KR101830883B1 - Method for outputting an audio signal and apparatus for outputting an audio signal thereof - Google Patents

Abstract

A drive signal generator for generating at least one drive signal for controlling the switching amplification operation in accordance with the modulated audio signal; and a drive signal generator for generating a drive signal in response to the drive signal, And a power switching amplifier unit including at least one switching element that is turned on or off and performs the switching amplification operation and outputs an amplified audio signal corresponding to the modulated audio signal using the switching element, The at least one switching element is described as an audio signal output device comprising at least one of a gallium nitride transistor, a gallium arsenide transistor and a silicon carbide transistor.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an audio signal output method,

The present invention relates to an audio signal output method and an audio signal output apparatus therefor.

More particularly, the present invention relates to an audio signal output apparatus capable of high-speed operation. The present invention also relates to an audio signal output method capable of rapidly amplifying an audio signal to a high voltage and an audio signal output apparatus therefor.

The present invention also relates to an audio signal output method and an audio signal output apparatus therefor, which can prevent deterioration of sound quality of an audio signal.

Class A, Class B, Class AB and Class D are used as power amplifiers for audio that can output audible signals that can be received by receiving audio signals. Among these, Class D amplifiers are widely used because they can reduce the amplification efficiency degradation caused by Class A, Class B, and Class AB amplifiers.

Class D amplifiers are digital amplifiers that digitally modulate audio signals input in analog form and amplify and output digitally modulated audio signals.

Digital amplifiers are widely used because they have little data conversion loss and theoretically achieve 100% amplification efficiency. It is important that an audio signal output apparatus using such a digital amplifier outputs an input audio signal to a maximum output without generating signal distortion.

Accordingly, there is a need to provide an audio signal output method and apparatus capable of minimizing noise degradation and minimizing signal distortion to minimize audio quality degradation.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an audio signal output method and an audio signal output apparatus capable of minimizing errors and noise generated during a switching amplification operation by performing a switching amplification operation at a high speed.

It is another object of the present invention to provide an audio signal output method capable of minimizing the deterioration of sound quality of an audio signal by increasing a signal-to-noise ratio and an audio signal output apparatus therefor.

The apparatus for outputting an audio signal according to an embodiment of the present invention includes a pulse modulator for pulse-modulating an input audio signal to output a modulated audio signal, and generating at least one drive signal for controlling the switching amplification operation in accordance with the modulated audio signal And at least one switching element that is turned on or off in response to the driving signal and performs the switching amplification operation, wherein the switching element is used to amplify the modulated audio signal corresponding to the modulated audio signal, And a power switching amplifier for outputting an audio signal.

Wherein the at least one switching element comprises at least one of a gallium nitride transistor, a gallium arsenide transistor and a silicon carbide transistor.

The pulse modulating unit may include a pulse density modulating unit that performs pulse density modulation of the input audio signal and generates the modulated audio signal corresponding to the input audio signal.

The pulse density modulation unit may filter at least one of a switching noise component and a power noise component in the input audio signal including the original audio signal and may pulse-density-modulate the filtered input audio signal to output a modulated audio signal have.

The pulse density modulation unit may include a delta sigma modulation unit that delta-sigma modulates the input audio signal to output a modulated audio signal.

The audio signal output apparatus according to an embodiment of the present invention may further include a feedback loop for outputting a feedback signal obtained by attenuating and delaying the amplified audio signal to the pulse density modulation unit.

The pulse density modulation unit may correct at least one of a delay and a gain of the original audio signal based on the feedback signal to generate the input audio signal. At least one of the switching noise component and the power noise component included in the input audio signal And a delta sigma modulating unit for filtering one of the signals.

The delta sigma modulator may include a loop filter for receiving an output signal of a summer and an adder for subtracting an output signal of the feedback loop from the original audio signal and for removing a noise component included in an output signal of the summer, And a quantizer for quantizing the output signal of the loop filter to generate the modulated audio signal.

The feedback loop may further include an attenuation unit that attenuates the amplified audio signal by applying a predetermined subtraction gain value, and a delay unit that delays the output signal of the attenuation unit by a predetermined time in accordance with a sampling period of the pulse density modulation unit, And a delay unit for outputting the delayed signal.

The pulse density modulating unit may filter at least one of a switching noise component and a power noise component generated in the power switching amplification unit included in the input audio signal and output a high order 1 bit single loop delta sigma And a modulation unit.

The driving signal generating unit may generate the at least one driving signal for driving the positive or negative power supply voltage of the switching device.

The driving signal generating unit may generate a first driving signal for driving the positive power supply voltage and a second driving signal for driving the negative power supply voltage.

The switching amplifier may include a first switching element that is turned on or off in response to the first driving signal, one end of which is connected to the positive power supply voltage and the other end of which outputs the amplified audio signal, And a second switching element that is turned on or off in response to the second driving signal, one end of which is connected to the negative power supply voltage, and the other end of which outputs the amplified audio signal.

The driving signal generating unit may further include a first transforming unit for stepping up the first driving signal to output the first driving signal, and a second transforming unit for stepping up the second driving signal to output the driving signal.

The apparatus for outputting an audio signal according to an embodiment of the present invention includes a low pass filter for converting the amplified audio signal into an analog signal and a speaker unit for converting the output signal of the low pass filter into a physical vibration signal and outputting the physical signal .

The apparatus for outputting an audio signal according to an embodiment of the present invention includes a step of pulse-modulating an input audio signal to output a modulated audio signal, and generating at least one drive signal for controlling a switching amplification operation in accordance with the modulated audio signal And turning on or off at least one switching element including at least one of a gallium nitride transistor, a gallium arsenide transistor and a silicon carbide transistor using the driving signal to generate an amplification corresponding to the modulated audio signal, And outputting the audio signal.

1 is a block diagram of an audio signal output apparatus according to an embodiment of the present invention.
2 is a block diagram of an audio signal output apparatus according to another embodiment of the present invention.
FIG. 3 is a timing diagram showing signals generated and output in the audio signal output apparatus of FIG. 2. FIG.
FIG. 4 is a view showing the drive signal generator of FIG. 2 in detail.
5 is another diagram showing the driving signal generator of FIG. 2 in detail.
6 is a flowchart illustrating an audio signal output method according to an embodiment of the present invention.
7 is a flowchart illustrating an audio signal output method according to another embodiment of the present invention.

In implementing a Class D amplifier, the digitally modulated audio signal is amplified into a signal having a high voltage level. Here, the amplification is performed through a switching amplifier. The switching amplifier is also referred to as a power switching amplifier. The switching amplifier performs a switching amplification operation that turns on or off the switching element in accordance with the input digital signal, and outputs an audio signal having a high voltage level.

Switching noise may occur when performing the above-described switching amplification operation. In addition, power supply noise may occur in supplying power at a high voltage level and a low voltage level. This switching noise and power supply noise reduce the signal to noise ratio (SNR) of the switching amplifier. In addition, the reduction of the signal-to-noise ratio (SNR) causes the audio quality of the audio signal output through the class-D amplifier to deteriorate.

Further, in order to increase the signal-to-noise ratio (SNR) of the switching amplifier, the switching amplifier must be driven at a high speed.

Hereinafter, an audio signal output method and an audio signal output apparatus according to the present invention capable of increasing the signal-to-noise ratio and driving the switching amplifier at high speed will be described in detail with reference to the accompanying drawings.

1 is a block diagram of an audio signal output apparatus according to an embodiment of the present invention. 1 (a) is a diagram showing an audio signal output apparatus 100 according to an embodiment of the present invention. 1 (b) is a diagram showing the audio signal output apparatus 100 of FIG. 1 (a) in more detail.

1, an audio signal output apparatus 100 according to an exemplary embodiment of the present invention includes a pulse modulator 110, a driving signal generator 120, and a power switching amplifier (130).

1 (a), the pulse modulator 110 pulse modulates an input audio signal (not shown) to generate a pulse signal corresponding to an input audio signal (not shown). As pulse modulation performed by the pulse modulator 110, pulse density modulation (PDM) may be used. In the following drawings including FIG. 1 (a), a case where a pulse density modulation unit (PDM unit) 110 is used as the pulse modulation unit 110 is shown as an example.

The pulse density modulation unit 110 performs pulse density modulation (PDM) on an input audio signal (not shown) to output a modulated audio signal S_DSM.

Here, the input audio signal is a signal corresponding to the original audio signal S_IN to be output. The input audio signal may be the original audio signal S_IN itself or a signal including a predetermined noise in the original audio signal S_IN. Alternatively, the input audio signal may be a signal obtained by correcting the original audio signal S_IN to compensate for the total gain and delay value of the audio output apparatus in consideration of the output of the power switching amplifier 130. [

The pulse density modulation unit 110 may filter at least one of a switching noise component and a power noise component in an input audio signal when the input audio signal includes a switching noise component and a power noise component, Pulse density modulation can be output. Here, the switching noise component and the power supply noise component may be caused by the noise generated in the switching amplification operation performed in the power switching amplifier and the noise included in the power supply. The filtering operation of the pulse density modulation unit 110 will be described in detail below with reference to FIG.

The driving signal generating unit 120 generates at least one driving signal CON for driving the power switching unit 130 in accordance with the modulated audio signal S_DSM.

Specifically, the driving signal generating unit 120 generates a switching control signal for controlling a switching amplifying operation performed in the power switching amplifying unit 130. That is, the driving signal CON is provided in the power switching amplifier 130 and serves as a signal for turning on / off at least one switching element (not shown) for performing a switching amplification operation.

The power switching amplifier 130 includes at least one switching element (not shown) turned on or off in response to the driving signal CON output from the driving signal generator 120. Then, an amplified audio signal corresponding to the modulated audio signal S_DSM is generated using a switching element (not shown). Hereinafter, a signal output from the power switching amplifier 130 is referred to as an amplified audio signal S_OUT.

Here, the amplified audio signal S_OUT may be a signal obtained by amplifying the amplitude of the modulated audio signal S_DSM. For example, the power switching amplifier 130 outputs the input audio signal corresponding to the original audio signal S_IN input to the audio signal output apparatus 100 in accordance with the rated maximum output of the audio signal output apparatus 100 The modulated audio signal S_DSM can be amplified.

The switching device (not shown) included in the power switching amplifier 130 includes at least one of a gallium nitride (GaN) transistor, a gallium arsenide (GaAs) transistor, and a silicon carbide (SiC) transistor.

Gallium nitride and gallium arsenide transistors have short propagation delays and are capable of high-speed operation at high voltages. Here, the propagation delay means the time taken for a saturated signal to be output to the source terminal or the drain terminal, which is the output terminal of the transistor, after the control signal for turning on the transistor is input to the gate of the transistor.

When the gallium nitride light transistor or the gallium arsenide transistor is used as the switching element for performing the switching amplification operation in the power switching amplifier 130, the switching operation can be performed at a high speed. Accordingly, the switching noise can be minimized, so that the signal-to-noise ratio (SNR) of the audio signal output apparatus 100 can be reduced. In addition, the modulated audio signal S_DSM can be quickly amplified and output at a high voltage, thereby increasing the maximum output of the audio signal output apparatus 100.

In addition, the gallium nitride transistor used as the switching device may be a hetero junction field effect transistor (HFET).

1 (b), the audio signal output apparatus 160 may further include a feedback loop 185 in comparison with the audio signal output apparatus 100 shown in FIG. 1 (a) have. Further, it may further include a low pass filter (LPF) 190 and a speaker unit 195. The pulse density modulation unit 170, the drive signal generation unit 175 and the power switching amplification unit 180 of FIG. 1 (b) are the same as the pulse density modulation unit 110 of FIG. 1 (a) Power amplifier 120 and the power-power switching amplifier 130, respectively. Therefore, the description of the audio signal output apparatus 160 of FIG. 1 (b) that is the same as that of the audio signal output apparatus 100 of FIG. 1 (a) will be omitted.

The feedback loop 185 outputs the feedback signal S_OUT2 obtained by attenuating and delaying the amplified audio signal S_OUT to the pulse density modulation section 170.

The pulse density modulation unit 170 corrects at least one of a delay and a gain of the original audio signal S_IN based on the feedback signal S_OUT2 to generate an input audio signal. Then, at least one of the switching noise component and the power source noise component included in the input audio signal is filtered. Then, the filtered input audio signal can be subjected to pulse density modulation.

The low pass filter 190 demodulates the amplified audio signal S_OUT output from the power switching amplifying unit 180 into an analog audio signal and outputs the analog audio signal. That is, since the signal output from the power switching amplifier 180 is a digital signal, it is converted into an analog signal and output.

The speaker unit 195 converts the output signal of the low-pass filter 190 into a physical vibration signal that the user can perceive audibly and outputs the physical vibration signal.

2 is a block diagram of an audio signal output apparatus according to another embodiment of the present invention.

2, the pulse density modulation unit 210, the drive signal generation unit 220, and the power switching amplification unit 230 of the audio signal output apparatus 200 are connected to the pulse density modulation unit (FIG. 1 110, the driving signal generator 120, and the power switching amplifier 130, respectively. 2, the pulse density modulation unit 210, the drive signal generation unit 220, the power switching amplification unit 230, the feedback loop 240, the low pass filter 250, and the speaker unit 260 A power switching amplifier 180, a feedback loop 185, a low-pass filter 190, and a speaker unit 195 shown in FIG. 1 (b) . Therefore, in the audio signal output apparatus 200, the description overlapping with the audio signal output apparatuses 100 and 160 of FIG. 1 will be omitted.

2, the pulse density modulation unit 210 may include a delta-sigma modulator (DSM) for delta-sigma modulating an input audio signal to output a modulated audio signal S_DSM. In FIG. 2, the pulse density modulation unit 210 includes a delta sigma modulation unit. The pulse density modulation unit 210 is referred to as a delta sigma modulation unit 210 hereinafter.

The delta sigma modulator 210 receives the original audio signal S_IN and delta-sigma modulates the input audio signal S_IN1 corresponding to the original audio signal S_IN to generate a modulated audio signal S_DSM. . Specifically, at least one of the switching noise component and the power source noise component included in the input audio signal S_IN may be filtered, and the filtered input audio signal S_IN1 may be subjected to delta sigma modulation.

Specifically, the delta sigma modulation unit 210 receives the input audio signal S_IN, which is a signal obtained by adding and subtracting a predetermined value from the original audio signal S_IN in consideration of the value of the amplified audio signal S_OUT, which is the output signal value of the audio signal output apparatus 200, (S_IN1) can be delta sigma modulated. When the input audio signal S_IN1 obtained by correcting the original audio signal S_IN in consideration of the value of the amplified audio signal S_OUT is subjected to delta sigma modulation, the output of the audio signal output apparatus 200 and the overall gain value Can be adjusted more accurately.

2, the delta sigma modulation unit 210 includes an adder 211, a loop filter 212, and a quantization unit 214. [ In addition, the delta sigma modulation section 210 may further include a clock generator 213.

Specifically, the delta sigma modulator 210 may include a higher order 1-bit single-loop delta sigma modulator (DSM) that generates a 1-bit output signal. 2, a delta sigma modulation unit 210 receives a feedback signal S_OUT2 and a circular audio signal S_IN, which are signals output from the feedback loop 240, and outputs a quantized 1-bit output signal. A 1-bit single-loop DSM is shown as an example.

The summer 211 receives the feedback signal S_OUT2 and the original audio signal S_IN. Then, subtracting the feedback signal S_OUT2 from the original audio signal S_IN and outputting it. The delta sigma modulation unit 210 generates the input audio signal S_IN1 by reflecting the value of the amplified audio signal S_OUT to the original audio signal S_IN using the summer 211, ) Can be performed in accordance with the target gain or the rated maximum output of the power amplifier.

The loop filter 212 filters and outputs a noise component included in the input audio signal S_IN1.

The feedback signal S_OUT2 is a signal obtained by attenuating and amplifying the amplified audio signal S_OUT. Accordingly, the feedback signal S_OUT2 may include quantization noise, power supply noise, and switching noise included in the amplified audio signal S_OUT.

Here, the quantization noise is a noise generated due to a quantization error generated when the quantization unit 214 quantizes a predetermined signal. The power supply noise is a noise component included in the power source (+ VDD, -VDD) applied when performing the switching amplification operation in the power switching amplifying unit 230 and is a DC component of the power (+ VDD, -VDD) (AC) power supply components such as jitter or ripple in addition to the power supply voltage and the power supply voltage. In addition, the switching noise is a noise generated during switching in performing the switching amplification operation in the power switching amplifier 230.

Since the input audio signal S_IN1 is obtained by subtracting the feedback signal S_OUT2 which is the output signal of the feedback loop 240 from the original audio signal S_IN, the input audio signal S_IN1 has the quantization noise ), Power supply noise, and switching noise.

Therefore, the loop filter 212 filters and outputs the above-mentioned noise components in the input audio signal S_IN1.

The clock generator 213 generates a clock signal S_CLK for setting the sampling period of the loop filter 213.

In general, the input audio signal S_IN1 is a signal of a low frequency component, and the noise component is a signal of a high frequency component, so that the loop filter 212 can filter signal components other than a predetermined frequency band. Here, the predetermined frequency band is the frequency band of the original audio signal S_IN to be output. For example, a music or voice signal to be output has a lower frequency band than a noise signal. Accordingly, the loop filter 212 may be a low-pass filter that filters a signal having a predetermined frequency value or more to remove a noise signal.

The quantization unit 214 receives the signal output from the loop filter 212 and quantizes the input signal to generate a modulated audio signal S_DSM having the form of a digital signal.

The driving signal generating unit 220 receives the modulated audio signal S_DSM and generates at least one driving signal CON for controlling the switching amplifying operation in accordance with the input modulated audio signal S_DSM. Here, the switching amplification operation is performed using at least one switching element (not shown) provided in the power switching amplifier 230. The driving signal CON becomes a switching control signal for controlling the turn-on or turn-off of the switching element (not shown).

The power switching amplifier 230 may be constituted by a switching amplifier 231 including at least one switching element. The switching amplifier 231 receives a positive power supply voltage + VDD and a negative power supply voltage -VDD and outputs a positive power supply voltage (+ VDD) level and a negative power supply voltage ( -VDD) level. The switching device and the switching amplifier 231 will be described in detail below with reference to FIGS. 4 and 5. FIG.

The attenuation unit 242 attenuates the amplified audio signal S_OUT by applying a predetermined subtraction gain value to generate the attenuated audio signal S_OUT1. Specifically, when the amplified audio signal S_OUT is directly input to the delta sigma modulator 210 because the amplified audio signal S_OUT, which is an output signal of the power switching amplifier 230, is a high voltage signal, Resulting in a rash. Therefore, the attenuation unit 242 lowers the voltage level of the amplified audio signal S_OUT in accordance with the original audio signal S_IN level in order to prevent such oscillation.

The delay unit 241 generates the feedback signal S_OUT2 by delaying the attenuated audio signal S_OUT1 by a predetermined time in accordance with the sampling period of the delta sigma modulation unit 210. [

The clock signal S_CLK, the modulated audio signal S_DSM, the amplified audio signal S_OUT, the reduced audio signal S_OUT1 and the feedback signal S_OUT2 generated in the audio signal output apparatus 200 of FIG. 3 will be described in detail.

3 is a timing diagram showing signals generated in the audio signal output apparatus of FIG.

Referring to FIG. 3, a clock generator 213 generates a clock signal S_CLK having a predetermined period.

The delta sigma modulation section 210 generates a modulated audio signal S_DSM in accordance with a sampling rate according to the clock signal S_CLK.

The modulated audio signal S_DSM passes through the power switching amplifier 230 and becomes a high-voltage amplified audio signal S_OUT having a high voltage level (+ VDD) and a low voltage level (-VDD).

The attenuation unit 242 lowers the voltage level of the amplified audio signal S_OUT using a predetermined subtraction gain value G to output the reduced audio signal S_OUT1. Here, the signal level of the attenuated audio signal S_OUT1 may correspond to the signal level of the modulated audio signal S_DSM. 3, the signal level of the attenuated audio signal S_OUT1 is a value obtained by dividing the signal level of the amplified audio signal S_OUT by a predetermined gain value G (+ VDD / G, -VDD / G).

The delay unit 241 delays the attenuated audio signal S_OUT1 according to the rising edge of the clock signal S_CLK, which is the sampling period of the delta sigma modulation unit 210, to generate the feedback signal S_OUT2.

Here, in order for the audio signal output apparatus to operate normally, the power switching amplifier 230 must generate an amplified audio signal S_OUT that transitions within one period P1 of the clock signal S_CLK, which is a sampling period . Therefore, the delay value d1 of the amplified audio signal S_OUT should not exceed one period P1 of the clock signal S_CLK.

However, the larger the logic high level voltage of the amplified audio signal S_OUT, the longer the rising time that transits from the low voltage level (-VDD) to the high voltage level (+ VDD).

In this embodiment, the switching amplifier 231 includes at least one of a gallium nitride transistor, a gallium arsenide transistor, and a silicon carbide transistor, so that the switching operation can be performed quickly, thereby minimizing the above-described rising time. Accordingly, it is possible to output the amplified audio signal S_OUT at a high voltage level, thereby increasing the maximum output of the audio signal output apparatus 200. [

FIG. 4 is a view showing the drive signal generator of FIG. 2 in detail. The driving signal generating unit 420 of FIG. 4A corresponds to the driving signal generating units 120, 175, and 220 shown in FIGS. 1 and 2, so that a description overlapping with FIGS. 1 and 2 It is omitted. 4 (b) is a diagram for explaining the drive signal generator 420 of FIG. 4 (a) in detail.

4A, the driving signal generating unit 420 may include a driving signal generating unit 421 and a transforming unit 423. The driving signal generating unit 421 may include a driving signal generating unit 421 and a transforming unit 423. [

The driving signal generating unit 421 generates at least one first driving signal for driving at least one switching element included in the switching amplifier 231 to drive a positive power supply voltage (+ VDD) or a negative power supply voltage (-VDD) And generates a signal CON1.

The transformer 423 boosts the first drive signal and outputs the drive signal CON. The boosted drive signal CON can turn on the switching element more quickly.

4B, the driving signal generating unit 450, the driving signal generating unit 451, the transforming unit 453, and the switching amplifier 460 may include a driving signal generating unit 420, The transformer 421, the transformer 421, the switching amplifier 421, and the switching amplifier 231, so that the explanations that are the same as those in FIGS. 2 and 4 (a) will be omitted. 4B illustrates an example in which the switching amplifier 460 includes one switching element 461. In FIG.

The driving signal generating unit 451 outputs the first driving signal CON1 corresponding to the modulated audio signal S_DSM.

The transformer 453 includes a transformer for boosting the input voltage at a 1: N ratio, and boosts the first drive signal CON1 by N times to output the drive signal CON.

The switching element 461 receives the driving signal CON at the gate terminal and outputs a positive power supply voltage + VDD or a negative power supply voltage -VDD according to the signal level of the driving signal CON.

5 is another diagram showing the driving signal generator of FIG. 2 in detail.

The driving signal generator 520 and the switching amplifier 530 of FIG. 5 correspond to the driving signal generators 220, 420 and 450 and the switching amplifiers 231 and 461 of FIGS. 2 and 4, And the description overlapping with that in Fig. 4 will not be described in detail.

5, the driving signal generating unit 520 includes a driving IC 540 and a transforming unit 550. The driving IC 540 includes a driving unit 540 and a transforming unit 550. [ The transforming unit 550 includes a first transforming unit 551 and a second transforming unit 561.

In addition, the switching amplifier 530 includes a first switching device 531 and a second switching device 532 connected in series.

The driving integrated circuit 540 receives the modulated audio signal S_DSM and accordingly generates a first driving signal for driving the positive power supply voltage + VDD and a second driving signal for driving the negative power supply voltage- Thereby generating a driving signal. In FIG. 5, the negative power supply voltage -VDD is 0V, that is, ground, for example. Here, the first driving signal is output to the first transforming unit 550, and the second driving signal is output to the second transforming unit 560.

The first switching device 531 has one end connected to the positive power supply voltage (+ VDD) and outputs the amplified audio signal S_OUT to the other end. The second switching element 532 outputs the amplified audio signal S_OUT at one end, and the other end is connected to the negative power supply voltage.

The first transforming unit 551 includes a transformer 552 and a plurality of capacitors 553 and 554. The first transforming unit 551 boosts the input first driving signal and outputs the voltage to the gate terminal of the first switching device 531. In addition, it may further include a diode 556 for preventing the current of the transformer 552 from flowing backward.

The first switching device 531 can be quickly turned on or turned off in response to the first driving signal that is boosted and outputted at a high voltage level.

The configuration of the second transforming unit 560 is the same as that of the first transforming unit 551 and boosts the second driving signal to output to the gate terminal of the second switching unit 532.

The second switching device 532 can be quickly turned on or turned off in response to the second driving signal that is boosted and outputted at a high voltage level.

6 is a flowchart illustrating an audio signal output method according to an embodiment of the present invention.

Referring to FIG. 6, an audio signal output method 600 according to an embodiment of the present invention pulse-modulates an input audio signal S_IN1 and outputs a modulated audio signal S_DSM in operation 610. Pulse density modulation may be used for the pulse modulation, and the following description will be made using the pulse density modulation as the pulse modulation as an example. Step 620 may be performed in the pulse density modulation unit 110.

And generates at least one driving signal CON for controlling the switching amplification operation in accordance with the modulated audio signal S_DSM (operation 620). Step 620 may be performed in the driving signal generating unit 120.

The driving signal CON is used to turn on or turn off at least one switching element including at least one of a gallium nitride transistor, a gallium arsenide transistor and a silicon carbide transistor to generate a modulation signal corresponding to the modulated audio signal S_DSM And outputs the amplified audio signal S_OUT (step 630).

The audio signal output method shown in FIG. 6 is the same as the operation of the audio signal output apparatuses 100 and 200 according to the present invention described with reference to FIGS. 1 and 5. Therefore, a description overlapping with those in Figs. 1 to 5 will be omitted.

7 is a flowchart illustrating an audio signal output method according to another embodiment of the present invention. The steps 710, 720, and 730 of FIG. 7 correspond to the steps 610, 620, and 630 of FIG. 6, respectively, so that the description overlapping with FIG. 6 is omitted.

Referring to FIG. 7, the audio signal output method 700 may further include steps 740 and 750 as compared to the audio signal output method 600 of FIG.

In operation 740, the amplified audio signal S_OUT generated in operation 730 is attenuated and delayed to generate a feedback signal S_OUT2. Step 740 may be performed in the feedback loop 185.

In operation 750, at least one of the delay and the gain of the original audio signal S_IN is corrected based on the feedback signal S_OUT2 generated in operation 740 to generate an input audio signal S_IN1. The operation of step 750 may be performed in the pulse density modulation unit 170.

When the input audio signal S_IN1 is generated, at least one of the switching noise component and the power noise component included in the input audio signal S_IN1 is filtered in operation 712. Step 712 may be performed in the pulse density modulation unit 170.

Then, the filtered input audio signal is quantized to generate a modulated audio signal S_DSM (step 714).

The audio signal output method shown in FIG. 7 is the same as the detailed operation of the audio signal output apparatus 100, 200 according to the present invention described with reference to FIGS. 1 and 5, and its operation configuration. Therefore, a description overlapping with those in Figs. 1 to 5 will be omitted.

As described above, the audio signal output apparatus and the audio signal output method according to the present invention can perform at least one of switching noise and power noise components included in the input audio signal by pulse modulation, for example, pulse density modulation, By generating an audio signal, the signal-to-noise ratio can be increased. Further, by performing a switching amplification operation using a switching amplifier including at least one of a gallium nitride transistor, a gallium arsenide transistor, and a silicon carbide transistor, an amplified audio signal having a high voltage level can be quickly generated and output. Therefore, the audio signal output apparatus and the audio signal output method according to the present invention have a high signal-to-noise ratio and are capable of high-speed operation.

The method of the present invention can also be embodied as computer-readable codes or programs on a computer-readable recording medium. A computer-readable recording medium includes all kinds of recording apparatuses in which data that can be read by a computer system is stored. Examples of the computer-readable recording medium include a ROM, a RAM, a CD-ROM, a magnetic tape, a hard disk, a floppy disk, a flash memory, and an optical data storage device. The computer readable recording medium may also be distributed over a networked computer system and stored and executed as computer readable code in a distributed manner.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, the scope of the present invention should not be limited to the above-described embodiments, but should be construed to include various embodiments within the scope of the claims.

100, 200: Audio signal output device
110, 170, 210: Pulse density modulation section
120, 175, and 220: a driving signal generator
130, 180, 230: Power switching amplifier section
185, 240: feedback loop
250: Low-pass filter
260: speaker section

Claims (18)

A pulse modulator for pulse-modulating an input audio signal to output a modulated audio signal;
A driving signal generator for generating at least one driving signal for controlling a switching amplification operation in accordance with the modulated audio signal; And
And at least one switching element that is turned on or off in response to the driving signal and performs the switching amplification operation, wherein the switching element is an amplified one corresponding to the modulated audio signal, And a power switching amplifier unit for outputting an audio signal,
The at least one switching element
At least one of a gallium nitride transistor, a gallium arsenide transistor, and a silicon carbide transistor,
And the delay value of the amplified audio signal does not exceed the sampling period. The apparatus of claim 1, wherein the pulse modulator
And a pulse density modulation unit for performing pulse density modulation on the input audio signal to generate the modulated audio signal corresponding to the input audio signal. The apparatus of claim 2, wherein the pulse density modulating unit
Wherein at least one of a switching noise component and a power noise component is filtered in the input audio signal including the original audio signal and the modulated audio signal is output by pulse density modulation of the filtered input audio signal. . The apparatus of claim 3, wherein the pulse density modulating unit
And a delta sigma modulator for delta-sigma modulating the input audio signal to output a modulated audio signal. 3. The method of claim 2,
And a feedback loop for outputting a feedback signal obtained by attenuating and delaying the amplified audio signal to the pulse modulator. The apparatus of claim 5, wherein the pulse density modulating unit comprises:
A delta-sigma modulator for correcting at least one of a delay and a gain of the original audio signal based on the feedback signal to generate the input audio signal, and filtering at least one of a switching noise component and a power- And an audio signal output unit. 7. The apparatus of claim 6, wherein the delta sigma modulator
An adder for subtracting an output signal of the feedback loop from the original audio signal;
A loop filter for receiving an output signal of the summer adder and removing a noise component included in the output signal of the summer; And
And a quantizer for quantizing an output signal of the loop filter to generate the modulated audio signal. 6. The method of claim 5, wherein the feedback loop
An attenuator for attenuating the amplified audio signal by applying a predetermined subtraction gain value; And
And a delay unit delaying an output signal of the attenuation unit by a predetermined time in accordance with a sampling period of the pulse density modulation unit and outputting the feedback signal. The apparatus of claim 2, wherein the pulse density modulating unit
And a high-order 1-bit single-loop delta-sigma modulator for filtering at least one of a switching noise component and a power-supply noise component generated in the power switching amplifier included in the input audio signal and generating a 1-bit output signal. The audio signal output apparatus comprising: 3. The apparatus of claim 2, wherein the drive signal generator
Wherein the switching element generates the at least one driving signal for driving a positive power supply voltage or a negative power supply voltage. 11. The apparatus of claim 10, wherein the drive signal generator
And generates a first drive signal for driving the positive power supply voltage and a second drive signal for driving the negative power supply voltage. 12. The display device according to claim 11, wherein the switching amplifier
A first switching device that is turned on or off in response to the first driving signal, has one end connected to the positive power supply voltage and outputs the amplified audio signal to another end; And
And a second switching element which is turned on or off in response to the second driving signal and whose one end is connected to the negative power supply voltage and outputs the amplified audio signal to another end. Device. 12. The apparatus of claim 11, wherein the drive signal generator
A first transformer for boosting and outputting the first drive signal; And
Further comprising a second transformer for boosting and outputting the second drive signal. 2. The device of claim 1, wherein the gallium nitride transistor
Gallium nitride heterojunction field effect transistor. The method according to claim 1,
A low pass filter for converting the amplified audio signal into an analog signal; And
And a speaker unit converting the output signal of the low-pass filter into a physical vibration signal and outputting the physical vibration signal. Pulse modulating an input audio signal to output a modulated audio signal;
Generating at least one drive signal for controlling a switching amplification operation in accordance with the modulated audio signal; And
Wherein the drive signal is used to turn on or off at least one switching element comprising at least one of a gallium nitride transistor, a gallium arsenide transistor and a silicon carbide transistor to correspond to the modulated audio signal, And outputting an amplified audio signal to be transited in the audio signal,
Wherein the delay value of the amplified audio signal does not exceed the sampling period. 17. The method of claim 16,
Generating a feedback signal by attenuating and delaying the amplified audio signal; And
And correcting at least one of a delay and a gain of the original audio signal based on the feedback signal to generate the input audio signal. 18. The method of claim 17, wherein outputting the modulated audio signal comprises:
Filtering at least one of a switching noise component and a power noise component included in the input audio signal; And
And quantizing the filtered input audio signal to generate the modulated audio signal.

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