CN102142815A - Class-D-based multi-power supply switching modulation method and circuit - Google Patents
Class-D-based multi-power supply switching modulation method and circuit Download PDFInfo
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- CN102142815A CN102142815A CN2010102231498A CN201010223149A CN102142815A CN 102142815 A CN102142815 A CN 102142815A CN 2010102231498 A CN2010102231498 A CN 2010102231498A CN 201010223149 A CN201010223149 A CN 201010223149A CN 102142815 A CN102142815 A CN 102142815A
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Abstract
The invention provides a Class-D-based multi-power supply switching modulation method and a Class-D-based multi-power supply switching modulation circuit. The method comprises the following steps of: providing a group of low power supplies and keeping low power supply before output power reaches the maximal output power which can be supported by the low power supply; providing a group of high power supplies and switching to high power supply when the output power reaches a maximum value which can be provided by the low power supplies; judging whether an input sound source amplitude value exceeds the power supply capacity of the low power supplies to switch the low power supplies and the high power supplies; and dynamically switching the amplitudes of a triangular wave, wherein two groups of the amplitudes of the triangular wave are in a proportional relation with the voltages of the low power supplies and the high power supplies respectively. Due to the adoption of the multi-power supply audio modulation method and the multi-power supply audio modulation circuit, high output power and high linearity can be provided under the condition of limited power supply voltage, and detection and judgment can be performed in each period of inputting audio signals so as to determine whether the high-power supplies need to be switched for supplying power in the high-amplitude value part of each period to make a system reach maximum work efficiency.
Description
Technical field
The audio power that the present invention relates in the microelectronic field of analog integrated circuit amplifies modulator approach and circuit, specifically, the present invention relates to a kind ofly under the environment of low voltage power supply, switch modulator approaches and circuit for audio frequency output provides many power supplys of bigger power output and better tonequality.
Background technology
In handheld device, adopt lithium battery power supply usually, the cell voltage working range is between 3.5V to 4.2V, common audio frequency power amplifier chip is at this operation at low power supply voltage, the peak power output that can provide is subjected to the restriction of supply voltage, and can be because excessive the causing of source of sound amplitude exported serious distortion.
In order to address the above problem, existing a kind of scheme adopts charge pump to cooperate the framework of Class-AB to reach high-output power, and has improved the excessive problem of dtmf distortion DTMF that causes of source of sound amplitude, and this framework is called as Class-G class audio frequency power amplifier.
But the framework of Class-G is used also existing problems in handheld device: handheld device is very responsive for power consumption and efficient, and limited by volume, and the internal heat dissipating environment is also relatively harsher.The efficient of Class-AB class self is very low, is multiplied by the efficient of charge pump self again, causes the efficient of Class-G relatively poor, and average efficiency only has about 35%, so efficient and heat radiation cause the application of Class-G in handheld device to be restricted.
Correspondingly, existing C lass-D technology also has problems.Be illustrated in figure 1 as a kind of PWM modulation circuit structure of existing Class-D technology, comprise triangular wave generation module 101, pwm signal generation module 102, input source of sound 103, driving tube control module 104, output PMOS driving tube 105, load 106.Modulation produces pwm signal to this PWM modulation circuit to input signal by triangular wave, and pwm signal enters driving tube control module 104 back generation disjoint signals and drives PMOS efferent duct and NMOS efferent duct respectively, obtains output signal at last and drives the loudspeaker even load.
Be illustrated in figure 2 as the PWM modulation legend of prior art, wherein 201 is the input source of sound, and 202 is the pwm signal that obtains after triangular wave is modulated with the input source of sound.As shown in Figure 2, along with the source of sound amplitude increases, the high impulse duty ratio of pwm signal can increase in proportion.
As shown in Figure 3, in existing Class-D technology, the source of sound amplitude is bigger when importing, and distortion will appear in the pwm signal that obtains after the modulation.301 are the input source of sound, and 302 are the corresponding pwm signal that obtains after the source of sound modulation of importing.As seen from the figure, the source of sound amplitude is bigger when importing, surpassed the scope that supply voltage is supported, distortion can appear in the pwm signal of output, promptly in the appearance early of higher its corresponding pwm signal of part of source of sound amplitude 100% duty ratio, after 100% duty ratio occurring, pwm signal can't continue to embody 301 input amplitude and change, distortion promptly occurred, peak power output is also limited by supply voltage simultaneously.
Summary of the invention
Purpose of the present invention provides a kind of many power supplys audio modulation method and circuit based on Class-D, be subjected to the restriction of supply voltage with the peak power output that overcomes present audio frequency power amplifier chip, and can be because the excessive technical problem that causes the serious distortion of output of source of sound amplitude.
For achieving the above object, technical scheme of the present invention is as follows:
A kind of many power supplys based on Class-D switch modulator approach, comprise the steps: to provide one group low power supply, keep low power supply power supply when power output reaches before the peak power output that low power supply power supply can be supported; One group of high power supply is provided, after power output has reached the available maximum of low power supply, switches to high power supply power supply; Judge whether input source of sound amplitude surpasses the power supply capacity of low power supply to switch low power supply and high power supply; And the amplitude of dynamically switching triangular wave, two groups of amplitudes of this triangular wave respectively with low power supply, the proportional relation of high power source voltage.
A kind of many power supplys based on Class-D switch modulation circuit, comprising: low power supply kept low power supply power supply when power output reaches before the peak power output that low power supply power supply can be supported; High power supply after power output has reached the available maximum of low power supply, switches to high power supply power supply; With the switch driving circuit that described high power supply, low power supply link to each other by driving tube respectively, realize the control of the open and close of the driving tube under the different electrical power voltage; The circuit for generating triangular wave that one amplitude can dynamically be switched, two groups of amplitudes of this triangular wave respectively with driving tube on two groups of proportional relations of supply voltage, produce pwm signal, the duty ratio of this pwm signal and the proportional relation of the supply voltage on the driving tube by this triangular wave and input signal modulation back; The one input source of sound amplitude detection circuit that links to each other with described switch driving circuit, the cut-in timing of determining high power supply in each cycle by this circuit with cut out the time.
Adopt above-mentioned many power supplys audio modulation method and circuit, can under limited supply voltage condition, provide bigger power output, and can all detect and judge in each cycle of input audio signal, determine whether the high-amplitude value part in each cycle needs to switch high power supply power supply.
Description of drawings
Fig. 1 is the electrical block diagram of a kind of PWM modulation of existing Class-D technology;
Fig. 2 is the PWM modulation schematic diagram of prior art;
Fig. 3 is bigger when importing the source of sound amplitude, and the schematic diagram of distortion appears in prior art PWM modulation;
Fig. 4 is bigger when importing the source of sound amplitude, and many power supplys switch the modulation schematic diagrames among the present invention;
Fig. 5 is the electrical block diagram that efferent duct control cooperates with many power supply modulation of the present invention;
Fig. 6 is the concern schematic diagram of intermediate cam wave amplitude of the present invention with power supply;
Fig. 7 is that intermediate cam ripple of the present invention produces pwm signal switching schematic diagram with the input signal modulation;
Fig. 8 is a driving tube control section schematic diagram among the present invention;
Fig. 9 is a source of sound amplitude detection schematic diagram among the present invention;
Figure 10 is at typical music signal, and framework of the present invention can obtain the greater efficiency schematic diagram;
Figure 11 is an intermediate cam wave generation circuit schematic diagram of the present invention;
Figure 12 is that intermediate cam ripple of the present invention switches schematic diagram.
Embodiment
Be illustrated in figure 5 as the electrical block diagram that power output tube cooperates with active PWM chopping phase, wherein 501 is the triangular wave generation module, 502 is the pwm signal generation module, 503 are the input source of sound, 504 is the driving tube control module, 505 PMOS driving tubes for low electric power supply, 506 are load, 507 is the PMOS driving tube of high power supply power supply, 508 is source of sound amplitude detection module, with the following PMOS driving tube 507 of work of the one group of high power supply that the present invention includes, this driving tube 507 is exported the driving function with deserved PWM being cooperated finish switching high power supply power supply back.Source of sound detection module 508 is controlled the time of switching the height power supply by detecting the source of sound amplitude.Triangular wave generation module 501 produces the triangular wave of respective amplitude according to two groups of different electrical power voltages, and switches to high amplitude triangular wave carry out the PWM modulation when switching high power supply.
The triangular wave amplitude among the present invention of being illustrated in figure 6 as is with the relation of supply voltage, Δ V in the amplitude formula is the amplitude of triangular wave, R1 and R2 are the resistance that is connected between supply voltage and the ground, HV and LV represent high power supply voltage and low supply voltage respectively, 601 are the low pairing low amplitude value triangular wave of power supply, and its amplitude is multiplied by electric resistance partial pressure (R2/R1) for low supply voltage LV.602 is the pairing high amplitude triangular wave of high power supply voltage, and its amplitude is multiplied by electric resistance partial pressure (R2/R1) for high power supply voltage HV.As seen the amplitude of two groups of triangular waves is respectively with the proportional relation of its corresponding supply voltage.The specific implementation circuit is seen Figure 11, shown in Figure 12.
As Fig. 7 is the triangular wave (Fig. 6) of corresponding different electrical power voltage and the pwm signal switching waveform of input signal modulation back generation, wherein 701 are the input waveform, 702 low amplitude value triangular wave waveforms for low power supply correspondence, 703 is the high amplitude triangular wave waveform of high power supply correspondence, 704 are the low amplitude value PWM waveform under the low supply voltage, 705 are the high amplitude PWM waveform under the high power supply voltage, input signal for same magnitude, low amplitude value PWM waveform 704 under the low supply voltage and the high impulse area of the high amplitude PWM waveform 705 under the high power supply voltage (Pulse A and Pulse B) equate, illustrate that the signal of exporting after the pwm signal filtering of two groups of different amplitudes will be consistent, proved that simultaneously many in the present invention power supplys switch its output signal of back and can keep the extraordinary linearity.
Be output driving tube control module as Fig. 8,801 is the logical schematic of control module, 504 parts in the corresponding diagram 5, the 802 power supply switching notice signals for the PMOS driving tube under the different electrical power voltage, the 803rd, the pwm signal of input, this signal detail has been set forth clear in Fig. 7.The 805th, the signal of final output.When being high, will open the signal when 802 that (804 work of PMOS under high power supply voltage pipe, correspondence was open at the PMOS pipe of operation at low power supply voltage when 802 signal was low.Match with driving tube under the different electrical power voltage by active PWM drive signal, obtain the output signal 805 after many power supplys modulation.
As Fig. 9 is source of sound amplitude detection module, 508 parts of 902 corresponding diagram 5 wherein, and 901 is the system closed loop gain of test point to output, supposes that this closed loop gain 901 is RFB/RIN.902 is source of sound amplitude judge module, and whether its output decision needs Switching power voltage.The differential output signal of 903 corresponding first order amplifiers with 904,905 and 906 are respectively pairing high-low level VA of source of sound amplitude detection and VB, its VA is relevant with setting homologous ray closed loop gain 901 loop gains of VB voltage, wherein VA is less than VCOM*RIN/RFB+VCOM, and in like manner VB is greater than VCOM-VCOM*RIN/RFB.When the differential output signal 903 of first order amplifier or 904 any one section scope that has surpassed VA or VB of amplitude, then source of sound amplitude judge module 902 is output as height, notice back level is switched high power supply voltage switching tube down, and correspondingly triangular wave is switched to high amplitude triangular wave carries out power supply and switch and modulate.
As Figure 11 is intermediate cam wave generation circuit schematic diagram of the present invention, wherein 1101 for hanging down the common mode electrical levels of power supply, 1102 is the common mode electrical level of high power supply, 1103 is the current switch of low amplitude triangular wave correspondence, 1104 is the current switch of high-amplitude triangular wave correspondence, 1105 is the electric current of low amplitude triangular wave correspondence, 1106 is the electric current of high-amplitude triangular wave correspondence, 1107 for setting the charging current of triangular wave frequency, 1109 for setting the discharging current of triangular wave frequency, and 1108 for setting the setting electric current of triangular wave height amplitude leyel.Triangular wave has a lot of methods to realize, adopted the design that electric capacity is discharged and recharged with constant current to finish the generation of triangular wave among the present invention, when capacitance voltage is higher than triangular wave high-amplitude level VOH, switch 1111 disconnects, switch 1110 conductings are to capacitor discharge, when capacitance voltage was lower than triangular wave low amplitude level VOL, switch 1110 disconnected, and switch 1111 conductings are charged to electric capacity.Resistance R 2 and resistance R 3 resistances equate among the figure, and resistance is assumed to R, and its central point is set at the VCOM level, and the high low amplitude value of the triangular wave that obtains will be respectively VCOM+R*IV, VCOM-R*IV.This triangular wave exports among Fig. 5 502 to and is used to produce pwm signal.
As shown in figure 12,1201 is the low amplitude triangular wave, and 1202 is the high-amplitude triangular wave.When needs switch high level modulation, the setting electric current 1108 of the charging current 1107 of the setting triangular wave frequency among Figure 11 and setting triangular wave height amplitude leyel will switch to the electric current of high power supply correspondence, constant to obtain frequency, central point is constant, and changes in amplitude is with the proportional triangular wave waveform of power source change.
As shown in Figure 4, the source of sound amplitude is bigger when importing, and the many power supplys voice modulation technology among the present invention can effectively promote power output, and suppresses problem of dtmf distortion DTMF.Wherein 401 are the input source of sound, 402 is the pwm signal when hanging down the power supply power supply, 403 for adopting the high power supply corresponding pwm signal of powering among the present invention, 404 dotted line display parts for supposition high-amplitude value part continue to adopt low power supply power supply down pwm signal the waveform of distortion will appear.In the bigger part of input source of sound amplitude, owing to switch to high power supply power supply, the amplitude of triangular wave also will be switched the amplitude of corresponding high power supply simultaneously, triangular wave through high amplitude is modulated with the audio frequency signal, the high pulse signal duty ratio of the PWM of its generation diminishes, can effectively suppress problem of dtmf distortion DTMF shown in 404 dotted lines, and, significantly improve peak power output because output switches to high power supply power supply.
As shown in figure 10, at typical music signal, the present invention can reach very high efficient.Because charge pump can provide the output voltage higher than supply voltage, so the present invention can provide higher power output when charge pump is powered.But the efficient of charge pump is lower, if the power supply of omnidistance maintenance charge pump will cause decrease in efficiency.The framework that the present invention adopts has effectively been alleviated the decrease in efficiency problem.As shown in figure 10,1001 is the out drive stage power supply, 1003 be typical music signal through difference output after the system drive and filtered after waveform, 1002 is high power supply switching judging level, when amplitude output signal has surpassed the switching judging level, low power supply continues power supply distortion phenomenon will occur, and then output will enter the charge pump powering mode, and promptly out-put supply switches to high power supply power supply by low power supply.When supply voltage is 3.6V, when charge pump output voltage is 5.5V, can reach 90% by power supply self power supplying efficiency, need be multiplied by the efficient of charge pump self when switching the charge pump power supply, so whole efficiency reduces to 65%, characteristics of the present invention are the amplitude according to handled signal, and different power supply power supplies is switched in system intelligence control.The part that amplitude output signal is lower is powered by low power supply, and is only too high in power output, just switches high power supply when low power supply can't be supported and is responsible for power supply, therefore significantly improved efficient.As seen from Figure 10, the present invention can obtain than the more excellent efficient of sine wave test for the audio signal of reality.
This shows, this circuit can be completely achieved based on the multi-power source voltage power supply switching modulation of the Class-D of work down, active modulation design in this technology guarantees that system linearity degree index can not reduce under the Switching power condition, and has significantly improved operating efficiency when increasing power output.Because the efficient of Class-D self can reach more than 90%, and high in the present invention power supply is only just got involved power supply in needs, possess according to input and change the feature of Switching power immediately, therefore the present invention possesses than the Class-G framework above efficient that doubles, to the novel framework that this performance significantly promotes, called after I class audio frequency power amplifier.
Distortion to above-mentioned execution mode of the present invention is possible.For example high power supply has multiple mode to obtain, and only is exemplified as charge pump in this patent and obtains high power supply voltage; The switching of low power supply and high power supply can extend to the switching of low power supply pressure with negative supply equally, simultaneously the corresponding NMOS driving tube that switches of drive control part.In addition, also can only switch the power supply of efferent duct, not finish this design and do not switch the output driving tube, because there are two groups of switches between output and low power supply, cost only is to have reduced efficient under low power supply powering mode.Only given an example among the present invention the height two groups of power supplys, this design can extend to the switching of multi-group power equally.Source of sound amplitude detection part can be judged by pwm signal equally, when finding its duty ratio appearance 100% of pwm signal that low supply voltage produces down or the switching of promptly hanging down the paramount power supply of power supply greater than set point, the pwm signal duty ratio under the discovery high power supply voltage is then carried out the switching of high power supply to low power supply less than a set point.These distortion or other execution mode all should be in protection scope of the present invention.
Claims (8)
1. the many power supplys based on Class-D switch modulator approach, comprise the steps:
One group low power supply is provided, before the peak power output that low power supply power supply can be supported, keeps low power supply power supply when power output reaches;
One group of high power supply is provided, after power output has reached the available maximum of low power supply, switches to high power supply power supply;
Judge whether input source of sound amplitude surpasses the power supply capacity of low power supply to switch low power supply and high power supply; And
Dynamically switch the amplitude of triangular wave, two groups of amplitudes of this triangular wave respectively with low power supply, the proportional relation of high power source voltage.
2. the many power supplys based on Class-D as claimed in claim 1 switch modulator approach, it is characterized in that, produce pwm signal, the duty ratio of this pwm signal and the proportional relation of the supply voltage of current power supply by described triangular wave and input signal modulation back.
3. the many power supplys based on Class-D as claimed in claim 1 switch modulator approach, it is characterized in that high power supply is realized by charge pump.
4. the many power supplys based on Class-D as claimed in claim 1 switch modulator approaches, it is characterized in that, the switching of high power supply and low power supply is controlled in the open and close of the driving tube by high power supply and low supply voltage.
5. the many power supplys based on Class-D as claimed in claim 2 switch modulator approach, it is characterized in that described pwm signal drives corresponding high power supply, the driving tube of low supply voltage.
6. the many power supplys based on Class-D as claimed in claim 1 switch modulator approach, it is characterized in that, the amplitude of described input sound source signal is relevant to the closed loop gain of output with this test point.
7. the many power supplys based on Class-D as claimed in claim 1 switch modulator approach, it is characterized in that, when switching power supply, described triangular wave is adjusted simultaneously, adjusted triangular wave frequency is constant, and central point is constant, and changes in amplitude is with the proportional relation of mains voltage variations.
8. the many power supplys based on Class-D switch modulation circuit, comprising:
Low power supply kept low power supply power supply when power output reaches before the peak power output that low power supply power supply can be supported;
High power supply after power output has reached the available maximum of low power supply, switches to high power supply power supply;
With the switch driving circuit that described high power supply, low power supply link to each other by driving tube respectively, realize the control of the open and close of the driving tube under the different electrical power voltage;
The circuit for generating triangular wave that one amplitude can dynamically be switched, two groups of amplitudes of this triangular wave respectively with driving tube on two groups of proportional relations of supply voltage, produce pwm signal, the duty ratio of this pwm signal and the proportional relation of the supply voltage on the driving tube by this triangular wave and input signal modulation back;
The one input source of sound amplitude detection circuit that links to each other with described switch driving circuit, the cut-in timing of determining high power supply in each cycle by this circuit with cut out the time.
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| CN2010102231498A CN102142815A (en) | 2010-07-09 | 2010-07-09 | Class-D-based multi-power supply switching modulation method and circuit |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104333331A (en) * | 2014-11-10 | 2015-02-04 | 上海华勤通讯技术有限公司 | Power-supplying method and device of audio power-amplifying circuit and audio playing equipment |
| TWI721750B (en) * | 2020-01-06 | 2021-03-11 | 晶豪科技股份有限公司 | Class d power amplifier |
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| US20090022339A1 (en) * | 2005-03-28 | 2009-01-22 | Nec Corporation | Amplifier |
| CN101404443A (en) * | 2008-06-05 | 2009-04-08 | 美芯晟科技（北京）有限公司 | Pulse-width modulator and boosting type converter employing the same |
| US20090102295A1 (en) * | 2006-02-24 | 2009-04-23 | Lars Petersen | Audio Power Conversion System |
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| CN1711678A (en) * | 2002-11-15 | 2005-12-21 | 松下电器产业株式会社 | Power amplifier |
| US20090022339A1 (en) * | 2005-03-28 | 2009-01-22 | Nec Corporation | Amplifier |
| US20090102295A1 (en) * | 2006-02-24 | 2009-04-23 | Lars Petersen | Audio Power Conversion System |
| CN101404443A (en) * | 2008-06-05 | 2009-04-08 | 美芯晟科技（北京）有限公司 | Pulse-width modulator and boosting type converter employing the same |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104333331A (en) * | 2014-11-10 | 2015-02-04 | 上海华勤通讯技术有限公司 | Power-supplying method and device of audio power-amplifying circuit and audio playing equipment |
| CN104333331B (en) * | 2014-11-10 | 2017-04-19 | 华勤通讯技术有限公司 | Power-supplying method and device of audio power-amplifying circuit and audio playing equipment |
| TWI721750B (en) * | 2020-01-06 | 2021-03-11 | 晶豪科技股份有限公司 | Class d power amplifier |
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Application publication date: 20110803 |