JP2007243530A - Method and device for voice amplification - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform high-resolution reproduction of a high-frequency component and a high-efficient reproduction of a low-frequency component, and reduce cross modulation noise generated by a difference of sampling frequencies in a PWM (pulse width modulation) amplifier which performs pulse width modulation of an input analog voice signal and power amplification. <P>SOLUTION: A voice amplification device comprises a pulse oscillator 17 which generates and outputs a clock pulse; a frequency divider 18 which divides output of the pulse oscillator; a high frequency pulse width modulation amplifier which receives output of the pulse oscillator as a clock pulse, extracts the high-frequency component from the voice signal, applies pulse width modulation, and performs power amplification; and a low-frequency pulse width modulation amplifier which receives the output of the frequency divider as a clock signal, extracts the low-frequency component from the voice signal, applies pulse width modulation, and performs power amplification. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an audio amplifying apparatus using a PWM amplifier that amplifies an analog audio signal and converts it into a pulse width modulation (hereinafter abbreviated as PWM) pulse signal, and a technique for achieving both high sound quality and high efficiency. It is about.

  Low power consumption is desired in recent AV equipment, and an audio amplifying apparatus using a PWM amplifier is known as one of audio signal power amplifying methods. The audio amplifier using the PWM amplifier performs pulse width modulation on an analog audio signal in accordance with the audio signal level, and integrates the pulse width modulated pulse width modulated signal to thereby power-amplify the analog audio signal. And the speaker is driven by the output. By configuring such a PWM amplifier with a hybrid IC or the like, the PWM amplifier can be made smaller than an analog amplifier, and attention is paid to the purpose of downsizing AV equipment.

  FIG. 4 is a diagram showing an example of a sound amplifying apparatus using a conventional general PWM amplifier.

  Hereinafter, the operation of a conventional general PWM amplifier will be described with reference to FIG.

  The triangular wave generator 54 converts the input clock pulse (rectangular pulse signal) (TP2) into a triangular wave signal (TP3), and generates a clock pulse that serves as a reference frequency for pulse width modulation.

  The analog audio signal is amplified with a predetermined amplification degree by the amplifier 51 (amplified analog audio signal (TP1)) and output to the level comparison timing generator 52.

  The level comparison timing generator 52 compares the triangular wave signal output from the triangular wave generator 54 with the amplified analog audio signal output from the amplifier 51, and the two FETs of the MOS-FET output unit 53 are simultaneously turned on. The timing is adjusted so as not to occur, and an H or L signal is output to the MOS-FET output unit 53.

  The MOS-FET output unit 53 increases the voltage of the H or L signal so as to obtain a predetermined power and outputs it as a PWM pulse signal (TP4).

  The integrator 55 includes an inductor and a capacitor. The integrator 55 integrates the PWM pulse signal output from the PWM amplifier 50 after removing its high-frequency components, converts the PWM pulse signal into an analog audio signal, and reproduces and outputs the sound as audio through the speaker 56.

  FIG. 5 shows the state of each signal from TP1 to TP4 shown in FIG. The PWM pulse signal (TP4) becomes an H signal if the level of the triangular wave signal (TP3) is higher than the amplified analog audio signal (TP1), and the L signal if the triangular wave signal (TP3) is lower than the amplified analog audio signal (TP1). Indicates that

  The PWM pulse signal output of the PWM amplifier 50 configured as described above is a pulse having a voltage of several tens of volts, while the input analog audio signal has a voltage difference from a signal of several hundred mV. For this reason, the PWM pulse signal interferes with the analog audio signal, and distortion and an increase in residual noise occur. However, as described in Patent Document 1, improvement of sound quality is improved by adopting a hybrid IC and devising a substrate pattern arrangement method. can do.

  FIG. 6 is a block diagram of a sound amplifying apparatus using a conventional PWM amplifier for improving the sound quality deterioration.

  Hereinafter, with reference to FIG. 6, a description will be given of a sound amplifying apparatus using a conventional PWM amplifier for improving sound quality degradation.

  The analog audio signal input through the band pass filter 60 is input to a differential input operational amplifier of the PWM driver 61, so that noise in the input signal is canceled as a common mode. Audio is output from the PWM amplifier through the output filter 66, and the speaker 67 is connected to a BTL (Bridged Tied Load). Hybridization of PWM driver 61, output switch device 62 and negative feedback device 63 (hybrid IC 64), independence of power source and ground of PWM driver 61 and output switch device 62 (including MOS-FET 65), board wiring pattern length By adopting a configuration for shortening, symmetrically arranging the substrate pattern, and preventing radiation noise due to the metal cover, the influence of switching noise can be reduced, and the distortion rate and power consumption can be reduced.

  By the way, in power amplification of an audio signal, high resolution is usually required in the high range and high power is required in the low range.

  The realization of a high-resolution PWM amplifier can be solved by setting the clock pulse frequency, which is the reference frequency for pulse width modulation of the PWM amplifier, as high as possible and increasing the sampling frequency. However, a switching loss occurs due to an increase in the number of times of switching, and the efficiency is lowered. Therefore, there is a problem that the high power required for low frequency reproduction cannot be handled. FIG. 7 shows an outline of the sampling frequency and efficiency characteristics of the PWM amplifier. As shown in FIG. 7, the efficiency decreases as the sampling frequency increases (the switching frequency increases).

As a means for solving this problem, a bi-amplifier configuration using two PWM amplifiers is used, and a clock pulse serving as a reference frequency for pulse width modulation of each PWM amplifier is changed and used.
JP 2004-56177 A

  However, when a bi-amplifier is configured using a PWM amplifier, interference occurs in each PWM amplifier due to a difference in clock pulse frequency of each PWM amplifier, and cross-modulation noise occurs.

  FIG. 8 shows an audio amplifying apparatus having a conventional bi-amplifier configuration including two PWM amplifier processing units each integrating a PWM amplifier and an integrator. The PWM amplifier processing unit 68 is used for high-frequency amplification, and the PWM amplifier processing unit. 69 has a bi-amplifier configuration for low-frequency amplification.

  In the PWM amplifier, the oscillation frequency of the clock pulse is not required to be so accurate, and is configured by an RC oscillator that can be configured at low cost by the resistor R and the capacitor C. However, since the RC oscillator has a variation accuracy between the resistor R and the capacitor C, the oscillation frequency oscillates at a frequency with an error of about several percent.

Here, the clock pulse frequency of the low frequency PWM amplifier processing unit is f _SL , and the clock pulse frequency of the high frequency PWM amplifier processing unit is f _SH . The clock pulse frequency f _SL of the low-frequency PWM amplifier processing unit is assumed to oscillate at 125 KHz, and the clock pulse frequency f _SH of the high-frequency PWM amplifier processing unit is set with a target of 500 KHz, but the RC oscillator variation accuracy Therefore, it is assumed that the oscillation frequency is 510 KHz.

Some of the harmonic of the low-frequency oscillation frequency f _SL, four times harmonic components 500KHz occurs, power, ground, if you had influence of clock pulses leakage from such radiation, f _SH (510 kHz) -4 * f _SL (4 * 125 KHz) = 10 KHz intermodulation noise is generated, and a single spectrum signal of 10 KHz is folded back within an audible band of 20 KHz, so that folding noise is generated. FIG. 9 shows the appearance of aliasing noise.

  The present invention solves such a conventional problem, and using a PWM amplifier, the high-frequency high-resolution and low-frequency high-power bi-amplifier characteristics, but no cross-modulation noise is generated. The object is to construct a low-cost audio amplifying apparatus.

  In order to achieve the above object, the present invention generates a reference clock by a pulse oscillator, amplifies the power of the high frequency component of the audio signal by pulse width modulation using the reference clock, and the low frequency component of the audio signal. Is amplified by pulse width modulation using a clock obtained by dividing the reference clock.

  The present invention also provides a pulse oscillator that generates and outputs a clock pulse, a frequency divider that divides the output of the pulse oscillator, and an output of the pulse oscillator that is input as a clock pulse to generate a high frequency component from an audio signal. A pulse width modulation amplifier for high frequency that amplifies the power by pulse width modulation of the extracted one, and a pulse width modulation of the low frequency component extracted from the audio signal by inputting the output of the frequency divider as a clock pulse It consists of a low-frequency pulse width modulation amplifier that amplifies power.

  Further, the present invention provides a pulse oscillator that generates and outputs a clock pulse, a frequency divider that divides the output of the pulse oscillator, and an output of the pulse oscillator that is input as a clock pulse. A pulse width modulation amplifier for L channel that amplifies power by pulse width modulation of the extracted band component, and a pulse obtained by extracting the high band component from the R channel analog audio signal by inputting the output of the pulse oscillator as a clock pulse R channel pulse width modulation amplifier that performs width modulation and power amplification, and an output of the frequency divider as a clock pulse, and a combination of the L channel analog audio signal and the R channel analog audio signal to a low frequency component And a low-frequency pulse width modulation amplifier that amplifies the power by pulse width modulation.

  The audio amplifying apparatus using the PWM amplifier according to the present invention can perform high-frequency component power amplification with high resolution and low-frequency component power amplification with high efficiency by the above-described configuration. It is possible to realize an audio amplifying apparatus that does not generate cross-modulation noise caused by the difference in clock pulse frequency of the PWM amplifier with a simple circuit configuration.

  In the audio amplifying apparatus using the PWM amplifier according to the embodiment of the present invention, the high frequency is high resolution and the low frequency is high-efficiency power amplification. This is a voice amplifying device that is not affected by the oscillation error of the two PWM amplifiers by the configuration used as the oscillation frequency of the high-frequency and low-frequency PWM amplifiers, and as a result no intermodulation noise occurs.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
The operation and each component of the audio amplifying apparatus using the PWM amplifier according to the first embodiment of the present invention will be described in detail below. FIG. 1 is a block diagram showing a configuration of a sound amplifying apparatus using a PWM amplifier according to Embodiment 1 of the present invention.

  1, the audio amplifying apparatus using the PWM amplifier according to the first embodiment of the present invention includes a pulse oscillator 17, a high-pass filter 1, a first PWM amplifier 2, a first integrator 7, a high-frequency reproduction speaker 8, a low-pass. It comprises a filter 9, a second PWM amplifier 10, a frequency divider 18, a second integrator 15, and a low frequency reproduction speaker 16.

  The pulse oscillator 17 generates a reference clock pulse by oscillation and outputs it to the first triangular wave generator 6 and the frequency divider 18.

  The frequency divider 18 divides the pulse clock output from the pulse oscillator 17 and outputs it to the second triangular wave generator 14.

(High frequency amplification and playback)
First, the high-frequency amplification and reproduction of the input analog audio signal will be described.

  High-frequency amplification and reproduction of the input analog audio signal is performed by the high-pass filter 1, the first PWM amplifier 2, the first integrator 7, and the high-frequency reproduction speaker 8.

  The high pass filter 1 extracts a high frequency component from the input analog audio signal and outputs it to the first amplifier 3.

  The first PWM amplifier 2 includes a first amplifier 3, a first triangular wave generator 6, a first level comparison timing generator 4, and a first MOS-FET output device 5.

  Hereinafter, each configuration of the first PWM amplifier 2 will be described.

  The first amplifier 3 receives the high frequency component of the analog audio signal output from the high-pass filter 1 as input, amplifies it with a predetermined amplification degree, and outputs it to the first level comparison timing generator 4.

  The first triangular wave generator 6 converts the inputted clock pulse into a triangular wave signal and outputs it to the first level comparison timing generator 4. This clock pulse serves as a reference frequency for pulse width modulation.

  The first level comparison timing generator 4 compares the triangular wave signal output from the triangular wave generator 6 with the amplified high frequency component of the analog audio signal output from the amplifier 3, and the triangular wave signal is converted to analog audio. If the level is higher than that obtained by amplifying the high frequency component of the signal, the H signal is output. Conversely, if the level of the triangular wave signal is lower than that obtained by amplifying the high frequency component of the analog audio signal, the L signal is output. At that time, the first level comparison timing generator 4 adjusts the timing so that the two FETs of the MOS-FET output device 5 do not become conductive at the same time, and outputs the H signal or the signal to the first MOS-FET output device 5. The L signal is output.

  The first MOS-FET output unit 5 outputs a PWM pulse signal obtained by raising the voltage of the output signal of the H signal or the L signal output from the first level comparison timing generator 4 so as to obtain a predetermined power. Output.

  The first integrator 7 converts the PWM pulse signal output from the first PWM amplifier 2 into an analog audio signal for audio reproduction by integrating after removing the high frequency component.

  The high frequency reproduction speaker 8 inputs an analog audio signal for audio reproduction output from the first integrator 7 and reproduces and outputs it as audio.

(Low frequency amplification and playback)
Next, low-frequency amplification and reproduction of the input analog audio signal will be described.

  The low frequency amplification and reproduction of the input analog audio signal is performed by the low pass filter 9, the second PWM amplifier 10, the second integrator 15, and the low frequency reproduction speaker 16.

  The low pass filter 9 extracts a low frequency component from the input analog audio signal and outputs the low frequency component to the second amplifier 11.

  The second PWM amplifier 10 includes a second amplifier 11, a second triangular wave generator 14, a second level comparison timing generator 12, and a second MOS-FET output device 13. Each configuration of the second PWM amplifier 10 is the same as that of the first PWM amplifier except that the analog audio signal input to the second amplifier 11 and the clock pulse input to the second triangular wave generator 14 are different. Since the configuration is the same as that of No. 2, description of internal signal processing is omitted.

  The second amplifier 11 amplifies the low frequency component of the analog audio signal output from the low-pass filter 9 with a predetermined amplification level, and outputs the amplified signal to the second level comparison timing generator 12.

  The second triangular wave generator 14 converts the clock pulse input from the frequency divider 18 into a triangular wave signal and outputs it to the second level comparison timing generator 12.

  Thereafter, the second PWM amplifier 10 outputs a PWM pulse signal corresponding to the low frequency range of the input audio signal processed in the same manner as the first PWM amplifier.

  The second integrator 15 converts the PWM pulse signal output from the second PWM amplifier 10 into an analog audio signal for audio reproduction by integrating after removing the high frequency component.

  The low frequency reproduction speaker 16 receives the analog audio signal for audio reproduction output from the second integrator 15, and reproduces and outputs it as audio.

  With reference to FIG. 2, the principle that the folded intermodulation noise does not occur with the above configuration will be described.

For example, assume that the oscillation frequency of the pulse oscillator 17 is 500 KHz, and the frequency divider 18 divides the frequency by 4. The oscillation frequency 500 KHz of the pulse oscillator 17 is supplied to the first PWM amplifier, and 125 KHz, which is a frequency obtained by dividing the oscillation frequency 500 KHz of the pulse oscillator 17 by 4, is supplied to the second PWM amplifier. In this state, even if leakage occurs in the first PWM amplifier 2 and the second PWM amplifier 10 due to the power supply, ground, radiation, etc., the influence of the quadruple harmonic is f _SH (500 KHz) −4 * F _SL (4 * 125 KHz) = 0 KHz, and generation of intermodulation noise due to an error between clocks used for the first PWM amplifier 2 and the second PWM amplifier 10 is eliminated. And there is no noise that turns back within an audible band of 20 KHz.

  As described above, in the audio amplifying device using the PWM amplifier according to the first embodiment of the present invention, the output of the pulse oscillator and the frequency division are performed while enabling high frequency high resolution and low frequency highly efficient power amplification. As a result of using these as the oscillation frequencies of the high-frequency and low-frequency PWM amplifiers, there is no influence of the oscillation errors of the two PWM amplifiers, and as a result, the intermodulation noise does not return to the audible band. Can be. For this reason, it is possible to realize a bi-amplifier system having a good sound quality using a PWM amplifier. Moreover, since the number of pulse oscillators is reduced and only one frequency divider is added, the circuit scale is not increased significantly, and a low-cost, low-power consumption audio amplifying apparatus can be realized. .

  Further, the pulse oscillator 17, the frequency divider 18, the first PWM amplifier 2, and the second PWM amplifier 10 may be integrated as a hybrid IC, and further, the high pass filter 1, the low pass filter 9, and the like are included. It can also be configured as a single hybrid IC, and in that case, a smaller audio amplifier can be realized. FIG. 1 shows an example 101 of a hybrid IC.

  The internal configuration of the PWM amplifier is not limited to the first embodiment of the present invention. Furthermore, in the first embodiment of the present invention, the PWM amplifier has been described as an example. However, the present invention may be applied to other digital amplifiers such as pulse amplitude modulation (PAM) and pulse density modulation (PDM).

(Embodiment 2)
The audio amplifying apparatus using the PWM amplifier according to the second embodiment of the present invention has a 3D system configuration in which the high frequency of each of the L channel and the R channel has high resolution and the low frequency enables high-efficiency power amplification. However, the output of one pulse oscillator is supplied as the clock pulse of the PWM amplifier for the high frequency of each of the L channel and the R channel, and the output of the same pulse oscillator is divided and the output of the PWM amplifier for the low frequency is used. The configuration used as the clock pulse is not affected by the oscillation error of the three PWM amplifiers, and as a result, the intermodulation noise does not return to the audible band.

  The operation and components of the audio amplifying apparatus using the PWM amplifier according to the second embodiment of the present invention will be described in detail below. FIG. 3 is a block diagram showing a configuration of an audio amplifying apparatus using a PWM amplifier according to the second embodiment of the present invention.

  The audio amplifying apparatus using the PWM amplifier in Embodiment 2 of the present invention in FIG. 3 includes a pulse oscillator 43, an adder 41, a high-pass filter 19, a first PWM amplifier 20, a first integrator 25, and an L channel reproduction. Speaker 26, high-pass filter 45, second PWM amplifier 27, second integrator 32, R channel reproduction speaker 33, low-pass filter 42, frequency divider 44, third PWM amplifier 34, third integrator 39, It consists of a low frequency reproduction speaker 40.

  The pulse oscillator 43 generates a reference clock pulse by oscillation and outputs it to the first triangular wave generator 24, the second triangular wave generator 31, and the frequency divider 44.

  The frequency divider 44 divides the pulse clock supplied from the pulse oscillator 43 and outputs it to the third triangular wave generator 38.

  The adder 41 adds the input L-channel analog audio signal and the R-channel analog audio signal, and outputs the result to the low-pass filter 42.

  In the audio amplifying apparatus using the PWM amplifier according to the second embodiment of the present invention, the high-pass filter 19, the first PWM amplifier 20, and the first amplifier amplify and reproduce the high-frequency component of the input L-channel analog audio signal. The integrator 25 and the L channel reproduction speaker 26 are used.

  Further, amplification and reproduction of the high frequency component of the input R channel analog audio signal is performed by the high pass filter 45, the second PWM amplifier 27, the second integrator 32, and the R channel reproduction speaker 33.

  Further, amplification and reproduction of the low-frequency component in the input analog audio signal is performed by the low-pass filter 42, the third PWM amplifier 34, the third integrator 39, and the low-frequency reproduction speaker 40.

  The first PWM amplifier 20 includes a first amplifier 21, a first triangular wave generator 24, a first level comparison timing generator 22, and a first MOS-FET output unit 23.

  The second PWM amplifier 27 includes a second amplifier 28, a second triangular wave generator 31, a second level comparison timing generator 29, and a second MOS-FET output device 30.

  The first PWM amplifier 20 and the second PWM amplifier 27 include an analog audio signal input to the first amplifier 21 and the second amplifier 28, a first triangular wave generator 24, and a second triangular wave generator 31. Since the configuration is the same as that of the first PWM amplifier described in the first embodiment of the present invention except that the clock pulses input to are different from each other, description of internal signal processing is omitted.

(L channel high frequency amplification and playback)
The first amplifier 21 amplifies the high-frequency component of the L-channel analog audio signal output from the high-pass filter 19 with a predetermined amplification degree, and outputs the amplified signal to the first level comparison timing generator 22.

  The first triangular wave generator 24 converts the clock pulse input from the pulse oscillator 43 into a triangular wave signal and outputs it to the first level comparison timing generator 22.

  Thereafter, the first PWM amplifier 20 is processed in the same manner as the first PWM amplifier according to the first embodiment of the present invention, and a PWM pulse signal corresponding to the high range of the input L channel audio signal is output. The

  The first integrator 25 converts the PWM pulse signal output from the first PWM amplifier 20 into an L-channel analog audio signal for audio reproduction by integrating after removing the high frequency component.

  The L channel reproduction speaker 26 receives the L channel analog audio signal output from the first integrator 25 for audio reproduction, and reproduces and outputs it as audio.

(R channel high frequency amplification and playback)
The second amplifier 28 amplifies the high-frequency component of the R-channel analog audio signal output from the high-pass filter 45 with a predetermined amplification level, and outputs the amplified signal to the second level comparison timing generator 29.

  The second triangular wave generator 31 converts the clock pulse input from the pulse oscillator 43 into a triangular wave signal and outputs it to the second level comparison timing generator 29.

  Thereafter, the PWM pulse signal corresponding to the high range of the input R channel audio signal is processed from the second PWM amplifier 27 in the same manner as the first PWM amplifier described in the first embodiment of the present invention. Is output.

  The second integrator 32 converts the PWM pulse signal output from the second PWM amplifier 27 into an R channel analog audio signal for audio reproduction by integrating the PWM pulse signal after removing the high frequency component.

  The R channel reproduction speaker 33 receives the R channel analog audio signal output from the second integrator 32 and is reproduced and output as audio.

(Low frequency amplification and playback)
The low pass filter 42 extracts a low frequency component from the analog audio signal output from the adder 41 and outputs the low frequency component to the third amplifier 35.

  The third PWM amplifier 34 includes a third amplifier 35, a third triangular wave generator 38, a third level comparison timing generator 36, and a third MOS-FET output device 37. Each configuration of the third PWM amplifier 34 is an embodiment of the present invention except that the analog audio signal input to the third amplifier 35 and the clock pulse input to the third triangular wave generator 38 are different. Since it is the same as that of the 2nd PWM amplifier 10 described in the form 1, description of an internal signal process is abbreviate | omitted.

  The third amplifier 35 amplifies the low-frequency component of the analog audio signal output from the low-pass filter 42 with a predetermined amplification level, and outputs the amplified signal to the third level comparison timing generator 36.

  The third triangular wave generator 38 converts the clock pulse input from the frequency divider 44 into a triangular wave signal and outputs it to the third level comparison timing generator 36.

  Hereinafter, the third PWM amplifier 34 outputs a PWM pulse signal corresponding to the low frequency range of the input audio signal processed in the same manner as the second PWM amplifier described in the first embodiment of the present invention. .

  The third integrator 39 converts the PWM pulse signal output from the third PWM amplifier 34 into an analog audio signal for audio reproduction by integrating after removing the high frequency component.

  The low frequency reproduction speaker 40 receives the analog audio signal for audio reproduction output from the third integrator 39, and reproduces and outputs it as audio.

  The audio amplifying apparatus using the PWM amplifier according to the second embodiment of the present invention has a 3D system configuration in which the high frequency of each of the L channel and the R channel has high resolution and the low frequency enables high-efficiency power amplification. However, the output of one pulse oscillator is output as the clock pulse of the L-channel and R-channel high-frequency PWM amplifier, and the output of the same pulse oscillator is divided to oscillate the low-frequency PWM amplifier. The configuration used as the frequency is not affected by the oscillation error of the three PWM amplifiers, and as a result, the intermodulation noise does not return to the audible band. For this reason, a 3D system with good sound quality using a PWM amplifier can be realized. Moreover, since the number of pulse oscillators is reduced and only one frequency divider is added, the circuit scale is not increased significantly, and a low-cost, low-power consumption audio amplifying apparatus can be realized. .

  Further, the pulse oscillator 43, the frequency divider 44, the first PWM amplifier 20, the second PWM amplifier 27, and the third PWM amplifier 34 may be integrally configured as a hybrid IC, and further, the first high-pass filter. 19, the second high-pass filter 45, the low-pass filter 42, the adder 41, and the like can be configured as a single hybrid IC. In that case, a smaller audio amplifying apparatus can be realized. FIG. 3 shows an example 102 of a hybrid IC.

  The internal configuration of the PWM amplifier is not limited to the second embodiment of the present invention. Furthermore, in the second embodiment of the present invention, the PWM amplifier has been described as an example. However, the present invention may be applied to other digital amplifiers such as pulse amplitude modulation (PAM) and pulse density modulation (PDM).

  According to the audio amplifying method and the audio amplifying device according to the present invention, high frequency components can have high resolution and low frequency components can achieve high-efficiency power amplification at the same time. It is particularly useful for audio amplification of AV equipment, such as being able to amplify the power of an audio signal that does not occur and enabling it with a simple circuit configuration.

The block diagram which shows the structure of the audio | voice amplification apparatus using the PWM amplifier in Embodiment 1 of this invention. The figure explaining the principle that aliasing cross modulation noise does not occur The block diagram which shows the structure of the audio | voice amplification apparatus using the PWM amplifier in Embodiment 2 of this invention. Block diagram showing an example of a sound amplifying device using a conventional general PWM amplifier The figure which shows the operation waveform of each part of the audio | voice amplification apparatus using the conventional general PWM amplifier. Block diagram of a conventional audio amplifier using a PWM amplifier Diagram showing sampling frequency and efficiency characteristics of PWM amplifier The block diagram which shows the structure of the audio | voice amplification apparatus of the conventional biamplifier structure which consists of two PWM amplifier processing units which integrated PWM amplifier and an integrator. The figure explaining the principle by which the aliasing cross modulation noise generate | occur | produces in the audio | voice amplification apparatus of the conventional biamplifier structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 High pass filter 2 1st PWM amplifier 3 1st amplifier 4 1st level comparison timing generator 5 1st MOS-FET output device 6 1st triangular wave generator 7 1st integrator 8 High frequency reproduction | regeneration speaker 9 Low-pass filter 10 Second PWM amplifier 11 Second amplifier 12 Second level comparison timing generator 13 Second MOS-FET output device 14 Second triangular wave generator 15 Second integrator 16 Low-frequency reproduction speaker 17 Pulse Oscillator 18 Frequency Divider 19 High-Pass Filter 20 First PWM Amplifier 21 First Amplifier 22 First Level Comparison Timing Generator 23 First MOS-FET Output Unit 24 First Triangular Wave Generator 25 First Integrator 26 L channel reproduction speaker 27 Second PWM amplifier 28 Second amplifier 29 Second level comparison timing Generator 30 Second MOS-FET output device 31 Second triangular wave generator 32 Second integrator 33 R channel reproduction speaker 34 Third PWM amplifier 35 Third amplifier 36 Third level comparison timing generator 37 Third MOS-FET output unit 38 Third triangular wave generator 39 Third integrator 40 Low-frequency reproduction speaker 41 Adder 42 Low-pass filter 43 Pulse oscillator 44 Frequency divider 45 High-pass filter 50 PWM amplifier 51 Amplifier 52 Level comparison Timing generator 53 MOS-FET output device 54 Triangular wave generator 55 Integrator 56 Speaker 60 Band pass filter 61 PWM driver 62 Output switch device 63 Negative feedback device 64 Hybrid IC
65 MOS-FET
66 Output Filter 67 Speaker 68 PWM Amplifier Processing Unit 69 PWM Amplifier Processing Unit 101 Hybrid IC
102 Hybrid IC

Claims (5)

A reference clock is generated by a pulse oscillator, power is amplified by pulse width modulation using the reference clock for the high frequency component of the audio signal, and a clock obtained by dividing the reference clock is used for the low frequency component of the audio signal. A method for amplifying a sound, wherein the power is amplified by pulse width modulation. A pulse oscillator that generates and outputs a clock pulse, a frequency divider that divides the output of the pulse oscillator, and a pulse width obtained by extracting the high frequency component from the audio signal by inputting the output of the pulse oscillator as a clock pulse A high-frequency pulse width modulation amplifier that modulates and amplifies power, and a low-frequency signal that amplifies power by pulse width modulation of the audio signal that is obtained by inputting the output of the divider as a clock pulse and extracting a low frequency component from the audio signal An audio amplifier comprising a pulse width modulation amplifier. A pulse oscillator that generates and outputs a clock pulse, a frequency divider that divides the output of the pulse oscillator, and a pulse width obtained by extracting the high frequency component from the audio signal by inputting the output of the pulse oscillator as a clock pulse A high-frequency pulse width modulation amplifier that modulates and amplifies power, and a low-frequency signal that amplifies power by pulse width modulation of the audio signal that is obtained by inputting the output of the divider as a clock pulse and extracting a low frequency component from the audio signal An audio amplifier that integrates a pulse width modulation amplifier into an IC A pulse oscillator that generates and outputs a clock pulse, a frequency divider that divides the output of the pulse oscillator, and an output of the pulse oscillator that is input as a clock pulse to extract a high frequency component from an L-channel analog audio signal A pulse width modulation amplifier for L channel that amplifies power by pulse width modulation and power amplification by pulse width modulation of a high frequency component extracted from an R channel analog audio signal by inputting the output of the pulse oscillator as a clock pulse A pulse width modulation amplifier for R channel, and a pulse obtained by extracting the low frequency component from the sum of the L channel analog audio signal and the R channel analog audio signal by inputting the output of the frequency divider as a clock pulse. A voice characterized by comprising a low-frequency pulse width modulation amplifier that performs width modulation and power amplification Width devices. A pulse oscillator that generates and outputs a clock pulse, a frequency divider that divides the output of the pulse oscillator, and an output of the pulse oscillator that is input as a clock pulse to extract a high frequency component from an L-channel analog audio signal A pulse width modulation amplifier for L channel that amplifies power by pulse width modulation and power amplification by pulse width modulation of a high frequency component extracted from an R channel analog audio signal by inputting the output of the pulse oscillator as a clock pulse A pulse width modulation amplifier for R channel, and a pulse obtained by extracting the low frequency component from the sum of the L channel analog audio signal and the R channel analog audio signal by inputting the output of the frequency divider as a clock pulse. An audio amplifying device that integrates a low-frequency pulse width modulation amplifier that performs power modulation by width modulation.

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