CN101202535A - Control method of new type digital audio power amplifier - Google Patents
Control method of new type digital audio power amplifier Download PDFInfo
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- CN101202535A CN101202535A CNA2007100500708A CN200710050070A CN101202535A CN 101202535 A CN101202535 A CN 101202535A CN A2007100500708 A CNA2007100500708 A CN A2007100500708A CN 200710050070 A CN200710050070 A CN 200710050070A CN 101202535 A CN101202535 A CN 101202535A
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Abstract
The invention relates to a digital audio power amplifier. By adopting dual-ring feedback, a lowest switch frequency restrictor is inserted behind two level modulators; pulse signals output by the two level modulators are taken as the input signals of the lowest switch frequency restrictor, thus controlling the frequency of the two level pulse signals not less than the arranged value. An error sampling amplifier 1 is additionally provided with a resonant detector; the difference signal obtained by the feedback signal minus the audio input signal is taken as the input signal of the resonant detector after a filter is demodulated, and the resonant is detected and restrained betimes. The lowest switch frequency restrictor is a pulse signal high and low level controller which consists of a timer and a logic gate. The resonant detector is a controller which consists of a threshold decision device and a simulation photocoupler. The method greatly improves the quality of power amplifier, greatly enhances stability performance and improves efficiency. The invention is a high-end product for audio power amplifier, and has the advantages of simple and reliable structure, easy processing and manufacture, low cost and easy generalization.
Description
Affiliated technical field
The present invention relates to the control method of digital audio frequency power amplifier, particularly the control method of the high efficiency audio-frequency power amplifier of 10Hz～100kHz frequency range.
Background technology
Analog audio-frequency power amplifier is low because of its efficient, and volume is big, the development that heaviness and cost height have been out of step with the times.And along with the development of integrated circuit technique and power switch field effect transistor (MOSFET) technology, digital audio frequency power amplifier (abbreviation digital power amplifier) more and more is applied.The final stage power amplifier pipe of digital power amplifier is operated in D class on off state, and theoretical efficiency can reach 100%.The raising of efficient can reduce caloric value, thereby improves the power amplifier reliability, reduces radiator, reduces volume and weight, saves cost.
Existing digital power amplifier has two kinds, and a kind of is that feedback signal is taken from demodulator filter monocycle feedback amplifier before.This amplifier nonlinearity distortion is comparatively serious, and effect is relatively poor.Another kind of is the dicyclo feedback, and feedback signal is taken from demodulator filter simultaneously before with afterwards.Demodulator filter is in the loop control range, thereby eliminates some non-ideal characteristics of filter, and effect is better than monocycle feedback amplifier.
The problem of this dicyclo feedback amplifier has two:
At first, demodulator filter is second order LC (inductance capacitance) structure normally, and the 3dB cut-off frequency is set to 30kHz～60kHz.When demodulator filter output underloading or zero load, resonance appears in the meeting underdamping near cut-off frequency point; When filter output connect capacitive load, cut-off frequency point can reduce, even enters in the voiced band, and produces resonance near the cut-off frequency point after the reduction.If feedback signal is taken from after the filter, the stability of control system just becomes design challenges, and this is the problem that existing dicyclo digital audio amplifier faces.Solution commonly used is to improve filter damping coefficient or regulation and control system compensating network, to improve the system dynamics response speed.Improving the filter damping coefficient is exactly additional damping resistance in filter, certainly will increase the power amplifier internal loss like this, influences power amplification efficiency; The regulation and control system compensating network can increase power amplifier control system complexity greatly, brings negative effect for debugging, production, cost.
Secondly, when input audio signal constantly increases, and the supply power voltage of switch bridge is fixed, when input audio signal increases to certain value, the amplitude limit phenomenon can appear in power amplifier output, and this moment, the output pulse signal frequency of two level modulation can reduce, to such an extent as to can drop in the voiced band.The cut-off frequency of demodulator filter is set to 30kHz～60kHz usually, when being lower than this cut-off frequency, pulse frequency just can't reach the effect of filtering, no matter adopt monocycle or dicyclo feedback, pulse frequency all can directly enter audio amplifier by filter, brings serious distortion to audio signal.
Therefore, need the pulse signal low-limit frequency of two level debuggers output be limited, guarantee by the abnormal signal of the effective filtering of demodulator filter; Resonance is detected, suppresses effectively to guarantee the stability of power amplifier.
Summary of the invention
The control method that the purpose of this invention is to provide a kind of new digital power amplifier is to solve the pulse signal low-limit frequency restricted problem that resonance is unstable and two level modulation are exported after the digital power amplifier feedback signal is taken from demodulator filter.
The objective of the invention is to reach like this:
A kind of control method of new type digital audio amplifier, employing dicyclo feedback, feedback signal is taken from demodulator filter simultaneously before with afterwards, it is characterized in that: after two level modulation, insert lowermost switch frequency limitation device, two level modulation are exported the input signal of the pulse signal of two level as lowermost switch frequency limitation device, the frequency of controlling two level pulse signals is not less than set point; On error sampling amplifier 1, add the resonance detector, feedback signal after the demodulator filter is deducted the input signal of the difference signal of audio input signal as the resonance detector, in time detect and suppress resonance.Described lowermost switch frequency limitation device is the high and low level controller of pulse signal that timer and gate constitute.Described resonance detector is the controller that comprises that threshold judgement device and simulated light idol constitute.
Described lowermost switch frequency limitation device is the high level control that constitutes by timer 1 and NOT logic door, with gate, by timer 2 and or the low level control that constitutes of gate.
Described simulated light idol is made of light-emitting diode and photo resistance, and the threshold judgement device is a comparator.
The described difference signal that feedback signal after the demodulator filter is deducted audio input signal is to adopt analog computing amplifier by the acquisition of differentiating as the input signal of resonance detector.
Advantage of the present invention is:
1, the method that has adopted lowermost switch frequency limitation and resonance to detect, suppress improves the quality of amplifirer greatly, and stability significantly strengthens, and power amplification efficiency improves, and has opened up road for the upgrading of product, is the high-end product of audio frequency apparatus.
2, structure is very simple, and reliable, processing and fabricating is easy.
3, with low cost, be easy to promote.
Description of drawings
Fig. 1 is a circuit diagram of the present invention.
Fig. 2 is a lowermost switch frequency limitation device structured flowchart of the present invention.
Fig. 3 is a resonance detector arrangement block diagram of the present invention.
Embodiment
The new digital power amplifier control method that the present invention proposes totally as shown in Figure 1.The present invention has adopted the dicyclo feedback technique, and feedback signal is taken from demodulator filter simultaneously before with afterwards.Different with existing dicyclo feedback technique is, has inserted lowermost switch frequency limitation device after two level modulation, guarantees that the frequency of two level pulse signals is not less than set point; On error sampling amplifier 1, added the resonance detector, can be in time detected when resonance occurs, and be inhibited, guarantee that power amplifier is stable.
Below in conjunction with accompanying drawing the present invention is elaborated.
Audio signal is divided into two-way after sending into power amplifier, send sampling error amplifier 1 and resonance detector respectively, and feedback signal is also sent sampling error amplifier 1 and resonance detector respectively behind the filter after differential, ratio decay.Sampling error amplifier 1 usefulness is sent into audio signal and is deducted feedback signal, extracts the reference signal of the error signal of audio input signal and feedback signal as sampling error amplifier 2.
The input signal of resonance detector is to deduct audio input signal with feedback signal behind the filter, the difference signal that obtains, the situation of the size reflection resonance of difference signal.When not having resonance, difference is approximately zero; When resonance, difference is with non-vanishing, and resonance big difference more is big more.Difference signal is delivered to the threshold judgement device, and when difference signal surpasses decision threshold, the threshold judgement device will produce the light-emitting diode that output signal is lighted the simulated light idol.The simulated light idol is made of light-emitting diode and photo resistance, and photo resistance is not having under light-struck situation, and resistance value is very big, can be greater than 1 megohm; Under rayed, the resistance of photo resistance can reduce.The photo resistance of simulated light idol is parallel on the amplification arm of error amplifier 1, and under the power amplifier normal operation, photo resistance can not have any influence to the work of power amplifier; When resonance appearred in power amplifier, threshold judgement device meeting output signal was lighted the light-emitting diode of simulated light idol, and photo resistance resistance under illumination can reduce, and the gain meeting of error amplifier 1 reduces along with reducing of photo resistance.Resonance is serious more, and the photo resistance resistance is more little, and Amplifier Gain is low more.Suppress resonance by the step-down amplifier gain, guarantee the The whole control loop stability.
Subtraction between feedback signal and the audio input signal, available analog computing amplifier waits as the NE5532 of PHILIPS company and to realize.The threshold judgement device can be used comparator, realizes as the LM393 of National Semiconductor company.Simulated light can also can be bought ready-made product with light-emitting diode and photo resistance self-control by chance.
Error sampling amplifier 2 usefulness error sampling amplifiers 1 are sent into reference signal and are deducted the preceding feedback signal of filter, and the gained error signal is sent two level modulation.Two level modulation are exported two level pulse signals, and when amplitude limit appearred in power amplifier, high level that pulse signal can occur continuing or low level caused switching frequency to reduce, and amplitude limit is serious more, and switching frequency is low more.
Two level pulse signals are delivered to lowermost switch frequency limitation device.Lowermost switch frequency limitation device operation principle as shown in Figure 2.Lowermost switch frequency limitation device is the high level control that constitutes by timer 1 and NOT logic door, with gate, by timer 2 and or the low level control that constitutes of gate.
Among the figure, timer 1 is rising edge set, the trailing edge zero clearing, and this timer is used for the high level lasting time of sense switch pulse signal.When high level lasting time during less than setting, timer can not produce and overflow, and the output perseverance is a low level signal; When high level lasting time surpasses setting, timer 1 can produce and overflow, and exports a high level narrow pulse signal.
Timer 2 is trailing edge set, the rising edge zero clearing, and this timer is used for the low duration of sense switch pulse signal.When low duration less than setting, timer output perseverance is a low level signal; When low duration surpasses setting, timer can produce and overflow, and exports a high level narrow pulse signal.
When the switching pulse signal frequency was higher than the lowermost switch frequency setting value, timer 1, timer 2 all can not produce and overflow, and switching pulse signal can directly pass through lowermost switch frequency limitation device, does not have any change.When the switching pulse signal frequency is lower than the lowermost switch frequency setting value, when occurring continuing high level, timer 1 can produce and overflow, the output overflow pulse, behind inverter, by with gate, overflow pulse is added on the two level pulse signals, thereby is implemented on the high level low level of forcing to insert the certain hour width; When the switching pulse signal frequency is lower than the lowermost switch frequency setting value, when occurring continuing low level, timer 2 can produce and overflow, the output overflow pulse, and pass through or gate, overflow pulse is added on the two level pulse signals, thereby is implemented in the high level of forcing to insert the certain hour width on the low level.By the insertion by force of high-low level, reach the effect of restriction low switching frequency.Insert the time width of level, can influence the modulation efficiency of two level modulation, get 300～500ns usually.Lowermost switch frequency limitation device adopts the generic logic device to realize, also can realize by programmable logic device.
The pulse signal of lowermost switch frequency limitation device output is delivered to driver, and driver is that pulse signal is converted into switch bridge drive signal.The switch bridge is exported the pulse signal that amplifies under the control of drive signal, demodulator filter is reduced to simulated audio signal with pulse signal, from realize the amplification of simulated audio signal by switch amplification mode.
Claims (4)
1. the control method of a new type digital audio amplifier, employing dicyclo feedback, feedback signal is taken from demodulator filter simultaneously before with afterwards, it is characterized in that: after two level modulation, insert lowermost switch frequency limitation device, two level modulation are exported the input signal of the pulse signal of two level as lowermost switch frequency limitation device, and the frequency of controlling two level pulse signals is not less than set point; On error sampling amplifier 1, add the resonance detector, feedback signal after the demodulator filter is deducted the input signal of the difference signal of audio input signal as the resonance detector, in time detect and suppress resonance; Described lowermost switch frequency limitation device is the high and low level controller of pulse signal that timer and gate constitute; Described resonance detector is the controller that comprises that threshold judgement device and simulated light idol constitute.
2. control method as claimed in claim 1 is characterized in that: described lowermost switch frequency limitation device be the high level control that constitutes by timer (1) and NOT logic door, with gate, by timer (2) and or the low level that constitutes of gate control.
3. control method as claimed in claim 1 is characterized in that: described simulated light idol is made of light-emitting diode and photo resistance, and the threshold judgement device is a comparator.
4. control method as claimed in claim 1 is characterized in that: the difference signal that feedback signal after the demodulator filter is deducted audio input signal is to adopt analog computing amplifier by the acquisition of differentiating as the input signal of resonance detector.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2007100500708A CN100561859C (en) | 2007-09-20 | 2007-09-20 | New type digital audio power amplifier |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2007100500708A CN100561859C (en) | 2007-09-20 | 2007-09-20 | New type digital audio power amplifier |
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| CN101202535A true CN101202535A (en) | 2008-06-18 |
| CN100561859C CN100561859C (en) | 2009-11-18 |
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| CNB2007100500708A Expired - Fee Related CN100561859C (en) | 2007-09-20 | 2007-09-20 | New type digital audio power amplifier |
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101980441A (en) * | 2010-10-08 | 2011-02-23 | 徐州泰思电子科技有限公司 | Digital audio power amplifier and control method thereof |
| CN101742180B (en) * | 2008-11-10 | 2012-06-27 | 康佳集团股份有限公司 | Circuit for realizing two-way sound transmission on same port |
| CN101720051B (en) * | 2009-11-20 | 2012-12-05 | 天津市华音宇科工贸有限公司 | Novel intelligent automatic audio mixing method and device thereof |
| CN103004083A (en) * | 2010-03-02 | 2013-03-27 | 帝瓦雷公司 | Very high fidelity audio amplifier |
| CN103782514A (en) * | 2011-09-08 | 2014-05-07 | 伯斯有限公司 | Versatile audio power amplifier |
| US9264000B2 (en) | 2010-03-04 | 2016-02-16 | Bose Corporation | Versatile audio power amplifier |
| EP3474027A1 (en) * | 2017-10-23 | 2019-04-24 | Nxp B.V. | Method for identifying a fault at a device output and system therefor |
| US10436839B2 (en) | 2017-10-23 | 2019-10-08 | Nxp B.V. | Method for identifying a fault at a device output and system therefor |
-
2007
- 2007-09-20 CN CNB2007100500708A patent/CN100561859C/en not_active Expired - Fee Related
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101742180B (en) * | 2008-11-10 | 2012-06-27 | 康佳集团股份有限公司 | Circuit for realizing two-way sound transmission on same port |
| CN101720051B (en) * | 2009-11-20 | 2012-12-05 | 天津市华音宇科工贸有限公司 | Novel intelligent automatic audio mixing method and device thereof |
| CN103004083A (en) * | 2010-03-02 | 2013-03-27 | 帝瓦雷公司 | Very high fidelity audio amplifier |
| US9264000B2 (en) | 2010-03-04 | 2016-02-16 | Bose Corporation | Versatile audio power amplifier |
| CN101980441A (en) * | 2010-10-08 | 2011-02-23 | 徐州泰思电子科技有限公司 | Digital audio power amplifier and control method thereof |
| CN103782514A (en) * | 2011-09-08 | 2014-05-07 | 伯斯有限公司 | Versatile audio power amplifier |
| EP3474027A1 (en) * | 2017-10-23 | 2019-04-24 | Nxp B.V. | Method for identifying a fault at a device output and system therefor |
| US10436839B2 (en) | 2017-10-23 | 2019-10-08 | Nxp B.V. | Method for identifying a fault at a device output and system therefor |
| US10782347B2 (en) | 2017-10-23 | 2020-09-22 | Nxp B.V. | Method for identifying a fault at a device output and system therefor |
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| CN100561859C (en) | 2009-11-18 |
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Address after: 610036, Sichuan Jinniu District hi tech Industrial Development Zone, nine groups of Soil Bridge Village, Chengdu Patentee after: CHENGDU SPACEON ELECTRONICS Co.,Ltd. Address before: 610036 Sichuan city of Chengdu province Jinniu District Chadianzi Road No. 1 building, Austria Patentee before: Chengdu Spaceon Electronics Co.,Ltd. |
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Granted publication date: 20091118 Termination date: 20210920 |