CN101557200A - Power amplifier capable of regulating noise - Google Patents
Power amplifier capable of regulating noise Download PDFInfo
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- CN101557200A CN101557200A CNA2008100909998A CN200810090999A CN101557200A CN 101557200 A CN101557200 A CN 101557200A CN A2008100909998 A CNA2008100909998 A CN A2008100909998A CN 200810090999 A CN200810090999 A CN 200810090999A CN 101557200 A CN101557200 A CN 101557200A
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- differential mode
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Abstract
The invention relates to a power amplifier capable of regulating noise and solving the noise interference problem suffered by general power amplifiers. The power amplifier comprises a differential motion mode integrator, an integrating and regulating unit and a switch unit. The differential motion mode integrator is used for receiving an input signal and an output signal of a differential motion mode and outputting a first signal of the differential motion mode; the integrating and regulating unit is coupled with the differential motion mode integrator and used for receiving the first signal and the output signal of the differential motion mode and outputting a second signal of a single-terminal mode; and the switch unit receives the second signal and outputs the output signal of the differential motion mode to drive a load. The invention eliminates common-mode noise by using a common-mode input signal to replace a single-terminal input signal and obtains better effect on eliminating a band stop signal by using an integrating circuit of two orders or more than two orders to replace a traditional filter.
Description
Technical field
The present invention relates to a kind of power amplifier, but particularly relate to a kind of power amplifier of regulating noise.
Background technology
With reference to figure 1, general power amplifier, especially audio-frequency power amplifier can adopt the negative feedback design to obtain a constant gain, simultaneously in order to eliminate high-frequency noise, can be connected in series a low pass filter, and this low pass filter is generally an integrating circuit.As shown in Figure 1, feedback circuit 110 is converted to differential mode output signal the feedback signal Vsum_P of single-ended mode to Vo1 and Vo2.This feedback signal Vsum_P and input signal VI pass through integrator 120 again with filtering noise.
Yet after amplifier evolved to transistor by vacuum tube, noise jamming was that audio-frequency power amplifier meets with maximum problem always.The main source of noise has two, and one is that power supply is groaned sound (Power Supply Hum).This is because power output amplifying stage 130 can be from power source supply end V
DDExtract big electric current, but but can't be to power source supply end V
DDCarry out effective filtering.So, require power source supply end V when signal triggers
DDDuring by a pure big electric current, this big electric current itself promptly contains noise but not is pure, so can be with noise by feedback circuit 110 feed-in integrated circuits.Above content please refer to Adel S.Sedra ﹠amp; Kenneth C.Smith shows the 4th edition chapter 8 of Microelectronic Circuit second joint.Therefore practice widely followed is to add that in feedback circuit 110 filter is to eliminate noise.Yet this type of design as shown in Figure 1, only relies on conventional filter to eliminate noise, and effect is unsatisfactory.
Noise source second be radio frequency interference, when radiofrequency signal during near audio frequency amplifier, the relatively poor relatively circuit framework of Common Mode Rejection Ratio (common rejection ratio), just radiofrequency signal can be received in the lump and become the noise jamming of audio frequency amplifier itself, the buzz that is produced when for example mobile phone is near loudspeaker, and the conventional audio amplifier does not use the whole differential framework to promote Common Mode Rejection Ratio.
Summary of the invention
But purpose of the present invention just provides a kind of power amplifier of regulating noise, make amplifier reach the peak signal noise ratio (signal to noise ratio, SNR).The present invention can provide and better end band signal elimination effect with delta-sigma circuit serial connection second order or above integrating circuit; Replace the conventional audio amplifier is provided with filter in feedback circuit the practice.In addition, also utilize common mode input signal, replace traditional single-ended input signal, promote Common Mode Rejection Ratio, the ability of intensifier circuit opposing radio frequency interference by the whole differential framework.
But the present invention proposes a kind of power amplifier of regulating noise.This power amplifier comprises differential mode integrator, integration and regulon and switch element.Differential mode integrator is in order to receiving differential mode input signal and differential mode output signal, and carries out integration operation, to produce differential mode first signal.Integration and regulon are coupled to differential mode integrator, in order to receiving differential mode first signal and differential mode output signal and to carry out integration operation, and are the secondary signal of single-ended mode with differential mode first Signal Regulation.This secondary signal inputs to switch element.The operating state of switch element decides based on secondary signal, and the output differential mode output signal is to drive load.
The present invention utilizes the design of full differential mode, with common mode input signal, replaces traditional single-ended input signal, improves Common Mode Rejection Ratio and eliminates common-mode noise, increases the ability of circuit opposing radio frequency interference.In addition, differential mode integrator and integration and regulon all comprise a delta-sigma circuit, both are connected in series and form a second-order low-pass filter circuit, than of the combination of conventional negative feedback circuit with filter, provide the stronger band signal that ends to eliminate effect, to reach higher filter effect, can get a preferable signal noise ratio.Right the present invention is not as limit, and the more integrating circuit of the visual demand serial connection of those skilled in the art are to constitute three rank or above filter circuit.
For above and other objects of the present invention, feature and advantage can be become apparent, preferred embodiment cited below particularly, and be described with reference to the accompanying drawings as follows.
Description of drawings
Fig. 1 illustrates the circuit block diagram into the prior art audio frequency amplifier.
But Fig. 2 is for illustrating the circuit block diagram of the power amplifier of regulating noise according to the embodiment of the invention.
Fig. 3 is for illustrating the circuit diagram of Fig. 2 power amplifier according to the embodiment of the invention.
The reference numeral explanation
110: feedback circuit
120: integrator
130: power-amplifier stage
140: load
210: differential mode integrator
220: integration and regulon
230: switch element
240: load
311: the first resistance
312: the second resistance
313: the three resistance
314: the four resistance
315: the first operational amplifiers
316: the first electric capacity
317: the second electric capacity
Impedance in 321: the first
Impedance in 322: the second
Impedance in 323: the three
Impedance in 324: the four
325: the second operational amplifiers
Impedance in 326: the five
Impedance in 327: the six
331: the pulse-width modulation level
332: the first switches
333: second switch
334: the three switches
335: the four switches
Embodiment
Below will be with D genus audio power amplifier (class-D audio power amplifier) as enforcement example of the present invention.But the present invention is not as limit, and those skilled in the art also can be used for various power amplifier with it cover according to spirit of the present invention, for example category-A, category-B, AB class constant power amplifier.
But Fig. 2 is for illustrating the circuit block diagram of the power amplifier of regulating noise according to the embodiment of the invention.Please refer to Fig. 2, this power amplifier comprises differential mode integrator 210, integration and regulon 220 and switch element 230.Differential mode integrator 210 is carried out integration operation with the audio signal (is that differential mode input signal is to VIN and VIP at this) and the differential mode output signal that are received to VON and VOP, to produce differential mode first signal to VIN ' and VIP '.Integration and regulon 220 receive differential mode first signal to VIN ' and VIP ' and differential mode output signal to VON and VOP and carry out integration operation.In addition, integration and regulon 220 more are adjusted to the secondary signal Vo of single-ended mode with differential mode first signal to VIN ' and VIP ', and export secondary signal Vo to switch element 230.Switch element 230 decides its operating state based on secondary signal Vo, and switch element 230 output differential mode output signal VON and VOP are with driving load 240.In present embodiment, this load 240 can be loudspeaker or other load.
Fig. 3 is for illustrating the enforcement example of Fig. 2 power amplifier according to the present invention.Please refer to Fig. 3, differential mode integrator 210 comprises first resistance 311, second resistance 312, the 3rd resistance 313, the 4th resistance 314, first operational amplifier 315, first electric capacity 316 and second electric capacity 317.
The resistance 311 and 312 first end receive the first end signal VIN and the second end signal VIP of this differential mode input signal separately.The resistance 313 and 314 first end receive the first end signal VON and the second end signal VOP of this differential mode output signal separately.First operational amplifier 315, its first input end (for example being positive input terminal) is coupled to second end of second resistance 312 and second end of the 3rd resistance 313, and its second input (for example being negative input end) then is coupled to second end of first resistance 311 and second end of the 4th resistance 314.First output of first operational amplifier 315 (for example being positive output end) and second output (for example being negative output terminal) are exported the first end signal VIN ' and the second end signal VIP ' of this differential mode first signal respectively.First end of first electric capacity 316 and second end are coupled to first output and second input of first operational amplifier 315 respectively.First end of second electric capacity 317 and second end are coupled to second output and the first input end of first operational amplifier 315 respectively.So just can constitute the integrating circuit of a differential input and output.Affiliated field has knows that usually the knowledgeable can and allocate the resistance of resistance 311～314 and the capacitance of electric capacity 316～317 according to its demand, that is adjusts the lower passband frequency range of its impedance matching with control differential mode integrator 210.In present embodiment, the resistance of first resistance 311 and second resistance 312 is R for example
1, and the resistance of the 3rd resistance 313 and the 4th resistance 314 is G*R for example
1(G and R
1Be real number).The capacitance of first electric capacity 316 and second electric capacity 317 for example is C
1(C
1Be real number).
Integration and regulon 220 comprise first impedance 321, second impedance 322, the 3rd impedance 323, the 4th impedance 324, second operational amplifier 325, the 5th impedance 326 and the 6th impedance 327.The impedance 321 and 322 first end are coupled to first output and second output of differential mode integrator 210 separately, with the first end signal VIN ' and the second end signal VIP ' that receives this differential mode first signal.First termination of the 3rd impedance 323 is received the first end signal VON of differential mode output signal.First termination of the 4th impedance 324 is received the second end signal VOP of differential mode output signal.The first input end of second operational amplifier 325 (for example being positive input terminal) is coupled to second end of first impedance 321 and the 3rd impedance 323, and its second input (for example being negative input end) then is coupled to second end of second impedance 322 and the 4th impedance 324.The secondary signal Vo of the output output single-ended mode of first operational amplifier 315.First end of the 5th impedance 326 is coupled to the first input end of second operational amplifier 325, and its second end then receives first voltage.In present embodiment, above-mentioned first voltage is earthed voltage for example.First end of the 6th impedance 327 and second end are coupled to the output and second input of second operational amplifier 325 respectively.
Those skilled in the art can be according to its demand, and implements first impedance～the 6th impedance with any means, and the resistance value that determines each impedance according to demand is to obtain required circuit characteristic.In present embodiment, first impedance 321 and second impedance 322 all are R with the resistance
2Resistance implement, and the 3rd impedance 323 and the 4th impedance 324 all are F*R with the resistance
2Resistance (F is a real number) implemented.In addition, present embodiment is to be C with the capacitance
2Electric capacity implement the 5th impedance 326 and the 6th impedance 327.And first voltage can be a reference voltage level, comprises earthed voltage, chassics earth and look the level voltage that design requirement adopts.
This switch element 230 comprises pulse-width modulation level (pulse width modulation stage, PWMstage) 331 and bridge circuit.Pulse-width modulation level 331 is in order to produce at least one pulse-width signal (present embodiment is the first pulse-width signal PWMS1 and the second pulse-width signal PWMS2).Wherein, pulse-width modulation level 331 is modulated the pulsewidth of pulse-width signal PWMS1 and PWMS2 according to the secondary signal Vo of single-ended mode.The bridge circuit of present embodiment is to be example with the Class-D output amplifier stage, so not as limit.This bridge circuit comprises a plurality of switches (present embodiment is first switch 332, second switch 333, the 3rd switch 334 and the 4th switch 335) that controlled by pulse-width signal PWMS1 and PWMS2.In bridge circuit, first termination of first switch 332 is received second voltage (for example being supply voltage VDD), and its second end exports the first end signal VON of differential mode output signal at first end of load 240.First termination of second switch 333 is received tertiary voltage (for example being earthed voltage), and its second end is coupled to first end of load 240.Wherein, switch 332 and 333 all is controlled by the first pulse-width signal PWM1.
First termination of the 3rd switch 334 is received second voltage, and its second end exports the second end signal VOP of differential mode output signal at second end of load 240.First termination of the 4th switch 335 is received tertiary voltage, and its second end is coupled to second end of load 240.Wherein, switch 334 and 335 all is controlled by the second pulse-width signal PWM2.
In present embodiment, above-mentioned first switch 332 and the 3rd switch 334 are the P transistor npn npn, and second switch 333 and the 4th switch 335 then are the N transistor npn npn, and four constitute a Class-D output amplifier stage.Pulse-width modulation level 331 is controlled the switch 332～335 of bridge circuit by the pulsewidth of modulation pulse-width signal PWMS1 and PWMS2 and phase place.Therefore, switch element 230 can output audio signal (promptly this differential mode output signal is to VON and VOP) drives load 240 according to secondary signal Vo.In present embodiment, second voltage is a supply voltage, is meant the voltage that drives output amplifier stage, but not exceeds with the supply voltage of integrated circuit; Tertiary voltage also is a Voltage Reference level, but not exceeds with earthed voltage.
Differential mode input signal constitutes output signal Vo=(Vip-Vin)/{ S in the present embodiment after two-layer integrator calculation process
2R
2C
2+ SRC/F+1/G}+S
2R
2C
2* (THD+Noise)/{ S
2R
2C
2+ SRC/F+1/G}, S=j.=j2f wherein, f is frequency.THD is total harmonic distortion (TotalHarmonic Distortion) in the above-mentioned equation, this is with the root mean square of differential mode output signal harmonic components (rootmean square, rms) after value is removed primary harmonic, be expressed as the percentage of primary harmonic root-mean-square value.The amount of commenting of general output stage design quality is promptly based on this THD parameter.The THD of a common high fax (high-fidelity) audio frequency amplifier is about the order of magnitude of several percentages at zero point.By above-mentioned equation as can be known, SRC under sound signal＜＜1, so Noise will significantly be decayed, and obtain splendid signal noise ratio.
Though the present invention discloses as above with preferred embodiment; right its is not in order to limit the present invention; those skilled in the art can do a little change and retouching under the premise without departing from the spirit and scope of the present invention, so protection scope of the present invention is as the criterion with the application's claim.
Claims (16)
1. power amplifier, in order to produce a differential mode output signal to drive a load according to the differential mode input signal that is received, this power amplifier comprises:
One differential mode integrator is in order to receive this differential mode input signal and this differential mode output signal and to carry out integration operation, to export a differential mode first signal;
One integration and regulon are in order to receiving this differential mode first signal and this differential mode output signal and to carry out integration operation, being the secondary signal of single-ended mode with this differential mode first Signal Regulation; And
One switch element, be coupled to this differential mode integrator and this integration and regulon, wherein this secondary signal of exporting based on this integration and regulon of the operating state of this switch element decides, and this differential mode output signal of this switch element output differential mode is to drive this load.
2. power amplifier as claimed in claim 1, wherein this differential mode integrator comprises:
One first resistance, its first termination is received first end signal of this differential mode input signal;
One second resistance, its first termination is received second end signal of this differential mode input signal;
One the 3rd resistance, its first termination is received first end signal of this differential mode output signal;
One the 4th resistance, its first termination is received second end signal of this differential mode output signal;
One first operational amplifier, its first input end is coupled to second end of this second resistance and second end of the 3rd resistance, its second input is coupled to second end of this first resistance and second end of the 4th resistance, with and first output and second output export first end signal and second end signal of this differential mode first signal respectively;
One first electric capacity, its be coupled to first output of this first operational amplifier and second input between; And
One second electric capacity, its be coupled to second output of this first operational amplifier and first input end between.
3. power amplifier as claimed in claim 2, wherein this first resistance is identical with the resistance of this second resistance.
4. power amplifier as claimed in claim 2, wherein the 3rd resistance is identical with the resistance of the 4th resistance.
5. power amplifier as claimed in claim 2, wherein this first electric capacity is identical with the capacitance of this second electric capacity.
6. power amplifier as claimed in claim 1, wherein this integration and regulon comprise:
One first impedance, its first termination is received first end signal of this differential mode first signal;
One second impedance, its first termination is received second end signal of this differential mode first signal;
One the 3rd impedance, its first termination is received first end signal of this differential mode output signal;
One the 4th impedance, its first termination is received second end signal of this differential mode output signal;
One second operational amplifier, its first input end is coupled to second end of this first impedance and second end of the 3rd impedance, its second input is coupled to second end of this second impedance and second end of the 4th impedance, with and this secondary signal of output output single-ended mode;
One the 5th impedance, its first end is coupled to the first input end of this second operational amplifier, with and second termination receive one first voltage; And
One the 6th impedance, its first end and second end are coupled to the output and second input of this second operational amplifier respectively.
7. power amplifier as claimed in claim 6, is resistance with the 4th impedance at wherein this first impedance, this second impedance, the 3rd impedance.
8. power amplifier as claimed in claim 7, wherein this first impedance is identical with the resistance of this second impedance.
9. power amplifier as claimed in claim 7, wherein the 3rd impedance is identical with the resistance of the 4th impedance.
10. power amplifier as claimed in claim 6, wherein the 5th impedance and the 6th impedance are electric capacity.
11. power amplifier as claimed in claim 10, wherein the 5th impedance is identical with the capacitance of the 6th impedance.
12. power amplifier as claimed in claim 6, wherein this first voltage comprises earthed voltage.
13. power amplifier as claimed in claim 1, wherein this switch element comprises:
One pulse-width modulation level in order to produce at least one pulse-width signal, wherein is modulated to the pulsewidth of this pulse-width signal according to this secondary signal of single-ended mode; And
One bridge circuit, it has a plurality of switches that controlled by this pulse-width signal.
14. power amplifier as claimed in claim 13, wherein this pulse-width modulation level produces one first pulse-width signal and one second pulse-width signal, and the pulsewidth of modulating this first pulse-width signal and this second pulse-width signal according to this secondary signal of single-ended mode.
15. power amplifier as claimed in claim 14, wherein this bridge circuit comprises:
One first switch, its first termination is received one second voltage, and its second end is coupled to first end of this load, and this first switch is controlled by this first pulse-width signal;
One second switch, its first termination is received a tertiary voltage, and its second end is coupled to first end of this load, and this second switch is controlled by this first pulse-width signal;
One the 3rd switch, its first termination is received this second voltage, and its second end is coupled to second end of this load, and the 3rd switch is controlled by this second pulse-width signal; And
One the 4th switch, its first termination is received this tertiary voltage, and its second end is coupled to second end of this load, and the 4th switch is controlled by this second pulse-width signal.
16. power amplifier as claimed in claim 15, wherein this first switch and the 3rd switch are the P transistor npn npn, and this second switch and the 4th switch are the N transistor npn npn.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2008100909998A CN101557200B (en) | 2008-04-08 | 2008-04-08 | Power amplifier capable of regulating noise |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2008100909998A CN101557200B (en) | 2008-04-08 | 2008-04-08 | Power amplifier capable of regulating noise |
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| Publication Number | Publication Date |
|---|---|
| CN101557200A true CN101557200A (en) | 2009-10-14 |
| CN101557200B CN101557200B (en) | 2011-05-18 |
Family
ID=41175174
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2008100909998A Expired - Fee Related CN101557200B (en) | 2008-04-08 | 2008-04-08 | Power amplifier capable of regulating noise |
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| Country | Link |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106330117A (en) * | 2010-10-27 | 2017-01-11 | 梅鲁斯音频有限公司 | Class D audio amplifier and sound representation assembly |
| CN108768320A (en) * | 2014-08-08 | 2018-11-06 | 意法半导体股份有限公司 | The method of D classes switching amplifier and controlling loudspeaker |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3941443B2 (en) * | 2001-09-27 | 2007-07-04 | ヤマハ株式会社 | Self-propelled PWM amplifier |
| CN1859000A (en) * | 2005-05-08 | 2006-11-08 | 中国科学院半导体研究所 | Feedback type full difference modulator |
| US7339425B2 (en) * | 2006-08-03 | 2008-03-04 | Elite Semiconductor Memory Technology, Inc. | Class-D audio amplifier with half-swing pulse-width-modulation |
-
2008
- 2008-04-08 CN CN2008100909998A patent/CN101557200B/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106330117A (en) * | 2010-10-27 | 2017-01-11 | 梅鲁斯音频有限公司 | Class D audio amplifier and sound representation assembly |
| CN108768320A (en) * | 2014-08-08 | 2018-11-06 | 意法半导体股份有限公司 | The method of D classes switching amplifier and controlling loudspeaker |
| CN108768320B (en) * | 2014-08-08 | 2022-05-13 | 意法半导体股份有限公司 | Class D switching amplifier and method of controlling a loudspeaker |
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| Publication number | Publication date |
|---|---|
| CN101557200B (en) | 2011-05-18 |
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Granted publication date: 20110518 Termination date: 20190408 |