CN100417016C - Shock-wave noise preventing circuit - Google Patents
Shock-wave noise preventing circuit Download PDFInfo
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- CN100417016C CN100417016C CNB2005100728043A CN200510072804A CN100417016C CN 100417016 C CN100417016 C CN 100417016C CN B2005100728043 A CNB2005100728043 A CN B2005100728043A CN 200510072804 A CN200510072804 A CN 200510072804A CN 100417016 C CN100417016 C CN 100417016C
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Abstract
The present invention provides a shock-wave noise preventing circuit composed of a diode. The bias voltage state of the diode is changed by a control signal so that shock-wave noise generated when a power supply (Vcc) is switched on or off is led out.
Description
[technical field]
The invention relates to a kind of mute circuit, and particularly relevant for a kind of mute circuit that utilizes diode to design.
[background technology]
Traditionally; 100 designs of voice output circuit as shown in Figure 1; one electrostatic discharge protective circuit 102; damage internal circuit in order to prevent external static electrification from entering this voice output circuit 100; one comes from the voice signal of sound integrated circuit or enlarger, output behind this low pass filter 104 and electrostatic discharge protective circuit 102.
Yet; regular meeting makes the voice signal of output have one " sonic boom " phenomenon to produce when switching on and shutting down; this is the interference of the surging of Zhao Yin when output signal is subjected to the power Vcc startup; because when the moment of Switching Power Supply Vcc; when power Vcc does not enter stable state as yet, and can't confirm the output quality of sound.Therefore, be this bad sound quality of solution traditionally, that is solve " sonic boom " phenomenon that meeting is gone again and added a shock-wave noise preventing circuit 106, in order to elimination power Vcc surging in voice output circuit 100.
Traditional shock-wave noise preventing circuit 106 comprises bipolarity junction transistor (Bipolar Junction Transistor, BJT) 108 and 110 of two positive-negative-positives as shown in Figure 1.When power Vcc is opened, for " sonic boom " phenomenon that prevents that power Vcc unlatching unstable voltage of moment from being caused, control signal can trigger shock-wave noise preventing circuit 106 in advance before power Vcc is opened, conducting bipolarity junction transistor 110 is used and is eliminated " sonic boom " phenomenon that power Vcc is opened moment.
Therefore, in operation, this control signal is input one low level signal earlier, make bipolarity junction transistor 108 be in closing state, it can be exported a high-level voltage and came conducting bipolarity junction transistor 110 this moment, to open by this or " sonic boom " that powered-down Vcc moment produces, derive via bipolarity junction transistor 110.Traditionally, can set a fixing ON time, 10ms for example, after this setting-up time arrives, control signal can be transformed into the high levels signal, makes 108 conductings of bipolarity junction transistor and exports low level voltage, closes bipolarity junction transistor 110, this moment, shock-wave noise preventing circuit 106 was no longer worked, and normal output sound signal.
Traditional shock-wave noise preventing circuit because control signal is opposite with power Vcc polarity, therefore need adopt bipolarity junction transistor 108 as inverter in design, needs the cost extra cost.And on the other hand, because control signal need cooperate the unlatching of power Vcc or shut-in time to trigger shock-wave noise preventing circuit, so the control of the priority of above signal and power Vcc sequential is quite important.Therefore need a kind of simplicity of design badly and do not require the shock-wave noise preventing circuit of complicated sequencing control.
[summary of the invention]
Therefore, main purpose of the present invention is exactly that a kind of shock-wave noise preventing circuit of simplicity of design is being provided.
According to above-mentioned purpose, the invention provides a kind of shock-wave noise preventing circuit that is constituted by a diode, utilize a control signal to change the bias state of diode, use power Vcc is opened or turn-off transient produced " sonic boom " derived.
In another embodiment, shock-wave noise preventing circuit of the present invention comprises one first diode and a charge-discharge circuit, wherein this charge-discharge circuit is to be formed and be connected in main power source Vcc by resistance and electric capacity in a preferred embodiment, its common joint and first diode join, and utilize the operating time of being decided shock-wave noise preventing circuit the required time of capacitor charge and discharge.
[description of drawings]
Fig. 1 system illustrates the voice output circuit skeleton diagram of traditional tool shock-wave noise preventing circuit.
Fig. 2 system illustrates the voice output circuit skeleton diagram of the shock-wave noise preventing circuit of tool first embodiment of the invention.
Fig. 3 system illustrates the voice output circuit skeleton diagram of the shock-wave noise preventing circuit of tool second embodiment of the invention.
Fig. 4 system illustrates the voice output circuit skeleton diagram of the shock-wave noise preventing circuit of tool third embodiment of the invention.
[embodiment]
Below will shock-wave noise preventing circuit of the present invention be described, it should be noted that in the corresponding diagram of following each embodiment institute reference that electrostatic discharge protective circuit shown in it 102 is non-to be a necessary circuitry with several embodiment.That is in some applications, the voice output circuit can not use electrostatic discharge protective circuit.Even but in not using the voice output circuit of electrostatic discharge protective circuit, still can use shock-wave noise preventing circuit of the present invention.
Consult and Figure 2 shows that according to the formed shock-wave noise preventing circuit of first embodiment of the invention.According to present embodiment; voice output circuit 209 is made of input 207, low pass filter 203, electrostatic discharge protective circuit 201, output 210; and shock-wave noise preventing circuit 200 is made of one first diode 202, and uses an independent control signal that is produced by control signal source 211 to trigger first diode 202.In the setting-up time interval that power Vcc is opened or closed; for fear of producing " sonic boom " phenomenon; first diode 202 can maintain the forward bias voltage drop state; according to embodiments of the invention; system is set in a low level state with control signal; use and open this shock-wave noise preventing circuit 200, the voice signal that produces when allowing power Vcc moment open and to close is derived via low pass filter 203, electrostatic discharge protective circuit 201 and first diode 202.Then; behind one section setting-up time interval; 8ms for example; this first diode 202 can be converted into reverse bias; according to embodiments of the invention; system is set in a high levels state with control signal, and this moment, this shock-wave noise preventing circuit 200 was closed, and voice signal is exported behind low pass filter 203 and electrostatic discharge protective circuit 201.Therefore, the control signal that control signal source 211 is produced, its high levels signal system falls behind the time point that this power Vcc is opened with one section Preset Time, and wherein this control signal source for example is a GPIO (gernal purpose inputoutput).And when power Vcc was closed, this control signal can be about to first diode 202 earlier and be become the forward bias voltage drop state by the reverse bias state exchange, and " sonic boom " phenomenon of using moment when power Vcc closed derives through first diode 202 thus.
According to the first embodiment of the present invention, only use one first diode 202 to constitute a shock-wave noise preventing circuit, not only circuit is simple, and required cost also only is the price of one first diode.And because therefore control signal system and power Vcc homophase in control, only need after setting-up time arrives, switch-over control signal makes first diode convert reverse bias to by forward bias voltage drop and gets final product, and its sequencing control is not complicated.
Consult and Figure 3 shows that according to the formed shock-wave noise preventing circuit of second embodiment of the invention.In present embodiment, the charge-discharge circuit of forming by a resistance and an electric capacity comes setting-up time, and after setting-up time arrives, first diode is switched to reverse bias by forward bias voltage drop, wherein can change the length of setting-up time by the size of adjusting resistance value and capacitance.
According to present embodiment; voice output circuit 309 is made of input 307, low pass filter 303, electrostatic discharge protective circuit 301, output 310; and shock-wave noise preventing circuit 300 is made of one first diode 302, a resistance 304 and an electric capacity 306; wherein first diode 302 is connected on the common joint 308 of 306 of resistance 304 and electric capacity, and resistance 304 and electric capacity 306 are then formed a charge-discharge circuit.
When power Vcc is just opened; first diode 302 can maintain the forward bias voltage drop state; shock-wave noise preventing circuit 300 unlatchings this moment; allow " sonic boom " phenomenon of moment derive through first diode 302 thus; power Vcc can begin to charge to electric capacity 306 through this charge-discharge circuit simultaneously; when voltage across electric capacity 306 two ends; that is the voltage at common joint 308 places; after reaching the bias state of this first diode 302 of conversion; this first diode 302 is converted into reverse bias; this moment, this shock-wave noise preventing circuit 300 was closed, and voice signal is exported behind low pass filter 303 and electrostatic discharge protective circuit 301.Similar, when power Vcc is closed, electric capacity 306 can discharge via resistance 304, make the voltage at common joint 308 places descend, and with the bias state of first diode 302, convert forward bias voltage drop once more to by the reverse bias state, " sonic boom " phenomenon of moment derived via first diode 302 when power Vcc was closed.
According to a second embodiment of the present invention, one charge-discharge circuit of being made up of resistance 304 and electric capacity 306 is connected on the power Vcc, when this moment, electric capacity 306 was charged to convertible first diode, 302 of-state voltages, required time was the operating time of shock-wave noise preventing circuit 300.Therefore, under circuit structure of the present invention, can utilize the size of adjusting resistance value and capacitance and the operating time that changes shock-wave noise preventing circuit 300.In other words,, when it lies in power-on Vcc, promptly start shock-wave noise preventing circuit 300, and when electric capacity 306 charges to convertible first diode, 302 states, close shock-wave noise preventing circuit 300, therefore, do not need extra control signal according to present embodiment.
Consult and Figure 4 shows that according to the formed shock-wave noise preventing circuit of third embodiment of the invention.According to present embodiment; voice output circuit 409 is made of input 407, low pass filter 403, electrostatic discharge protective circuit 405, output 410; and shock-wave noise preventing circuit 400 is made of first diode 402 and second diode 401, a resistance 404 and an electric capacity 406; wherein first diode 402 is connected on the common joint 408 of 406 of resistance 404 and electric capacity, and resistance 404 and electric capacity 406 are then formed a charge-discharge circuit.401 of second diodes are as a discharge path.One control signal connects resistance 404.
When power Vcc was opened, for fear of producing " sonic boom " phenomenon, diode 402 can maintain the forward bias voltage drop state, allowed moment " sonic boom " to derive through first diode 402 thus.Then, after one period scheduled time, this first diode 402 is converted to reverse bias, uses and close this shock-wave noise preventing circuit 400, voice signal is exported behind low pass filter 403 and electrostatic discharge protective circuit 405.In this embodiment, this section scheduled time is the time required when electric capacity 406 is charged to convertible first diode, 402 of-state voltages.
According to present embodiment, when power Vcc is opened, also open simultaneously in control signal source 411, and charge via 404 pairs of electric capacity 406 of resistance, this moment, first diode 402 can temporarily maintain the forward bias voltage drop state, and " sonic boom " that will open moment derive, and wherein this control signal source 411 can be a GPIO (gernal purpose input output).When voltage, that is the voltage at common joint 408 places across electric capacity 406 two ends, reach the bias state of this first diode 402 of conversion after, this first diode 402 is converted into reverse bias, this moment, this shock-wave noise preventing circuit 400 was closed.Similar, when power Vcc is closed, electric capacity 406 can discharge via the resistance 404 and second diode 401, make the voltage at common joint 408 places descend, and with the bias state of first diode 402, convert forward bias voltage drop once more to by the reverse bias state, " sonic boom " phenomenon of moment derived via first diode 402 when power Vcc was closed.
A third embodiment in accordance with the invention by the charge-discharge circuit that resistance 404 and electric capacity 406 are formed, can determine the reversal time of first diode 402, easy speech, and reversing time can make alterations by adjusting resistance value and capacitance.On the other hand, when first diode 402 becomes along bias state by the reverse blas state exchange, the invention provides an extra discharge path that is constituted by second diode 401, the change-over time when quickening powered-down Vcc, but make 400 moments of shock-wave noise preventing circuit start, eliminate " sonic boom ".
In sum, shock-wave noise preventing circuit of the present invention is made up of first diode, is in the operating time of deciding shock-wave noise preventing circuit along bias state or reverse blas state by it.Therefore quite simple in design.And the present invention also utilizes a charge-discharge circuit of being made up of resistance and electric capacity, decide the action time point of shock-wave noise preventing circuit, therefore can be by adjusting the purpose that resistance value or capacitance reach adjustment, and do not need as the preceding skill, need to use an extra inverter and a subsidiary count tool, the counting that carries out setting-up time is with switch-over control signal.
Though the present invention discloses as above with a preferred embodiment; right its is not in order to limit the present invention; anyly have the knack of this skill person; without departing from the spirit and scope of the present invention; when can being used for a variety of modifications and variations, so protection scope of the present invention is as the criterion when looking accompanying the claim person of defining.
Claims (13)
1. shock-wave noise preventing circuit, system is coupled to a voice output circuit, and in order to prevent a sonic boom phenomenon of a voice signal, a supply coupling is in this voice output circuit, one voice signal also is coupled to an input of this voice output circuit, and this shock-wave noise preventing circuit comprises at least:
One control signal source produces a control signal, and this control signal more comprises a low level signal and a high levels signal;
One first diode, two ends are respectively coupled to one second input and this control signal source of this voice output circuit, when this first diode system is in one along bias state, this voice signal enters this first diode and is exported by this first diode, be in a reverse blas state and work as this first diode system, this voice signal is by the output output of this voice output circuit;
Wherein this low level signal system impels this first diode to be in one along bias state, and this high levels signal system impels this first diode to be in a reverse blas state.
2. shock-wave noise preventing circuit according to claim 1 is characterized in that, this control signal source is a GPIO.
3. shock-wave noise preventing circuit according to claim 1 is characterized in that, the very first time point system that this control signal source begins to produce this high levels signal lags behind one second time point that this power supply begins to open with a Preset Time interval.
4. shock-wave noise preventing circuit according to claim 1 more comprises:
One charge-discharge circuit is coupled to this first diode, and this charge-discharge circuit system is by this control signal control;
One discharge path is connected in this charge-discharge circuit, and this discharge path system is made up of one second diode.
5. shock-wave noise preventing circuit according to claim 4 is characterized in that, this charge-discharge circuit comprises the connection of contacting each other of resistance and an electric capacity.
6. shock-wave noise preventing circuit according to claim 5 is characterized in that, this first diode system is connected on the common contact with this resistance, this electric capacity and this second diode.
7. shock-wave noise preventing circuit according to claim 5 is characterized in that, this control signal can be charged to this electric capacity, uses the bias state of this first diode of conversion.
8. shock-wave noise preventing circuit, system is coupled to a voice output circuit, and in order to prevent the sonic boom of a voice signal, a power supply also is coupled to this voice output circuit, one voice signal also is coupled to an input of this voice output circuit, and this shock-wave noise preventing circuit comprises at least:
One first diode is coupled to this voice output circuit; And
One charge-discharge circuit, be coupled to this first diode, use the bias state of this first diode of control, when this first diode system is in one along bias state, this voice signal enters this shock-wave noise preventing circuit, be in a reverse blas state and work as this first diode system, this voice signal is by the output output of this voice output circuit.
9. shock-wave noise preventing circuit according to claim 8 is characterized in that, this charge-discharge circuit system is coupled to this power supply.
10. shock-wave noise preventing circuit according to claim 9 is characterized in that, this charge-discharge circuit comprises the connection of contacting each other of resistance and an electric capacity, and this first diode system is connected on the common contact that this resistance and this electric capacity polyphone connect.
11. shock-wave noise preventing circuit according to claim 10 is characterized in that, can charge to this electric capacity when this electric power starting, uses the bias state of this first diode of conversion.
12. shock-wave noise preventing circuit according to claim 8 is characterized in that, this charge-discharge circuit system is coupled to a control signal source;
One discharge path is connected in this charge-discharge circuit, and this discharge path system is made up of one second diode.
13. shock-wave noise preventing circuit according to claim 12 is characterized in that, this control signal source is a GPIO.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2005100728043A CN100417016C (en) | 2005-05-09 | 2005-05-09 | Shock-wave noise preventing circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2005100728043A CN100417016C (en) | 2005-05-09 | 2005-05-09 | Shock-wave noise preventing circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1862950A CN1862950A (en) | 2006-11-15 |
| CN100417016C true CN100417016C (en) | 2008-09-03 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2005100728043A Active CN100417016C (en) | 2005-05-09 | 2005-05-09 | Shock-wave noise preventing circuit |
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| CN (1) | CN100417016C (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101330277B (en) * | 2007-06-20 | 2012-02-08 | 震一科技股份有限公司 | Circuit and method for eliminating horn popping when turning on and turning down power amplifier |
| CN102082983B (en) * | 2009-11-26 | 2013-11-06 | 鸿富锦精密工业（深圳）有限公司 | Crackle suppression circuit |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1050442A (en) * | ||||
| GB1029343A (en) * | 1964-08-18 | 1966-05-11 | Communications Patents Ltd | Improvements in or relating to electric wave receivers |
| US4223357A (en) * | 1978-10-23 | 1980-09-16 | Alden Research Foundation | Facsimile recorder with sweep rate detection |
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2005
- 2005-05-09 CN CNB2005100728043A patent/CN100417016C/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1050442A (en) * | ||||
| GB1029343A (en) * | 1964-08-18 | 1966-05-11 | Communications Patents Ltd | Improvements in or relating to electric wave receivers |
| US4223357A (en) * | 1978-10-23 | 1980-09-16 | Alden Research Foundation | Facsimile recorder with sweep rate detection |
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| CN1862950A (en) | 2006-11-15 |
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