KR200371118Y1 - Ground Connection Circuit to Block the Switching Noise of a Digital Amplifier - Google Patents

Abstract

The present invention relates to a ground connection circuit for cutting off switching noise of a digital amplifier so that switching noise generated in a digital amplifier of an audio set employing a digital amplifier does not enter the other devices in the audio set through a ground line and cause a malfunction. .

The ground connection circuit of the present invention includes an inductor for blocking noise current generated in the digital amplifier from being applied to another device of the audio set; And a snubber for preventing a high voltage from being applied across the inductor by the turn-on-off operation of the power supplies, the snubber being directly connected to the ground of the audio set, And ground lines from the tuner, CD drive and audio control of the audio set.

According to the present invention, the noise generated by the switching operation of the digital amplifier can be prevented from entering other circuits in the audio set, thereby improving the performance of the audio set employing the digital amplifier.

Description

Ground connection circuit to block the switching noise of a digital amplifier

The present invention relates to a ground connection circuit for cutting off switching noise of a digital amplifier. More specifically, the ground wire from the digital amplifier of the audio set is connected to the ground wires from other components of the audio set through the ground connection circuit, so that the noise generated by the digital amplifier affects the other components of the audio set. It relates to a ground connection circuit that cuts off the noise so as not to cause damage.

In the past, analogue audio signals were recorded on magnetic tape or LP to reproduce audio signals. However, as digital technology advances, audio signals are recorded digitally on media such as CD or DVD to reduce information loss, and Sound quality has been achieved.

In order to reproduce a digital audio signal, a digital signal is converted to an analog signal using a digital-to-analog converter (DAC), and then the audio signal is reproduced by amplifying the signal with an analog amplifier. However, an analog amplifier using a vacuum tube or a transistor generates a signal distortion due to noise caused by electron thermal motion and incomplete linearity of an amplifying device, and has a problem in that power efficiency is not high.

Therefore, in recent years, digital amplifiers have been proposed to compensate for the shortcomings of analog amplifiers and to implement higher performance sound. However, since digital amplifiers have a lot of switching noise, it is easy to reduce the performance of other circuits.

1 is a block diagram schematically showing the configuration of an audio set using a conventional digital amplifier.

As shown in FIG. 1, the audio set includes a digital amplifier 140, a tuner 150, a CD driver 160, an audio controller 170, and a power supply device 100 to 130 for supplying power required for each device. And the like.

The tuner 150 is a device for selecting and receiving a radio wave by tuning to a radio wave having a specific frequency and receiving a radio signal of a specific frequency band set by a user. The CD driver 160 is a device for reproducing sound signals from a CD on which sound signals are recorded. The CD driver 160 is not limited to a CD player, and reproduces sound signals from various media such as a DVD on which digital sound signals are recorded. It includes. The audio controller 170 controls the overall operation of the audio set, and has additional functions such as an alarm function and a clock function as well as a control for reproducing an audio signal.

The digital amplifier 140 amplifies and reproduces a sound signal received from the tuner 150 or the CD driver 160 in a digital manner. As described above, the digital amplifier 140 converts the received audio signal into a pulse width modulation (PWM) signal. The PWM signal has a constant pulse size and transmits information about the original analog signal to the width of the pulse. Store in Therefore, the PWM signal can be defined in two states, 0/1 or ON / OFF, and amplifies the digital signal using a switching method.

However, since the digital amplifier 140 repeatedly performs the switching operation, noise is generated due to electromagnetic waves generated during the switching operation, and the noise of the digital amplifier 140 is the performance of other components of the audio set. Can affect.

Since components of the tuner 150 and the CD driver 160 of the audio set are connected to different power supplies, noise generated by the power supply voltage can be removed using a noise filter. However, since the ground line is for setting the electrical reference of each component, the ground lines of each component are connected to each other as shown in FIG. Therefore, noise generated in the digital amplifier 140 is transmitted to other component devices of the audio set through the ground line, thereby degrading the performance of other component devices.

In particular, when the tuner 150 tunes to a frequency corresponding to a switching frequency or a multiple of the switching frequency, the tuner 150 may not properly receive the frequency signal under the influence of the switching harmonic noise of the digital amplifier 140.

In order to solve the above problems, the present invention connects the ground line from the digital amplifier of the audio set with the ground lines from the other components of the audio set through the ground connection circuit, so that the noise generated in the digital amplifier is different from that of the audio set. An object of the present invention is to provide a ground connection circuit that cuts off noise so as not to affect a component device.

1 is a block diagram schematically showing the configuration of an audio set using a conventional digital amplifier;

2 is a block diagram showing a configuration of an audio set including a ground connection circuit for cutting off noise of a digital amplifier according to a preferred embodiment of the present invention;

3 to 5 are block diagrams showing the configuration of an audio set including a ground connection circuit including a snubber composed of diodes;

FIG. 6A illustrates an output signal of a tuner tuned to a tuner and outputting a broadcast frequency of 1332 KHz received through a tuner without applying the ground connection circuit of the present invention in an audio set including a digital amplifier having a switching frequency of 450 KHz. Graph showing waveforms,

Figure 6b is a waveform of the output signal of the tuner tuned to the tuner and outputting the broadcast frequency of 1332 KHz received through the tuner by applying the ground connection circuit of the present invention in an audio set including a digital amplifier having a switching frequency of 450 KHz to the tuner Graph showing

FIG. 7A shows an output signal of a tuner tuned to a tuner and outputting a broadcast frequency of 1350 KHz received through a tuner without applying the ground connection circuit of the present invention in an audio set including a digital amplifier having a switching frequency of 450 KHz. Graph showing waveforms,

7B shows a waveform of an output signal of a tuner tuned to a tuner and outputting a broadcasting frequency of 1350 KHz received through a tuner by applying the ground connection circuit of the present invention in an audio set including a digital amplifier having a switching frequency of 450 KHz. Is a graph.

<Explanation of symbols for the main parts of the drawings>

100, 110, 120, 130: power supply

140: digital amplifier 150: tuner

160: CD drive unit 170: audio control unit

200: ground connection circuit 202: inductor

204: snubber

According to an object of the present invention, in the ground connection circuit for blocking the noise generated in the digital amplifier of an audio set including a tuner, a CD drive unit, an audio control unit and a power supply, the noise current generated in the digital amplifier is An inductor blocking the application of the device to another device of the invention; And a snubber for preventing a high voltage from being applied across the inductor by a turn-on-off operation of the power supplies, the snubber being directly connected to the ground of the audio set, A ground connection circuit for blocking switching noise of a digital amplifier is connected to the ground line from the digital amplifier and the ground lines from the tuner, the CD driver, and the audio controller.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are used as much as possible even if displayed on different drawings. In addition, in describing the present invention, when it is determined that the detailed description of the related known configuration or function may obscure the subject matter of the present invention, the detailed description thereof will be omitted.

2 is a block diagram illustrating a configuration of an audio set including a ground connection circuit for cutting off noise of a digital amplifier according to a preferred embodiment of the present invention.

As shown in FIG. 2, an audio set including a ground connection circuit for blocking noise of a digital amplifier according to an exemplary embodiment of the present invention includes a digital amplifier 140, a tuner 150, a CD driver 160, The audio controller 170 may include a power supply device 100 to 130, a ground connection circuit 200, and the like that supply power to each device. Here, detailed description of the same components as those shown in FIG. 1 will be omitted.

The ground connection circuit 200 according to the preferred embodiment of the present invention is directly connected to the ground, and the ground line from the digital amplifier 140 is connected to the tuner 150 and the CD driver 160 through the ground connection circuit 200. And ground lines from the audio control unit 170. The ground connection circuit 200 includes an inductor 202 and a snubber 204 to block switching noise generated in the digital amplifier 140.

The inductor 202 has a characteristic that the impedance is 0 ohm (DC) directly in DC, and the impedance increases as the frequency increases. Therefore, when the inductor 202 is connected to the ground line from the digital amplifier 140 in series, the DC bias between the devices is normally maintained and the high frequency switching generated by the switching operation of the digital amplifier 140 is performed. Even if the noise current flows into the inductor 202, an induced current is generated to block the inflow of the noise current so that the noise current does not flow to other components in the audio set. As a result, performance degradation due to switching noise does not occur in the tuner 150, the CD driver 160, and the audio controller 170 of the audio set, and in particular, the reception function of the tuner 150 can be improved.

However, when only the inductor 202 is connected, a transient response generated by the turn-on-off operation of the power supplies 100 to 130 when power is applied to the audio set. A high voltage is applied across the inductor 202 so that circuits in the audio set may malfunction or be damaged. Therefore, the ground connection circuit 200 of the present invention is configured by connecting the snubber 204 in parallel with the inductor 202 in order to prevent high voltage from being applied across the inductor 202. Here, the snubber 204 circuit may be implemented using a diode, which will be described in detail with reference to FIGS. 3 to 5.

3 to 5 are block diagrams showing the configuration of an audio set including a ground connection circuit including a snubber composed of diodes.

As shown in FIG. 3, the snubber 204 of the present invention can be implemented by connecting two diodes in anti-parallel and connected in parallel with the inductor 202. Since the diode has a threshold voltage of about 0.6 to 0.7 V, a voltage above the threshold voltage of the diode is not applied to the inductor 202 even when the power supply is turned on. In addition, if the noise voltage generated in the digital amplifier 140 is lower than the threshold voltage, the noise voltage is not applied to other components of the audio set.

Meanwhile, when the noise voltage generated by the digital amplifier 140 is higher than the threshold voltage of the diode, as shown in FIG. 4, two or more diodes connected in series are connected in reverse parallel to each other to increase the threshold voltage, or FIG. 5. As shown in FIG. 2, two zener diodes may be connected in parallel to implement the snubber 204 circuit. Here, the zener diode has a characteristic that current starts to flow when a voltage higher than the breakdown voltage is applied in the reverse direction, but the voltage across the zener diode does not increase. It can serve to isolate the component from noise voltage.

As shown in FIGS. 6A, 6B, 7A, and 7B, oscilloscope waveform 1 (upper waveform) of the graph is a tuned signal from tuner 150, and oscilloscope waveform 2 (lower waveform) is waveform 1 This signal is amplified and output to the speaker. Here, the digital amplifier 140 of the audio set in which the waveforms shown in the graphs of FIGS. 6A, 6B, 7A and 7B are measured operates at a switching frequency of 450 KHz, and the tuner 150 is from 530 KHz to 1540 KHz. It is an AM tuner that receives signals in the frequency band of.

FIG. 6A illustrates an output signal of a tuner tuned to a tuner and outputting a broadcast frequency of 1332 KHz received through a tuner without applying the ground connection circuit of the present invention in an audio set including a digital amplifier having a switching frequency of 450 KHz. Figure 6b is a graph showing the waveform, Figure 6b is a tuner tuned to the broadcast frequency of 1332 KHz received through the tuner by applying the ground connection circuit of the present invention in an audio set including a digital amplifier having a switching frequency of 450 KHz with a tuner This graph shows the waveform of the output signal of the tuner.

FIG. 7A shows an output signal of a tuner tuned to a tuner and outputting a broadcast frequency of 1350 KHz received through a tuner without applying the ground connection circuit of the present invention in an audio set including a digital amplifier having a switching frequency of 450 KHz. Figure 7b is a graph showing the waveform, Figure 7b is a tuner tuned to the broadcast frequency of 1350 KHz received via the tuner by applying the ground connection circuit of the present invention in an audio set including a digital amplifier having a switching frequency of 450 KHz with a tuner This graph shows the waveform of the output signal of the tuner.

Since the switching noise generated in the digital amplifier 140 includes a switching frequency or a multiple of the switching frequency, the switching noise has frequency components such as 450 KHz, 900 KHz, 1350 KHz. The signal having a frequency of 1332 KHz is less affected by switching noise because it is different from the frequency of 1350 KHz, which is a multiple of the switching frequency, so that the ground connection circuit 200 of the present invention as shown in FIGS. Regardless of whether or not it is applied, the tuner 150 may normally receive and amplify the corresponding frequency signal.

However, since the signal having a frequency of 1350 KHz is the same frequency as the frequency of 1350 KHz, which is a multiple of the switching frequency, interference with switching noise having a frequency of 1350 KHz occurs and the reception sensitivity of the tuner 150 is reduced. Therefore, as shown in FIG. 7A, the tuner 150 is not synchronized with a signal having a frequency of 1350 KHz so that a noise waveform is output. On the other hand, when the ground connection circuit 200 of the present invention is applied, since the reception sensitivity of the tuner 150 is improved by cutting off switching noise having a frequency of 1350 KHz, the tuner 150 is shown in FIG. 7B. A signal having a frequency of 1350 KHz can be received and amplified.

The above description is merely illustrative of the present invention, and those skilled in the art to which the present invention pertains will be capable of various modifications without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present specification are not intended to limit the present invention but to describe the present invention, and the spirit and scope of the present invention are not limited thereto. The scope of the present invention should be construed by the claims below, and all the technologies within the equivalent scope should be construed as being included in the scope of the present invention.

As described above, the present invention connects a ground connection circuit between the ground line of the digital amplifier of the audio set and the ground line of another component of the audio set, so that the noise generated by the digital amplifier affects the other components of the audio set. There is an effect that can block the noise so as not to.

In addition, the ground connection circuit can be easily implemented using an inductor and snubber, and the performance of an audio set employing a digital amplifier can be improved.

Claims (4)

A ground connection circuit for blocking noise generated from a digital amplifier of an audio set including a tuner, a CD driver, an audio controller, and a power supply, An inductor which blocks noise current generated in the digital amplifier from being applied to another device of the audio set; And A snubber for preventing a high voltage from being applied across the inductor by a turn-on-off operation of the power supplies; A ground line directly connected to the ground of the audio set and connected to ground lines from the tuner, the CD driver, and the audio controller, for cutting off switching noise of the digital amplifier. Ground connection circuit. The method of claim 1, The snubber is a ground connection circuit for blocking switching noise of the digital amplifier, characterized in that the diode connected in parallel configuration. The method of claim 2, The snubber is a ground connection circuit for blocking the switching noise of the digital amplifier, characterized in that by configuring two or more diodes connected in series in a reverse parallel connection or a zener diode in a parallel connection. The method of claim 3, wherein And a different power supply device is connected to the digital amplifier, the tuner, the CD driver, and the audio controller to supply necessary power.