CN104201997B - A kind of D audio frequency amplifier - Google Patents
A kind of D audio frequency amplifier Download PDFInfo
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- CN104201997B CN104201997B CN201410440955.9A CN201410440955A CN104201997B CN 104201997 B CN104201997 B CN 104201997B CN 201410440955 A CN201410440955 A CN 201410440955A CN 104201997 B CN104201997 B CN 104201997B
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Abstract
The application provides a kind of D audio frequency amplifier, including carrier generating circuit, driving stream generation circuit, pseudo-random signal generation circuit and clock generating circuit.One group of pseudo-random signal is produced by pseudo-random signal generation circuit, and the carrier signal of frequency pseudorandom change is produced according to the pseudo-random signal so that the signal that the pwm signal obtained by the carrier signal also changes for a frequency pseudorandom.Meanwhile the driving current of size pseudorandom change is produced always according to the pseudo-random signal.The pwm signal of frequency pseudorandom change and the driving current of size pseudorandom change cause the switching frequency of power switch pipe to change within the specific limits, and the opening time of switching tube and turn-off time change in the range of first, so as to break up the spectrum energy at switching frequency and its frequency multiplication, reduce peak energy so that D audio frequency amplifier is respectively provided with preferable EMI rejections in low-frequency range and high band.
Description
Technical field
The present invention relates to electric and electronic technical field, more particularly to a kind of D audio frequency amplifier.
Background technology
The advantages of Class D audio-frequency amplifiers are due to high efficiency, low-power consumption, is increasingly used in such as
In the portable sets such as PDA, mobile phone, MP3.
In traditional D audio frequency amplifier, the carrier signal by audio input signal and high frequency fixed frequency is first passed through
Compare the pwm signal to form fixed frequency, then the pwm signal of the fixed frequency of formation is carried out by the MOSFET of high-voltage power
Amplification, the pwm signal after amplification remove carrier frequency by low pass filter again, can recover original base-band audio signal.
Although this traditional D audio frequency amplifier is with higher operating efficiency, however, the switch by its power device
Frequency fixes (frequency of the pwm signal of control power device on off state is fixed), causes the energy in frequency to concentrate on switch
At frequency and its frequency multiplication, substantial amounts of radiation EMI (electromagnetic interference) can be produced, have impact on EMI performances.Further, since for controlling
The driving current of power device switching speed is relatively fixed, i.e. the opening time of power device and the turn-off time is relatively fixed, and makes
In frequency spectrum, there is peak value in corresponding Frequency point, and this EMI performance to high frequency radiation also has large effect.
The content of the invention
In view of this, the present invention provides a kind of D audio frequency amplifier, to solve D audio frequency amplifier of the prior art
Due to switching frequency fix and switching rate is fixed and caused by EMI rejections cannot improve the problem of.
A kind of D audio frequency amplifier, including carrier generating circuit, driving current generation circuit, pseudo-random signal produce electricity
Road and clock generating circuit；
The carrier signal that the clock generating circuit exports according to the carrier generating circuit produces clock signal；
The pseudo-random signal generation circuit produces pseudo-random signal according to the clock signal；
The carrier generating circuit produces the carrier signal according to the pseudo-random signal and the clock signal, described
The frequency pseudorandom change of carrier signal；
The driving current generation circuit produces the driving current of size pseudorandom change according to the pseudo-random signal.
Preferably, the clock generating circuit includes a first comparator and a reference voltage source；
The input of the first comparator receives the benchmark of the carrier signal and reference voltage source output respectively
Voltage signal, output end export the clock signal.
Preferably, the pseudo-random signal generation circuit is made up of for one n shift register and XOR feedback circuit
M-sequence generation circuit, n is natural number；
The n shift registers are sequentially connected in series, and the input of first shift register and XOR feedback electricity
Road output end is connected, and the Clock control end of each shift register receives the clock signal, with according to it is described when
Clock signal produces an elemental signals；
The XOR feedback circuit comprises at least an XOR gate, and each input of the XOR gate receives an institute
Elemental signals are stated, make the n elemental signals composition m-sequences of the n shift register output, the n elemental signals
The m-sequence of composition is as the pseudo-random signal.
Preferably, the carrier generating circuit includes the first Pseudo-random Current generation circuit, the first current source, discharge and recharge electricity
Hold and charge and discharge control switch,
It is what pseudorandom changed that the first Pseudo-random Current generation circuit produces a size according to the pseudo-random signal
First Pseudo-random Current；
The output current of first current source is the first electric current of predetermined value；
The charge and discharge control switch carries out turn-on and turn-off according to the clock signal；
First Pseudo-random Current and first electric current are superimposed to form charging and discharging currents, when the charge and discharge control is opened
During shut-off, the charging and discharging currents charge to the charge and discharge capacitance, described to fill when the charge and discharge control switch conduction
Discharge current charges to the charge and discharge capacitance, and the voltage signal on the charge and discharge capacitance is the carrier signal.
Preferably, the first Pseudo-random Current generation circuit includes j the first Pseudo-random Current branch road in parallel, and j is
Natural number less than or equal to n；
Each described first Pseudo-random Current branch route the elemental signals control output or not defeated one first
Branch current, the tie point electric current of output are superimposed to form first Pseudo-random Current.
Preferably, the first Pseudo-random Current branch road includes the first output control switch and tie point current source, institute
The output current for stating tie point electric current is the tie point electric current, and first output control switch is according to a member
Plain signal carries out turn-on and turn-off；
When first output control switch turns on, the tie point electric current is output to first Pseudo-random Current
The output end of branch road, when first output control switch turns off, it is pseudo- that the tie point electric current is not output to described first
The output end of random current branch road.
Preferably, the driving current generation circuit includes the second Pseudo-random Current generation circuit and the second current source；
The second Pseudo-random Current generation circuit according to the pseudo-random signal produce size be pseudorandom change the
Two Pseudo-random Currents；
The output current of second current source is the second electric current of predetermined value；
Second Pseudo-random Current and second electric current are superimposed to form the driving current.
Preferably, the second pseudo-random signal current generating circuit includes i the second Pseudo-random Current branch road in parallel,
I is the natural number less than or equal to n；
Each described second Pseudo-random Current branch route the elemental signals control output or not defeated one second
Branch current, second branch current of output are superimposed to form second Pseudo-random Current.
Preferably, the second Pseudo-random Current branch road includes the second output control switch and the second branch current source, institute
The output current for stating the second branch current is second branch current, and second output control switch is according to a member
Plain signal carries out turn-on and turn-off；
When second output control switch turns on, second branch current is output to second Pseudo-random Current
The output end of branch road, when second output control switch turns off, it is pseudo- that second branch current is not output to described second
The output end of random current branch road.
Preferably, the D audio frequency amplifier also includes comparator circuit, drive circuit and output-stage circuit；
The comparator circuit is used to compare an input signal and the carrier signal, and output pulse width modulation letter
Number；
The drive circuit is used to receive the pulse width modulating signal and driving current, and output switch control letter
Number；
The output-stage circuit is used to export an output voltage according to the switch controlling signal.
Therefore D audio frequency amplifier disclosed in this invention produces pseudorandom by pseudo-random signal generation circuit
Signal, and carrier generating circuit is controlled according to the pseudo-random signal so that carrier generating circuit produces a frequency pseudorandom
The carrier signal of change, so that being compared with the carrier signal and an input signal, the pwm signal of output is also pseudo- for a frequency
The signal changed at random.Meanwhile driving current generation circuit is controlled always according to the pseudo-random signal, its is exported a size
The driving current of pseudorandom change.Last drive circuit receives the pwm signal changed according to frequency pseudorandom and size pseudorandom
The driving current of change, to drive the power switch pipe in output-stage circuit so that the switching frequency of power switch pipe is certain
In the range of change, and the opening time of switching tube and turn-off time change in the range of first, i.e., switching rate is in certain model
Interior change is enclosed, so as to break up the spectrum energy at switching frequency and its frequency multiplication, reduces peak energy.Therefore, institute of the present invention
Disclosed D audio frequency amplifier is respectively provided with preferable EMI rejections in low-frequency range and high band.
Brief description of the drawings
In order to illustrate more clearly about the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing
There is the required accompanying drawing used in technology description to be briefly described, it should be apparent that, drawings in the following description are only this
The embodiment of invention, for those of ordinary skill in the art, on the premise of not paying creative work, can also basis
The accompanying drawing of offer obtains other accompanying drawings.
Fig. 1 is a kind of structured flowchart of D audio frequency amplifier disclosed in the embodiment of the present application；
Fig. 2 is the frequency spectrum and the frequency of traditional D audio frequency amplifier of the D audio frequency amplifier disclosed in the embodiment of the present application
The comparison diagram of spectrum；
Fig. 3 is that the circuit of an optional mode of the clock generating circuit in the D audio frequency amplifier shown in Fig. 1 shows
It is intended to；
Fig. 4 is the circuit of an optional mode of the pseudo-random signal generation circuit in the D audio frequency amplifier shown in Fig. 1
Schematic diagram.
Fig. 5 is the circuit signal of an optional mode of the carrier generating circuit in the D audio frequency amplifier shown in Fig. 1
Figure；
Fig. 6 is that the circuit of an optional mode of the drive circuit generation circuit in the D audio frequency amplifier shown in Fig. 1 shows
It is intended to；
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is carried out clear, complete
Site preparation describes, it is clear that described embodiment is only part of the embodiment of the present invention, rather than whole embodiments.It is based on
Embodiment in the present invention, those of ordinary skill in the art are obtained every other under the premise of creative work is not made
Embodiment, belong to the scope of protection of the invention.
Fig. 1 is a kind of structured flowchart of D audio frequency amplifier disclosed in the embodiment of the present application.
Refer to Fig. 1, D audio frequency amplifier disclosed in the embodiment of the present application include clock generating circuit 01, it is pseudo- with
Machine signal generating circuit 02, carrier generating circuit 03 and driving current generation circuit 04.
The carrier signal V that the clock generating circuit 01 exports according to the carrier generating circuit 03tri, with output
One clock signal clk；
The pseudo-random signal generation circuit 02 produces pseudo-random signal Q according to the clock signal clk1…Qn, n is certainly
So number, wherein pseudo-random signal Q1…QnIt can be the m-sequence that the length being made up of n elemental signals is n；
The carrier generating circuit 03 is according to the pseudo-random signal Q1…QnAnd the clock signal produces the carrier wave letter
Number Vtri, the carrier signal VtriThe change of frequency pseudorandom, if such as the pseudo-random signal to be made up of n elemental signals
Length when being n m-sequence, the carrier generating circuit 03 can be according to n elemental signals for forming the pseudo-random signal
In at least elemental signals produce the carrier signal；
The driving current generation circuit 04 is according to the pseudo-random signal Q1…QnProduce the drive of size pseudorandom change
Streaming current IGIf such as the pseudo-random signal, when being the m-sequence that the length that is made up of n elemental signals is n, the driving is electric
Flowing generation circuit 04 can produce according at least a portion elemental signals in n elemental signals for forming the pseudo-random signal
The driving current.
D audio frequency amplifier disclosed in the present embodiment also includes comparator circuit 05, drive circuit 06 and output stage electricity
Road 07；
Comparator circuit 05 includes a comparator, and the comparator is used to compare an input signal Vin(such as audio input is believed
Number) and the carrier signal Vtri, and output pulse width modulated signal pwm signal；
Drive circuit 06 receives the pwm signal and the driving current IG, and output switch control signal VG；
The output-stage circuit 07 includes power switch pipe, and the power switch pipe is by switch controlling signal VGControl is carried out
Switch motion so that the output-stage circuit exports an output voltage.Wherein, the power switch pipe can be opened including a power
Close pipe and the second power switch pipe, then the switch controlling signal include control first switch pipe first switch control signal and
Control the second switch control signal of second switch pipe.
In the D audio frequency amplifier disclosed in the embodiment of the present application, puppet is produced by pseudo-random signal generation circuit 02
Random signal Q1…Qn, then according to pseudo-random signal Q1…QnTo control carrier generating circuit 03 so that carrier generating circuit 03
Caused carrier signal VtriFor the signal of a frequency pseudorandom change, the carrier signal is that triangular signal or sawtooth waveforms are believed
Number, the pseudo-random signal is used for the frequency for controlling the carrier signal, is allowed to pseudorandom change, such carrier signal is led to
After comparator circuit 05 is crossed compared with the input signal of such as audio signal, the frequency of caused pwm signal is also pseudo-
Change at random, then the pwm signal that drive circuit 06 changes according to frequency pseudorandom is produced for controlling in output-stage circuit 07
The switching signal V of switching tubeGFrequency also change immediately, i.e., the switching tube in output-stage circuit 07 switching frequency pseudorandom become
Change, so as to be broken up the energy at switching frequency and its frequency multiplication, can effectively improve the EMI rejections of low-frequency range.Together
When, always according to pseudo-random signal Q1…QnTo control driving current generation circuit 04, it is set to export what a size pseudorandom changed
Driving current IG, i.e., the driving force of drive circuit 06 is controlled by one group of pseudo-random signal, so as to change output-stage circuit
The switching speed of switching tube in 07, even if the opening time and turn-off time of the switching tube are no longer as traditional D class audio frequencies are put
Keep fixed like that in big device, but pseudorandom changes in certain scope so that the spectrum energy in the range of being somebody's turn to do uniformly divides
Cloth, the peak energy of respective frequencies point is reduced, can effectively improve the EMI rejections of high band.
Fig. 2 is the frequency spectrum and the frequency of traditional D audio frequency amplifier of the D audio frequency amplifier disclosed in the embodiment of the present application
The comparison diagram of spectrum, dotted portion represents traditional switching frequency f in figuresThe D audio frequency amplifier that fixed and switching rate is fixed
Frequency spectrum, bold portion represents the frequency spectrum of the D audio frequency amplifier disclosed in the embodiment of the present application.It can be seen that pass
The switching frequency f of the D audio frequency amplifier of systemsAnd its energy at frequency multiplication is concentrated and peak value is larger, easy radiation EMI, and this
Apply the switching frequency of disclosed D audio frequency amplifier described in embodiment in fs1~fs2Pseudorandom changes and opened in the range of this
Closing speed, also pseudorandom changes so that energy is broken up and is uniformly distributed in the range of this, and energy peak reduces.
Fig. 3 is that the circuit of an optional mode of the clock generating circuit in the D audio frequency amplifier shown in Fig. 1 shows
It is intended to.
Fig. 3 is refer to, clock generating circuit includes a first comparator 011 and a reference voltage source 012.
Two inputs of first comparator 011 receive the load of the frequency pseudorandom change of carrier generating circuit output respectively
Ripple signal VtriWith the output voltage signal V of reference voltage sourceref, it is compared by the signal received to the two inputs,
To export a clock signal clk in output end, due to the carrier signal that an input signal of input is the change of frequency pseudorandom
Vtri, another input signal is the voltage signal of steady state value, then by clock generating circuit as shown in Figure 3 export when
Clock signal CLK is also the signal of frequency pseudorandom change.
Fig. 4 is the circuit of an optional mode of the pseudo-random signal generation circuit in the D audio frequency amplifier shown in Fig. 1
Schematic diagram.
Fig. 4 is refer to, pseudo-random signal generation circuit is one by n shift register 021 and XOR feedback circuit 022
The m-sequence generation circuit of composition, n are natural number.
As shown in figure 4, in an optional mode, n shift register 021 is respectively d type flip flop D1、D2…Dn, n
Shift register D1、D2…DnIt is sequentially connected in series, the output end of previous shift register and the input of the latter shift register
Be connected, i.e. d type flip flop Dh-1Output end and d type flip flop DhInput be connected, 2≤h≤n, and each shift register
Clock control end receives clock signal clk caused by clock generating circuit 01, to be produced according to the clock signal clk
An elemental signals are given birth to, then n elemental signals Q of n shift register output1…Qn；
The XOR feedback circuit 022 comprises at least an XOR gate NOR, each input of the XOR gate NOR
Receive an elemental signals Qw, 1≤w≤n, so that the n elemental signals Q of the n shift register 021 output1…Qn
Form m-sequence, the n elemental signals Q1…QnThe m-sequence of composition is as the pseudo-random signal.
Fig. 5 is the circuit signal of an optional mode of the carrier generating circuit in the D audio frequency amplifier shown in Fig. 1
Figure.
Fig. 5 is refer to, carrier generating circuit includes the first Pseudo-random Current generation circuit 031, the first current source 032, filled
Discharge capacity 033 and charge and discharge control switch 034.
Caused pseudorandom described in pseudo-random signal circuit of the first Pseudo-random Current generation circuit 011 according to Fig. 4
Signal Q1…QnGenerate the first Pseudo-random Current I of size pseudorandom changex1。
With continued reference to Fig. 5, in an optional mode, the first Pseudo-random Current generation circuit 031 includes the of j parallel connection
One Pseudo-random Current branch road 0311, j are the branch current of the natural number, i.e. each such current branch less than or equal to n
Output end is connected, and each branch route in j the first Pseudo-random Current branch road 0311 in parallel forms pseudo-random signal Q1…Qn
Elemental signals control output or do not export a tie point electric current to the output end of the branch current, i.e., j parallel connection
The first Pseudo-random Current branch road 0311 respectively by j elemental signals Qy…QzControl, the tie point electric current of output are superimposed to be formed
First Pseudo-random Current Ix1。
Referring again to Fig. 5, in an optional mode, the first Pseudo-random Current branch road 0311 includes the first output control switch
With tie point current source, S in the first output control switch such as Fig. 511、S12…S1jIt is shown, in tie point current source such as Fig. 5
Output current be respectively I11、I12…I1jCurrent source shown in, i.e., in j the first Pseudo-random Current branch road 0311 in parallel
First Pseudo-random Current branch road includes the first output control switch S11It is I with output current11Branch current source, x-th is pseudo-
Random current branch road the first output control switch of bag S1xIt is I with output current1xBranch current source, wherein 1≤x≤j.First
The electric current of branch current source output, such as I11、I12…I1jFor the branch current S of each the first Pseudo-random Current branch road 031111、
S12…S1jIn each first output control switch all in accordance with j elemental signals Qy…QzIn elemental signals carry out
Turn-on and turn-off.As the first output control switch S1xDuring conducting, branch current I1xIt is output to the first Pseudo-random Current branch road 0311
Output end, as the first output control switch S1xDuring shut-off, branch current I1xThe first Pseudo-random Current branch road 0311 is not output to
Output end, wherein 1≤x≤j.
As shown in figure 5, it is the first electric current I that the first current source 032, which is an output current,1Current source, the current source and j
Individual first Pseudo-random Current branch road 0311 in parallel is in parallel, i.e. the current output terminal of the first current source and the first Pseudo-random Current branch
The output end on road 0311 is connected.First electric current I1Size to need the properties institute that meets pre- according to D audio frequency amplifier
The value first set, i.e., it is a predetermined value, such as the first electric current I1Set according to minimal switching frequency, itself it is required that
Minimal switching frequency should be greater than maximal audio 20kHz, and the first electric current I1Setting also need the output for meeting D audio frequency amplifier
Design requirement and total harmonic distortion (THD) requirement of wave filter.First current source I1With the first Pseudo-random Current generation circuit 011
First Pseudo-random Current I of outputx1Superposition forms charging and discharging currents It。
Please continue to refer to Fig. 5, the clock signal according to caused by clock generating circuit of charge and discharge control switch 034
CLK carries out turn-on and turn-off, and in an optional mode, the charge and discharge control switch 034 includes switch St, that is, switch St
Turn-on and turn-off be controlled by clock signal clk, switch St is connected in parallel with the first current source, and and charge and discharge capacitance
034 is also connected in parallel.When the shut-off of charge and discharge control switch 034, that is, switch StDuring shut-off, charging and discharging currents ItTo charge and discharge capacitance
033 charging, when the conducting of charge and discharge control switch 034, that is, switch StDuring conducting, charging and discharging currents ItCharge and discharge capacitance 033 is put
Electricity, the charge and discharge capacitance 034 is in Figure 5 such as CtShown, it is connected in parallel with the first current source, electric capacity CtOn voltage i.e. fill
Voltage signal on discharge capacity 033 is the load that frequency pseudorandom caused by carrier generating circuit as shown in Figure 5 changes
Ripple signal Vtri。
Fig. 6 is that the circuit of an optional mode of the drive circuit generation circuit in the D audio frequency amplifier shown in Fig. 1 shows
It is intended to.
Fig. 6 is refer to, drive circuit generation circuit includes the second Pseudo-random Current generation circuit 041 and the second electric current 042.
Second Pseudo-random Current generation circuit 041 according to caused by signal generating circuit immediately as shown in Figure 4 puppet with
Machine signal Q1…QnProduce the second Pseudo-random Current I of size pseudorandom changex2。
With continued reference to Fig. 6, in an optional mode, the second Pseudo-random Current generation circuit 041 includes the of i parallel connection
The branch current output end of two Pseudo-random Current branch roads 0411, i.e. each such current branch is connected, i in parallel first
Each branch route in Pseudo-random Current branch road 0411 forms pseudo-random signal Q1…QnN elemental signals in a member
Plain signal control output or not one second branch current to the output end of the branch current, i.e., j the second puppet in parallel
Random current branch road 0411 is respectively by j elemental signals Qa…QbControl, the second branch current of output be superimposed to be formed second it is pseudo- with
Electromechanics stream Ix2。
Referring again to Fig. 6, in an optional mode, the second Pseudo-random Current branch road 0411 includes the and output control switch
With the second branch current source, S in the second output control switch such as Fig. 621、S22…S2iIt is shown, in the second branch current source such as Fig. 6
Output current be respectively I21、I22…I2iCurrent source shown in, i.e., in i the second Pseudo-random Current branch road 0411 in parallel
First Pseudo-random Current branch road includes the second output control switch S21It is I with output current21Branch current source, k-th is pseudo-
Random current branch road the second output control switch of bag S2kIt is I with output current2kBranch current source, wherein 1≤k≤i.Second
The electric current of branch current source output, such as I21、I22…I2iFor the branch current S of each the second Pseudo-random Current branch road 041121、
S22…S2iIn each second output control switch all in accordance with i elemental signals Qa…QbIn an elemental signals turned on
And shut-off.As the second output control switch S2kDuring conducting, branch current I2kIt is output to the defeated of the second Pseudo-random Current branch road 0411
Go out end, as the second output control switch S2kDuring shut-off, branch current I2kThe defeated of the second Pseudo-random Current branch road 0411 is not output to
Go out end, wherein 1≤k≤i.
As shown in fig. 6, it is the second electric current I that the second current source 042, which is an output current,2Current source, the current source and i
Individual second Pseudo-random Current branch road 0411 in parallel is in parallel, i.e. the current output terminal of the second current source and the second Pseudo-random Current branch
The output end on road 0411 is connected.Second electric current I2Size to need the properties institute that meets pre- according to D audio frequency amplifier
The value first set, i.e., it is a predetermined value, such as the second electric current I1Switching frequency is set to meet that D audio frequency amplifier is total
Harmonic distortion (THD) requirement.Second current source I2With the second Pseudo-random Current of the second Pseudo-random Current generation circuit 041 output
Ix2Superposition forms driving current IG。
Therefore D audio frequency amplifier disclosed in this invention produces pseudorandom by pseudo-random signal generation circuit
Signal, and carrier generating circuit is controlled according to the pseudo-random signal so that carrier generating circuit produces a frequency pseudorandom
The carrier signal of change, so that being compared with the carrier signal and an input signal, the pwm signal of output is also pseudo- for a frequency
The signal changed at random.Meanwhile driving current generation circuit is controlled always according to the pseudo-random signal, its is exported a size
The driving current of pseudorandom change.Last drive circuit receives the pwm signal changed according to frequency pseudorandom and size pseudorandom
The driving current of change, to drive the power switch pipe in output-stage circuit so that the switching frequency of power switch pipe is certain
In the range of change, and the opening time of switching tube and turn-off time change in the range of first, i.e., switching rate is in certain model
Interior change is enclosed, so as to break up the spectrum energy at switching frequency and its frequency multiplication, reduces peak energy.Therefore, institute of the present invention
Disclosed D audio frequency amplifier is respectively provided with preferable EMI rejections in low-frequency range and high band.
Each embodiment is described by the way of progressive in this specification, what each embodiment stressed be and other
The difference of embodiment, between each embodiment same or similar part mutually referring to.
The foregoing description of the disclosed embodiments, professional and technical personnel in the field are enable to realize or using the present invention.
A variety of modifications to these embodiments will be apparent for those skilled in the art, as defined herein
General Principle can be realized in other embodiments without departing from the spirit or scope of the present invention.Therefore, it is of the invention
The embodiments shown herein is not intended to be limited to, and is to fit to and principles disclosed herein and features of novelty phase one
The most wide scope caused.
Claims (10)
1. a kind of D audio frequency amplifier, including carrier generating circuit, driving current generation circuit, pseudo-random signal generation circuit
And clock generating circuit；
The carrier signal that the clock generating circuit exports according to the carrier generating circuit produces clock signal；
The pseudo-random signal generation circuit produces pseudo-random signal according to the clock signal；
The carrier generating circuit produces the carrier signal, the carrier wave according to the pseudo-random signal and the clock signal
The frequency pseudorandom change of signal so that the pwm signal obtained by the carrier signal is the letter that a frequency pseudorandom changes
Number, the pwm signal is used for the switching frequency for controlling the switching tube in output-stage circuit so that the switching frequency of the switching tube
Pseudorandom changes；
The driving current generation circuit produces the driving current of size pseudorandom change according to the pseudo-random signal, with output
To the drive circuit of the D audio frequency amplifier, to change the switching speed of the switching tube.
2. D audio frequency amplifier according to claim 1, it is characterised in that the clock generating circuit includes one
First comparator and a reference voltage source；
The input of the first comparator receives the reference voltage of the carrier signal and reference voltage source output respectively
Signal, output end export the clock signal.
3. D audio frequency amplifier according to claim 1, the pseudo-random signal generation circuit is one by n displacement
The m-sequence generation circuit of register and XOR feedback circuit composition, n is natural number；
The n shift registers are sequentially connected in series, and the input of first shift register and the XOR feedback circuit are defeated
Go out end to be connected, the Clock control end of each shift register receives the clock signal, according to the clock to be believed
Number produce an elemental signals；
The XOR feedback circuit comprises at least an XOR gate, and each input of the XOR gate receives a member
Plain signal, make the n elemental signals composition m-sequences of the n shift register output, the n elemental signals compositions
M-sequence as the pseudo-random signal.
4. D audio frequency amplifier according to claim 3, it is characterised in that it is pseudo- that the carrier generating circuit includes first
Random current generation circuit, the first current source, charge and discharge capacitance and charge and discharge control switch,
The first Pseudo-random Current generation circuit produces a size as the first of pseudorandom change according to the pseudo-random signal
Pseudo-random Current；
The output current of first current source is the first electric current of predetermined value；
The charge and discharge control switch carries out turn-on and turn-off according to the clock signal；
First Pseudo-random Current and first electric current are superimposed to form charging and discharging currents, are closed when the charge and discharge control switchs
When disconnected, the charging and discharging currents charge to the charge and discharge capacitance, when the charge and discharge control switch conduction, the discharge and recharge
Electric current discharges the charge and discharge capacitance, and the voltage signal on the charge and discharge capacitance is the carrier signal.
5. D audio frequency amplifier according to claim 4, it is characterised in that the first Pseudo-random Current generation circuit
Including j the first Pseudo-random Current branch road in parallel, j is the natural number less than or equal to n；
Each described first Pseudo-random Current branch route the elemental signals control output or a not defeated tie point
Electric current, the tie point electric current of output are superimposed to form first Pseudo-random Current.
6. D audio frequency amplifier according to claim 5, it is characterised in that the first Pseudo-random Current branch road includes
First output control switch and tie point current source, the output current of the tie point electric current is tie point electricity
Stream, first output control switch carry out turn-on and turn-off according to the elemental signals；
When first output control switch turns on, the tie point electric current is output to the first Pseudo-random Current branch road
Output end, when first output control switch turns off, the tie point electric current is not output to first pseudorandom
The output end of current branch.
7. D audio frequency amplifier according to claim 3, it is characterised in that the driving current generation circuit includes the
Two Pseudo-random Current generation circuits and the second current source；
It is the second puppet that pseudorandom changes that the second Pseudo-random Current generation circuit produces size according to the pseudo-random signal
Random current；
The output current of second current source is the second electric current of predetermined value；
Second Pseudo-random Current and second electric current are superimposed to form the driving current.
8. D audio frequency amplifier according to claim 7, it is characterised in that the second pseudo-random signal electric current produces
Circuit includes i the second Pseudo-random Current branch road in parallel, and i is the natural number less than or equal to n；
Each described second Pseudo-random Current branch route the elemental signals control and exports or do not export one second
Road electric current, second branch current of output are superimposed to form second Pseudo-random Current.
9. D audio frequency amplifier according to claim 8, it is characterised in that the second Pseudo-random Current branch road includes
Second output control switch and the second branch current source, the output current of second branch current is second branch road electricity
Stream, second output control switch carry out turn-on and turn-off according to the elemental signals；
When second output control switch turns on, second branch current is output to the second Pseudo-random Current branch road
Output end, when second output control switch turns off, second branch current is not output to second pseudorandom
The output end of current branch.
10. according to any described D audio frequency amplifier in claim 1~9, it is characterised in that also including comparator circuit,
Drive circuit and output-stage circuit；
The comparator circuit is used to compare an input signal and the carrier signal, and output pulse width modulated signal；
The drive circuit is used to receive the pulse width modulating signal and driving current, and output switch control signal；
The output-stage circuit is used to export an output voltage according to the switch controlling signal.
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| CN104537780B (en) * | 2015-01-19 | 2017-12-01 | 河南辉瑞生物医电技术有限公司 | A kind of impulse waveform modulation circuit |
| CN105048980B (en) | 2015-08-18 | 2018-09-18 | 矽力杰半导体技术(杭州)有限公司 | A kind of D audio frequency amplifier |
| US10027262B2 (en) * | 2016-09-13 | 2018-07-17 | Ford Global Technologies, Llc | Pseudorandom PWM variation based on motor operating point |
| CN106452028B (en) * | 2016-09-26 | 2019-03-26 | 中国人民解放军海军工程大学 | A kind of triangular carrier slope random distribution pulse duration modulation method |
| CN111698628B (en) * | 2020-06-02 | 2022-02-01 | 上海艾为集成电路技术有限公司 | Spread spectrum modulation method and circuit, audio amplifier |
| CN114172389B (en) * | 2021-12-02 | 2022-09-06 | 陕西亚成微电子股份有限公司 | Ton timing circuit and method capable of reducing electromagnetic interference of switching power supply and switching power supply |
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| CN102832887A (en) * | 2012-09-11 | 2012-12-19 | 电子科技大学 | High-fidelity D type voice frequency amplifier |
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| US5729175A (en) * | 1996-04-26 | 1998-03-17 | Motorola Inc. | Method of driving a class D audio power amplifier using non-overlapping edge drive signals |
| CN101714853B (en) * | 2009-11-20 | 2012-12-12 | 恩平市西特尔电子科技有限公司 | Bipolar soft-switching PWM power amplifier |
| CN102594272B (en) * | 2010-02-26 | 2015-05-27 | 比亚迪股份有限公司 | Circuit for reducing electromagnetic interference of class-D audio-frequency power amplifier |
| EP2432124B1 (en) * | 2010-09-21 | 2016-05-11 | Harman Becker Automotive Systems GmbH | Pulse width modulator |
| CN103475324A (en) * | 2013-09-13 | 2013-12-25 | 昆山新金福精密电子有限公司 | Audio amplification output circuit |
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