CN1917364B - Limiter of segmented gains, and control method - Google Patents
Limiter of segmented gains, and control method Download PDFInfo
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- CN1917364B CN1917364B CN2005100917967A CN200510091796A CN1917364B CN 1917364 B CN1917364 B CN 1917364B CN 2005100917967 A CN2005100917967 A CN 2005100917967A CN 200510091796 A CN200510091796 A CN 200510091796A CN 1917364 B CN1917364 B CN 1917364B
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Abstract
The invention is designed for use in connecting with an external audio amplifier which has a gain value and outputs an outputting signal according to an inputted signal and said gain value. It sectional gain limiter comprises a comparator and a limiter. The comparator has a threshold value used to receive an outputted signal; when the outputted signal is more then said threshold, the comparator outputs a driving signal. The limiter is used to receive said driving signal from the comparator and outputs a control signal in order to control the output signal of the audio amplifier.
Description
[technical field]
The invention relates to a kind of limiter of segmented gains and control method thereof, and particularly relevant for a kind of limiter of segmented gains and control method thereof of audio frequency amplifier.
[background technology]
Because the multimedization demand of electronics technology, no matter be personal computer, mobile computer, video disk player, digital music player etc. at present, all towards multi-functional designer trends, for example in personal computer, video disk player or mobile computer, all often be used to as audio and video player separately, and the user also expects all that personal computer, video disk player and mobile computer as audio and video player can have preferable audio-visual result of broadcast.With present mobile computer, though employed loudspeaker specification is generally 8/1W, the highest input voltage that can bear is 2.282Vrms (maximum is 4V), and the power output of general walkman is big.But in practical application, because of the power supply that audio frequency amplifier connect of mobile computer is 5V, make the voltage export loudspeaker to have loudspeaker burnt above the possibility of 4V, thus the engineering staff when design, the voltage gain that can reduce audio frequency amplifier burns to avoid loudspeaker.But when reducing voltage gain, will cause the real output deficiency of sound.For example, even the loudspeaker volume in the mobile computer is transferred to maximum, also can't reach the shock effect of playing via walkman.
Figure 1A illustrates the circuit diagram into inverting amplifier in the conventional audio amplifier.Inverting amplifier 100 comprises operational amplifier 110, resistance R 1 and resistance R 2.The direct-current working volts Vcc of operational amplifier 110 is provided by external power source 160.The yield value of inverting amplifier is
The AC-input voltage V1 of inverting amplifier 100 amplifies back output one ac output voltage V1 ', its ac output voltage according to above-mentioned yield value power
Figure 1B illustrates the circuit diagram into non-inverting amplifier in the conventional audio amplifier.Non-inverting amplifier 200 comprises operational amplifier 110, resistance R 3, resistance R 4, resistance R 5 and resistance R 6.The direct-current working volts Vcc of operational amplifier 110 is provided by external power source 160.The yield value of non-inverting amplifier is
The AC-input voltage V2 of non-inverting amplifier 200 amplifies back output one ac output voltage V2 ', its output voltage according to above-mentioned yield value power
Because the ac output voltage V1 ' of inverting amplifier 100 (Figure 1A) is the direct-current working volts Vcc that depends on the operational amplifier 110 with the amplitude maximum of the ac output voltage V2 ' of non-inverting amplifier 200 (Figure 1B), and ac output voltage V1 ' (Figure 1A) and V2 ' (Figure 1B) need via loudspeaker 190 to produce auditory effect.Whether the amplitude that therefore will pay special attention to ac output voltage V1 ' or V2 ' surpasses the load of loudspeaker 190.As previously mentioned, the employed loudspeaker specification of mobile computer is generally 8/1W, thereby the ac output voltage V1 ' that can bear of loudspeaker 190 or the peak of V2 ' are about 4V to peak value (Vp-p).The direct-current working volts that provide because of mobile computer inside are 5V again, therefore, when AC-input voltage V1 or V2 through the ac output voltage V1 ' that produced after the power amplification and V2 ' during greater than 4V, loudspeaker 190 promptly burn because of bearing its load.
For fear of burning of loudspeaker 190, the ac output voltage amplitude maximum Vomax that must can bear according to loudspeaker 190 downgrades the AC-input voltage of the yield value or the audio frequency amplifier of original audio frequency amplifier.Purpose with the amplitude that reaches limiting AC output voltage V 1 ' or V2 '.Yet, when downgrading yield value, representing original output volume of sacrificing loudspeaker 190 also, also cause the reduction of whole auditory effect simultaneously.
Please be simultaneously with reference to Fig. 2 A and Fig. 2 B, Fig. 2 A illustrates the circuit diagram for the inverting amplifier that increases by one group of dc voltage changer.Fig. 2 B illustrates the circuit diagram for the non-inverting amplifier that increases by one group of dc voltage changer.For fear of burning of loudspeaker 190, another method of the ac output voltage V1 ' of restriction operational amplifier 110 and the amplitude of V2 ' promptly is the direct-current working volts Vcc that reduces on the operational amplifier 110.Make the amplitude maximum Vomax of the ac output voltage that direct-current working volts Vcc and loudspeaker 190 can bear identical.Because the amplitude maximum Vomax of the ac output voltage of operational amplifier 110 equals the direct-current working volts Vcc of operational amplifier 110, and the direct-current working volts Vcc of conventional operation amplifier 110 system is directly provided by external power source 160, therefore by increasing by one group of dc voltage changer 170 that the amplitude maximum Vomax that the voltage of external power source 160 transfers to the ac output voltage that can bear with loudspeaker 190 is identical, can reach the purpose of the ac output voltage amplitude of restriction operational amplifier 110.
Yet, increase the area that one group of dc power converter 170 needs to increase printed circuit board (PCB), cause the raising of production cost.And, increase by one group of dc power converter 170 and not only will occupy space in the previous system, (Electro Magnetic Interference EMI) disturbs the regular event of electronic product to be easy to generate electromagnetic interference effect simultaneously.
[summary of the invention]
In view of this, purpose of the present invention is providing a kind of limiter of segmented gains exactly.When utilizing limiter of segmented gains of the present invention can not reach the ac output voltage amplitude maximum that loudspeaker can bear in the ac output voltage amplitude of audio frequency amplifier, after AC-input voltage done signal and amplify according to original yield value of audio frequency amplifier, export an ac output voltage, make the real output of sound be kept original sound field shock effect by be allowed loudspeaker.And when ac output voltage was about to reach the ac output voltage amplitude maximum that loudspeaker can bear, AC-input voltage or yield value that limiter of segmented gains promptly limits audio frequency amplifier were not burnt by excessive ac output voltage to reach the protection loudspeaker.
According to purpose of the present invention, a kind of limiter of segmented gains is proposed.Limiter of segmented gains is in order to an external audio frequency amplifier.Audio frequency amplifier has a yield value, and audio frequency amplifier amplifies output one output signal in back according to yield value with an input signal power.Limiter of segmented gains comprises a comparator and a limiter.Comparator has a critical value, comparator and in order to detecting the output signal of audio frequency amplifier, and, export a drive signal when the output signal of audio frequency amplifier during greater than the critical value of comparator.Limiter is in order to receive drive signal and to export a control signal according to drive signal and limit its output signal with the control audio amplifier.
According to another object of the present invention, a kind of control method of application of aforementioned limiter of segmented gains is proposed.The external audio frequency amplifier of limiter of segmented gains, limiter of segmented gains comprises a comparator and a limiter.At first, utilize comparator to detect an output signal of audio frequency amplifier.Then, judge that output signal is whether greater than a critical value of comparator.And then, when output signal during, export a drive signal greater than critical value.Then, export a control signal according to the drive limiter.At last, according to control signal control audio amplifier with the restriction output signal.
For above-mentioned purpose of the present invention, feature and advantage can be become apparent, a preferred embodiment cited below particularly, and cooperate appended graphicly, be described in detail below:
[description of drawings]
Figure 1A illustrates the circuit diagram into inverting amplifier in the conventional audio amplifier.
Figure 1B illustrates the circuit diagram into non-inverting amplifier in the conventional audio amplifier.
Fig. 2 A illustrates the circuit diagram for the inverting amplifier that increases by one group of dc voltage changer.
Fig. 2 B illustrates the circuit diagram for the non-inverting amplifier that increases by one group of dc voltage changer.
Fig. 3 illustrates according to the present invention and utilizes limiter of segmented gains to be connected to the calcspar of audio frequency amplifier.
Fig. 4 A illustrates the schematic diagram that is connected to inverting amplifier according to a kind of limiter of segmented gains of the present invention one first embodiment.
Fig. 4 B illustrates the schematic diagram that is connected to inverting amplifier according to a kind of limiter of segmented gains of the present invention one second embodiment.
Fig. 4 C illustrates the schematic diagram that is connected to inverting amplifier according to a kind of limiter of segmented gains of the present invention 1 the 3rd embodiment.
Fig. 5 A illustrates the schematic diagram that is connected to inverting amplifier according to a kind of limiter of segmented gains of the present invention 1 the 4th embodiment.
Fig. 5 B illustrates the schematic diagram that is connected to inverting amplifier according to a kind of limiter of segmented gains of the present invention 1 the 5th embodiment.
Fig. 5 C illustrates the schematic diagram that is connected to inverting amplifier according to a kind of limiter of segmented gains of the present invention 1 the 6th embodiment.
Fig. 6 A illustrates the schematic diagram that is connected to non-inverting amplifier according to a kind of limiter of segmented gains of the present invention 1 the 7th embodiment.
Fig. 6 B illustrates the schematic diagram that is connected to non-inverting amplifier according to a kind of limiter of segmented gains of the present invention 1 the 8th embodiment.
It illustrates the schematic diagram that is connected to non-inverting amplifier according to a kind of limiter of segmented gains of the present invention 1 the 9th embodiment Fig. 6 C.
Fig. 7 A illustrates the schematic diagram that is connected to non-inverting amplifier according to a kind of limiter of segmented gains of the present invention 1 the tenth embodiment.
Fig. 7 B illustrates the schematic diagram that is connected to non-inverting amplifier according to a kind of limiter of segmented gains of the present invention 1 the 11 embodiment.
Fig. 7 C illustrates the schematic diagram that is connected to non-inverting amplifier according to a kind of limiter of segmented gains of the present invention 1 the 12 embodiment.
Fig. 8 illustrates the circuit diagram that is connected to inverting amplifier according to the limiter of segmented gains of the present invention 1 the 13 embodiment.
Measurement oscillogram when Fig. 9 A illustrates ac output voltage for the conventional inverter amplifier and do not reach critical value.
Measurement oscillogram when Fig. 9 B illustrates and do not reach critical value for ac output voltage of the present invention.
Fig. 9 C illustrates the measurement oscillogram that surpasses critical value into the ac output voltage of conventional inverter amplifier.
Fig. 9 D illustrates the measurement oscillogram that surpasses critical value into ac output voltage of the present invention.
Figure 10 illustrates according to the limiter of segmented gains of a preferred embodiment of the present invention control method flow chart to audio frequency amplifier.
[embodiment]
Please refer to Fig. 3, it illustrates according to the present invention and utilizes limiter of segmented gains to be connected to the calcspar of audio frequency amplifier.As shown in Figure 3, limiter of segmented gains 300 is in order to external audio frequency amplifier 310.Audio frequency amplifier 310 for example can be an inverting amplifier or a non-inverting amplifier.Audio frequency amplifier 310 amplifies output one output signal S2 in back according to a yield value with input signal S1 power.Limiter of segmented gains 300 comprises comparator 330 and limiter 320.Comparator 330 is in order to receive the output signal S2 of audio frequency amplifier 310.As the output signal S2 of audio frequency amplifier 310 during greater than the critical value of comparator 330, comparator 330 output drive signal S4.Limiter 320 is according to the drive signal S4 output control signal S5 of comparator 330, limiter of segmented gains 300 is according to the input signal S1 or the yield value of control signal S5 control audio amplifier 310, to reach the purpose of the output signal S2 that limits audio frequency amplifier 310.Utilize the design of limiter of segmented gains 300 of the present invention, can solve effectively in the conventional audio amplifier needs integral body to sacrifice original voltage gain in the audio frequency amplifier 310 for fear of burning of loudspeaker, cause the integral body of power output to descend, the related original sound field shock of the loudspeaker effect that influences.
First embodiment
Please refer to Fig. 4 A, it illustrates the schematic diagram that is connected to inverting amplifier according to a kind of limiter of segmented gains of the present invention one first embodiment.Furthermore, audio frequency amplifier can be an inverting amplifier 400 in one embodiment.Inverting amplifier 400 comprises a resistance R 7a, resistance R 7b, a resistance R 8 and an operational amplifier 410.Second end of resistance R 7a and first end of resistance R 7b electrically connect.The inverting input of second end of resistance R 7b and first end of resistance R 8 and operational amplifier 410 electrically connects.Second end of resistance R 8 and the output of operational amplifier 410 electrically connect.The normal phase input end of operational amplifier 410 and an earth terminal electrically connect.Inverting amplifier 400 is according to resistance R 7a, resistance R 7b and resistance R 8 yield value with decision inverting amplifier 400.
When the input signal of inverting amplifier 400 is an AC-input voltage V3, and when entering inverting amplifier 400 via first end of resistance R 7a, inverting amplifier 400 amplifies the comparator 330 that back output one outputs signal to limiter of segmented gains 300 according to yield value with AC-input voltage V3 power, and output signal for example can be ac output voltage V3 '.The critical value of comparator 330 can be a reference voltage Vref.As ac output voltage V3 ' during greater than reference voltage Vref, comparator 330 outputs one drive signal S4.Limiter 320 is exported a control signal S5 according to drive signal S4, and V3 falls within the voltage of the inverting input of operational amplifier 410 with the control AC-input voltage, and then reaches the purpose of limiting AC output voltage V 3 '.
Second embodiment
The output signal that the comparator 330 of limiter of segmented gains 300 is received is except can be for the ac output voltage V3 ', and output signal can also for example be the potential difference at resistance R 8 two ends.Please refer to Fig. 4 B, it illustrates the schematic diagram that is connected to inverting amplifier according to a kind of limiter of segmented gains of the present invention one second embodiment.The comparator 330 of limiter of segmented gains 300 does one relatively according to the potential difference at resistance R 8 two ends and the reference voltage (not shown) of comparator 330, when the potential difference at resistance R 8 two ends during greater than the reference voltage of comparator 330, comparator 330 outputs one drive signal S4.Limiter 320 is exported a control signal S5 according to drive signal S4, and V3 falls within the voltage of the inverting input of operational amplifier 410 with the control AC-input voltage, and then reaches the purpose of limiting AC output voltage V 3 '.
The 3rd embodiment
Please refer to Fig. 4 C, it illustrates the schematic diagram that is connected to inverting amplifier according to a kind of limiter of segmented gains of the present invention 1 the 3rd embodiment.Similarly, output signal can also for example be the potential difference at resistance R 7b two ends.The comparator 330 of limiter of segmented gains 300 does one relatively according to the potential difference at resistance R 7b two ends and reference voltage Vref, when the potential difference at resistance R 7b two ends during greater than reference voltage Vref, and comparator 330 outputs one drive signal S4.Limiter 320 is exported a control signal S5 according to drive signal S4, and V3 falls within the voltage of the inverting input of operational amplifier 410 with the control AC-input voltage, and then reaches the purpose of limiting AC output voltage V 3 '.
The 4th embodiment
The limiter 320 of limiter of segmented gains 300 is exported a control signal S5 according to drive signal S4, the control signal S5 of limiter 320 not only may command AC-input voltage V3 falls within the voltage of the inverting input of operational amplifier 410, limiter 320 also can make limiter 320 to change the yield value of resistance R 8 with control inverting amplifier 400 according to control signal S5 by the design of circuit.Please refer to Fig. 5 A, it illustrates the schematic diagram that is connected to inverting amplifier according to a kind of limiter of segmented gains of the present invention 1 the 4th embodiment.The comparator 330 of limiter of segmented gains 300 does one relatively according to the output signal and the reference voltage Vref of inverting amplifier 400, and output signal for example can be ac output voltage V3 '.As the ac output voltage V3 ' of inverting amplifier 400 during greater than the reference voltage Vref of comparator 330, comparator 330 outputs one drive signal S4.Limiter 320 is exported a control signal S5 according to drive signal S4, and limiter 320 changes the yield value of resistance R 8 with control inverting amplifier 400 according to control signal S5, and then reaches the purpose of limiting AC output voltage V 3 '.
The 5th embodiment
The output signal that the comparator 330 of limiter of segmented gains 300 is received is except can be for the ac output voltage V3 ', and output signal can also for example be the potential difference at resistance R 8 two ends.Please refer to Fig. 5 B, it illustrates the schematic diagram that is connected to inverting amplifier according to a kind of limiter of segmented gains of the present invention 1 the 5th embodiment.Comparator 330 is done one relatively (reference voltage is not illustrated among Fig. 5 B) according to the reference voltage of the potential difference at resistance R 8 two ends and comparator 330, when the potential difference at resistance R 8 two ends during greater than reference voltage, and comparator 330 outputs one drive signal S4.Limiter 320 is exported a control signal S5 according to drive signal S4, and limiter 320 changes the yield value of resistance R 8 with control inverting amplifier 400 according to control signal S5, and then reaches the purpose of limiting AC output voltage V 3 '.
The 6th embodiment
Please refer to Fig. 5 C, it illustrates the schematic diagram that is connected to inverting amplifier according to a kind of limiter of segmented gains of the present invention 1 the 6th embodiment.Similarly, output signal can also for example be the potential difference at resistance R 7 two ends.The comparator 330 of limiter of segmented gains 300 also can do one relatively according to the reference voltage (not shown) of the potential difference at resistance R 7 two ends and comparator 330, when the potential difference at resistance R 7 two ends during greater than reference voltage, and comparator 330 outputs one drive signal S4.Limiter 320 is exported a control signal S5 according to drive signal S4, and limiter 320 changes the yield value of resistance R 8 with control inverting amplifier 400 according to control signal S5, and then reaches the purpose of limiting AC output voltage V 3 '.
The 7th embodiment
The present invention except that can use inverting amplifier, also can be applicable to non-inverting amplifier.Please refer to Fig. 6 A, it illustrates the schematic diagram that is connected to non-inverting amplifier according to a kind of limiter of segmented gains of the present invention 1 the 7th embodiment.Audio frequency amplifier can be a non-inverting amplifier 600.Non-inverting amplifier 600 comprises a resistance R 9, a resistance R 10, a resistance R 11, a resistance R 12 and an operational amplifier 610.The normal phase input end of second end of resistance R 12, first end of resistance R 11 and operational amplifier 610 electrically connects.Second end of resistance R 11 and an earth terminal electrically connect.The inverting input of first end of resistance R 9, first end of resistance R 10 and operational amplifier 610 electrically connects.Second end of resistance R 9 and earth terminal electrically connect.Second end of resistance R 10 and the output of operational amplifier 610 electrically connect.Non-inverting amplifier 600 is according to resistance R 9, resistance R 10, resistance R 11 and the yield value of resistance R 12 with decision non-inverting amplifier 600.
When the input signal of non-inverting amplifier 600 is an AC-input voltage V4, and when entering non-inverting amplifier 600 via first end of resistance R 12, non-inverting amplifier 600 amplifies back output one according to yield value with AC-input voltage V4 power and outputs signal to comparator 330, and output signal for example can be an ac output voltage V4 '.The critical value of comparator 330 can be a reference voltage Vref.As ac output voltage V4 ' during greater than reference voltage Vref, comparator 330 outputs one drive signal S4.Limiter 320 is exported a control signal S5 according to drive signal S4, and V4 falls within the voltage at resistance R 11 two ends with the control AC-input voltage, and then reaches the purpose of limiting AC output voltage V 4 '.
The 8th embodiment
The output signal that the comparator 330 of limiter of segmented gains 300 is received is except can be for the ac output voltage V4 ', and output signal can also for example be the potential difference at resistance R 10 two ends.Please refer to Fig. 6 B, be connected to the schematic diagram of non-inverting amplifier according to a kind of limiter of segmented gains of the present invention 1 the 8th embodiment.The comparator 330 of limiter of segmented gains 300 does one relatively according to the potential difference at resistance R 10 two ends and reference voltage (not shown), when the potential difference at resistance R 10 two ends during greater than reference voltage, and comparator 330 outputs one drive signal S4.Limiter 320 is exported a control signal S5 according to drive signal S4, and V4 falls within the voltage at resistance R 11 two ends with the control AC-input voltage, and then reaches the purpose of limiting AC output voltage V 4 '.
The 9th embodiment
Please refer to Fig. 6 C, it illustrates the schematic diagram that is connected to non-inverting amplifier according to a kind of limiter of segmented gains of the present invention 1 the 9th embodiment.Similarly, output signal can also for example be the potential difference at resistance R 9 two ends.Comparator 330 also can do one relatively according to the potential difference at resistance R 9 two ends and reference voltage Vref, when the potential difference at resistance R 9 two ends during greater than reference voltage Vref, and comparator 330 outputs one drive signal S4.Limiter 320 is exported a control signal S5 according to drive signal S4, and V4 falls within the voltage at resistance R 11 two ends with the control AC-input voltage, and then reaches the purpose of limiting AC output voltage V 4 '.
The tenth embodiment
The limiter 320 of limiter of segmented gains 300 is exported a control signal S5 according to drive signal S4, not only may command AC-input voltage V4 falls within the voltage at resistance R 11 two ends, limiter 320 also can make limiter 320 to change the yield value of resistance R 10 with control non-inverting amplifier 600 according to control signal S5 by the design of circuit.Please refer to Fig. 7 A, it illustrates the schematic diagram that is connected to non-inverting amplifier according to a kind of limiter of segmented gains of the present invention 1 the tenth embodiment.The comparator 330 of limiter of segmented gains 300 does one relatively according to the output signal and the reference voltage Vref of non-inverting amplifier 600, and output signal for example can be ac output voltage V4 '.As the ac output voltage V4 ' of non-inverting amplifier 600 during greater than the reference voltage Vref of comparator 330, comparator 330 outputs one drive signal S4.The limiter 320 of limiter of segmented gains 300 is exported a control signal S5 according to drive signal S4, limiter 320 can change the yield value of resistance R 10 with control non-inverting amplifier 600 according to control signal S5, and then reaches the purpose of limiting AC output voltage V 4 '.
The 11 embodiment
The output signal that comparator 330 is received is except can be for the ac output voltage V4 ', and output signal can also for example be the potential difference at resistance R 10 two ends.Please refer to Fig. 7 B, it illustrates the schematic diagram that is connected to non-inverting amplifier according to a kind of limiter of segmented gains of the present invention 1 the 11 embodiment.Comparator 330 does one relatively according to the reference voltage (not shown) of the potential difference at resistance R 10 two ends and comparator 330, when the potential difference at resistance R 10 two ends during greater than reference voltage, and comparator 330 outputs one drive signal S4.Limiter 320 is exported a control signal S5 according to drive signal S4, and limiter 320 can change the yield value of resistance R 10 with control non-inverting amplifier 600 according to control signal S5, and then reaches the purpose of limiting AC output voltage V 4 '.
The 12 embodiment
Please refer to Fig. 7 C, it illustrates the schematic diagram that is connected to non-inverting amplifier according to a kind of limiter of segmented gains of the present invention 1 the 12 embodiment.Similarly, output signal can also for example be the potential difference at resistance R 9 two ends.The comparator 330 of limiter of segmented gains 300 also can do one relatively according to the reference voltage (not shown) of the potential difference at resistance R 9 two ends and comparator 330, when the potential difference at resistance R 9 two ends during greater than reference voltage, and comparator 330 outputs one drive signal S4.Limiter 320 is exported a control signal S5 according to drive signal S4, and limiter 320 can change the yield value of resistance R 10 with control non-inverting amplifier 600 according to control signal S5, and then reaches the purpose of limiting AC output voltage V 3 '.
The 13 embodiment
Please refer to Fig. 8, it illustrates the circuit diagram that is connected to inverting amplifier according to the limiter of segmented gains of the present invention 1 the 13 embodiment.Its circuit of the 13 embodiment comprises operational amplifier 710, resistance R 13, resistance R _ f 1, resistance R _ f 2, resistance R _ f 3, the first transistor Q1 and transistor seconds Q2.Be to utilize the cut-in voltage system of base stage-emitter junction of the first transistor Q1 and transistor seconds Q2 can be in the present embodiment, and the voltage that utilizes the collection utmost point of the first transistor Q1 and transistor seconds Q2 and emitter-base bandgap grading two ends be as limiter 320 as the reference voltage of a comparator 330.Limit it when making the first transistor Q1 and transistor seconds Q2 surpass reference voltage with negative half period respectively at the positive half cycle of ac output voltage simultaneously and export, the resistance value with resistance R _ f 3 is identical in fact for resistance R _ f 1 general.
The inverting input of the emitter-base bandgap grading of second end of resistance R 13, first end of resistance R _ f 1, the first transistor Q1, the collection utmost point of transistor seconds Q2 and operational amplifier 710 electrically connects.The base stage of second end of resistance R _ f 1, first end of resistance R _ f 2 and the first transistor Q1 electrically connects.The base stage of second end of resistance R _ f 2, first end of resistance R _ f 3 and transistor seconds Q2 electrically connects.The emitter-base bandgap grading of second end of resistance R _ f 3, the collection utmost point of the first transistor Q1, transistor seconds Q2 and the output of operational amplifier electrically connect.The normal phase input end of operational amplifier 710 and an earth terminal electrically connect.
Behind input AC input voltage V3, during in the potential difference at resistance R _ f 1 two ends or in the potential difference at resistance R _ f 2 two ends if less than reference voltage (being transistorized limit voltage (threshold) in this embodiment), then the first transistor Q1 and transistor seconds Q2 still are in cut-off state this moment, and this circuit is according to AC-input voltage V3 output AC output voltage
Behind input AC input voltage V3, during in the potential difference at resistance R _ f 1 two ends or in the potential difference at resistance R _ f 2 two ends if greater than reference voltage, then the first transistor Q1 and transistor seconds Q2 this moment non-original cut-off state, the base terminal electric current of the first transistor Q1 or transistor seconds Q2 begins to increase.Electric current on feasible the flow through first feedback resistance Rf1, the second feedback resistance Rf2 or the 3rd feedback resistance Rf3 reduces relatively.This moment, circuit will be according to the electric current of the resistance of flowing through and resistance R _ f 1, resistance R _ f 2, resistance R _ f 3 to determine ac output voltage V3 '.
The circuit of present embodiment except the cut-in voltage by transistorized base stage-emitter junction to reach the purpose of limiting AC output voltage.The characteristic that cut-in voltage and temperature by transistorized base stage-emitter junction is inversely proportional to makes present embodiment can have the function of temperature-compensating simultaneously.
Right the present invention is not limited to be reached by transistor the function of comparator, and the circuit design by operational amplifier also can reach the function identical with present embodiment.
Please refer to Fig. 9 A and Fig. 9 B, the measurement oscillogram when Fig. 9 A illustrates ac output voltage for the conventional inverter amplifier and do not reach critical value.Measurement oscillogram when Fig. 9 B illustrates and do not reach critical value for ac output voltage of the present invention.When the ac output voltage of inverting amplifier did not reach the critical value of comparator, the ac output voltage of ac output voltage of the present invention and conventional inverter amplifier was all pressed and is exported after original yield value power is amplified in the inverting amplifier.
Please refer to Fig. 9 C and Fig. 9 D, Fig. 9 C illustrates the measurement oscillogram that surpasses critical value into the ac output voltage of conventional inverter amplifier.Fig. 9 D illustrates the measurement oscillogram that surpasses critical value into ac output voltage of the present invention.When the ac output voltage of inverting amplifier surpassed the critical value of comparator, the conventional inverter amplifier will AC-input voltage amplify back output by original yield value, will cause loudspeaker can't bear excessive load and burnt.When the ac output voltage of the inverting amplifier among the present invention surpassed the critical value of comparator, the present invention was the limiting AC output voltage, and it is limited in the loading range that loudspeaker can bear, and do not burnt with the protection loudspeaker.
Please refer to Figure 10, it illustrates according to the limiter of segmented gains of a preferred embodiment of the present invention control method flow chart to audio frequency amplifier.Comprise five steps in the control method flow chart of limiter of segmented gains:
At first shown in step 11, utilize comparator to detect the output signal of audio frequency amplifier.Then shown in step 12, judge that output signal is whether greater than the critical value of comparator.And then shown in step 13, when output signal during greater than critical value, output drive signal.Then shown in step 14, according to drive limiter output control signal.At last shown in step 15, according to control signal control audio amplifier with the restriction output signal.
The disclosed limiter of segmented gains of the above embodiment of the present invention; the input signal that does not reach critical value is amplified back output one output signal to keep original sound field effect according to the yield value power of audio frequency amplifier; when input signal has when burning loudspeaker possible greater than critical value; downgrade the yield value or the input signal of audio frequency amplifier, do not burnt because of output signal is excessive with the protection loudspeaker.
In sum; 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 (10)
1. a limiter of segmented gains is that this audio frequency amplifier has a yield value in order to an external audio frequency amplifier, and this audio frequency amplifier amplifies output one output signal in back according to this yield value with an input signal power, and this limiter of segmented gains comprises:
One comparator, this comparator has a critical value, this comparator and in order to receiving this output signal, and, export a drive signal when this output signal during greater than this critical value; And
One limiter is in order to receive this drive signal and to export a control signal in order to control this audio frequency amplifier to limit this output signal according to this drive signal.
2. limiter of segmented gains according to claim 1 is characterized in that, this input signal of this control signal system this audio frequency amplifier of control of this limiter is to limit this output signal.
3. limiter of segmented gains according to claim 1 is characterized in that, this yield value of this control signal system this audio frequency amplifier of control of this limiter is to limit this output signal.
4. limiter of segmented gains according to claim 1 is characterized in that, this audio frequency amplifier is an inverting amplifier, and this inverting amplifier comprises:
One operational amplifier comprises:
One inverting input;
One normal phase input end is to electrically connect with an earth terminal; And
One output;
One first resistance comprises:
One first end is to receive this input signal; And
One second end is to electrically connect with this inverting input;
One second resistance comprises:
One first end is second end electric connection with this first resistance; And
One second end is this output electric connection with this operational amplifier;
Wherein this yield value system of this sign-changing amplifier is according to this first resistance and the decision of this second resistance.
5. limiter of segmented gains according to claim 4, it is characterized in that this output signal is the output voltage of this operational amplifier, this first end of this second resistance and potential difference or this first end of this first resistance and the potential difference of this second end of this second end.
6. limiter of segmented gains according to claim 1 is characterized in that, this audio frequency amplifier is a non-inverting amplifier, and this non-inverting amplifier comprises:
One operational amplifier comprises:
One normal phase input end;
One inverting input; And
One output;
One first resistance comprises:
One first end is to electrically connect with this inverting input; And
One second end is to electrically connect with this earth terminal;
One second resistance comprises:
One first end is to electrically connect with this inverting input; And
One second end is to electrically connect with this output;
One the 3rd resistance comprises:
One first end is in order to receive this input signal; And
One second end is to electrically connect with this normal phase input end; And
One the 4th resistance comprises:
One first end is to electrically connect with this normal phase input end; And
One second end is to electrically connect with this earth terminal;
Wherein this yield value system of this non-inverting amplifier is according to this first resistance, second resistance, the 3rd resistance and the decision of the 4th resistance.
7. limiter of segmented gains according to claim 6, it is characterized in that this output signal is the output voltage of this operational amplifier, this first end of this second resistance and potential difference or this first end of this first resistance and the potential difference of this second end of this second end.
8. an application rights requires the control method of 1 described limiter of segmented gains, and this control method comprises:
Utilize this comparator to detect an output signal of this audio frequency amplifier;
Judge that this output signal is whether greater than a critical value of this comparator;
When this output signal during, export a drive signal greater than this critical value;
Export a control signal according to this limiter of this drive; And
Control this audio frequency amplifier to limit this output signal according to this control signal.
9. control method according to claim 8 is characterized in that, controls this input signal of this audio frequency amplifier system this audio frequency amplifier of control according to this control signal.
10. control method according to claim 8 is characterized in that, controls this yield value of this audio frequency amplifier system this audio frequency amplifier of control according to this control signal.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2005100917967A CN1917364B (en) | 2005-08-15 | 2005-08-15 | Limiter of segmented gains, and control method |
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| CN2005100917967A CN1917364B (en) | 2005-08-15 | 2005-08-15 | Limiter of segmented gains, and control method |
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| CN1917364A CN1917364A (en) | 2007-02-21 |
| CN1917364B true CN1917364B (en) | 2010-10-13 |
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Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102064830B (en) * | 2011-01-31 | 2013-12-11 | 中国科学院声学研究所 | Logarithmic digital gain control device with positive and negative gain range |
| CN102148607B (en) * | 2011-04-15 | 2016-03-30 | 昆腾微电子股份有限公司 | For gain control and method, the telephone set of amplifier |
| JP2016152583A (en) * | 2015-02-19 | 2016-08-22 | 旭化成エレクトロニクス株式会社 | Output amplifier and ic chip including the same |
| CN116165471B (en) * | 2023-04-20 | 2023-07-07 | 泉州昆泰芯微电子科技有限公司 | Signal overload monitoring system, monitoring method and programmable gain amplifier |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3790896A (en) * | 1972-01-11 | 1974-02-05 | Sony Corp | Automatic gain control circuit |
| CN1627636A (en) * | 2003-12-09 | 2005-06-15 | 沃福森微电子股份有限公司 | Signal processors and associated methods |
| JP2005217769A (en) * | 2004-01-29 | 2005-08-11 | Fujitsu Ten Ltd | Digital limiter circuit |
-
2005
- 2005-08-15 CN CN2005100917967A patent/CN1917364B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3790896A (en) * | 1972-01-11 | 1974-02-05 | Sony Corp | Automatic gain control circuit |
| CN1627636A (en) * | 2003-12-09 | 2005-06-15 | 沃福森微电子股份有限公司 | Signal processors and associated methods |
| JP2005217769A (en) * | 2004-01-29 | 2005-08-11 | Fujitsu Ten Ltd | Digital limiter circuit |
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| CN1917364A (en) | 2007-02-21 |
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