CN101453198B - The popping inhibition method of exchange audio power amplifier - Google Patents
The popping inhibition method of exchange audio power amplifier Download PDFInfo
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- CN101453198B CN101453198B CN200710196292.0A CN200710196292A CN101453198B CN 101453198 B CN101453198 B CN 101453198B CN 200710196292 A CN200710196292 A CN 200710196292A CN 101453198 B CN101453198 B CN 101453198B
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Abstract
A kind of exchange audio power amplifier and popping inhibition method thereof.This exchange audio power amplifier, comprises a pulse-width signal generator, is used for generation one pulse-width signal; One counting unit, produces multiple accumulated number k according to this pulse-width signal
1-k
n, described accumulated number k
1-k
nadhere to different N number of time sections separately; N number of switching transistor, mutually in parallel and its conducting with disconnect by described accumulated number k
1-k
ndetermined; And an impedance switching unit, its grid receives an exchange of audio signals, separately has one end to be coupled to described switching transistor, and outputs signal in this end.Because N number of switching transistor opens at different time or cuts out, so exchange audio power amplifier of the present invention effectively can suppress sonic boom respectively.
Description
Technical field
The present invention relates to exchange audio power amplifier and popping inhibition method, particularly relate to utilize multiple control switch to open gradually or to close mode to suppress the exchange audio power amplifier of sonic boom.
Background technology
Audio-frequency power amplifier at electric power starting or when closing, voice signal by without to have with by having among the process of nothing, if conversion is level and smooth not, often causes and make the uncomfortable sonic boom of hearer (Pop Noise).Figure 1A-1D be pulse by without to have with by have to without time, through the waveform that a low pass filter produces.As shown in Figure 1A, when input signal only has a pulse, this input signal there will be upper and lower two surgings after low pass filter.As shown in Figure 1B, when input signal is a series of pulse, this input signal then can not produce surging after low pass filter.But the series of pulses of Figure 1B necessarily has beginning (electric power starting Power On) and terminates (power-off Power Off), as Fig. 1 C and Fig. 1 D is corresponding beginning and the signal of end.So as shown in figs 1 c and 1d, its input signal still there will be surging after low pass filter.If this surging reach people's ear can the size of identification time, just can cause the sonic boom of disturbing people.
General audio-frequency power amplifier is divided into analog power amplifier (amplitude of output signal can change) and switch type audio-frequency power amplifier (amplitude of output signal is fixed).And the sonic boom of analog power amplifier suppresses existing many patents to propose, such as United States Patent (USP) 4,788,508,5,682,121,6,157,726,6,516,067 etc.But these patents are all the circuit coordinating analog power stage, inapplicable for script and discontinuous switch type audio-frequency power amplifier.
Summary of the invention
Because the problems referred to above, the object of the invention is to propose a kind of utilization and open or close the circuit of multiple transistor switch gradually to suppress the exchange audio power amplifier of sonic boom.
For achieving the above object, exchange audio power amplifier of the present invention, comprises a pulse-width signal generator, is used for generation one pulse-width signal; One counting unit, produces multiple accumulated number k according to this pulse-width signal
1-k
n, described accumulated number k
1-k
nadhere to different N number of time sections separately; N number of switching transistor, mutually in parallel and its conducting with disconnect by described accumulated number k
1-k
ndetermined; And an impedance switching unit, its grid receives an exchange of audio signals, separately has one end to be coupled to described switching transistor, and outputs signal in this end.
Because N number of switching transistor opens at different time or cuts out, so exchange audio power amplifier of the present invention effectively can suppress sonic boom respectively.
Accompanying drawing explanation
Figure 1A-1D be pulse by without to have with by have to without time, through the waveform that a low pass filter produces.
Fig. 2 A shows pulse amplitude and becomes large waveform gradually by 0.
Fig. 2 B shows the waveform of pulse amplitude by large change 0 gradually.
Fig. 3 shows the circuit diagram of invention exchange audio power amplifier.
Fig. 4 A shows output voltage Vout, the control signal S of exchange audio power amplifier of the present invention when power initiation and the schematic diagram of switching transistor conducting number.
Fig. 4 B shows output voltage Vout, the control signal S of exchange audio power amplifier of the present invention when power-off and the schematic diagram of switching transistor conducting number.
Fig. 5 is the calcspar of exchange audio power amplifier first embodiment of the present invention.
Fig. 6 is the calcspar of exchange audio power amplifier second embodiment of the present invention.
The pulse-width signal when system that Fig. 7 A shows the second embodiment starts and the schematic diagram of output voltage Vout.
Pulse-width signal when Fig. 7 B shows the system closing of the second embodiment and the schematic diagram of output voltage Vout.
Reference numeral explanation
30,40,60 exchange audio power amplifiers
31 adjustment transistors
32 switch transistors pipe units
32
1-32
nmultiple switching transistor
33 impedance switching unit
41 ramp signal generators
42 counting units
43 buffers
45 pulse-width signal generators
64 switch elements
Embodiment
The method of exchange audio power amplifier of the present invention and sonic boom suppression is described in detail below with reference to accompanying drawing.
Fig. 3 is the circuit diagram of exchange audio power amplifier of the present invention.As shown in the drawing, exchange audio power amplifier 30 of the present invention comprises an adjustment transistor 31, multiple switching transistor 32
1-32
n, an and impedance switching unit 33.
Adjustment transistor 31 and multiple switching transistor 32
1-32
nafter parallel connection, then connect with impedance switching unit 33.The grid of adjustment transistor 31 receives a control signal S and uses and change resistance value gradually.And multiple switching transistor 32
1-32
n, mutual parallel connection also receives one group of switching signal Y
1-Y
ncontrol, use indivedual conducting or open circuit gradually.The grid of impedance switching unit 33 receives exchange of audio signals, and one end is coupled to adjustment transistor 31 and multiple switching transistor 32
1-32
n, and this end points O is defined as an output to output signal.
If the pulse amplitude of output signal can be become large gradually by little when electric power starting, large waveform is become gradually by 0 as Fig. 2 A shows pulse amplitude, and when power-off by the pulse amplitude of output signal by diminishing gradually greatly, pulse amplitude is by the waveform of large change 0 gradually as shown in Figure 2 B, just surging can be become very little, people's ear cannot be discovered, and effectively suppresses the generation of sonic boom.
Therefore, when this exchange audio power amplifier starts to start, change resistance value gradually after adjustment transistor 31 reception control signal S, and this control signal S is changed to high level 5V repeatedly by low level 0V.When control signal S arrives high level 5V, utilize switching signal to increase a switching transistor conducting, this control signal S becomes low level 0V again simultaneously.Now because of adjustment transistor 31 and multiple switching transistor 32
1-32
nresistance value much larger than the resistance value of impedance switching unit 33, therefore the amplitude of output voltage Vout is minimum, so the sonic boom produced is minimum and people's ear cannot be discovered.And when this exchange audio power amplifier preparation is closed, change resistance value gradually after adjustment transistor 31 reception control signal S, and this control signal S is changed by high level 5V to low level 0V.When control signal S arrives low level 0V, utilize switching signal to reduce by a switching transistor conducting, this control signal S becomes high level 5V again simultaneously.
Fig. 4 A shows the schematic diagram of output voltage Vout, the control signal S of exchange audio power amplifier of the present invention when power initiation, clock signal clk, pulse-width signal PWM and switching transistor conducting number.Exchange audio power amplifier 30 of the present invention is changed and multiple switching transistor 32 gradually by the resistance value of adjustment transistor 31
1-32
nindivedual conducting, makes the voltage of output voltage Vout also promote gradually gradually.Therefore, output voltage Vout can present the rising waveform gradually of Fig. 2 A, and then the sonic boom that surging during effective minimizing power initiation produces.
Fig. 4 B shows the schematic diagram of output voltage Vout, the control signal S of exchange audio power amplifier of the present invention when power-off, clock signal clk, pulse-width signal PWM and switching transistor conducting number.Exchange audio power amplifier 30 of the present invention is changed gradually by the resistance value of adjustment transistor 31 and multiple switching transistor 321-32N closes individually gradually, and the voltage of output voltage Vout is also reduced gradually.Therefore, output voltage Vout can present the waveform of reduction gradually of Fig. 2 B, and then the sonic boom that surging during effective minimizing power-off produces.
Fig. 5 is the calcspar of exchange audio power amplifier first embodiment of the present invention.As shown in the drawing, exchange audio power amplifier 60 of the present invention comprises adjustment transistor 31, switch transistors pipe unit 32, impedance switching unit 33, ramp signal generator 41, counting unit 42, one buffer 43, pulse-width signal generator 45 and a switch element 64.
Ramp signal generator 41 is used for generation one control signal S, and the slope changing this control signal S according to a mode signal UP/DN is for just or be negative.When this control signal S arrives first threshold (be the minimum voltage of control signal S at the present embodiment) or Second Threshold (be the ceiling voltage of control signal S at the present embodiment), produce a recurrent pulse RDY.Counting unit 42, using recurrent pulse RDY as count signal, uses the number of computing cycle pulse RDY, and produces a count value C as switching signal Y
1-Y
n.This counting unit 42 also carries out the control of upper number or lower number according to mode signal UP/DN.And this counting unit 42 in this count value be 0 or equal a default value (being the number N of multiple switching transistor) time, produce a switching signal SLEW and this ramp signal generator 41 decommissioned.
Switch element 64 as Fig. 5 disclose, receive the pulse-width signal that this switching signal SLEW and pulse-width signal generator 45 produce, and when this count value C is 0, cause impedance switching unit 33 to decommission, then cause impedance switching unit 33 to maintain its handoff functionality when count value C is N.
Buffer 43 is configured between counting unit 42 and switch transistors pipe unit 32, uses and drives multiple switching transistor 32
1-32
n.Certainly, if the driving force of counting unit 42 is enough to drive multiple switching transistor 32
1-32
n, then this buffer 43 can omit.Mode signal UP/DN represents power initiation when being first mode, and now the slope of control signal S is for just and counting unit 42 carries out upper several UP, therefore multiple switching transistor 32
1-32
nindivedual conducting gradually.Contrary, represent power-off when mode signal UP/DN is the second pattern, now the slope of control signal S is for negative and counting unit 42 carries out lower several DN, therefore multiple switching transistor 32
1-32
nindivedual open circuit gradually.
Below describe the operating process of exchange audio power amplifier 60 of the present invention in detail and the number N=5 of hypothesis switching transistor.
Mode signal UP/DN is first mode: when this exchange audio power amplifier 60 is unlocked power supply, it is positive control signal S that ramp signal generator 41 produces a slope repeatedly, and (such as 5V) produces a recurrent pulse RDY when this control signal S is Second Threshold.Therefore, adjust the grid of transistor 31 to receive this control signal S and use and reduce resistance value gradually.Meanwhile, counting unit 42 count cycle pulse RDY also carries out upper number, produces count value C
1, C
2, C
3, C
4with C5 as switching signal Y
1, Y
2, Y
3, Y
4with Y
5, be used for indivedual driving switch transistor 32
1, 32
2, 32
3, 32
4with 32
5.And when this count value equals 5, switching signal SLEW activation makes ramp signal generator 41 keep final state by this counting unit 42.Therefore, when electric power starting, by multiple switching transistor 32
1, 32
2, 32
3, 32
4, 32
5indivedual conducting gradually, the pulse amplitude of output signal Vout becomes large gradually by little, and then reaches the sonic boom situation effectively reducing surging and produce.
Mode signal UP/DN is the second pattern: when this exchange audio power amplifier 60 is closed power supply, it is negative control signal S that ramp signal generator 41 produces a slope repeatedly, and (such as 0V) produces a recurrent pulse RDY when this control signal S is first threshold.Therefore, adjust the grid of transistor 31 to receive this control signal S and use and increase resistance value gradually.Meanwhile, counting unit 42 count cycle pulse RDY also carries out lower number, produces count value C
1, C
2, C
3, C
4with C
5as switching signal Y
1, Y
2, Y
3, Y
4with Y
5, be used for indivedual driving switch transistor 32
1, 32
2, 32
3, 32
4with 32
5.And when this count value equals 0, switching signal SLEW activation makes ramp signal generator 41 keep final state by this counting unit 42.Therefore, when electrical power is off, by multiple switching transistor 32
1, 32
2, 32
3, 32
4, 32
5indivedual open circuit gradually, the pulse amplitude of output signal Vout by diminishing gradually greatly, and then reaches the sonic boom situation effectively reducing surging and produce.
Fig. 6 is the calcspar of exchange audio power amplifier second embodiment of the present invention.As shown in the drawing, exchange audio power amplifier 40 comprises switch transistors pipe unit 32, impedance switching unit 33, counting unit 42, one buffer 43 and a pulse-width signal generator 45.This exchange audio power amplifier produces a count value C as switching signal Y according to the pulse-width signal that pulse-width signal generator 45 provides
1-Y
n, this count value C is by accumulated number k
1-k
ndetermined, wherein k
1-k
nthat the pulse-width signal of corresponding 1st section-N section is in the pulse number of the 1st section-N section or arbitrary reference clock signal in the pulse number of the 1st section-N section.Much more no longer all the other operating principles of the present embodiment and the first embodiment duplicate, therefore to repeat.
The operation principle of the second embodiment will be described with Fig. 7 A and Fig. 7 B below.As shown in Figure 7 A, the pulse-width signal provided via pulse-width signal generator 45 sequentially can obtain the accumulated number k of N number of section
1-k
n, according to the accumulated number k of gained
1-k
nwhether reach the default numerical value of corresponding section respectively, then distinguish the progressively multiple switching transistor 32 of conducting
1-32
n, and whenever many conducting one switching transistors, namely output voltage Vout promotes a grade, therefore, output voltage Vout is just in the situation risen gradually, and then the sonic boom that surging during effective minimizing power initiation produces.As shown in Figure 7 B, can according to the accumulated number k of gained according to Fig. 7 A
1-k
nwhether reach institute's default value, more progressively close multiple switching transistor 32 respectively
1-32
n, and whenever many closedowns one switching transistor, namely output voltage Vout voltage downgrade a grade.Therefore, output voltage Vout is just in the situation declined gradually, and then the sonic boom that surging during effective minimizing power-off produces.The principle that output voltage Vout progressively promotes or downgrades is addressed in a upper embodiment, therefore will repeat no more.
In the above-described embodiment, the default value that the present invention will reach at N number of section is assumed to be K
1-K
n, then can select to meet K
1> K
2> K
3... > K
ncondition smooth-going in the hope of the process of electric power starting and closedown, meaning namely at the electric power starting initial stage, accumulated number k
1-k
nmore pulse number is needed just to be reached default value K
1-K
nand in power-off latter stage, accumulated number k
1-k
nmore pulse number is needed just to be reached default value K
1-K
n, but this and be not used to limit interest field of the present invention, that is do not meet this device under this condition also can normal operation.
The popping inhibition method of exchange audio power amplifier of the present invention is below described.Exchange audio power amplifier of the present invention has an adjustment transistor, multiple switching transistor and impedance switching unit, and the multiple switching transistor of this adjustment transistor AND gate is in parallel mutually, afterwards again with this impedance switching unit coupled in series, and the node definition of adjustment transistor AND gate this impedance switching unit coupled in series is that output point is to produce output signal.The popping inhibition method of this exchange audio power amplifier comprises the following steps:
Produce a ramp signal, and the slope changing this ramp signal according to a mode signal is for just or be negative, and is producing a recurrent pulse when this ramp signal arrives a first threshold or a Second Threshold;
Change the resistance value of this adjustment transistor, utilize this ramp signal to control resistance value that this adjustment transistor changes this adjustment transistor gradually;
Produce one group of switching signal, produce a count value after counting this recurrent pulse as this switching signal, and carry out upper number or lower number according to this mode signal, and in this count value be 0 or equal a default value time by a switching signal activation; And
Control the plurality of switching transistor, according to the control of this switching signal;
Wherein this mode signal is that first mode represents power initiation, and now the slope of this ramp signal is for just and this counting unit carries out upper number, and the indivedual conducting gradually of the plurality of switching transistor; And this mode signal is the second modal representation power-off, now the slope of this ramp signal is for negative and this counting unit carries out lower number, and the indivedual open circuit gradually of the plurality of switching transistor.
Though the present invention is described with embodiment above, therefore do not limit scope of the present invention, only otherwise depart from main idea of the present invention, those skilled in the art can carry out some distortion or change.
Claims (12)
1. an exchange audio power amplifier, comprising:
One pulse-width signal generator, is used for generation one pulse-width signal;
One counting unit, produces multiple accumulated number k according to this pulse-width signal
1-k
n, described accumulated number k
1-k
nadhere to different N number of time sections separately;
N number of switching transistor, mutually in parallel and its conducting with disconnect by described accumulated number k
1-k
ndetermined; And
One impedance switching unit, its grid receives an exchange of audio signals, separately has one end to be coupled to described switching transistor, and outputs signal in this end.
2. exchange audio power amplifier, wherein k as claimed in claim 1
xfor this pulse-width signal or a reference clock signal in the X time section of correspondence are in the pulse number of this X time section, wherein X=1-N.
3. exchange audio power amplifier as claimed in claim 1, when starting to start, accumulated number k
xthe default numerical value K of this section is reached in X time section
x, and one of them of switching transistor described in conducting, wherein X=1-N.
4. exchange audio power amplifier as claimed in claim 1, when preparing closedown, accumulated number k
xreach the default numerical value of this section in X time section, and disconnect described switching transistor one of them, wherein X=1-N.
5. exchange audio power amplifier as claimed in claim 1, when starting to start, the more numerical value K preset of the time section at initial stage
xlarger, when preparing closedown, the more numerical value K preset of the time section in latter stage
xlarger, wherein X=1-N.
6. an exchange audio power amplifier, comprising:
Multiple switching transistor, mutually in parallel and receive the control of one group of switching signal, use indivedual conducting or open circuit gradually;
One adjustment transistor, in parallel with described switching transistor, its grid receives a control signal and uses and change resistance value gradually; And
One impedance switching unit, its grid receives an exchange of audio signals, and one end is coupled to switching transistor described in this adjustment transistor AND gate, and outputs signal in this end,
Wherein by a counting unit by using recurrent pulse as count signal, and produce a count value and be used as described switching signal.
7. exchange audio power amplifier as claimed in claim 6, wherein when this exchange audio power amplifier starts to start, resistance value is reduced gradually after this adjustment transistor receives this control signal, and this control signal is changed to high level by low level, when control signal arrive high level time, utilize this switching signal increase a switching transistor conducting simultaneously this control signal become low level again.
8. exchange audio power amplifier as claimed in claim 6, wherein when this exchange audio power amplifier preparation is closed, resistance value is improved gradually after this adjustment transistor receives this control signal, and this control signal is changed to low level by high level, when control signal arrive low level time, utilize this switching signal reduce a switching transistor conducting simultaneously this control signal become high level again.
9. exchange audio power amplifier as claimed in claim 6, it also comprises:
One ramp signal generator, is used for producing this control signal, and the slope changing this control signal according to a mode signal is for just or be negative, and produces a recurrent pulse when this control signal arrives a first threshold or a Second Threshold; And
One counting unit, produces a count value as this switching signal, and carries out upper number or lower number according to this mode signal after counting this recurrent pulse, and in this count value be 0 or equal a default value time by a switching signal activation.
10. exchange audio power amplifier as claimed in claim 9, wherein this first threshold is the minimum voltage of this ramp signal, and this Second Threshold is the ceiling voltage of this ramp signal.
11. exchange audio power amplifiers as claimed in claim 9, when wherein this mode signal represents power initiation, the slope of this control signal is for just and this counting unit carries out upper number, and the indivedual conducting gradually of described switching transistor, and when this mode signal represents power-off, the slope of this control signal is negative and this counting unit carries out lower number, and the indivedual open circuit gradually of the plurality of switching transistor.
The popping inhibition method of 12. 1 kinds of exchange audio power amplifiers, this exchange audio power amplifier comprises multiple switching transistor and an impedance switching unit, wherein said switching transistor is in parallel mutually, and its grid of this impedance switching unit receives an exchange of audio signals, one end is separately had to be coupled to described switching transistor, and output signal in this end, this popping inhibition method comprises the following steps:
When starting to start, often through one of them of switching transistor described in a time section and conducting; And
When preparing closedown, often namely disconnect one of them of described switching transistor through a time section;
Wherein conducting controlled by one group of switching signal with disconnection, and
Multiple accumulated number that this group switching signal is produced by a pulse-width signal or the count value produced by a recurrent pulse determined.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200710196292.0A CN101453198B (en) | 2007-12-07 | 2007-12-07 | The popping inhibition method of exchange audio power amplifier |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200710196292.0A CN101453198B (en) | 2007-12-07 | 2007-12-07 | The popping inhibition method of exchange audio power amplifier |
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| CN101453198B true CN101453198B (en) | 2015-08-05 |
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4788508A (en) * | 1987-03-06 | 1988-11-29 | Kabushiki Kaisha Toshiba | Pop noise suppression circuit for audio amplifier |
| US5682121A (en) * | 1995-01-31 | 1997-10-28 | National Semiconductor Corporation | No turn-on pop noise amplifier |
| CN1192083A (en) * | 1997-02-26 | 1998-09-02 | 汤姆森多媒体公司 | Anti-pop for power off |
| US6157726A (en) * | 1997-12-05 | 2000-12-05 | Motorola, Inc. | Circuit and method of preventing audio pop in an electronic audio device |
| CN1610393A (en) * | 2004-10-27 | 2005-04-27 | 海信集团有限公司 | Graded silencing method for TV set |
| CN2802865Y (en) * | 2005-06-27 | 2006-08-02 | 海信集团有限公司 | Silent circuit of earphone |
-
2007
- 2007-12-07 CN CN200710196292.0A patent/CN101453198B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4788508A (en) * | 1987-03-06 | 1988-11-29 | Kabushiki Kaisha Toshiba | Pop noise suppression circuit for audio amplifier |
| US5682121A (en) * | 1995-01-31 | 1997-10-28 | National Semiconductor Corporation | No turn-on pop noise amplifier |
| CN1192083A (en) * | 1997-02-26 | 1998-09-02 | 汤姆森多媒体公司 | Anti-pop for power off |
| US6516067B1 (en) * | 1997-02-26 | 2003-02-04 | Thomson Licensing, S.A. | Anti pop for power off |
| US6157726A (en) * | 1997-12-05 | 2000-12-05 | Motorola, Inc. | Circuit and method of preventing audio pop in an electronic audio device |
| CN1610393A (en) * | 2004-10-27 | 2005-04-27 | 海信集团有限公司 | Graded silencing method for TV set |
| CN2802865Y (en) * | 2005-06-27 | 2006-08-02 | 海信集团有限公司 | Silent circuit of earphone |
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|---|---|
| CN101453198A (en) | 2009-06-10 |
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