CN101183855B - D-type amplifier - Google Patents
D-type amplifier Download PDFInfo
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- CN101183855B CN101183855B CN2007101878066A CN200710187806A CN101183855B CN 101183855 B CN101183855 B CN 101183855B CN 2007101878066 A CN2007101878066 A CN 2007101878066A CN 200710187806 A CN200710187806 A CN 200710187806A CN 101183855 B CN101183855 B CN 101183855B
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
- H03F3/21—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers with semiconductor devices only
- H03F3/217—Class D power amplifiers; Switching amplifiers
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
- H03F1/26—Modifications of amplifiers to reduce influence of noise generated by amplifying elements
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/181—Low frequency amplifiers, e.g. audio preamplifiers
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2200/00—Indexing scheme relating to amplifiers
- H03F2200/03—Indexing scheme relating to amplifiers the amplifier being designed for audio applications
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2200/00—Indexing scheme relating to amplifiers
- H03F2200/351—Pulse width modulation being used in an amplifying circuit
Abstract
The invention relates to a data processing apparatus such as a D-class amplifying circuit and so on, characterized in reduced manufacturing cost based on miniaturization and the reduction of the parts count, and enhanced operability and flexibility when constructing the system based on the simplicity of the waveform setting or regulating. The D-class amplifying apparatus (100) generates cosine wave data during the beginning or the ending and serves the cosine wave data as the PWM signals input to LPF (190) to control the output voltage of the LPF (190) so as not to change rapidly, selectively switchovers to the input data such as the voice data .etc, and serves the data as the data for an amplifying objects, and outputs the PWM signals which has been processed with noise shaping treatment and modulated to LPF (190) .
Description
Technical field
The present invention relates to a kind of D type amplifier that data processing is used to remove sonic boom noises such as (popup noise) that carries out.
The present invention is based on Japanese patent application 2006-309485 number of application on November 15th, 2006 and require priority, quote its content in this manual.
Background technology
Current, the amplifying device that various acoustic products such as known category-A amplifying circuit, category-B amplifying circuit or C class amplification circuit are used (below abbreviate " amplifying circuit " as), recently, from the miniaturization of this amplifying circuit and the viewpoint of high efficiency, digital amplifying device (below be called " D class amplification circuit ") is popularized.
This D class amplification circuit carries out PWM (PulseWidth Modulation) modulation to the voice signal as digital signal, directly the square wave to the modulation signal that obtains by this modulation amplifies, and exports loud speaker to via LPF (Low Pass Filter) then.
Known this D class amplification circuit produces so-called sonic boom when power connection or power supply disconnection.This sonic boom causes by the operate condition of the various circuit from input part to efferent of D class amplification circuit is unstable, if the bigger noise of output except meeting produces ear-piercing sense of hearing, also can make various devices generation faults such as loud speaker.
Current, as the D type amplifier that suppresses above-mentioned sonic boom generation, known following apparatus, it is provided with sonic boom and suppresses circuit in low pass filter output of simulating, control to simulation the output voltage (for example, with reference to patent documentation 1) of this low pass filter.
Patent documentation 1: the spy opens 2003-204590 communique (specification digest)
Summary of the invention
But, because in above-mentioned D class amplification circuit, the circuit that suppresses sonic boom is set to analog circuit, thus when construction system, must outside this amplifying circuit, prepare to be used to suppress the circuit of sonic boom, thus cost is increased, also limited miniaturization simultaneously.
In addition, because in this D class amplification circuit, the circuit that suppresses sonic boom is an analog circuit, amplifying circuit self starts and stops to need the stipulated time (for example 300ms), so can't easily change from power connection to the time between the startup elementary period that normally begins to move, and from release up to the time between power supply disconnects fully startup tailend, can't start at short notice and stop especially.
The present invention proposes in view of the above problems, its purpose is, a kind of D type amplifier is provided, it is by using digital waveform, thereby prevent sonic boom with simple structure, simultaneously can reduce and realize that manufacturing cost reduces based on miniaturization, number of components, and, realize improving operability and the flexibility when constructing system based on the easiness of wave setting or adjustment.
In order to solve above-mentioned problem, D type amplifier involved in the present invention, it exports the output voltage of the 1st level and these two values of the 2nd level, it constitutes, have: the data generating unit, its sampling period with regulation generates the Wave data of n position, this Wave data is expressed as follows waveform, that is, between the elementary period before will being about to begin to amplify action or just finished to amplify between tailend after the action at least one as given period between, with the level at the center of above-mentioned the 1st level and above-mentioned the 2nd level during as centered level, in between above-mentioned given period, the waveform that level gradually changes between above-mentioned the 1st level and above-mentioned centered level, wherein, said n is a natural number; Selection portion, it is supplied to voice data and above-mentioned Wave data that above-mentioned centered level is the amplitude center, and this selection portion is selected above-mentioned Wave data between above-mentioned given period, select tut data, the line output of going forward side by side during carrying out the action of amplifying action; Noise remove portion, it receives the above-mentioned Wave data of selecting from above-mentioned selection portion, above-mentioned Wave data is applied noise shaping handle and the transform data of generation m position, and wherein, above-mentioned m is for satisfying the natural number of n＞m; Pulse-width modulation portion, it carries out pulse-width modulation and generates pulse-width signal above-mentioned transform data; And efferent, it amplifies above-mentioned pulse-width signal with single-ended format, exports above-mentioned output voltage, and above-mentioned data generating unit generates this Wave data in the following manner, that is and, the feasible fundamental frequency that constitutes the waveform of above-mentioned Wave data is in outside the audio-band.
According to the present invention, output voltage rises to the situation of specified level or output voltage drops between the given periods such as situation of level "0" from specified level when stopping from level "0" when starting, the Wave data that can gradually change based on level and generate pulse-width signal.Thus, because this D type amplifier, the output voltage that can suppress output circuit when starting or stoping sharply changes and the noise that produces, simultaneously can be by using digital waveform, and prevent sonic boom with simple structure, and easily set or the change waveform, so can reduce and reduce manufacturing cost based on miniaturization or number of components, the flexibility when realizing improving operability and constructing system based on the easiness of wave setting or adjustment.
In addition, because the fundamental frequency that makes the waveform that constitutes Wave data is outside audio-band, so inhibition sonic boom in can be between given period.Here, audio-band is meant the scope that can be identified sound by people's the sense of hearing, the i.e. frequency band of 20Hz～20kHz.In addition, existing under the situation of distortion in the waveform that constitutes Wave data, also can be that 3 times of high order harmonic component compositions to fundamental frequency are in outside the audio-band with the frequency setting of Wave data.
Above-mentioned D type amplifier has selection portion, it is supplied to voice data and above-mentioned Wave data that above-mentioned centered level is the amplitude center, this selection portion is selected above-mentioned Wave data between above-mentioned given period, select tut data, the line output of going forward side by side during carrying out the action of amplifying action.In the case, because noise remove portion, pulse-width modulation portion and the efferent of use also can use between given period during the action, so can constitute the D type amplifier simply.
In addition, preferably in above-mentioned D type amplifier, the waveform that constitutes above-mentioned Wave data is a cosine waveform, above-mentioned data generating unit, and recurrence formula according to the rules generates above-mentioned Wave data.In the case owing to generate cosine waveform according to recurrence formula, so need be in memory the stored waveform data, can be easily and generate this Wave data with the waveform of low distortion.
In addition, in above-mentioned D type amplifier, preferred above-mentioned noise remove portion, corresponding with the value of above-mentioned Wave data and change the number of times that above-mentioned noise shaping is handled, so that in above-mentioned noise shaping is handled, in insensitive zone, do not carry out computing.So-called insensitive zone is meant that the computing of being handled by noise shaping causes the scope of information dropout, is typically referred to as the scope that underflow or overflow take place by computing.If information dropout then can produce noise in audio-band.On the other hand, the number of times that noise shaping is handled is high more, and just big more with the amplitude of the quantization error amount of transform data stack, insensitive zone becomes big, but the quantizing noise in the low-frequency band reduces.According to the present invention, owing to the corresponding number of times that changes above-mentioned noise shaping processing, so that in insensitive zone, do not carry out computing, so can suppress the noise in the audio-band with the value of above-mentioned Wave data.
In addition, in above-mentioned D type amplifier, preferred above-mentioned noise remove portion, corresponding with the time after the beginning between above-mentioned given period and change the number of times of above-mentioned noise shaping processing, so that in above-mentioned noise shaping processing, in insensitive zone, do not carry out computing.Insensitive zone is corresponding with the value of Wave data and determine, but under the situation that generates fixing Wave data, can be corresponding with the time after the beginning between given period and definite insensitive zone.According to the present invention, even because the value of detection waveform data not, number of times that also can the switching noise shaping is handled by the time is managed simplifies the structure so can make.
In addition, in above-mentioned D type amplifier, preferred above-mentioned pulse-width modulation portion does not reach under the situation of setting as yet in the value of above-mentioned Wave data, and duty ratio is gradually changed, and this duty ratio is between the high period of above-mentioned pulse-width signal and the ratio between low period.According to the present invention, because before the closing to an end after just the beginning between elementary period or between tailend etc., also must cause in insensitive zone, carrying out in the scope of computing even the number of times that noise shaping is handled changes, regardless of transform data, all make the change in duty cycle of pulse-width signal, thereby can prevent the noise that causes by insensitive zone.
In addition, in above-mentioned D type amplifier, preferred above-mentioned pulse-width modulation portion, between elementary period, extremely to pass through regulation constantly from beginning to start, or between stopping as above-mentioned given period to startup constantly from regulation between tailend, duty ratio is gradually changed, and this duty ratio is between the high period of above-mentioned pulse-width signal and the ratio between low period.Insensitive zone is corresponding with the value of Wave data and determine, but under the situation that generates fixing Wave data, can be corresponding with the time after the beginning between given period and definite insensitive zone.According to the present invention, because the duty ratio of pulse-width signal is gradually changed, and need not the value of detection waveform data, simplify the structure so can make.
In addition, preferably in above-mentioned D type amplifier, above-mentioned pulse-width modulation portion has: the portion that adds up, and it adds up above-mentioned Wave data and generates cumulative data in each sampling period, value if the value of above-mentioned cumulative data above setting, is then overflowed with above-mentioned cumulative data is reset to 0; And generating unit, it detects and above-mentionedly to add up overflowing of portion and the level of the above-mentioned pulse-width signal in 1 sampling period is set at above-mentioned the 2nd level, in this D type amplifier, take out the above-mentioned pulse-width signal that duty ratio gradually changes from above-mentioned generating unit, this duty ratio is the ratio between high period and between low period.In the case, the Wave data value is more little, and it is long more that then cumulative data overflows the required time, and duty ratio is more little.On the other hand, if the value of Wave data is big more, it is short more that then cumulative data overflows the required time, and duty ratio is big more.Thus, only, just can generate the pulse-width signal corresponding with the value of Wave data by monitoring overflowing of cumulative data.
Description of drawings
Fig. 1 is the block diagram of the summary structure of the related D type amplifier of expression an embodiment of the invention.
Fig. 2 is the figure of generating principle that is used to illustrate the cosine wave generative circuit of this device.
Fig. 3 is the figure that is used to illustrate the waveform of the cosine wave data that generated by this device.
Fig. 4 is the block diagram of configuration example of the cosine wave generative circuit of this device of expression.
Fig. 5 is the block diagram of other configuration examples of the cosine wave generative circuit of this device of expression.
Fig. 6 is the figure that is used to illustrate the operating principle that the noise shaping of this device is handled.
Fig. 7 is the figure that is used to illustrate the operating principle that the noise shaping of this device is handled.
Fig. 8 is the block diagram of noise shaping device of the Lch of this device.
Fig. 9 is the table of each coefficient device coefficient of using of the Lch noise shaping device of this device of expression.
Figure 10 is the figure of operating principle that is used to illustrate the dedicated PWM signal generating unit of this device.
Figure 11 is the block diagram of configuration example of dedicated PWM signal generating unit of the Lch of this device of expression.
Embodiment
Below, with reference to description of drawings preferred implementation of the present invention.In addition, the execution mode of following explanation is that data processing equipment of the present invention is used for execution mode under the situation of D type amplifier, and this D type amplifier amplifies after modulating by the PWM mode as the voice signal of digital signal.In addition, for the parts that are arranged on each passage, the parts of the expression L passage of mark in name of parts (L) (below be also referred to as " Lch "), the parts of the expression R passage of mark in name of parts (R) (below be also referred to as " Rch ").
At first, use Fig. 1 that the structure of the D type amplifier in the present embodiment is described.Fig. 1 is the block diagram of summary structure of the D type amplifier of expression present embodiment.
The D type amplifier 100 of present embodiment has: over-sampling portion 110, and its voice data to the PCM form supplied with from the outside via input terminal 10 (below abbreviate " PCM data " as) carries out over-sampling at each passage and handles; Cosine wave generative circuit 120, it generates cosine wave as data, and the regulation of (below be called " when stopping ") prevented that regularly sonic boom from producing when this cosine wave generative circuit 120 was used for when sending the indication of D type amplifier 100 action beginnings (below be called " during startup ") or sends the indication that action stops; And noise shaping device 130, it carries out noise shaping at each passage and handles.
In addition, this D type amplifier 100 has: the 1st switching part 140, and it is at each passage, and the data of PCM data and cosine wave (below be called " cosine wave data ") are switched to the output of noise shaping device 130; PWM (Pulse Width Modulation) signal generating unit 150, it is pwm signal at each passage with the PCM data conversion; And dedicated PWM signal generating unit 160, it generates pwm signal (below be called " dedicated PWM signal ") of regulation at each passage, is used to prevent when starting or the regulation in when stopping regularly to produce noise.
In addition, this D type amplifier 100 has: drive circuit 170, and it amplifies the signal level of pwm signal or dedicated PWM signal at each passage; The 2nd switching part 180, it switches to the output of drive circuit 170 pwm signal and dedicated PWM signal at each passage; And low pass filter 190, it generates drive signal by pwm signal is carried out low-pass filtering treatment, via the drive signal of lead-out terminal 20 these generations of output.
Over-sampling portion 110 is made of the over-sampling filter of regulation times (for example 4 times), and being used for improving is Qwest's frequency, reduces the quantizing noise grade of the PCM data of input.Specifically, over-sampling portion 110 for example, receives PCM data by 24 Lch that constitute or Rch respectively via input terminal 10 from the outside, to these PCM data that receive with regulation doubly the sample frequency of (for example 4 times) carry out over-sampling and handle.Then, the PCM data (voice data) after this over-sampling portion 110 handles over-sampling export the 1st switching part 140 to from each passage respectively.
Cosine wave generative circuit 120 (data generating unit), under the control of not shown control part, when D type amplifier 100 starts or the regulation in when stopping regularly, generate cosine wave as cosine wave data (Wave data), this cosine wave has the output voltage that is used to control low pass filter 190, the inhibition curve that suppresses sonic boom.Then, this cosine wave generative circuit 120 cosine wave data that will generate respectively as Lch with and Rch with and to 140 outputs of the 1st switching part.In addition, detailed descriptions such as the structure of the cosine wave generative circuit 120 of present embodiment and action thereof, narration below.
To input in the noise shaping device 130 from the data (the PCM data of Lch or Rch or cosine wave data) of the 1st switching part 140 outputs.This noise shaping device 130 is carried out noise shapings and is handled, and is 6 data with 24 data conversions, and wherein, this noise shaping handles that to be used for being reduced in whole be equally distributed quantizing noise in Qwest's frequency band in audio-band.Then, this noise shaping device 130 exports 6 data after the conversion to pwm signal generating unit 150 from each passage respectively.Especially, the noise shaping device 130 of present embodiment is when carrying out the noise shaping processing to the cosine wave data, in order to suppress the quantizing noise that the cosine wave data produce in audio-band, when starting or the regulation in when stopping regularly, with the number of times of the corresponding switching noise rightly of these cosine wave data apparatus for shaping 130.The detailed structure of the noise shaping device 130 of present embodiment and action narration below, wherein, owing in noise shaping is handled, be compressed to 6 with 24, thus produce quantization error.With respect to current sampling, the margin of error is dispensed in the sampling in the future.For example, in 2 noise shapings are handled, in next one sampling and next again 2 samplings of sampling such future, distribute the margin of error.Like this, number of times represents to be used to disperse the number of sampling in the future of quantization error.
Following data are imported the 1st switching part 140 from each passage respectively, that is, and Lch that exports respectively from over-sampling portion 110 or the PCM data of Rch and the cosine wave data that generate by cosine wave generative circuit 120.The 1st switching part 140 under the control of not shown control part, when starting or the regulation in when stopping regularly, switch at the PCM data or the cosine wave data of each passage subtend noise shaping device 130 output.Especially, the 1st switching part 140 of present embodiment, usually to each passage output PCM data separately, under the control of not shown control part, the regulation of following period regularly (below be called " between given period ") select output cosine wave data, be to start to the output voltage of low pass filter 190 from D type amplifier 100 and reach setting (V during above-mentioned
DD/ 2) during (below be called " between elementary period "), perhaps reach from the output voltage of indicating these D type amplifier 100 actions to stop to low pass filter 190 " 0 " during (below be called " between tailend ").In addition, if with the 100 pairs of PCM data of D type amplifier carry out amplify action during as during the action, then be between elementary period be about to during the action of starting before, be in during the action of firm end between tailend after.
Pwm signal generating unit 150, for example constitute by the digital circuit with comparator, decoder and parallel/serial converted circuit etc., carrying out PWM modulation based on the carrier wave of regulation, is the signal (below be called " PWM " signal) of 2 systems with the data-modulated of importing each passage respectively.Then, the data after this pwm signal generating unit 150 is modulated PWM export the drive circuit 170 of each passage respectively to.
On the other hand, dedicated PWM signal generating unit 160, even in order to remove also issuable noise under the situation of carrying out above-mentioned noise shaping processing, and between elementary period, wait regularly, based on the cosine wave data that generate by cosine wave generative circuit 120, generate the pwm signal that is used to drive low pass filter 190 (below be called " dedicated PWM signal ").Then, this dedicated PWM signal generating unit 160 is exported to drive circuit 170 respectively and pass through each passage via the 2nd switching part 180.In addition, the detailed structure and the action of the dedicated PWM signal generating unit 160 of present embodiment, narration in the back.
Following signal is imported the 2nd switching part 180 from each passage respectively, that is, and from the pwm signal of pwm signal generating unit 150 outputs and the dedicated PWM signal that generates by dedicated PWM signal generating unit 160.The 2nd switching part 180 switches to the output of drive circuit 170 pwm signal or dedicated PWM signal at each passage under the control of not shown control part.Especially, the 2nd switching part 180 of present embodiment, usually respectively to each passage output pwm signal, and under the control of not shown control part, between given period, to drive circuit 170 output dedicated PWM signals.
Will be by the pwm signal or the dedicated PWM signal of the 2nd switching part 180 selections, input driving circuit 170.This drive circuit 170 is amplified to specified level with the pwm signal of input, exports the pwm signal after this amplification to low pass filter 190.
Pwm signal after will amplifying by drive circuit 170, input low pass filter 190.Then, the drive signal of 190 pairs of inputs of this low pass filter is carried out high-frequency cut-off and is handled (low-pass filtering treatment) and generate following drive signal, and via lead-out terminal 20 this drive signal is exported to the outside, this drive signal is used to drive the not shown equipment that externally connects such as earphone or loud speaker.In addition,, will import external equipments such as earphone or loud speaker, then make its drive signal sounding based on this input from the drive signal of low pass filter 190 outputs if via lead-out terminal 20.
Below, use Fig. 2 to Fig. 5 that the cosine wave generative circuit 120 and the generating principle thereof of present embodiment are described.In addition, Fig. 2 is the figure of generating principle that is used to illustrate the cosine wave generative circuit 120 of present embodiment, and Fig. 4 is the example of block diagram of the cosine wave generative circuit 120 of present embodiment.In addition, Fig. 3 is the figure of waveform that is used to illustrate the cosine wave data of generation, and Fig. 5 is another example of block diagram of the cosine wave generative circuit 120 of present embodiment.
Usually, because the D class amplification circuit of single-ended format, the value that need make the output voltage of low pass filter is center amplitude current potential (driving voltage V
DD/ 2), so the state that stops from action at this D class amplification circuit (below be called " halted state ") is to the state that starts (below be called " starting state ") or carry out under the situation of state transition to halted state from starting state, need the pwm signal of operation input, the output voltage that makes this low pass filter 190 is from 0[V] to (V
DD/ 2) [V] or from (V
DD/ 2) [V] is to 0[V] change.
But, the D class amplification circuit of above-mentioned single-ended format, for example make its state when halted state is changed to starting state, pwm signal being switched to duty ratio is square wave pulse of 50% etc., adjust the duty ratio (Duty) of square wave, control is under the situation of the pwm signal of low pass filter 190 input, and the output voltage that can make low pass filter 190 is from 0[V] sharply be changed to (V
DD/ 2) [V], and produce noise (so-called sonic boom).This is because the waveform of output voltage has the frequency content of audio-band.
So, the cosine wave generative circuit 120 of present embodiment, be changed to the timing (between elementary period) of starting state or be changed to the timing (between tailend) of halted state from halted state at the state of D type amplifier 100, generate the cosine wave data from starting state.These cosine wave data, the waveform from 0V along cosine wave rises as shown in Figure 2, at moment t
0Its level reaches V
DDAfter/2, keep this level and do not make its decline.Usually, the lower frequency limit of audio-band is 20Hz.Therefore, if be more than or equal to 20Hz, then can hear sonic boom with the frequency setting of cosine wave.
In addition, if the accuracy of waveform of the cosine wave data that generate is lower, then can comprise various high order harmonic component compositions in the waveform of cosine wave data.In addition, the waveform of cosine wave is originally from moment t
0Begin to descend, but, make the waveform of cosine wave data keep V here
DD/ 2.Therefore, its difference can cause distortion.If above-mentioned distortion occurs in audio-band, and its level is bigger, then can export the noise that can hear.Usually, the radio-frequency component of distortion produces with the integral multiple of basic wave, and its multiple is big more, and then level is low more.Thus, if must be low more, then can suppress sonic boom more with the cosine wave frequency setting.On the other hand, reach V from 0V
DD/ 2 time reduces with the cosine wave frequency and prolongs.That is, the inhibition degree of sonic boom and the length between given period are in a kind of relation of mutual restriction.Therefore, in the present embodiment, the user can be 3Hz, 4Hz, 6Hz or 12Hz with the frequency setting of cosine wave, makes cosine wave generative circuit 120 generate the cosine wave data with assigned frequency.Especially, if owing to the frequency setting with cosine wave is the scope of 3Hz～6Hz, then 3 times of high order harmonic component compositions to basic wave are in outside the audio-band, so can suppress sonic boom effectively.
Specifically, the arithmetic unit that the cosine wave generative circuit 120 of present embodiment is used by noise shaping constitutes, and generates the cosine wave that obtains according to the recurrence formula shown in the formula 1 as the cosine wave data.Here, " T " represents the sampling period, and " ω " represents angular frequency, the individual sampling of n (n is the integer more than or equal to 0) of " n " expression cosine wave data.
Here, the recurrence formula shown in the formula 1.
Usually, as implied above, be " T " if make the sampling period, angular frequency is " ω ", then can make " n " individual sampling y[n of cosine wave] and be formula 2, " n+1 " and " n-1 " individual sampling y[n+1 of cosine wave] and y[n-1] by formula 3 expressions.
Y[n]=cos (ω nT) ... (formula 2)
y[n+1]＝cos(ω(n+1)T)
Y[n-1]=cos (ω (n-1) T) ... (formula 3)
In addition,, then become formula 4 if use the addition theorem of trigonometric function to launch this formula 3, if various (formula of " n+1 " and " n-1 " individual sampling y) of calculating formula 4 and, then obtain formula 5.
cos(ω(n+1)T)＝cos(ωnT)cos(ωT)-sin(ωnT)sin(ωT)
Cos (ω (n-1) T)=cos (ω nT) cos (ω T)+sin (ω nT) sin (ω T) ... (formula 4)
Cos (ω (n+1) T)=2cos (ω nT) cos (ω T)-cos (ω (n-1) T) ... (formula 5)
Because in this formula 5, the 2cos (ω T) in the 1st on the right is a constant, so can be by this formula 5 based on " n+1 " individual sampling y[n+1] and " n-1 " individual sampling y[n-1] carry out quadrature summation operation, the cosine wave of production 1.On the other hand, be the waveform shown in Fig. 3 (a) (below, be called " basic waveform ") because the recurrence formula shown in the formula 5 produces, so can't be as the waveform of removing sonic boom.Therefore, the cosine wave generative circuit 120 of present embodiment is for conversion basic waveform shown in Fig. 3 (b), with formula 5 distortion and the waveform shown in the production 1 (below be called " improvement waveform ").
The computing of cosine wave generative circuit 120 execution formulas 5 shown in Figure 4.This cosine wave generative circuit 120 has delay circuit 121-1 and 121-2, adder 122 and 125 and coefficient device 123-1,123-2 and 124.Delay circuit 121-1 and 121-2 have the time-delay of 1 sampling period ω T.Therefore, be n+1 sampling in the dateout of adder 122, promptly during the cos on the left side shown in the formula 5 (ω (n+1) T), the dateout of delay circuit 121-1 is n sampling than n+1 Zao 1 the sampling period ω T of sampling, i.e. cos (ω nT).Because coefficient device 123-1 multiply by constant 2cos (ω T) on the dateout of delay circuit 121-1, so its dateout is 2cos (ω nT) cos (ω T), promptly the right of formula 5 is the 1st.
In addition, because the dateout of delay circuit 121-2 is to make the dateout of delay circuit 121-1 postpone the data of 1 sampling period ω T, be cos (ω (n-1) T) therefore.Because coefficient device 123-2 multiply by coefficient " 1 " with these data, thus its dateout be-cos (ω (n-1) T), consistent with the 2nd on the right of formula 5.Thus, the dateout of adder 122 as mentioned above, and is consistent with the left side of formula 5.Then, owing to multiply by coefficient-0.5 by coefficient device 124, so its dateout is-cos (ω (n+1) T)/2.Because adder 125 adds-0.5 on this dateout, so the dateout of adder 125 is consistent with the left side of formula 1.
In addition, the cosine wave generative circuit 120 of present embodiment is realized its structure according to block diagram shown in Figure 4, but also can be as shown in Figure 5, from β point signal output waveform, rather than exports from the α point.In the case, cosine wave generative circuit 120 is carried out the computing of the recurrence formula that satisfies formula 6.When carrying out computing, need to set initial value according to recurrence formula.Cosine wave generative circuit 120 shown in Figure 5 by read the 1st data and the 2nd data from the memory of storing initial value, with they dateouts as delay circuit 121-1 and 121-2, and generates the 3rd data.For this reason, in side circuit, between adder 122 and coefficient device 124, need selection portion be set, be used to select the dateout of output adder 122 and from the data of memory at outlet side.But cosine wave generative circuit 120 shown in Figure 5 as long as will use as the dateout of delay circuit 121-1 and 121-2 from the 1st data and the 2nd data of memory, has the advantage that can omit selection portion.
Below, use Fig. 6 to Fig. 9 that the noise shaping device 130 and the operating principle thereof of present embodiment are described.Fig. 6 and Fig. 7 are the figure that is used to illustrate the operating principle that the noise shaping of present embodiment is handled, and Fig. 8 is the block diagram of the noise shaping device 130 (L) of expression present embodiment.In addition, Fig. 9 is the table of each coefficient device coefficient of using of the noise shaping device 130 (L) of expression present embodiment.
Usually, it is that data conversion with n (n is a natural number) position is the data of m (m is for satisfying the natural number of n＞m) position that noise shaping is handled, and is equally distributed quantizing noise in Qwest's frequency band integral body to reduce in audio-band.For example, pwm signal (64 grades pwm signals) by 6 situations about constituting under, shown in Fig. 6 (a), because from 0[V] to (V
DD/ 2) output voltage of the low pass filter of [V] is only stipulated with 32 rank, so when quantizing, can produce noise as quantizing noise in audio-band.Therefore, in order in the data of inputs such as PCM data, to reduce this quantizing noise, must carry out noise shaping and handle.Thus, the distribution of quantizing noise can be transferred to outside the audio-band.
On the other hand, if, then can cause shape information to lose, thereby in audio-band, produce noise contribution owing in the computing that noise shaping is handled, underflow or overflow take place.To be called insensitive zone by the scope that above-mentioned calculation process causes losing the signal level of shape information.Shown in Fig. 6 (b), handle if the data of input such as PCM data are carried out noise shaping, then the output voltage at low pass filter is 0[V] near insensitive zone in, the generation underflow, meeting generted noise in audio-band, and can't bring into play the effect that noise shaping is handled.
Fig. 7 (a) expression characteristic that noise shaping is handled from 1 time to 4 times (below, be also referred to as " noise shaping characteristic ").As shown in the drawing, by improving the number of times that this shaping is handled, can disperse quantizing noise, reduce the low-frequency noise grade in the signal component.But insensitive zone is then along with the number of times that noise shaping is handled increases and enlarges.This be because, number of times is high more as described later, the coefficient that multiplies each other with quantization error is big more.
So the noise shaping device 130 of present embodiment constitutes, between given period, at the 0[V of cosine wave] near switch successively and carry out the number of times of noise shaping when handling, the scope in insensitive zone is suppressed to be irreducible minimum, thereby prevents that noise from taking place.More particularly, the noise shaping device 130 of present embodiment is between elementary period, shown in Fig. 7 (b), from the waveform rising of cosine wave data, the number of times that noise shaping is handled switches to 2 times, 3 times and 4 times successively, suppress radio-frequency component, eliminate the generation in insensitive zone.
The noise shaping device 130 of present embodiment as shown in Figure 8, has: quantizer 131, its data-measuring with 24 are 6 data; And subtracter 132, it deducts 6 dateout from 24 input data that input to quantizer 131, generate the error information of expression quantization error.
In addition, this noise shaping device 130 has: (133-1～133-4), they give the time-delay in 1 sampling period respectively to a plurality of delay circuits to error information; (134-1～134-4), they have the coefficient of regulation to a plurality of coefficient devices 134, will multiply by this coefficient from the data of each delay circuit 133 output; And a plurality of adders 135 (135-1～135-4), they will postpone the error information in 1 sampling period and the data addition of input successively respectively, this noise shaping device 130 switches the coefficient of each coefficient device 134 with predetermined timing or based on the value of Wave data of input.
For example, the noise shaping device 130 of present embodiment as shown in Figure 9, according to 2 times, 3 times and 4 times, based on the value of the Wave data of predetermined timing or input, switches the value of coefficient C0, C1, C2 and the C3 of each coefficient device between elementary period.For coefficient C1, C1=-1 when number of times is 2 times, C1=-3 in the time of 3 times, in the time of 4 times C1=-6 like this, number of times is high more, then the absolute value of coefficient C1 is big more.Therefore, shown in Fig. 7 (b), number of times is high more, and then the amplitude with the error information of original cosine wave data stack is big more.In the figure, the border that switches to 3 times from 4 times is the upper limit in 4 insensitive zones, and the border that switches to 2 times from 3 times is the upper limit in 3 insensitive zones, and the border that switches to the dedicated PWM signal from 2 times is the upper limit in 2 insensitive zones.Owing to as the above-mentioned number of times of handling in the switching noise shaping of the upper limit place in insensitive zone, so can suppress simultaneously to lose and noise that produces in audio-band and the noise that produces along with quantification by shape information.
In addition, the noise shaping device 130 of present embodiment, between tailend in, descending from the cosine wave data begins to carry out 4 noise shapings and handles, and suitably number of times is switched to 3 times, 2 times, 1 time simultaneously and carries out this noise shaping and handle.In addition, Fig. 8 and noise shaping device 130 shown in Figure 9, only be a side passage, be the structure of the noise shaping device 130 (L) of Lch, the noise shaping device 130 (R) of opposite side passage (Rch) also has identical structure.
Below, use Figure 10 and Figure 11 that the dedicated PWM signal generating unit 160 and the operating principle thereof of present embodiment are described.In addition, Figure 10 is the figure of operating principle that is used to illustrate the dedicated PWM signal generating unit 160 of present embodiment, and Figure 11 is the example of block diagram of the dedicated PWM signal generating unit 160 (L) of present embodiment.
Usually, definite method of the output voltage of low pass filter 190 is: if the driving voltage of this low pass filter 190 is made as V
DD, be made as t between the high period of pwm signal
On, and be made as t between the low period of this pwm signal
Off, the output voltage (V of low pass filter 190 then
Out) as shown in Equation 7, according to during t
OnWith during t
OffRatio and determine.
Thus, (t between low period
Off) and high period between (t
On) compare under the very large situation output voltage (V of low pass filter 190
Out) be very little level.In addition, if (t between low period
Off) shorten gradually, then duty ratio increases gradually.For example, if make (t between high period
On) constant, from (t between the low period shown in Figure 10 (a)
Off) be changed to (t between the low period shown in Figure 10 (b)
Off), then can make the output voltage (V of low pass filter 190
Out) rise gradually, that is, and the processing of carrying out Yu carrier frequency variation being equal to.
So, the dedicated PWM signal generating unit 160 of present embodiment, between elementary period from beginning to start to through regulation (moment of 2 times noise shaping is handled underflow taking place also) constantly, or between tailend, stop from regulation (moment of 2 times noise shaping is handled underflow taking place also) to startup constantly, generate the dedicated PWM signal that duty ratio and cosine wave data interlock change.The 2nd switching part 180 replaces the pwm signal by 130 outputs of noise shaping device in this period, and the dedicated PWM signal is exported to drive circuit 170 and low pass filter 190.
Specifically, the dedicated PWM signal generating unit 160 of present embodiment, shown in Figure 11 (a), be benchmark with the sampling period, (for example with the cosine wave data, in value is the high 13 of timing) addition, under the situation that this additive value overflows, generate dedicated PWM signal with regulation pulsewidth (minimum pulse width), replace pwm signal generating unit 150, and with the pwm signal that generates as the dedicated PWM signal, via the 2nd switching part 180 to drive circuit 170 and low pass filter 190 outputs.
For example, the dedicated PWM signal generating unit 160 of present embodiment shown in Figure 11 (b), is made of following part: input handling part 161, and its execution input is handled, and is used for the figure place of cosine wave data shaping for stipulating that will import; A plurality of delay circuits 162, they have the time-delay in 1 sampling period; Comparator 163, it will be worth high 13 bit data for positive cosine wave data (below abbreviate " bit data " as) and fiducial value Dref relatively, to export; Adder 164, its each sampling period with the bit data addition; Detection unit 165, it overflows judgement; And generating unit 166, it is based on the result of determination of detection unit 165 and generate the dedicated PWM signal.In addition, a plurality of delay circuits 162 also can be by the D circuits for triggering formation that for example latchs (latch) action by sampled clock signal.
From cosine wave generative circuit 120, make 24 cosine wave data input to input handling part 161, to give up for low 11 of 24 the data that this input handling part 161 will be imported, output is by expression positive and negative sign bit and high 12 bit data of 13 that constitute.
Comparator 163 will by 13 bit data after input handling part 161 shapings and fiducial value Dref relatively when bit data is less than or equal to fiducial value Dref, be exported " 0 ", during greater than fiducial value Dref, exports this bit data in bit data.
Dateout to comparator 163 adds up adder 164 in each sampling period, exports the value that adds up to detection unit 165.In addition, this adder 164 in the case of overflow, resets value, and begins the value from comparator 163 outputs is added up from " 0 " once more.Detection unit 165 judges whether the bit data after the addition overflows in each sampling period, that is, under 13 situation, on the 14th, whether produce carry (whether the 14th become " 1 "), in the case of overflow, generate the dedicated PWM signal to generating unit 166 indications.Generating unit 166 under the situation of the generation indication of having imported the dedicated PWM signal from detection unit 165, generates the pwm signal of regulation pulsewidth, for example has the dedicated PWM signal of minimum pulse width, and to 180 outputs of the 2nd switching part.
In said structure, if bit data greater than fiducial value Dref, just can begin to generate the dedicated PWM signal, be less than or equal in bit data under the situation of fiducial value Dref, then can not generate the dedicated PWM signal.If this is because the duty ratio of dedicated PWM signal is very low, then be heard as noise sometimes.So, when just beginning to generate the cosine wave data, under the very little situation of the value of bit data, stop the generation of dedicated PWM signal and prevent to produce noise.Here, fiducial value Dref is set at following value, that is, under with its situation as the output of dedicated PWM signal, can not be heard as noise.
In addition, in above-mentioned dedicated PWM signal generating unit 160, adder 164 and delay circuit 162-3, work as following unit, promptly, in each sampling period, Wave data is added up and generate cumulative data,, then overflow and the value of cumulative data is reset to 0 if the value of cumulative data surpasses setting.Detection unit 165 and generating unit 166 are overflowed as detection and the unit that the level of the PWM modulation signal in 1 sampling period is set at high level are worked.
In addition, the D type amplifier 100 of present embodiment is because between tailend, the bit data that inputs in the cosine wave data of dedicated PWM signal generating unit 160 reduces gradually, so have (t between the high period of Rack
On) spacing elongated, can make output voltage (V
Out) descend gradually.In addition, dedicated PWM signal generating unit 160 shown in Figure 11 only is the structure of the dedicated PWM signal generating unit 160 (L) of the passage of a side, for example Lch, and the dedicated PWM signal generating unit 160 (R) of opposite side passage also has identical structure.
As mentioned above, the D type amplifier 100 of present embodiment, output voltage rises to the center voltage (V of output voltage from level "0" when starting
DD/ 2) under the situation, perhaps when stopping output voltage from center voltage (V
DD/ 2) drop under the situation of level "0", can generate pwm signal based on the cosine wave data that level changes.Its result, D type amplifier 100, when the output voltage of control low pass filter 190, by use have the n position of the frequency content outside the audio-band Wave data, be the Wave data of digital waveform, can control the output voltage of low pass filter 190, and Wave data self also is made of the frequency content outside the audio-band.
Its result, the D type amplifier 100 of present embodiment, owing to can be suppressed at when starting or when stopping, the noise that produces along with rapid variation of output voltage of output circuit, by using digital waveform, can prevent sonic boom with simple structure, and can easily set or change waveform simultaneously, so can reduce and reduce manufacturing cost based on miniaturization or number of components, the flexibility when realizing improving operability and constructing system based on the easiness of wave setting and adjustment.
In addition, D type amplifier 100, because by generating cosine waveform according to recurrence formula, can be easily and generate this Wave data with the waveform of low distortion, so also can get rid of the principal element that produces noise by the waveform self of this Wave data.In addition, D type amplifier 100, by data value or time from beginning between given period based on Wave data, the number of times that the switching noise shaping is handled, thereby with this Wave data under the situation of low pass filter 190 output, the output voltage that can prevent to cause this low pass filter 190 by insensitive zone is for negative, and at 0[V] near the generation noise.
Claims (9)
1. D type amplifier, it exports the output voltage of the 1st level and these two values of the 2nd level,
It is characterized in that having:
The data generating unit, its sampling period with regulation generates the Wave data of n position, this Wave data is expressed as follows waveform, promptly, between the elementary period before will being about to begin to amplify action or just finished to amplify between tailend after the action at least one as given period between, with the level at the center of above-mentioned the 1st level and above-mentioned the 2nd level during as centered level, in between above-mentioned given period, the waveform that level gradually changes between above-mentioned the 1st level and above-mentioned centered level, wherein, said n is a natural number;
Selection portion, it is supplied to voice data and above-mentioned Wave data that above-mentioned centered level is the amplitude center, and this selection portion is selected above-mentioned Wave data between above-mentioned given period, select tut data, the line output of going forward side by side during carrying out the action of amplifying action;
Noise remove portion, it receives the above-mentioned Wave data of selecting from above-mentioned selection portion, above-mentioned Wave data is applied noise shaping handle and the transform data of generation m position, and wherein, above-mentioned m is for satisfying the natural number of n＞m;
Pulse-width modulation portion, it carries out pulse-width modulation and generates pulse-width signal above-mentioned transform data; And
Efferent, it amplifies above-mentioned pulse-width signal with single-ended format, exports above-mentioned output voltage,
Above-mentioned data generating unit generates this Wave data in the following manner, that is, the feasible fundamental frequency that constitutes the waveform of above-mentioned Wave data is in outside the audio-band.
2. D type amplifier according to claim 1 is characterized in that,
The waveform that constitutes above-mentioned Wave data is a cosine waveform,
Above-mentioned data generating unit, recurrence formula according to the rules generates above-mentioned Wave data.
3. D type amplifier according to claim 1 is characterized in that,
Above-mentioned noise remove portion, corresponding with the value of above-mentioned Wave data and change the number of times that above-mentioned noise shaping is handled, so that in above-mentioned noise shaping is handled, in insensitive zone, do not carry out computing.
4. D type amplifier according to claim 1 is characterized in that,
Above-mentioned noise remove portion, corresponding with the time after the beginning between above-mentioned given period and change the number of times of above-mentioned noise shaping processing, so that in above-mentioned noise shaping processing, in insensitive zone, do not carry out computing.
5. D type amplifier according to claim 3 is characterized in that,
Above-mentioned pulse-width modulation portion does not reach under the situation of setting as yet in the value of above-mentioned Wave data, and duty ratio is gradually changed, and this duty ratio is between the high period of above-mentioned pulse-width signal and the ratio between low period.
6. D type amplifier according to claim 3 is characterized in that,
Above-mentioned pulse-width modulation portion, between elementary period, extremely to pass through regulation constantly from beginning to start, or between tailend from regulation constantly to start stop as above-mentioned given period between, duty ratio is gradually changed, this duty ratio is between the high period of above-mentioned pulse-width signal and the ratio between low period.
7. D type amplifier according to claim 4 is characterized in that,
Above-mentioned pulse-width modulation portion does not reach under the situation of setting as yet in the value of above-mentioned Wave data, and duty ratio is gradually changed, and this duty ratio is between the high period of above-mentioned pulse-width signal and the ratio between low period.
8. D type amplifier according to claim 4 is characterized in that,
Above-mentioned pulse-width modulation portion, between elementary period, extremely to pass through regulation constantly from beginning to start, or between tailend from regulation constantly to start stop as above-mentioned given period between, duty ratio is gradually changed, this duty ratio is between the high period of above-mentioned pulse-width signal and the ratio between low period.
9. according to any described D type amplifier in the claim 5 to 8, it is characterized in that,
Above-mentioned pulse-width modulation portion has:
The portion that adds up, it adds up above-mentioned Wave data and generates cumulative data in each sampling period, if the value of above-mentioned cumulative data surpasses setting, then overflow and the value of above-mentioned cumulative data is reset to 0; And
Generating unit, it detects and above-mentionedly to add up overflowing of portion and the level of the above-mentioned pulse-width signal in 1 sampling period is set at above-mentioned the 2nd level,
Take out the above-mentioned pulse-width signal that duty ratio gradually changes from above-mentioned generating unit, this duty ratio is the ratio between high period and between low period.
Applications Claiming Priority (3)
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|---|---|---|---|
| JP2006309485A JP4311437B2 (en) | 2006-11-15 | 2006-11-15 | Class D amplifier |
| JP2006309485 | 2006-11-15 | ||
| JP2006-309485 | 2006-11-15 |
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| Publication Number | Publication Date |
|---|---|
| CN101183855A CN101183855A (en) | 2008-05-21 |
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| KR20100008749A (en) * | 2008-07-16 | 2010-01-26 | 삼성전자주식회사 | Switching power amplifier and control method thereof |
| US20110007912A1 (en) * | 2009-07-07 | 2011-01-13 | Mediatek Singapore Pte. Ltd. | Double integral method of powering up or down a speaker |
| CN102291645B (en) * | 2011-06-29 | 2013-12-18 | 北京时代民芯科技有限公司 | Explodent elimination circuit |
| CN105974997B (en) * | 2016-04-29 | 2018-08-14 | 洛阳理工学院 | A kind of Digital Implementation method of sine wave signal |
| CN111164896A (en) * | 2017-09-29 | 2020-05-15 | 国立大学法人名古屋工业大学 | Re-quantization device with noise shaping function, signal compression device with noise shaping function, and signal transmission device with noise shaping function |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001223536A (en) * | 2000-02-14 | 2001-08-17 | Rohm Co Ltd | Mute circuit and digital audio amplifier circuit |
| JP2005217583A (en) * | 2004-01-28 | 2005-08-11 | Renesas Technology Corp | Switching amplifier |
| JP2005348288A (en) * | 2004-06-07 | 2005-12-15 | Alpine Electronics Inc | Digital amplifier |
| CN1835394A (en) * | 2005-03-18 | 2006-09-20 | 雅马哈株式会社 | Class-D amplifier |
| CN1835395A (en) * | 2005-03-18 | 2006-09-20 | 雅马哈株式会社 | Class-D amplifier |
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| JP4078543B2 (en) * | 2002-12-20 | 2008-04-23 | ソニー株式会社 | Audio amplifier |
| JP4326933B2 (en) * | 2002-12-27 | 2009-09-09 | 株式会社ルネサステクノロジ | Digital amplifier |
| JP4306428B2 (en) | 2003-11-27 | 2009-08-05 | ヤマハ株式会社 | Pop noise reduction circuit |
| JP4568572B2 (en) * | 2004-10-07 | 2010-10-27 | ローム株式会社 | Audio signal output circuit and electronic device for generating audio output |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001223536A (en) * | 2000-02-14 | 2001-08-17 | Rohm Co Ltd | Mute circuit and digital audio amplifier circuit |
| JP2005217583A (en) * | 2004-01-28 | 2005-08-11 | Renesas Technology Corp | Switching amplifier |
| JP2005348288A (en) * | 2004-06-07 | 2005-12-15 | Alpine Electronics Inc | Digital amplifier |
| CN1835394A (en) * | 2005-03-18 | 2006-09-20 | 雅马哈株式会社 | Class-D amplifier |
| CN1835395A (en) * | 2005-03-18 | 2006-09-20 | 雅马哈株式会社 | Class-D amplifier |
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| KR100941797B1 (en) | 2010-02-10 |
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