CN105703717A - Explosion sound suppression circuit and method - Google Patents
Explosion sound suppression circuit and method Download PDFInfo
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- CN105703717A CN105703717A CN201410681408.XA CN201410681408A CN105703717A CN 105703717 A CN105703717 A CN 105703717A CN 201410681408 A CN201410681408 A CN 201410681408A CN 105703717 A CN105703717 A CN 105703717A
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Abstract
The invention provides an explosion sound suppression circuit and method which are used for suppressing boot explosion sound of a single-ended output D type power amplifier. The circuit includes: a pulse signal generator which outputs a first signal with a gradually increasing duty ratio; a modulator which modulates an input sound signal and outputs a second signal; and a selector, wherein an output signal of the selector is an output signal of the D type power amplifier, and the selector is configured to selectively output the second signal after the second signal is in a stable state, otherwise selectively output the first signal. The explosion sound suppression circuit is simple in structure, the method is easy and rapid, and the cost and the complexity of a system can be lowered.
Description
Technical field
The present invention relates to a kind of explosion sound suppression circuit and method, particularly to the suppression circuit of start explosion sound and the method for the D-type power amplifier for Single-end output。
Background technology
D-type power amplifier is widely used in home theater, sound system, stereo record-player, servo amplifier isoelectronic series system。In recent years, D-type power amplifier obtains increasing application in various electronic systems (especially the portable equipment such as mobile phone), and MP3, FM radio, mobile TV, digital photographing etc. are all increasingly becoming the requisite function of middle and high end mobile phone。Especially the tonequality to mobile phone of releasing of music phone is had higher requirement, it is desirable to start explosion sound is as far as possible little。But in the design of handset audio, explosion sound problem is always up one of difficult problem of puzzlement engineer。
Because factors such as input capacitance, biased electrical perhaps output capacitance chargings, producing ear-piercing start explosion sound at outfan when D-type power amplifier start powers on, the D-type power amplifier start explosion sound of Single-end output is especially serious。Prior art typically requires and suppresses start explosion sound with peripheral circuit, and this method not only adds system cost, and makes application become complicated。
Summary of the invention
For this, the invention provides a kind of explosion sound suppression circuit that can be integrated in chip internal and corresponding explosion sound suppressing method, its circuit structure is simple, and method is convenient, reduces cost and the complexity of system。
On the one hand, the invention provides a kind of explosion sound suppression circuit, for the suppression of start explosion sound of the D-type power amplifier of Single-end output, this circuit includes: pulse signal generator, the first signal that its output duty cycle is gradually increased；Manipulator, the acoustical signal of input is modulated by it, exports secondary signal；Selector, its output signal is the output signal of described D-type power amplifier, and it is configured to, and selects to export described secondary signal after described secondary signal is in steady statue, otherwise selects to export described first signal。
Further, described pulse signal generator includes the first comparator, and its input anode connects the voltage signal of external partially installing capacitor, and the triangular signal of its input negative terminal connection oscillator output, it exports described first signal。
Further, described selector includes the control end being connected to control signal, and when described control signal is the first state, described selector selects to export described first signal, when described control signal is the second state, described selector selects to export described secondary signal。
Further, described suppression circuit also includes control signal generator, comprising: the second comparator, its input anode connects the voltage signal of described external partially installing capacitor, and its input negative terminal connects constant voltage signal；Timer, the rising edge of the output signal of described second comparator triggers it and starts timing, timing time was the 3rd scheduled time, before described 3rd scheduled time passes through, the described control signal of described timer output is described first state, described 3rd scheduled time through the described control signal that described timer afterwards exports be described second state, wherein, described 3rd scheduled time is in steady statue through described secondary signal afterwards。
Further, the valley of described triangular signal be zero and peak value be the magnitude of voltage of accessory power supply, the magnitude of voltage of described constant voltage signal is the half of the magnitude of voltage of described accessory power supply。
On the other hand, present invention also offers a kind of explosion sound suppressing method, the method comprises the steps: that S1. closes described manipulator and described selector makes it not export signal, and makes other modules of described D-type power amplifier be in normal operating conditions, then starts shooting；S2. waiting for first scheduled time, the signal to other modules described is in steady statue；S3. open described selector and make described selector select to export described first signal, being then turned on described manipulator；S4. waited for second scheduled time, be in steady statue to described secondary signal；S5. described selector is made to select to export described secondary signal。
The explosion sound suppression circuit of the present invention, when Single-end output D-type power amplifier starts, the first output pulse signal that is gradually increased of one dutycycle, waits the output signal of output modulator again after the stable output signal of manipulator。Because the dutycycle of the output signal of D-type power amplifier is gradually increased, therefore, slowly tend towards stability in the LC wave filter of outfan and the operating point of capacitance, output pressure drop in loudspeaker load is also slowly rise, sudden change will not be produced, from without producing ear-piercing start explosion sound on output loudspeaker load。Therefore, the application of this circuit can suppress the start explosion sound of Single-end output D-type power amplifier effectively。
Accompanying drawing explanation
Fig. 1 is the structural representation of the explosion sound suppression circuit of the present invention；
Fig. 2 is the schematic diagram of an embodiment of the explosion sound suppression circuit of the present invention；
Fig. 3 is the schematic diagram of the signal output waveform of the D-type power amplifier of Single-end output in prior art；
Fig. 4 is the schematic diagram of the signal output waveform of the D-type power amplifier of Single-end output after the application explosion sound suppression circuit of the present invention and method。
Detailed description of the invention
It is described in further detail below in conjunction with the drawings and specific embodiments explosion sound suppression circuit to the present invention and method, but not as a limitation of the invention。
The schematic diagram of the signal output waveform of the D-type power amplifier that Fig. 3 show in prior art Single-end output。Wherein, the output signal that VM ' is the manipulator in D-type power amplifier in prior art, VO ' is the output signal of D-type power amplifier in prior art。It can be seen that when D-type power amplifier is just started working after powering, the output of manipulator is unstable, has irregular broad pulse W and occur, therefore the output signal of D-type power amplifier also has this broad pulse W '。When this shows in loudspeaker load, namely there will be the signal that amplitude becomes suddenly big, thus forming ear-piercing start explosion sound。
If it is possible to eliminate start time D-type power amplifier output signal in this irregular broad pulse, it is possible to eliminate start explosion sound。
Accordingly, the invention provides a kind of explosion sound suppression circuit, for the suppression of start explosion sound of the D-type power amplifier of Single-end output。As it is shown in figure 1, this circuit: include a pulse signal generator, the first signal VD that its output duty cycle is gradually increased。One manipulator, the acoustical signal VIN of input is modulated by it, exports secondary signal VM。One selector (as it can be seen, preferably alternative selector), its output signal is the output signal of D-type power amplifier。This selector is configured to, and selects output secondary signal VM after secondary signal VM is in steady statue, otherwise selects output the first signal VD。
The explosion sound suppression circuit of the present invention, when Single-end output D-type power amplifier starts, the first output pulse signal VD that is gradually increased of one dutycycle, the output signal VM of output modulator again after waiting the output signal VM of manipulator stably。Because the dutycycle of the output signal of D-type power amplifier is gradually increased, therefore, slowly tend towards stability in the LC wave filter of outfan and the operating point of capacitance CL, output pressure drop in loudspeaker load is also slowly rise, sudden change will not be produced, from without producing ear-piercing start explosion sound on output loudspeaker load。Visible, the application of this circuit can suppress the start explosion sound of Single-end output D-type power amplifier effectively。
Fig. 2 is the schematic diagram of an embodiment of the invention。Wherein, pulse signal generator includes the first comparator 10, and its input anode connects the voltage signal VCB of external partially installing capacitor CB, the triangular signal VS of its input negative terminal connection oscillator output, and the signal of the first comparator 10 output is the first signal VD。The magnitude of voltage VDD that the valley of triangular signal VS is 0, peak value is accessory power supply。
The principle of this pulse signal generator can be more fully understood that with reference to the oscillogram of Fig. 4。D-type power amplifier can an external partially installing capacitor CB, this external partially installing capacitor CB be used for stablizing the bias voltage of amplifier in manipulator, and its stationary value is VDD/2。After D-type power amplifier electrifying startup, this external partially installing capacitor CB is provided electric current to start to charge up by biasing module, and as shown in Figure 4, VCB starts slowly to rise from 0, until stable at VDD/2。In pulse signal generator, with the VCB being gradually increased compared with the triangular wave VS that agitator exports, pulse signal (i.e. the first signal) VD that a dutycycle is gradually increased can be produced。
Further, selector includes the control end being connected to control signal VT, and when control signal VT is the first state, selector selects output the first signal VD, and when control signal VT is the second state, selector selects output secondary signal VM。This control signal VT is exported by control signal generator。With reference to Fig. 2, control signal generator includes: the second comparator 20, and its input anode connects the voltage signal VCB of external partially installing capacitor CB, and its input negative terminal connects constant voltage signal, the magnitude of voltage of this constant voltage signal is the half of the magnitude of voltage of accessory power supply VDD, is VDD/2。One timer, the rising edge of the output signal V2 of the second comparator 20 triggers this timer and starts timing, timing time is the 3rd scheduled time T3, before the 3rd scheduled time T3 passes through, the control signal VT of timer output is the first state (low level in such as figure), and now selector selects the signal of output to be the first signal VD；The 3rd scheduled time T3 through the control signal VT that timer afterwards exports be the second state (high level in such as figure), now selector select output signal be secondary signal VM。
Wherein, the length of the 3rd scheduled time T3 depends on the demand of system, but must assure that, need to be in steady statue at the 3rd scheduled time T3 through secondary signal VM afterwards。
With reference to Fig. 4, when VCB rising reaches stationary value VDD/2, the output signal V2 of the second comparator 20 is high level from low transition, and the rising edge triggered timer of V2 starts timing, and its timing duration is the 3rd scheduled time T3。When the 3rd scheduled time T3 through after, the output signal VT of timer is high level by low transition。The rising edge trigger selector of control signal VT starts to select output secondary signal VM, and D-type power amplifier initially enters normal operating conditions。
Present invention also offers a kind of explosion sound suppressing method based on foregoing circuit, the method comprises the steps:
S1. close manipulator and selector makes it not export signal, and make other modules (such as, internal bias module, logic module etc.) of D-type power amplifier be in normal operating conditions, then start shooting, namely start D-type power amplifier。
S2. waiting the first scheduled time T1, the signal to other modules enters steady statue。With reference to Fig. 4, in during this period of time, the output signal VO of D-type power amplifier is high-impedance state, owing to this period D-type power amplifier just starts, its internal modules all can produce some noises when starting, by turning off the output of D-type power amplifier so that these internal noises will not be exaggerated and export load speaker, when therefore this process is conducive to reduction chip to power on, biasing module etc. start the noise caused。
S3. open selector and make this selector select output the first signal VD, being then turned on manipulator。As previously mentioned, it is possible to control selector by control signal VT and select output the first signal VD。
S4. wait the second scheduled time T2, be in steady statue to secondary signal VM。As shown in Figure 4, in during this period of time, the output signal VO and the first signal VD of D-type power amplifier are identical, the pulse signal that namely one dutycycle of output is gradually increased or is gradually increased and tends towards stability。In this process, because the dutycycle of the output signal of D-type power amplifier is gradually increased, therefore, slowly tend towards stability in the LC wave filter of outfan and the operating point of capacitance CL, output pressure drop in loudspeaker load is also slowly rise, sudden change will not be produced, from without producing ear-piercing start explosion sound on output loudspeaker load。
S5. selector is made to select output secondary signal VM。As previously mentioned, it is possible to control selector by control signal VT and select output secondary signal VM。As shown in Figure 4, at the second scheduled time T2 through afterwards, the output signal VO of D-type power amplifier is identical with secondary signal VM, and D-type power amplifier starts normal operation, the input signal VIN that output is exaggerated。
Therefore, explosion sound suppression circuit and the method for the present invention are used, it is possible to effectively suppress the start explosion sound of Single-end output D-type power amplifier。
Above detailed description of the invention is only the illustrative embodiments of the present invention, it is impossible to being used for limiting the present invention, protection scope of the present invention is defined by the claims。The present invention in the essence of the present invention and protection domain, can be made various amendment or equivalent replacement by those skilled in the art, and these are revised or be equal to replacement and also should be regarded as being within the scope of the present invention。
Claims (6)
1. an explosion sound suppression circuit, for Single-end output D-type power amplifier start explosion sound suppression, this circuit includes:
Pulse signal generator, the first signal that its output duty cycle is gradually increased；
Manipulator, the acoustical signal of input is modulated by it, exports secondary signal；
Selector, its output signal is the output signal of described D-type power amplifier, and it is configured to, and selects to export described secondary signal after described secondary signal is in steady statue, otherwise selects to export described first signal。
2. explosion sound suppression circuit according to claim 1, it is characterized in that, described pulse signal generator includes the first comparator, and its input anode connects the voltage signal of external partially installing capacitor, the triangular signal of its input negative terminal connection oscillator output, it exports described first signal。
3. explosion sound suppression circuit according to claim 2, it is characterized in that, described selector includes the control end being connected to control signal, when described control signal is the first state, described selector selects to export described first signal, when described control signal is the second state, described selector selects to export described secondary signal。
4. explosion sound suppression circuit according to claim 3, it is characterised in that described suppression circuit also includes control signal generator, comprising:
Second comparator, its input anode connects the voltage signal of described external partially installing capacitor, and its input negative terminal connects constant voltage signal；
Timer, the rising edge of the output signal of described second comparator triggers it and starts timing, timing time was the 3rd scheduled time, before described 3rd scheduled time passes through, the described control signal of described timer output is described first state, described 3rd scheduled time through the described control signal that described timer afterwards exports be described second state, wherein, described 3rd scheduled time is in steady statue through described secondary signal afterwards。
5. explosion sound suppression circuit according to claim 4, it is characterised in that the valley of described triangular signal be zero and peak value be the magnitude of voltage of accessory power supply, the magnitude of voltage of described constant voltage signal is the half of the magnitude of voltage of described accessory power supply。
6., based on an explosion sound suppressing method for the explosion sound suppression circuit described in claim 1, the method comprises the steps:
S1. close described manipulator and described selector makes it not export signal, and make other modules of described D-type power amplifier be in normal operating conditions, then start shooting；
S2. waiting for first scheduled time, the signal to other modules described is in steady statue；
S3. open described selector and make described selector select to export described first signal, being then turned on described manipulator；
S4. waited for second scheduled time, be in steady statue to described secondary signal；
S5. described selector is made to select to export described secondary signal。
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410681408.XA CN105703717B (en) | 2014-11-24 | 2014-11-24 | Explosion sound suppression circuit and method |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410681408.XA CN105703717B (en) | 2014-11-24 | 2014-11-24 | Explosion sound suppression circuit and method |
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| CN105703717A true CN105703717A (en) | 2016-06-22 |
| CN105703717B CN105703717B (en) | 2019-04-12 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108768309A (en) * | 2018-06-11 | 2018-11-06 | 聚辰半导体(上海)有限公司 | Audio-frequency power amplifier and its transient noise suppressing method |
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| US20070121962A1 (en) * | 2005-11-07 | 2007-05-31 | Kazuki Adachi | Audio signal output control device that suppresses pop sound |
| CN101465619A (en) * | 2007-12-20 | 2009-06-24 | 杭州茂力半导体技术有限公司 | Method and apparatus for restraining D-genus power amplifier noise and D-genus power amplifier with noise suppression |
| CN101977025A (en) * | 2010-11-02 | 2011-02-16 | 苏州顺芯半导体有限公司 | Method and device for eliminating noise in class-D power amplifier |
| CN102931931A (en) * | 2012-11-16 | 2013-02-13 | 上海贝岭股份有限公司 | Anti-sound break circuit for D-class power amplifier chip |
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2014
- 2014-11-24 CN CN201410681408.XA patent/CN105703717B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20070121962A1 (en) * | 2005-11-07 | 2007-05-31 | Kazuki Adachi | Audio signal output control device that suppresses pop sound |
| CN101465619A (en) * | 2007-12-20 | 2009-06-24 | 杭州茂力半导体技术有限公司 | Method and apparatus for restraining D-genus power amplifier noise and D-genus power amplifier with noise suppression |
| CN101977025A (en) * | 2010-11-02 | 2011-02-16 | 苏州顺芯半导体有限公司 | Method and device for eliminating noise in class-D power amplifier |
| CN102931931A (en) * | 2012-11-16 | 2013-02-13 | 上海贝岭股份有限公司 | Anti-sound break circuit for D-class power amplifier chip |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108768309A (en) * | 2018-06-11 | 2018-11-06 | 聚辰半导体(上海)有限公司 | Audio-frequency power amplifier and its transient noise suppressing method |
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