CN101325402B - Audio power amplifier with improved low frequency performance - Google Patents
Audio power amplifier with improved low frequency performance Download PDFInfo
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- CN101325402B CN101325402B CN2007100420506A CN200710042050A CN101325402B CN 101325402 B CN101325402 B CN 101325402B CN 2007100420506 A CN2007100420506 A CN 2007100420506A CN 200710042050 A CN200710042050 A CN 200710042050A CN 101325402 B CN101325402 B CN 101325402B
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Abstract
The invention discloses an audio power amplifier for improving the performance of the low frequency, which reduces the restrain of the audio power amplifier on the low frequency signal, also decreases the value of the separating capacitance, meanwhile illdefinedly adds the complexity of the system. The technical scheme is that, the audio power amplifier comprises a power amplifier module, supplying power through a single power, with a common mode input end, an inverted input end and an output end, wherein the inverted input end is connected with a first resistance, and the output end is connected with a speaker through the separating capacitance; a feedback channel module, connected between the output end of the power amplifier module and the inverted input end with a second resistance; a resistance-capacitance circuit connected with the second resistance, wherein the resistance-capacitance circuit is composed of a third resistance and a separating capacitance connected in parallel, to counteract the low frequency gain attenuation of the power amplifier module.
Description
Technical field
The present invention relates to a kind of power amplifying device, relate in particular to a kind of audio-frequency power amplifier spare in mobile terminal device.
Background technology
The general audio-frequency power amplifier apparatus that adopts single supply in mobile terminal device, Fig. 1 show traditional anti-phase amplification input signal of single-power supply audio power amplifier device to drive the situation of loudspeaker.Audio-frequency power amplifier module 101 links to each other with single supply VCC, audio-frequency power amplifier module 101 comprises inverting input that is used to receive the input signal Vin that is provided by prime and the in-phase input end that receives common mode reference voltage Vcm, and the output Vx of output signal.Audio-frequency power amplifier module 101 by input resistance R1 and feedback resistance R2 input signal Vin is realized amplifying or decay after, the output signal Vx that obtains is loaded on the loud speaker 109 after by capacitance Cout, i.e. tie point Vy.
Because the audio-frequency power amplifier module adopts single power supply, in order to make output signal higher output amplitude can be arranged all on forward and negative sense, and one side can not take place by the situation of another side amplitude limit, the specified Dc bias of general output is set to VCC/2.And the resistance value RL of loud speaker 109 often has only 8～32 ohm, therefore after the direct current output bias of having set audio-frequency power amplifier is VCC/2, the extra introducing capacitance Cout of needs stops the DC component among the output signal Vx, to avoid direct current power loss meaningless on the loud speaker.
Fig. 2 shows under the speaker resistor RL=32 Ω condition, capacitance Cout gets the curve chart to audio signal inhibition situation that different value obtains, wherein curve 21 is represented the situation of capacitance Cout=33 μ F, curve 22 is represented the situation of capacitance Cout=100 μ F, and curve 23 is represented the situation of capacitance Cout=220 μ F.As can be seen from Figure 2, adopt the little electric capacity of 33 μ F for the size that reduces mobile phone, the influence that is caused is huge, and when audio signal approached the infrasound frequency of 20Hz, decay had reached 18dB.
The problem that traditional approach brought is as can be seen from Figure 2, and it is very big that the capacitance Cout of capacitance 108 must get, and just can avoid the decay to low frequency signal.For example in Fig. 2, the resistance R L=32 Ω of loud speaker 109, for allow-the 3dB inhibition point is reduced to the infrasound frequency band below the 20Hz, the capacitance Cout of capacitance 108 needs 250 μ F so big, and for the such portable set of similar mobile phone, big electric capacity means big size, and this will force mobile phone to increase volume to satisfy this demand.In addition, the big price of electric capacity own is also more expensive.
Summary of the invention
The objective of the invention is to address the above problem, a kind of audio-frequency power amplifier apparatus that improves low frequency performance is provided, both reduced the inhibition of audio-frequency power amplifier to low frequency signal, reduced the value of capacitance Cout again, simultaneously not obvious increase system complexity (quantity of outward element, size).
Technical scheme of the present invention is: the present invention proposes a kind of audio-frequency power amplifier apparatus that improves low frequency performance, the input signal that reception is provided by prime, to its amplify or the loud speaker that resulting output signal is carried in this audio-frequency power amplifier apparatus links to each other of decaying on, this audio-frequency power amplifier apparatus comprises:
Power amplifier module by single power supply, comprises in-phase input end, inverting input and output, and wherein this inverting input connects first resistance (R1), and this output is by the first capacitance (C
Out) be connected with this loud speaker;
The feedback network module is connected between the output and inverting input of this power amplifier module, comprising:
Second resistance (R2);
With the resistance-capacitance circuit that this second resistance (R2) is connected, this resistance-capacitance circuit is formed in parallel by the 3rd resistance (R3) and second capacitance (C1), decay with the low-frequency gain of offsetting this power amplifier module.
This audio-frequency power amplifier apparatus meets the following conditions:
R wherein
LBe the resistance value of this loud speaker, C
OutBe the capacitance of this first capacitance, C
1Be the capacitance of this second capacitance, R
2Be the resistance value of this second resistance, R
3It is the resistance value of the 3rd resistance.
The above-mentioned audio-frequency power amplifier apparatus that improves low frequency performance, wherein, the inverting input of this power amplifier module receives the input signal (Vin) that prime provides by this first resistance (R1), and in-phase input end receives common mode reference voltage (Vcm).
The above-mentioned audio-frequency power amplifier apparatus that improves low frequency performance, wherein, the inverting input of this power amplifier module receives common mode reference voltage (Vcm) by this first resistance (R1), in-phase input end receives the input signal (Vin) that prime provides by decoupling capacitor (Cin), also be connected with the 4th resistance (Rn) on the in-phase input end of this power amplifier module, the other end of the 4th resistance (Rn) receives common mode reference voltage (Vcm).
The above-mentioned audio-frequency power amplifier apparatus that improves low frequency performance, wherein, the inverting input of this power amplifier module is by this first resistance (R1) and first decoupling capacitor (Cn) ground connection, in-phase input end receives the input signal (Vin) that prime provides by second decoupling capacitor (Cin), also be connected with the 4th resistance (Rn) on the in-phase input end of this power amplifier module, the other end of the 4th resistance (Rn) receives common mode reference voltage (Vcm).
The present invention has proposed a kind of audio-frequency power amplifier apparatus that improves low frequency performance in addition, the input signal that reception is provided by prime, to its amplify or the loud speaker that resulting output signal is carried in this audio-frequency power amplifier apparatus links to each other of decaying on, this audio-frequency power amplifier apparatus comprises:
Power amplifier module by single power supply, comprises in-phase input end, inverting input and output, and wherein this inverting input connects first resistance (R1), and this output is connected with this loud speaker by first capacitance (Cout);
The feedback network module is connected between the output and inverting input of this power amplifier module, comprising:
The branch road that second resistance (R2) and capacitance (C1) are in series;
The 3rd resistance (R3), in parallel with the branch road that this second resistance (R2) and second capacitance (C1) are formed;
This audio-frequency power amplifier apparatus meets the following conditions:
R wherein
LBe the resistance value of this loud speaker, C
OutBe the capacitance of this first capacitance, C
1Be the capacitance of this second capacitance, R
2Be the resistance value of this second resistance, R
3It is the resistance value of the 3rd resistance.
The above-mentioned audio-frequency power amplifier apparatus that improves low frequency performance, wherein, the inverting input of this power amplifier module receives the input signal (Vin) that prime provides by this first resistance (R1), and in-phase input end receives common mode reference voltage (Vcm).
The above-mentioned audio-frequency power amplifier apparatus that improves low frequency performance, wherein, the inverting input of this power amplifier module receives common mode reference voltage (Vcm) by this first resistance (R1), in-phase input end receives the input signal (Vin) that prime provides by decoupling capacitor (Cin), also be connected with the 4th resistance (Rn) on the in-phase input end of this power amplifier module, the other end of the 4th resistance (Rn) receives common mode reference voltage (Vcm).
The above-mentioned audio-frequency power amplifier apparatus that improves low frequency performance, wherein, the inverting input of this power amplifier module is by this first resistance (R1) and first decoupling capacitor (Cn) ground connection, in-phase input end receives the input signal (Vin) that prime provides by second decoupling capacitor (Cin), also be connected with the 4th resistance (Rn) on the in-phase input end of this power amplifier module, the other end of the 4th resistance (Rn) receives common mode reference voltage (Vcm).
The present invention contrasts prior art following beneficial effect: increase a resistance-capacitance circuit on the basis of the feedback network of the present invention in traditional audio-frequency power amplifier apparatus, to offset the low-frequency gain decay of power amplifier module.The present invention is by rationally being provided with the capacitance-resistance parameter in the feedback network, allow first limit that produces by original device and offseting second zero point that produces by new equipment, and the value of second limit that new equipment produces reaches the low frequency inhibition effect that the big electric capacity of original needs 220 μ F could improve less than first limit with littler capacitance Cout (for example 33 μ F).
Description of drawings
Fig. 1 is traditional single-power supply audio power amplifier manipulated or operated apparatus.
Fig. 2 be capacitance in the traditional single-power supply audio power amplifier device different value correspondences audio signal is suppressed the curve chart of situation.
Fig. 3 is the circuit diagram of first embodiment of the audio-frequency power amplifier apparatus that improves low frequency performance of the present invention.
Fig. 4 is the system transfer function zero pole distribution figure of conventional audio power amplifier apparatus shown in Figure 1 of the present invention and the audio-frequency power amplifier apparatus that improves low frequency performance shown in Figure 3.
Fig. 5 is conventional audio power amplifier apparatus shown in Figure 1 of the present invention and the audio-frequency power amplifier apparatus that improves a low frequency performance shown in Figure 3 Bode diagram to the inhibition situation of low frequency signal.
Fig. 6 is the circuit diagram of second embodiment of the audio-frequency power amplifier apparatus that improves low frequency performance of the present invention.
Fig. 7 is the circuit diagram of the 3rd embodiment of the audio-frequency power amplifier apparatus that improves low frequency performance of the present invention.
Fig. 8 is the circuit diagram of the 4th embodiment of the audio-frequency power amplifier apparatus that improves low frequency performance of the present invention.
Embodiment
The invention will be further described below in conjunction with drawings and Examples.
Fig. 3 shows the circuit structure that improves the audio-frequency power amplifier apparatus of low frequency performance of the present invention.See also Fig. 3, the input signal Vin that is provided by prime is provided audio-frequency power amplifier apparatus, and input signal Vin is amplified or decays, and resulting output signal is carried on the loud speaker 109.
Input signal Vin is carried in the inverting input of power amplifier module 101 by resistance R 1, and common mode reference voltage Vcm is carried in the in-phase input end of power amplifier module 101.Power amplifier module 101 adopts the single power supply pattern, and VCC provides power supply by power supply.The output signal Vx of power amplifier module 101 is leaded up to resistance R 3, capacitor C 1 and resistance R 2 and is fed back to amplifier's inverting input, and another road is then by being carried in behind the capacitance Cout on the loud speaker 109, i.e. tie point Vy.Input resistance R1 realizes the adjusting to the device gain.In the audio-frequency power amplifier apparatus of present embodiment, increased the circuit of a capacitance-resistance structure, be used to offset the low-frequency gain decay, this resistance-capacitance circuit is formed in parallel by resistance R 3 and capacitance C1.
The structure of resistance-capacitance circuit makes the audio power amplifying apparatus of present embodiment on original transfer function basis, a pair of zero limit of extra increase, the form of transfer function as shown in Equation (1), wherein k is the scale factor that is used for regulating the audio-frequency power amplifier gain, za and zb are system's zero points, pa and pb are system's limits, and formula (2) has provided their expression formula.
By capacitance-resistance parameters R 3 and the C1 in the feedback network reasonably is set, allow the first limit pa that produces by primal system, with produce by new system second zero point zb offset, and the value of the second limit pb that is produced by new system so just can reach the low frequency inhibition effect that the big electric capacity of original needs 220 μ F could improve with littler capacitance Cout (for example 33 μ F) less than the first limit pa.
Fig. 4 shows the zero pole distribution of the system transfer function of conventional audio power amplifier apparatus shown in Figure 1 and the audio-frequency power amplifier apparatus that improves low frequency performance shown in Figure 3.Please be simultaneously referring to Fig. 4, the circle that symbol 41 promptly is positioned at the origin of coordinates is the zero point of conventional audio power amplifier apparatus, also is simultaneously the first zero of new amplifier installation; Symbol 42 is represented the limit of conventional audio power amplifier apparatus, also is first limit of new amplifier installation; Symbol 43 is second zero points of new amplifier installation; Symbol 44 is second limits of new amplifier installation.By formula (2) as can be known,, must satisfy in order to offset first limit 42 | the requirement of pa|=|zb|, simultaneously | and pb|＜| pa|.For instance, the circuit parameter R1=10K Ω in traditional audio-frequency power amplifier apparatus, R2=10k Ω, Cout=33 μ F, RL=32 Ω, new audio-frequency power amplifier apparatus is on the basis of inheriting these parameters, increased R3=200k Ω, C1=0.1 μ F.As can be seen from Figure 4, it is very near that first limit 42 in the new equipment and second 0. 43 is leaned on, and the influence of system transfer function is cancelled out each other basically.
Specifically, when the frequency of input signal Vin was higher than the frequency of the first limit pa that is determined by original device in the formula (2), the capacitive reactance of capacitor C 1 was very little, and resistance R 3 is equivalent to by short circuit, and the amplitude-frequency characteristic that new equipment showed is consistent with original device.And the value that is lower than limit pa when the frequency of input signal Vin is when being higher than the value of the second limit pb, capacitor C 1 begins to work, be serially connected in the feedback network of power amplifier module 101 after in parallel with resistance R 3, this has been equivalent to increase the impedance of feedback network, promptly the power of keeping on the loud speaker 109 by the output voltage amplitude that improves audio-frequency power amplifier apparatus is exported, and makes it be unlikely to and decays because of the increase of capacitor C out capacitive reactance.After the frequency of input signal Vin is lower than the second limit pb, the signal amplitude on the loud speaker 109 will no longer be kept, but the value of general pb can be set at the following infrasound end of 20Hz, and people's ear can not be discovered this.
Because determine the resistance R 3 of the second limit pb can be arranged on the above magnitude of k Ω, so capacitor C 1 does not need very big, and simultaneously because can be offset by second zero point by first limit of pa decision, so capacitor C out does not need to get very big value yet, new system has reached the purpose that realizes undamped low frequency performance with little electric capacity.
Fig. 5 further shows conventional audio power amplifier apparatus shown in Figure 1 and the audio-frequency power amplifier apparatus that improves low frequency performance shown in Figure 3 Bode diagram to the inhibition situation of low frequency signal.Wherein curve 51 is to adopt circuit structure shown in Figure 1, R1=10k Ω, R2=10k Ω, Cout=33uF, RL=32 Ω, the Bode diagram of loud speaker end system transfer function; Curve 52 also is to adopt circuit structure shown in Figure 1, and except that capacitance Cout=220uF, all the other parameters are the same with curve 51, the Bode diagram of loud speaker end transfer function; Curve 53 is to adopt new construction shown in Figure 3, the Bode diagram of loud speaker end transfer function.As can see from Figure 5, adopted two little electric capacity 0.1uF and 33uF just to reach the low frequency performance that needs 220uF to realize originally, even performance is more outstanding.
Except adopting anti-phase amplification mode shown in Figure 3, the present invention can also adopt the homophase amplification mode, and Fig. 6 and Fig. 7 show the circuit structure of homophase amplification mode respectively.See also Fig. 6, input signal Vin is by behind the decoupling capacitor Cin, be carried in the in-phase input end of power amplifier module 101, resistance R n one terminates at the in-phase input end of power amplifier module 101, another termination common mode reference voltage Vcm is in order to provide audio-frequency power amplifier common mode reference voltage Vcm.
Embodiment and Fig. 6 of Fig. 7 are similar, and difference is that the end that resistance R 1 met input signal Vin originally is connected on the ground level by decoupling capacitor Cn in the present embodiment.The benefit of doing like this is that common mode reference voltage Vcm can only be a reference voltage, needs to provide the ability of any driving load hardly.Decoupling capacitor Cn adopts the outer electric capacity of sheet to realize.
The embodiment of Fig. 6 and Fig. 7 is the same with the embodiment of Fig. 3, and all being has increased the capacitance-resistance structure that is used to offset the low-frequency gain decay on the basis of traditional structure: resistance R 3 and capacitor C 1.Their operation principle is also identical, does not therefore repeat them here.
Fig. 8 shows the circuit structure that another kind of the present invention improves the audio-frequency power amplifier apparatus of low frequency performance.See also Fig. 8, audio-frequency power amplifier apparatus comprises: power amplifier module 101 and feedback network module.Power amplifier module 101 adopts single supply VCC power supply, and its inverting input is by resistance R 1 receiving inputted signal Vin, and in-phase input end receives common mode reference voltage Vcm, and output connects loud speaker 109 by capacitance Cout.The feedback network module is connected between the output and inverting input of power amplifier module 101, is a parallel circuits, and first route resistance R 3 constitutes, and second route resistance R 2 and capacitance C1 form.In fact, circuit structure shown in Figure 8 is compared with the circuit of traditional audio-frequency power amplifier apparatus, has increased resistance R 3 and capacitor C 1 between the inverting input of power amplifier module 101 and output Vx.
The sort circuit structure makes the audio power amplifying apparatus of present embodiment on original transfer function basis, a pair of zero limit of extra increase, the form of transfer function as shown in Equation (3), wherein k is the scale factor that is used for regulating the audio-frequency power amplifier gain, za and zb are system's zero points, pa and pb are system's limits, and formula (4) has provided their expression formula.
By capacitance-resistance parameters R 3 and the C1 in the feedback network reasonably is set, allow the first limit pa that produces by primal system, with produce by new system second zero point zb offset, and the value of the second limit pb that is produced by new system so just can reach the low frequency inhibition effect that the big electric capacity of original needs 220 μ F could improve with littler capacitance Cout (for example 33 μ F) less than the first limit pa.
When input signal Vin was low frequency, the capacitive reactance of capacitor C 1 was very big, and first feedback network (resistance R 2 and capacitor C 1) is equivalent to be opened circuit, thus the gain of system mainly determined by second feedback network (R3), promptly equal R3/R1.When the frequency of input signal Vin increases, the capacitive reactance of capacitor C 1 reduces gradually, the impedance of last first feedback network levels off to resistance R 2, this moment device the R2/ (R2+R3) of gain when dropping to low frequency doubly, promptly the increase of capacitive reactance reduces when the output voltage V x of input signal Vin increase audio-frequency power amplifier during for low frequency offsets owing to capacitance Cout at input signal Vin low frequency is carried in power component on the loud speaker 109.
For this a kind of audio-frequency power amplifier apparatus that improves low frequency performance, also can adopt the homophase amplification mode that is similar to Fig. 6 and Fig. 7.In a kind of homophase amplification mode, similar with Fig. 6 embodiment, the inverting input of power amplifier module receives common mode reference voltage Vcm by resistance, in-phase input end receives the input signal Vin that prime provides by decoupling capacitor, also connect a resistance on the in-phase input end of power amplifier module, the other end of this resistance receives common mode reference voltage Vcm.In another kind of homophase amplification mode, similar with Fig. 7 embodiment, the inverting input of power amplifier module is by resistance and decoupling capacitor ground connection, in-phase input end receives the input signal Vin that prime provides by another decoupling capacitor, also be connected with resistance on the in-phase input end of power amplifier module, the other end of this resistance receives common mode reference voltage Vcm.
Working condition when above-mentioned Fig. 3 and Fig. 6～embodiment shown in Figure 8 has only provided a passage is if device is twin-channel stereo, then as long as two same being together in parallel as Fig. 3, Fig. 6, Fig. 7 or circuit shown in Figure 8 just can be realized.
The foregoing description provides to those of ordinary skills and realizes or use of the present invention; those of ordinary skills can be under the situation that does not break away from invention thought of the present invention; the foregoing description is made various modifications or variation; thereby protection scope of the present invention do not limit by the foregoing description, and should be the maximum magnitude that meets the inventive features that claims mention.
Claims (8)
1. audio-frequency power amplifier apparatus that improves low frequency performance, the input signal that reception is provided by prime, to its amplify or the loud speaker that resulting output signal is carried in this audio-frequency power amplifier apparatus links to each other of decaying on, this audio-frequency power amplifier apparatus comprises:
Power amplifier module by single power supply, comprises in-phase input end, inverting input and output, and wherein this inverting input connects first resistance (R1), and this output is by the first capacitance (C
Out) be connected with this loud speaker;
The feedback network module is connected between the output and inverting input of this power amplifier module, comprising:
Second resistance (R2);
With the resistance-capacitance circuit that this second resistance (R2) is connected, this resistance-capacitance circuit is formed in parallel by the 3rd resistance (R3) and second capacitance (C1), decay with the low-frequency gain of offsetting this power amplifier module,
This audio-frequency power amplifier apparatus meets the following conditions:
R wherein
LBe the resistance value of this loud speaker, C
OutBe the capacitance of this first capacitance, C
1Be the capacitance of this second capacitance, R
2Be the resistance value of this second resistance, R
3It is the resistance value of the 3rd resistance.
2. the audio-frequency power amplifier apparatus that improves low frequency performance according to claim 1, it is characterized in that, the inverting input of this power amplifier module receives the input signal (Vin) that prime provides by this first resistance (R1), and in-phase input end receives common mode reference voltage (Vcm).
3. the audio-frequency power amplifier apparatus that improves low frequency performance according to claim 1, it is characterized in that, the inverting input of this power amplifier module receives common mode reference voltage (Vcm) by this first resistance (R1), in-phase input end receives the input signal (Vin) that prime provides by decoupling capacitor (Cin), also be connected with the 4th resistance (Rn) on the in-phase input end of this power amplifier module, the other end of the 4th resistance (Rn) receives common mode reference voltage (Vcm).
4. the audio-frequency power amplifier apparatus that improves low frequency performance according to claim 1, it is characterized in that, the inverting input of this power amplifier module is by this first resistance (R1) and first decoupling capacitor (Cn) ground connection, in-phase input end receives the input signal (Vin) that prime provides by second decoupling capacitor (Cin), also be connected with the 4th resistance (Rn) on the in-phase input end of this power amplifier module, the other end of the 4th resistance (Rn) receives common mode reference voltage (Vcm).
5. audio-frequency power amplifier apparatus that improves low frequency performance, the input signal that reception is provided by prime, to its amplify or the loud speaker that resulting output signal is carried in this audio-frequency power amplifier apparatus links to each other of decaying on, this audio-frequency power amplifier apparatus comprises:
Power amplifier module by single power supply, comprises in-phase input end, inverting input and output, and wherein this inverting input connects first resistance (R1), and this output is connected with this loud speaker by first capacitance (Cout);
The feedback network module is connected between the output and inverting input of this power amplifier module, comprising:
The branch road that second resistance (R2) and capacitance (C1) are in series;
The 3rd resistance (R3), in parallel with the branch road that this second resistance (R2) and second capacitance (C1) are formed;
This audio-frequency power amplifier apparatus meets the following conditions:
R wherein
LBe the resistance value of this loud speaker, C
OutBe the capacitance of this first capacitance, C
1Be the capacitance of this second capacitance, R
2Be the resistance value of this second resistance, R
3It is the resistance value of the 3rd resistance.
6. the audio-frequency power amplifier apparatus that improves low frequency performance according to claim 5, it is characterized in that, the inverting input of this power amplifier module receives the input signal (Vin) that prime provides by this first resistance (R1), and in-phase input end receives common mode reference voltage (Vcm).
7. the audio-frequency power amplifier apparatus that improves low frequency performance according to claim 5, it is characterized in that, the inverting input of this power amplifier module receives common mode reference voltage (Vcm) by this first resistance (R1), in-phase input end receives the input signal (Vin) that prime provides by decoupling capacitor (Cin), also be connected with the 4th resistance (Rn) on the in-phase input end of this power amplifier module, the other end of the 4th resistance (Rn) receives common mode reference voltage (Vcm).
8. the audio-frequency power amplifier apparatus that improves low frequency performance according to claim 5, it is characterized in that, the inverting input of this power amplifier module is by this first resistance (R1) and first decoupling capacitor (Cn) ground connection, in-phase input end receives the input signal (Vin) that prime provides by second decoupling capacitor (Cin), also be connected with the 4th resistance (Rn) on the in-phase input end of this power amplifier module, the other end of the 4th resistance (Rn) receives common mode reference voltage (Vcm).
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| CN101325402B true CN101325402B (en) | 2010-09-29 |
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| US5701101A (en) * | 1995-03-20 | 1997-12-23 | The United States Of America As Represented By The Secretary Of The Navy | Charge amplifier for blast gauges |
| CN1327303A (en) * | 2001-02-28 | 2001-12-19 | 上海朗鹰科技有限公司 | Method for improving stability of operation amplifier circuit under determined frequency |
| US6545534B1 (en) * | 2001-02-13 | 2003-04-08 | Analog Devices, Inc. | Low voltage variable gain amplifier with constant input impedance and adjustable one-pole filtering characteristic |
| CN1426050A (en) * | 2001-12-14 | 2003-06-25 | 夏普公司 | Light reception amplifier circuit of optic disc device |
| JP2004282544A (en) * | 2003-03-18 | 2004-10-07 | Victor Co Of Japan Ltd | D-class power amplifying circuit |
| CN1681201A (en) * | 2004-04-06 | 2005-10-12 | 伍平荣 | Resistance-capacitance balanced feedback negative circuit |
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- 2007-06-15 CN CN2007100420506A patent/CN101325402B/en active Active
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1040719A (en) * | 1988-04-14 | 1990-03-21 | 约翰·弗勒克合股制造公司 | The AC amplifier of digitally controlled frequency response |
| US5701101A (en) * | 1995-03-20 | 1997-12-23 | The United States Of America As Represented By The Secretary Of The Navy | Charge amplifier for blast gauges |
| US6545534B1 (en) * | 2001-02-13 | 2003-04-08 | Analog Devices, Inc. | Low voltage variable gain amplifier with constant input impedance and adjustable one-pole filtering characteristic |
| CN1327303A (en) * | 2001-02-28 | 2001-12-19 | 上海朗鹰科技有限公司 | Method for improving stability of operation amplifier circuit under determined frequency |
| CN1426050A (en) * | 2001-12-14 | 2003-06-25 | 夏普公司 | Light reception amplifier circuit of optic disc device |
| JP2004282544A (en) * | 2003-03-18 | 2004-10-07 | Victor Co Of Japan Ltd | D-class power amplifying circuit |
| CN1681201A (en) * | 2004-04-06 | 2005-10-12 | 伍平荣 | Resistance-capacitance balanced feedback negative circuit |
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