in limited time, trigger rest-set flip-flop 803 upsets, the first upset control clock Q1 becomes low level from high level, the second upset control clock Q2 becomes high level from low level, enters the reverse integral link.
The difference triangular wave cycle that described difference circuit for generating triangular wave 402 produces is:
Wherein, T is difference triangle wave period, T
ClkBe the input clock cycle of four mutually non-overlapping clocks, C2 is the appearance value of the 3rd electric capacity 715, the 4th electric capacity 716, and C1 is the appearance value of first electric capacity 713, second electric capacity 714.
The non-ideal effects that described difference circuit for generating triangular wave 402 can be eliminated switch shows, the 9th switch, the tenth switch, the 11 switch, twelvemo are closed and are the fully differential switch, the switch non-ideal effects is the contribution of common mode electric charge, differential charge contribution to the electric charge contribution of third and fourth electric capacity.Triangle is only relevant with difference component wave period.
As shown in figure 15, described difference is changeed first resistance 901, second resistance 902, the 3rd resistance 903, the 4th resistance 904 and the operational amplifier 905 that single-end circuit 403 comprises the circuit connection.
One end of first resistance 901, second resistance 902 connects the positive and negative input that difference is changeed single-end circuit.One termination operational amplifier 905 of the other end of first resistance 901 and the 3rd resistance 903 negative input end.The other end of the 3rd resistance 903 links to each other with the output of operational amplifier 905.The anode of one termination operational amplifier 905 of the other end of second resistance 902 and the 4th resistance 904.The other end of the 4th resistance 904 connects the output from feedback voltage treatment circuit 401.
The reference voltage of single-end circuit 403 is changeed in the output of feedback voltage treatment circuit 401 as difference.Described difference is changeed the output of single-end circuit 403 and the pass of input is:
Wherein, Vout is the output that difference is changeed single-end circuit, Inp is the positive input that difference is changeed single-end circuit, Inn is the negative input that difference is changeed single-end circuit, R2 is the resistance of the 3rd resistance 903 and the 4th resistance 904, R1 is the resistance of second resistance 902 and the 3rd resistance 903, and VF is the output voltage from feedback voltage treatment circuit 401.
As shown in figure 16, described voltage controlled oscillator 404 comprises voltage-controlled current source 1001, first switch 1002 that circuit connects, second switch 1003, the three switches 1004, the four switches 1005, first electric capacity 1006, second electric capacity, 1007, the first comparators, 1008, the second comparators 1009, first inverter, 1010, the second inverters 1011 and rest-set flip-flop 1012.Described voltage-controlled current source 1001 produces two proportional electric currents of exporting with difference commentaries on classics single-end circuit of control voltage VC.Described current relationship is described below:
?…………………… （3）
Wherein, I
1Be first electric current, I
2Be second electric current, VC is control voltage, K
C1Be the voltage controlled current gain of first electric current, K
C2It is the voltage controlled current gain of second electric current.
First electric current I in the voltage controlled oscillator 404
1Link to each other with first electric capacity, 1006 anodes through first switch 1002.The negativing ending grounding of first electric capacity 1006.The anode of first electric capacity 1006 is through the 3rd switch 1004 ground connection.Second electric current I in the voltage controlled oscillator 404
2Link to each other with second electric capacity, 1007 anodes through second switch 1003.The negativing ending grounding of second electric capacity 1007.The anode of second electric capacity 1007 is through the 4th switch 1005 ground connection.The anode of first electric capacity 1006 and second electric capacity 1007 connects the anode of first comparator 1008 and second comparator 1009 respectively.The negative terminal of first comparator 1008 and second comparator 1009 fetches the VF of self feed back voltage treatment circuit.The output of first comparator 1008 and second comparator 1009 connects R end, the S end of rest-set flip-flop 1012.The output of rest-set flip-flop 1012 connects the input of first inverter 1010.The output of first inverter 1010 connects the input of second inverter 1011.First inverter 1010 is output as the first control signal Q3.Second inverter 1011 is output as the second control signal Q4.When the first control signal Q3 is high level, second switch 1003, the three switches 1004 closures.When the first control signal Q3 was low level, second switch 1003, the three switches 1004 disconnected.When the second control signal Q4 is high level, first switch 1002, the 4th switch 1005 closures.When the second control signal Q4 was low level, first switch 1002, the 4th switch 1005 disconnected.The waveform of electric capacity V2 and the second control signal Q4 and the first control signal Q3 is as shown in figure 17 on the voltage V1 and second electric capacity 1007 on first electric capacity 1006.The output clock cycle of described voltage controlled oscillator 404 is described below:
…………………… （5）
Wherein, T
ClkBe the output clock cycle of voltage controlled oscillator 404, C
VCO1Be the appearance value of first electric capacity 1006 of voltage controlled oscillator, C
VCO2Be the appearance value of second electric capacity 1007 of voltage controlled oscillator, K
C1First electric current I for voltage controlled oscillator
1Voltage controlled current gain, K
C2Second electric current I for voltage controlled oscillator
2Voltage controlled current gain, VF is the output voltage from the feedback voltage treatment circuit, Vout is the output voltage that changes single-end circuit from difference.
Comprehensively above-mentioned (1)～(5) formula, and in a frequency jitter cycle, quadraturing, another that can obtain the difference triangular wave cycle is described below:
The frequency jitter amount of voltage controlled oscillator and the average frequency of voltage controlled oscillator be according to amplitude and (2) formula of difference triangular wave, provides to be described below:
Wherein,
Be the frequency jitter amount of voltage controlled oscillator,
Average frequency for voltage controlled oscillator.
The average frequency of described frequency jitter circuit output with the change curve of load as shown in figure 19.
Be the average frequency of frequency jitter circuit output, f
MaxBe the maximum average frequency of frequency jitter circuit output, f
MinMinimum average B configuration frequency for frequency jitter circuit output.
The frequency jitter scope of described frequency jitter circuit and average frequency are with the change curve of the ratio of load as shown in figure 20.R represents the ratio of frequency jitter scope and average frequency.When changing appearred in load, the ratio of frequency jitter scope and average frequency remained unchanged.Therefore, when reducing electromagnetic interference preferably, kept the good stability of a system.
Although content of the present utility model has been done detailed introduction by above preferred embodiment, will be appreciated that above-mentioned description should not be considered to restriction of the present utility model.After those skilled in the art have read foregoing, for multiple modification of the present utility model with to substitute all will be conspicuous.Therefore, protection range of the present utility model should be limited to the appended claims.
Claims (10)
1. frequency jitter circuit that is used for Switching Power Supply, it is characterized in that this frequency jitter circuit comprises feedback voltage treatment circuit (401), difference circuit for generating triangular wave (402), difference commentaries on classics single-end circuit (403), the voltage controlled oscillator (404) that circuit connects;
The input termination feedback voltage of described feedback voltage treatment circuit (401), output connect difference circuit for generating triangular wave (402), difference is changeed single-end circuit (403), voltage controlled oscillator (404); The output of described difference circuit for generating triangular wave (402) connects difference changes single-end circuit (403); The output that described difference is changeed single-end circuit (403) connects voltage controlled oscillator (404); The output of described voltage controlled oscillator (404) connects difference circuit for generating triangular wave (402), and the output clock signal of voltage controlled oscillator (404).
2. the frequency jitter circuit that is used for Switching Power Supply as claimed in claim 1, it is characterized in that, described feedback voltage treatment circuit (401) comprises first comparator (1101), second comparator (1102), first NOR gate (1104), second NOR gate (1105), first switch (1106), second switch (1107), the 3rd switch (1108) and the inverter (1103) that circuit connects, the input of described feedback voltage treatment circuit comprises system feedback voltage (VFB), threshold value 5 (vth5) and threshold value 6 (vth6).
3. the frequency jitter circuit that is used for Switching Power Supply as claimed in claim 2, it is characterized in that first comparator (1101) in the described feedback voltage treatment circuit (401) all comprises current source (1301), the first transistor (1302), transistor seconds (1303), the 3rd transistor (1304), the 4th transistor (1305), the 5th transistor (1306), the 6th transistor (1307) that circuit is connected with second comparator (1102);
Described the first transistor (1302) and transistor seconds (1303) are the differential pair tube of common source, its source electrode links to each other with current source (1301), the drain electrode of the first transistor (1302) links to each other with the drain electrode of the 3rd transistor (1304) with the 4th transistor (1305), and the drain electrode of transistor seconds (1303) links to each other with the drain electrode of the 5th transistor (1306) with the 6th transistor (1307);
The 3rd transistor (1304) is connected the drain electrode of the first transistor (1302) with the grid of the 5th transistor (1306);
The grid of the 4th transistor (1305) and the 6th transistor (1307) is the drain electrode of transistor seconds (1303) in succession.
4. the frequency jitter circuit that is used for Switching Power Supply as claimed in claim 1, it is characterized in that, described difference circuit for generating triangular wave (402) comprises the four mutually non-overlapping clock generation circuits (501) that circuit connects, fully differential switched-capacitor integrator (502) and integration upset logical circuit (503).
5. frequency jitter circuit as claimed in claim 4, it is characterized in that, described four mutually non-overlapping clock generation circuits (501) comprise the inverter (1401) that circuit connects, first NOR gate (1402), second NOR gate (1403), first delay cell (1404), second delay cell (1405), the 3rd delay cell (1406) and the 4th delay cell (1407), input clock is CLK, and the not overlapping clock of four phases of output is the one or four phase not overlapping clock (P1), the two or four phase not overlapping clock (P2), the three or four phase not overlapping clock (P3), the four or four phase not overlapping clock (P4).
6. the frequency jitter circuit that is used for Switching Power Supply as claimed in claim 4, it is characterized in that, described four mutually non-overlapping clock generation circuits (501) comprise the frequency divider (1501) that circuit connects, inverter (1502), first NOR gate (1503), second NOR gate (1504), first delay cell (1505), second delay cell (1506), the 3rd delay cell (1507), the 4th delay cell (1508), the 5th delay cell (1509), the 6th delay cell (1510), input clock is CLK, and the not overlapping clock of four phases of output is the one or four phase not overlapping clock (P1), the two or four phase not overlapping clock (P2), the three or four phase not overlapping clock (P3), the four or four phase not overlapping clock (P4).
7. the frequency jitter circuit that is used for Switching Power Supply as claimed in claim 4, it is characterized in that, described fully differential switched-capacitor integrator (502) comprises first switch (701) that circuit connects, second switch (702), the 3rd switch (703), the 4th switch (704), the 5th switch (705), the 6th switch (706), minion is closed (707), octavo is closed (708), the 9th switch (709), the tenth switch (710), the 11 switch (711), twelvemo is closed (712), first electric capacity (713), second electric capacity (714), the 3rd electric capacity (715), the 4th electric capacity (716) and fully differential operational amplifier (717), first input voltage (V1), second input voltage (V2), the 3rd input voltage (V3) three's pass is: V3-V1=V1-V2.
8. the frequency jitter circuit that is used for Switching Power Supply as claimed in claim 4, it is characterized in that described integration upset logical circuit (503) comprises first comparator (801), second comparator (802), rest-set flip-flop (803), first inverter (804), second inverter (805) that circuit connects;
The negative input end of the positive input terminal of described first comparator (801) and second comparator (802) is connected the triangle wave voltage signal from fully differential switched-capacitor integrator (502), the negative input end of first comparator (801) connects voltage VF+K*VF, the positive input terminal of second comparator (802) connects voltage VF-K*VF, the output of first comparator (801) connects the R end of rest-set flip-flop (803), the output of second comparator (802) connects the S end of rest-set flip-flop (803), the output of rest-set flip-flop (803) connects the input of first inverter (804), the output of first inverter (804) connects the input of second inverter (805), first inverter (804) is output as the first upset control clock (Q1), and second inverter (805) is output as the second upset control clock (Q2).
9. the frequency jitter circuit that is used for Switching Power Supply as claimed in claim 1, it is characterized in that described difference is changeed single-end circuit (403) and comprised first resistance (901), second resistance (902), the 3rd resistance (903), the 4th resistance (904) and the operational amplifier (905) that circuit connects;
One end of first resistance (901), second resistance (902) connects the positive and negative input that difference is changeed single-end circuit, the negative input end of one termination operational amplifier (905) of the other end of first resistance (901) and the 3rd resistance (903), the other end of the 3rd resistance (903) links to each other with the output of operational amplifier (905), the anode of one termination operational amplifier (905) of the other end of second resistance (902) and the 4th resistance (904), the other end of the 4th resistance (904) connects the output from feedback voltage treatment circuit (401).
10. the frequency jitter circuit that is used for Switching Power Supply as claimed in claim 1, it is characterized in that, described voltage controlled oscillator (404) comprises the voltage-controlled current source (1001) that circuit connects, first switch (1002), second switch (1003), the 3rd switch (1004), the 4th switch (1005), first electric capacity (1006), second electric capacity (1007), first comparator (1008), second comparator (1009), first inverter (1010), second inverter (1011) and rest-set flip-flop (1012), described voltage-controlled current source (1001) produce two proportional electric currents of exporting with difference commentaries on classics single-end circuit of control voltage VC;
First electric current (I in the voltage controlled oscillator (404)
1) link to each other with first electric capacity (1006) anode through first switch (1002), the negativing ending grounding of first electric capacity (1006), the anode of first electric capacity (1006) be through the 3rd switch (1004) ground connection, second electric current (I in the voltage controlled oscillator (404)
2) link to each other with second electric capacity (1007) anode through second switch (1003), the negativing ending grounding of second electric capacity (1007), the anode of second electric capacity (1007) is through the 4th switch (1005) ground connection, the anode of first electric capacity (1006) and second electric capacity (1007) connects the anode of first comparator (1008) and second comparator (1009) respectively, the negative terminal of first comparator (1008) and second comparator (1009) fetches (VF) of self feed back voltage treatment circuit, the output of first comparator (1008) and second comparator (1009) connects the R end of rest-set flip-flop (1012), the S end, the output of rest-set flip-flop (1012) connects the input of first inverter (1010), the output of first inverter (1010) connects the input of second inverter (1011), first inverter (1010) is output as first control signal (Q3), and second inverter (1011) is output as second control signal (Q4).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010206083679U CN202004638U (en) | 2010-11-16 | 2010-11-16 | Frequency jittering circuit for switching power supply |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010206083679U CN202004638U (en) | 2010-11-16 | 2010-11-16 | Frequency jittering circuit for switching power supply |
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| Publication Number | Publication Date |
|---|---|
| CN202004638U true CN202004638U (en) | 2011-10-05 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2010206083679U Expired - Fee Related CN202004638U (en) | 2010-11-16 | 2010-11-16 | Frequency jittering circuit for switching power supply |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102025265A (en) * | 2010-11-16 | 2011-04-20 | 灿芯半导体(上海)有限公司 | Frequency jittering circuit |
| CN103780228A (en) * | 2014-01-16 | 2014-05-07 | 华为技术有限公司 | Clock jitter improving circuit and method |
| CN113776418A (en) * | 2021-09-15 | 2021-12-10 | 连云港杰瑞电子有限公司 | LVDT conversion circuit and method of single-chip fully differential structure |
| CN117614260A (en) * | 2024-01-22 | 2024-02-27 | 深圳市国电科技通信有限公司 | Frequency dithering circuit of self-adaptive power supply switching frequency, power supply and management chip thereof |
-
2010
- 2010-11-16 CN CN2010206083679U patent/CN202004638U/en not_active Expired - Fee Related
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102025265A (en) * | 2010-11-16 | 2011-04-20 | 灿芯半导体(上海)有限公司 | Frequency jittering circuit |
| CN102025265B (en) * | 2010-11-16 | 2013-08-21 | 灿芯半导体(上海)有限公司 | Frequency jittering circuit |
| CN103780228A (en) * | 2014-01-16 | 2014-05-07 | 华为技术有限公司 | Clock jitter improving circuit and method |
| CN103780228B (en) * | 2014-01-16 | 2016-11-23 | 华为技术有限公司 | A kind of clock jitter improves circuit and method |
| CN113776418A (en) * | 2021-09-15 | 2021-12-10 | 连云港杰瑞电子有限公司 | LVDT conversion circuit and method of single-chip fully differential structure |
| CN113776418B (en) * | 2021-09-15 | 2024-02-09 | 连云港杰瑞电子有限公司 | LVDT conversion circuit and method of single-chip full-differential structure |
| CN117614260A (en) * | 2024-01-22 | 2024-02-27 | 深圳市国电科技通信有限公司 | Frequency dithering circuit of self-adaptive power supply switching frequency, power supply and management chip thereof |
| CN117614260B (en) * | 2024-01-22 | 2024-04-02 | 深圳市国电科技通信有限公司 | Frequency dithering circuit of self-adaptive power supply switching frequency, power supply and management chip thereof |
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| C14 | Grant of patent or utility model | ||
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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: 20111005 Termination date: 20161116 |