CN102013875A - Digital power amplifier and control method thereof - Google Patents
Digital power amplifier and control method thereof Download PDFInfo
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- CN102013875A CN102013875A CN 201010503901 CN201010503901A CN102013875A CN 102013875 A CN102013875 A CN 102013875A CN 201010503901 CN201010503901 CN 201010503901 CN 201010503901 A CN201010503901 A CN 201010503901A CN 102013875 A CN102013875 A CN 102013875A
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Abstract
The invention relates to a digital power amplifier and a control method thereof. The digital power amplifier and the control method thereof can be used for feeding back a signal of an output node to the inverting input end of a comparer and simultaneously supplying a high-frequency triangular wave signal to the non-inverting input end of the comparer; and besides, the digital power amplifier and the control method thereof can also be used for connecting a bias voltage to the non-inverting input end of the comparer and connecting a fixed-frequency square wave signal, a feedback signal obtained from an output stage and an amplifier input signal to the inverting input end. The digital power amplifier and the control method thereof can keep the advantages of an adaptive modulation control technology at the same time of ensuring the switching frequency to be basically stable, thereby reducing the influence of EMI (Electro-Magnetic Interference) on a system; and in addition, a control circuit has simple structure.
Description
Technical field
The present invention relates generally to a kind of power amplifier, relates in particular to a kind of digital power amplifier and control method thereof.
Background technology
At present, digital power amplifier has a lot of different types of effects, as category-A, category-B, AB class etc., wherein digital power amplifier is a close power amplifier or pulse modulation power amplifier with different being of other power amplifiers substantially, in this digital power amplifier, device or conducting fully, turn-off fully, reduced the power consumption of output device significantly, audio signal is to be used for modulating pulse-width modulation (PWM) carrier signal, carrier signal drives output power stage and obtains the high-frequency PWM square wave, at last by the low pass filter output audio signal to load, people design digital power amplifier and pay much attention to and improve its power density and reduce cost simultaneously at present, from circuit structure, digital power amplifier can be regarded as traditional inverter, input DC power produces the audio signal of amplifying according to reference signal, therefore, the closed loop control method that all are traditional can be used in the middle of the digital power amplifier such as two feedback loop controls of transient voltage pattern FEEDBACK CONTROL or electric current and voltage etc.The typical device that this control method adopted is exactly an error amplifier.Usually not only complexity but also cost are higher for the sort circuit structure.
Summary of the invention
In order to solve the more technical unfavorable problems of existing power amplifier, the invention provides a kind of digital power amplifier and control method thereof, make the switching frequency of amplifier be maintained fixed constant, thereby be easy to avoid the wave band of some signal of interest, control circuit is simple in structure simultaneously, and some devices can be integrated.
The technical solution adopted for the present invention to solve the technical problems is: this digital power amplifier comprises input stage, output stage, filter, feedback network, described input stage is in order to receiving inputted signal, described input stage comprises comparator and triangular-wave generator, described comparator receives the high frequency triangle wave of described input signal and the generation of described triangular-wave generator, and exports first signal; Described output stage is connected to input stage, produces secondary signal by described first signal; Described filter is connected to the output node of described output stage, in order to described secondary signal is carried out filtering so that obtain output signal; Described feedback network, be connected between the input node of the output node of described output stage and described input stage, described feedback network carries out obtaining feedback signal behind the noise shaping to described secondary signal, and described input stage is arrived in described feedback signal negative feedback, so that deduct described feedback signal from described input signal.
The in-phase input end of described comparator adds cuts out described high frequency triangle wave, inverting input adds cuts out described input signal and described feedback signal, and described comparator compares and obtains described first signal by described high frequency triangle wave and described input signal being deducted the signal that obtains after the described feedback signal.
The in-phase input end of described comparator loads dc offset voltage, inverting input loads described input signal, described feedback signal and described high frequency square wave, and described comparator compares and obtains described first signal by described dc offset voltage and described input signal being deducted the signal that obtains behind the described high frequency square wave that superposes again after the described feedback signal.
Described feedback network comprises electric capacity, and first end of described electric capacity is connected to described input signal, described amplifier's inverting input and described secondary signal simultaneously, the second end ground connection or connect dc offset voltage.
Described feedback network is connected first end of described electric capacity and the feedback resistance between the described secondary signal.
Described high frequency triangle wave or described high frequency square wave are bigger to the charging and discharging capabilities of described electric capacity than described secondary signal.
Described input stage has a described comparator; Described output stage comprises: drive circuit is connected to described comparator; A half-bridge switch circuit is connected to described drive circuit, the drive signal that produces according to drive circuit and alternate conduction produces a secondary signal with correspondence.
Described input stage has a described comparator, and described output stage comprises: drive circuit is connected to described comparator; Two half-bridge switch circuit are connected to described drive circuit, the drive signal that produces according to drive circuit and alternate conduction produces two secondary signals with correspondence, and feed back one of them secondary signal.
Described input stage has two described comparators, and described output stage comprises: drive circuit is connected respectively with two described comparators; Two half-bridge switch circuit are connected respectively with described drive circuit, and the drive signal that produces according to drive circuit and alternate conduction producing two described secondary signals, and feed back to corresponding comparator respectively.
The step of the control method of digital power amplifier is: first step, the high frequency square wave that high frequency triangle wave that receiving inputted signal and triangular-wave generator generate or square-wave generator generate, and export first signal, second step responds described first signal and produces secondary signal; Third step carries out filtering to described secondary signal and obtains output signal; And the 4th step, described secondary signal is carried out obtaining feedback signal behind the noise shaping, and with described feedback signal negative feedback to the input that receives described input signal, so that deduct described feedback signal from described input signal.
Described second step responds described first signal and produces two described secondary signals; In the 4th step, in two described secondary signals at least one carried out noise shaping after negative feedback to described input.Digital power amplifier circuit of the present invention adopts the ring that stagnates enough little so that negligible comparator has substituted hysteresis comparator.At the input of comparator the low frequency part of power stage output signal and audio input signal are offset, HFS is sent into comparator, thus the output audio signal that obtains modulating at output.Can connect the triangular signal of a fixed frequency at the in-phase input end of comparator, connect feedback signal and the amplifier input signal that obtains from output stage at inverting input.
Also can meet bias voltage Vdd, the feedback signal and the amplifier input signal that connect the square-wave signal of a fixed frequency, obtain from output stage at inverting input at the in-phase input end of comparator.
Beneficial effect of the present invention: this kind digital power amplifier and control method thereof can provide a high frequency triangle wave signal for simultaneously the comparator in-phase input end the signal feedback of output node to the comparator inverting input.In addition, the present invention also can connect bias voltage at the in-phase input end of comparator, the feedback signal and the amplifier input signal that connect the square-wave signal of a fixed frequency, obtain from output stage at inverting input, when the present invention can keep Adaptive Modulation control technology advantage, guarantee the switching frequency basic fixed, thereby reduce the influence of electromagnetic interference (EMI) to system, control circuit is simple in structure.
Description of drawings
The present invention will be further described below in conjunction with drawings and Examples.
Accompanying drawing 1 is the circuit diagram that applies to single-ended digital power amplifier of first kind of embodiment of the present invention.
Accompanying drawing 2 is the audio input signal of accompanying drawing 1 circuit and the oscillogram of audio output signal.
Accompanying drawing 3 is the oscillogram of the signal of the signal of SW signal, in-phase input end Pin of accompanying drawing 1 circuit and inverting input Nin.
Accompanying drawing 4 is shown the circuit diagram that applies to single-ended digital power amplifier of second kind of embodiment of the present invention.
Accompanying drawing 5 is the audio input signal of accompanying drawing 4 circuit and the oscillogram of audio output signal.
Accompanying drawing 6 is the oscillogram of the signal of the signal of square wave, SW signal, in-phase input end Pin of accompanying drawing 4 circuit and inverting input Nin.
Accompanying drawing 7 is the circuit diagram that applies to the bridge-type digital power amplifier of the third embodiment of the present invention.
Accompanying drawing 8 (a) and accompanying drawing 8 (b) are the portion waveshape figure of accompanying drawing 7 circuit.
Accompanying drawing 9 is the circuit diagram that applies to the bridge-type digital power amplifier of the 4th kind of embodiment of the present invention.
Figure 10 (a) and Figure 10 (b) are the portion waveshape schematic diagram of the circuit of accompanying drawing 9.
Embodiment
Embodiment 1: among the figure, this digital power amplifier and control method thereof comprise digital power amplifier and load.One has the in-phase input end Pin (A) that the high frequency triangle wave Vcc/2 direct current biasing, the about hundreds of KHz of frequency has been added to comparator, the inverting input Nin (B) of comparator imported capacitor C in and resistance R i to capacitor C int charge/discharge by a capacitor C int ground connection.The output PWM ripple of comparator is through overdrive circuit oxide-semiconductor control transistors M1 and M2 alternate conduction, the source class of transistor M1 is connected to output node C, and the source ground of transistor M2, the drain electrode of transistor M1 is connected to power Vcc, and the drain electrode of transistor M2 is connected to output node C, transistor M1 and M2 play a part switch, they constitute the part of the output stage of digital power amplifier circuit, when under switching mode, using output stage with box lunch, produce square wave output at output node C, the waveform SW at output node C place is through the filter circuit of inductance L and capacitor C 1 composition, and revert to the audio signal that is exaggerated and be transported to load (as loud speaker) after the capacitance C2, simultaneously the SW signal by resistance R _ f to capacitor C int charge/discharge, ideally, audio signal is to the low frequency component V of the SW signal at the charge/discharge effect of capacitor C int and output node C place
SW_ l
OWCharge/discharge effect to Cint can be offset just, and promptly comparator inverting input Nin is at V
SW_ l
OWCan keep following the voltage of comparator in-phase input end down with the acting in conjunction of audio frequency input, promptly when comparator output high level, transistor M1 conducting, transistor M2 shutoff, comparator inverting input voltage V
NinWith comparator in-phase input end pin voltage and stagnant loop voltag sum V
Pin± dV is (wherein dV represent the comparator lagging voltage) relatively, and this moment, the SW signal was high level, causes the rising of Nin terminal voltage until greater than voltage V after the feedback
Pin+ dV, comparator output hopping are low level, and transistor M1 turn-offs, and input terminal voltage V is reacted in transistor M2 conducting this moment
NinWith V
Pin-dV relatively, SW low level signal feedback causes the Nin terminal voltage to descend until less than voltage V
Pin-dV, the comparator output hopping is a high level, causes the SW signal to be high level, so circulation is in order to realize this fixed FEEDBACK CONTROL frequently and guarantee system stability work that Nin terminal voltage rise and fall speed all should be held the variation slope of given triangular wave less than Pin.So will consider that Pin holds the pace of change of given triangular wave when design Cint electric capacity, Rf feedback resistance.The high fdrequency component of SW signal will obtain the grid level drive signal of transistor M1 and M2 under the high frequency triangle wave control of in-phase input end Pin.Amplifier Gain is determined by the ratio of resistance R _ f and Ri.
By the feedback modulation, when input audio signal changes, the meeting Adaptive Modulation SW of this system signal, make inverting input Nin terminal voltage give and follow in-phase input end Pin all the time, thereby reach the purpose of control output, certainly switching frequency is not that maintenance is definitely constant, but does small variation in the scope of hundreds of hertz.The reason that causes this minor variations is the little audio frequency sinusoidal signal that the comparator inverting input occurs, and this signal also can carry out charge/discharge to Cint, causes the variation of Nin voltage.But because this variation is very little with respect to switching frequency, so this control method still can be regarded as deciding frequency control.
Embodiment 2: among the last embodiment, requiring the slope of given triangular wave will be that integrating capacitor Cint goes up the slope that high frequency discharges and recharges ripple greater than inverting input Nin terminal voltage all the time, and triangular wave also is better than the discharge and recharge effect of feedback signal SW signal to capacitor C int to the effect that discharges and recharges of capacitor C int.Equally, given square wave also is better than the discharge and recharge effect of feedback signal SW signal to capacitor C int to the effect that discharges and recharges of capacitor C int among this embodiment.
The groundwork waveform of accompanying drawing 6 circuit is divided into 5 stages:
Phase I (t0-t1); At t0 constantly, square wave is by high step-down, and SW signal and square-wave signal discharge to capacitor C int simultaneously, and the voltage Vcint on the Cint continues to descend;
Second stage (t1-t2); At t1 constantly, Vcint＜1/2Vcc, the comparator output switching activity, the SW signal is uprised by low.The SW signal charges simultaneously to Cint that square wave continues Cint is discharged, because the effect of discharge is more strong, so Vcint descends with a less speed;
Phase III (t2-t3): at t2 constantly, square wave is uprised by low, and SW signal and square wave charge to Cint simultaneously, and Vcint rises;
Quadravalence section (t3-t4): at t3 constantly, Vcint＞1/2Vcc, comparator output upset once more, the SW signal is by high step-down, the SW signal discharges simultaneously to Cint that square wave continues Cint is charged, because the effect of charging is more strong, so Vcint rises with a less speed;
Five-stage (t4-t5); At t4 constantly, square wave is by high step-down, and SW signal and square wave discharge to Cint simultaneously, and Vcint continues to descend.
As mentioned above, that realizes this example decides the frequency FEEDBACK CONTROL, require the Nin terminal voltage to continue to descend by hanging down when uprising at second stage SW signal, continue to rise in the quadravalence section, promptly require given square wave that the effect that discharges and recharges of capacitor C int is better than the discharge and recharge effect of feedback signal SW signal to capacitor C int, because square wave will be better than the charge/discharge effect of the SW signal of feedback greatly to the charge/discharge effect of electric capacity, though so the variation of hundreds of hertz is arranged, the frequency of SW signal is still fixing generally, by the frequency decision of square wave.
Embodiment 3: the present invention also can be applied in the power amplifier of bridging load (BTL), and the intrinsic difference export structure of bridge type topology can harmonic carcellation distortion and direct current biasing.
The H bridge has two half-bridge switch circuit, usually power by single supply Vcc, for given Vcc, the spiking output amplitude that the differential mode of H bridge circuit provides is the twice of single ended mode, and power output is its four times, here only use a comparator, its output is through overdrive circuit oxide-semiconductor control transistors S1, S2, S3 and S4, make S1, S4 and S2, the S3 alternate conduction, thereby obtain opposite SW1 of phase place and SW2 signal, SW1 and SW2 pass through L1 again respectively, C1 and L2, the C2 rectifying and wave-filtering is delivered to the two ends of load, and one of them is used for feedback control loop and get final product only to need feedback between the two at SW1 and SW2, and employing SW2 is as feedback control signal in the accompanying drawing 7.Fig. 8 (a) has provided the audio frequency output waveform of Fig. 9 circuit, and Fig. 8 (b) is that amplify the part of work wave, can see and will just can obtain the SW1 signal after the SW2 signal inversion.
Embodiment 4: each half-bridge all has own special-purpose comparator among this embodiment, thereby can independently control two drive circuits, the switching frequency of each brachium pontis is all set by the same outside triangular wave that is added in node A, so their frequency is the same, except not having capacitance, the control circuit structure of each brachium pontis is consistent with single-ended amplifier, and gain also can calculate with Rf/Ri.The audio signal of input is a differential signal, and phase place is opposite, is added in the inverting input B1 and the B2 of two comparators respectively, and while and triangular wave compare.Accompanying drawing 10 (a) has provided the audio frequency input and the audio frequency output waveform of accompanying drawing 9 circuit, and Figure 10 (b) is that amplify the part of work wave.
Control method of the present invention may further comprise the steps:
First step; The high frequency square wave that high frequency triangle wave that receiving inputted signal and triangular-wave generator generate or square-wave generator generate, and export first signal;
Second step; Respond first signal and produce secondary signal, be i.e. the SW signal;
Third step; The SW signal is carried out filtering obtain output signal;
The 4th step; The SW signal is carried out obtaining feedback signal behind the noise shaping, and with the input of described feedback signal negative feedback to the described input signal of reception, so that deduct described feedback signal from described input signal.Compare with known " AAM " driving, the present invention only need increase direct current biasing power supply and suitable triangular wave or the square wave of a 1/2Vcc, after these parts are all integrated, just can realize closed loop control frequently surely quite easily to digital power amplifier.
Claims (9)
1. digital power amplifier and control method thereof, this digital power amplifier comprises input stage, output stage, filter, feedback network, it is characterized in that: described input stage comprises comparator and triangular-wave generator or square-wave generator, described comparator receives the high frequency triangle wave of described input signal and the generation of described triangular-wave generator or the high frequency square wave that described square-wave generator generates, and exports first signal; Described output stage is connected to input stage, responds described first signal and produces secondary signal; Described filter is connected to the output node of described output stage, described feedback network is connected between the input node of the output node of described output stage and described input stage, described feedback network carries out obtaining feedback signal behind the noise shaping to described secondary signal, and described input stage is arrived in described feedback signal negative feedback.
2. a kind of digital power amplifier as claimed in claim 1 and control method thereof, it is characterized in that: the in-phase input end of described comparator loads described high frequency triangle wave, inverting input adds cuts out described input signal and described feedback signal, and described comparator compares by the signal that will obtain after described high frequency triangle wave and the differential described feedback signal of described input signal and obtains described first signal.
3. a kind of digital power amplifier as claimed in claim 1 and control method thereof, it is characterized in that: the in-phase input end of described comparator adds the sanction dc offset voltage, inverting input adds cuts out described input signal, described feedback signal and described high frequency square wave, and described comparator compares by the signal that will obtain behind the described high frequency square wave that superpose again after described dc offset voltage and the differential described feedback signal of described input signal and obtains described first signal.
4. a kind of digital power amplifier as claimed in claim 1 and control method thereof, it is characterized in that: described feedback network comprises electric capacity and feedback resistance, first end of described electric capacity is connected to described input signal, described amplifier's inverting input and described secondary signal simultaneously, the second end ground connection or connect dc offset voltage, described feedback resistance are the feedback resistance that is connected between first end and the described secondary signal of electric capacity.
5. a kind of digital power amplifier as claimed in claim 1 and control method thereof is characterized in that: described high frequency triangle wave or described high frequency square wave are bigger to the charging and discharging capabilities of described electric capacity than described secondary signal.
6. a kind of digital power amplifier as claimed in claim 1 and control method thereof is characterized in that: described input stage has a comparator; Described output stage comprises drive circuit and a half-bridge switch circuit, and drive circuit is connected to described comparator, and a half-bridge switch circuit is connected to described drive circuit.
7. a kind of digital power amplifier as claimed in claim 1 and control method thereof is characterized in that: described input stage has a described comparator; Described output stage comprises drive circuit and two half-bridge switch circuit, and drive circuit is connected to described comparator, and two half-bridge switch circuit are connected to described drive circuit.
8. a kind of digital power amplifier as claimed in claim 1 and control method thereof is characterized in that: described input stage has two described comparators; Described output stage comprises drive circuit and two half-bridge switch circuit, and drive circuit is connected respectively with two described comparators; Two half-bridge switch circuit are connected respectively with described drive circuit, and the drive signal of giving birth to and alternate conduction producing two described secondary signals, and feed back to corresponding comparator respectively.
9. digital power amplifier and control method thereof, its steps characteristic is:
First step, the high frequency square wave that high frequency triangle wave that receiving inputted signal and triangular-wave generator generate or square-wave generator generate, and export first signal;
Second step responds described first signal and produces secondary signal;
Third step carries out filtering to described secondary signal and obtains output signal; And
The 4th step carries out obtaining feedback signal behind the noise shaping to described secondary signal, and with the input of described feedback signal negative feedback to the described input signal of reception, so that deduct described feedback signal from described input signal.
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102386850A (en) * | 2011-08-25 | 2012-03-21 | 杭州士兰微电子股份有限公司 | Voltage controlled oscillation modulator circuit |
| CN104185343A (en) * | 2014-08-13 | 2014-12-03 | 香港柏奇亚照明有限公司 | Sensing-power-supply LED lamp and emitting sensor thereof |
| CN106646932A (en) * | 2016-12-29 | 2017-05-10 | 中国电子科技集团公司第三十四研究所 | DC bias operating point control loop of Maher Zeng Del intensity modulator |
| CN108012218A (en) * | 2017-12-05 | 2018-05-08 | 恩平市金马士音频设备有限公司 | The digital power amplification system of electromotive force driving |
| CN108462417A (en) * | 2018-03-02 | 2018-08-28 | 无锡矽瑞微电子股份有限公司 | Motor-drive circuit |
| CN112653403A (en) * | 2020-12-24 | 2021-04-13 | 唯捷创芯(天津)电子技术股份有限公司 | Radio frequency power amplifier, chip and communication terminal for reducing load change sensitivity |
| CN113810028A (en) * | 2020-06-16 | 2021-12-17 | 意法半导体股份有限公司 | Modulator circuit, corresponding apparatus and method |
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| CN101369802A (en) * | 2007-08-16 | 2009-02-18 | 美国芯源系统股份有限公司 | Closed-loop D-class power amplifier and its control method |
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Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101369802A (en) * | 2007-08-16 | 2009-02-18 | 美国芯源系统股份有限公司 | Closed-loop D-class power amplifier and its control method |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102386850A (en) * | 2011-08-25 | 2012-03-21 | 杭州士兰微电子股份有限公司 | Voltage controlled oscillation modulator circuit |
| CN102386850B (en) * | 2011-08-25 | 2014-04-23 | 杭州士兰微电子股份有限公司 | Voltage controlled oscillation modulator circuit |
| CN104185343A (en) * | 2014-08-13 | 2014-12-03 | 香港柏奇亚照明有限公司 | Sensing-power-supply LED lamp and emitting sensor thereof |
| CN104185343B (en) * | 2014-08-13 | 2017-04-12 | 香港柏奇亚照明有限公司 | Sensing-power-supply LED lamp and emitting sensor thereof |
| CN106646932A (en) * | 2016-12-29 | 2017-05-10 | 中国电子科技集团公司第三十四研究所 | DC bias operating point control loop of Maher Zeng Del intensity modulator |
| CN108012218A (en) * | 2017-12-05 | 2018-05-08 | 恩平市金马士音频设备有限公司 | The digital power amplification system of electromotive force driving |
| CN108012218B (en) * | 2017-12-05 | 2024-04-02 | 恩平市金马士音频设备有限公司 | Electromotive force driven digital power amplifier system |
| CN108462417A (en) * | 2018-03-02 | 2018-08-28 | 无锡矽瑞微电子股份有限公司 | Motor-drive circuit |
| CN113810028A (en) * | 2020-06-16 | 2021-12-17 | 意法半导体股份有限公司 | Modulator circuit, corresponding apparatus and method |
| CN112653403A (en) * | 2020-12-24 | 2021-04-13 | 唯捷创芯(天津)电子技术股份有限公司 | Radio frequency power amplifier, chip and communication terminal for reducing load change sensitivity |
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Application publication date: 20110413 |