KR100582417B1 - a Graphic Equalizer Circuit of a Mobile Communication Terminal - Google Patents

Abstract

The present invention relates to a graphic equalizer circuit in a mobile communication terminal to implement a graphic equalizer function in hardware in a mobile communication terminal capable of playing an audio file, and includes an audio amplifier for amplifying and outputting an audio signal. A mobile communication terminal, comprising: a processor for giving a setting value for controlling a signal size of a specific frequency band; A first operational amplifier for amplifying an audio signal applied through the processor; A second operational amplifier for attenuating the audio signal output to the audio amplifier; A digital variable resistor unit configured to set a resistance value according to a set value provided by the processor and adjust a level of an audio signal applied through the first op amp according to the set resistance value; And a resonator configured to control the signal size according to the signal level of the digital variable resistor unit so as to achieve resonance of the audio signal, thereby significantly reducing the role of the processor so as to reduce the current consumption. At the same time, it is very easy to make ICs by eliminating elements constrained to becoming an integrated circuit (IC).

Description

Graphic equalizer circuit of a mobile communication terminal {a Graphic Equalizer Circuit of a Mobile Communication Terminal}             

1 is a block diagram illustrating a graphic equalizer circuit in a mobile communication terminal according to an exemplary embodiment of the present invention.

FIG. 2 is a circuit diagram showing the configuration of an equalizer in FIG. 1; FIG.

FIG. 3 is a circuit diagram illustrating a configuration of a digital potentiometer in FIG. 2. FIG.

4 is a circuit diagram showing the configuration of a resonator in FIG.

Explanation of symbols on the main parts of the drawings

10: processor 20-1, 20-2: equalizer

OP1, OP2: OP Amp

21-1 to 21-n: Digital potentiometer

22-1 to 22-n: resonator 23: controller

30: audio amplifier

The present invention relates to a graphic equalizer circuit in a mobile communication terminal, and more particularly, to a graphic equalizer circuit in a mobile communication terminal to implement a graphic equalizer function in hardware in a mobile communication terminal capable of playing an audio file.

In general, an equalizer is an electrical circuit for adjusting the overall frequency characteristic of an audio signal in a general audio device, and is mainly used to correct the characteristics of a recording or a speaker, or to emphasize a high note of a song.

Among these equalizers, Variable Equalizer has the advantage of freely manipulating audio signals compared to Fixed Equalizers such as Pre-emphasis or De-emphasis. One type of variable equalizer uses graphic equalizers.

The graphic equalizer may control the size of a signal for each frequency by using an adjustment terminal such as a slide bar. Also, since the slide bars for adjusting the signal size of each frequency are arranged in a line, the graph is called a graphic equalizer.

In addition, the graphic equalizer adjusts the signal size of a specific band by using an analog variable resistor, which is difficult to use in a mobile communication terminal due to problems such as its size or interface. .

Thus, in order to implement a graphic equalizer in a mobile communication terminal, another possible method is a software method for processing an MP3 (MPEG Layer 3) audio signal in the digital domain.

However, the method of processing the MP3 audio signal in the digital domain in software takes up a lot of processor resources, and therefore consumes a large amount of current in the processor due to a large amount of computation. It also has the disadvantage of requiring a lot of memory capacity.

That is, in the case of a mobile communication terminal, the processor used in the mobile communication terminal needs to perform various complex operations including call processing, thus requiring a lot of resources of the processor and consuming very much of the current. It also requires a lot of memory and is not suitable for mobile communication terminal applications.

SUMMARY OF THE INVENTION The present invention provides a graphic equalizer circuit in a mobile communication terminal to implement a graphic equalizer function in hardware in a mobile communication terminal capable of playing an audio file. have.

In addition, an object of the present invention is to hardware-implement the stereo graphic equalizer function that can be used in a mobile communication terminal capable of playing MP3 files.

In addition, the present invention implements the core elements that perform the stereo graphic equalizer function in hardware in a mobile communication terminal capable of playing MP3 files in the hardware, and only the control of the hardware to perform in the processor, thereby dramatically reducing the role of the processor Its purpose is to reduce the current consumption and to reduce the memory capacity.

In addition, the present invention implements a stereo graphic equalizer function without elements that are limited to the integrated circuit (IC) in a mobile communication terminal capable of playing MP3 files, so that it is very easy to IC and very low power consumption, The purpose is.

A graphic equalizer circuit in a mobile communication terminal according to an embodiment of the present invention for achieving the above object is a signal size of a specific frequency band in a mobile communication terminal having an audio amplifier for amplifying and outputting an audio signal. A processor which gives a setting value for controlling; A first operational amplifier for amplifying an audio signal applied through the processor; A second operational amplifier for attenuating the audio signal output to the audio amplifier; A digital variable resistor unit configured to set a resistance value according to a set value provided by the processor and adjust a level of an audio signal applied through the first op amp according to the set resistance value; It characterized in that it comprises a resonator for controlling the signal size according to the signal level control of the digital variable resistor unit to achieve the resonance of the audio signal.

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Preferably, the digital variable resistor unit may be programmable and implemented to digitize the variable resistor unit to be controlled by the processor.

Also preferably, the digital variable resistor unit may include: a plurality of switches configured to set the center tap position of the digital variable resistor unit in a plurality of stages to adjust the signal level of each resonator unit in a plurality of stages; A multiplex decoder for controlling opening and closing of each switch; An up / down counter for adjusting a center tap position of the digital variable resistor unit by increasing or decreasing a multiplicity decoder value connected thereto according to the control of the processor; And a nonvolatile memory configured to store information about a center tap position of the digital variable resistor unit.

Preferably, the resonator may be implemented in plural numbers for each frequency band by using an op amp, and may be connected to each of the digital variable resistors to control a plurality of frequencies.

The present invention implements a stereo graphic equalizer function in hardware in a mobile communication terminal capable of playing MP3 files. In this case, the variable resistor part is digitized to be controlled by an internal processor, and the resonance unit is implemented using an op amp. The resonator may be connected to the digital variable resistor to adjust the signal level of the resonator. In addition, the present invention is to control the 'n' frequency by using the 'n' resonator, and the 'm' step by connecting the digital variable resistor portion of the 'm' step to the resonant part corresponding to each frequency Control the signal size for each frequency. Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The graphic equalizer circuit in the mobile communication terminal according to an embodiment of the present invention is implemented in hardware so that it can be applied to a mobile communication terminal that can play an audio file (for example, an MP3 file) and control of the corresponding hardware in an internal processor. To accomplish this, it is implemented to enable low-power operation by reducing the size of each component and eliminating elements that are limited to IC. The overall hardware configuration includes a processor 10, equalizers 20-1 and 20-2, and an audio amplifier 30, as shown in FIG.

The processor 10 is a processor in a mobile station modem (MSM), or a processor in a separate multimedia chip, etc., and assigns a setting value for controlling a signal size of a specific frequency band to the equalizers 20-1 and 20-2. It gives the role that the size of the signal can be adjusted at the corresponding frequency. Here, the determination of the setting value is made after the user reads the value input by the user through the equalizer UI or the keypad displayed on the LCD of the mobile communication terminal. Alternatively, some combinations of setting values are generated in advance and stored in a memory (not shown in the figure for convenience of description) in the mobile communication terminal, and then the combinations of the setting values are applied. For example, in the case of Rock, Jazz, Classic, etc., a menu tree for this is constructed so that the user can select a desired item by displaying the menu tree through the LCD.

The equalizers 20-1 and 20-2 are applied to each of the right and left output signals using two because the processor 10 usually supports the output of MP3 files in stereo. The audio signal inputted from the processor 10 is transformed into a form desired by the user according to the control value applied according to the control, and is transmitted to the audio amplifier 30.

The audio amplifier 30 finally amplifies and outputs an audio signal applied from the equalizers 20-1 and 20-2.

As shown in FIG. 2, the equalizers 20-1 and 20-2 are composed of two op amps OP1 and OP2 and a plurality of digital variable resistors (eg, 'n'). 21-1 to 21-n, a plurality of (e.g., 'n') resonators 22-1 to 22-n, and a control unit 23.

The op amps OP1 and OP2 are positioned on an audio signal path, and the first op amp OP1 is a boost function (ie, a band pass) of an audio signal applied from the processor 10. The band-pass function, and the second op amp OP2 performs a cut function (ie, a notch function) of the audio signal output to the audio amplifier 30. .

Each of the digital variable resistor parts 21-1 to 21-n is programmable and implemented to be controlled by the processor 10 or the controller 23 by digitizing the variable resistor part, and the processor 10. Or three terminals except for the control input of the controller 23, the tab terminal in the middle of which is connected to each of the resonators 22-1 to 22-n, and the other two terminals are respectively It is connected to the op amps OP1 and OP2.

In addition, each of the digital variable resistor parts 21-1 to 21-n is connected to the resonator parts 22-1 to 22-n corresponding to each frequency band, and thus the respective resonator parts 22-1 to 22-n. Control the level of the signal, that is, the resistance value is set under the control of the processor 10 or the controller 23, and each resonator 22-1 to 22 connected to itself according to the set resistance value. -n) change the audio signal size.

Each of the resonators 22-1 to 22-n is implemented as a plurality of frequencies (e.g., 'n') for each frequency band using an op amp to control a plurality of frequencies (e.g., 'n'). According to the signal level control of each of the digital variable resistors 21-1 to 21-n, a plurality of steps (for example, 'm') are used to control signal sizes for respective frequency bands, thereby controlling the respective frequency bands. Resonance of the star signal is achieved.

The controller 23 controls the digital variable resistor units 21-1 to 21-n under the control of the processor 10 to determine the resistance values of the digital variable resistor units 21-1 to 21-n. Set it.

Each of the digital variable resistors 21-1 to 21-n has an up / down counter 24, a nonvolatile memory 25, and an m-th decoder 26, as shown in FIG. 3. ), A plurality of array resistors R1 to Rm-1, a plurality of switches S1 to Sm, and a resistor Rw.

The up / down counter 24 increases or decreases the value of the m-th decoder 26 connected thereto under the control of the processor 10 or the control unit 23 to control the digital variable resistor unit ( 21-1 to 21-n), adjust the position of the center tap.

The nonvolatile memory 25 stores position information on the center tap of the digital variable resistors 21-1 to 21-n.

The mth decoder 26 controls the opening and closing of the respective switches S1 to Sm according to the decoder value adjustment of the up / down counter 24.

Each of the switches S1 to Sm sets the center tap position of the digital variable resistors 21-1 to 21-n in an 'm' step according to the opening / closing control of the corresponding order-m decoder 26. Adjust the negative 22-1 ~ 22-n signal level in 'm' steps.

Each of the resonator parts 22-1 to 22-n includes the resistors R1 and R2, the capacitors C1 and C2, and the op amps OP, as shown in FIG. 4. In order to implement the resonators 22-1 to 22-n, the elements of the resistors, the inductors, and the capacitors are theoretically required, but the implementation of the inductor is important in an actual circuit. The resonance amplifier is implemented using the op amp, and the center frequency of the resonance circuit is determined by selecting appropriate values of the two capacitors C1 and C2 and the second resistor R2.

The operation of the graphic equalizer circuit in the mobile communication terminal according to an embodiment of the present invention will be described with reference to FIG. 1 as follows.

When the graphic equalizer is used in the mobile terminal, the user sets the frequency of the desired band through the equalizer UI or the keypad displayed on the LCD of the mobile terminal. When the user inputs data, MSM or multimedia The processor 10 in the chip or the like reads the input data, generates an equalizer setting value desired by the user from the input data, and controls the equalizers 20-1 and 20-2 so that the user himself or her desires. Allows you to listen to audio signals of a characteristic.

In other words, the processor 10 generates a setting value for controlling a signal size of a specific frequency band corresponding to the user's selection and assigns the set value to the equalizers 20-1 and 20-2 to signal the corresponding frequency. Allow the size of the to be adjusted.

Alternatively, a certain type of setting value (e.g., rock, jazz, classic, etc.) may be set, or some combination of setting values may be generated in advance and stored in a memory in the mobile communication terminal. After the menu tree is configured in the equalizer UI, the menu tree is displayed through the LCD to allow the user to select a desired setting value. For example, in the case of rock, jazz, classic, etc., a menu tree for this can be constructed to select a specific type of setting value desired by the user to listen to audio of a desired characteristic.

Accordingly, the equalizers 20-1 and 20-2 may form audio signals input from the processor 10 according to a setting value applied by the processor 10 (eg, lock, jazz, And the like to the audio amplifier 30.

Accordingly, the audio amplifier 30 finally amplifies and outputs the audio signals applied from the equalizers 20-1 and 20-2.

Meanwhile, the operations of the equalizers 20-1 and 20-2 will be described in detail with reference to FIG. 2 as follows.

First, the processor 10 directly controls the digital variable resistors 21-1 to 21-n or controls the processor 10 in the equalizers 20-1 and 20-2. By controlling the corresponding digital variable resistors 21-1 to 21-n according to the control of), the resistance values of the corresponding digital variable resistor parts 21-1 to 21-n are set.

Accordingly, the digital variable resistors 21-1 to 21-n set a resistance value under the control of the processor 10 or the controller 23, and resonator 22-1 to the corresponding resistance value. 22-n) to adjust the signal level.

Accordingly, the resonators 22-1 to 22-n control the size of the audio signal according to the signal level adjustment of the digital variable resistors 21-1 to 21-n to allow resonance of the corresponding audio signal. do.

Here, in order to control a plurality of frequencies (for example, 'n'), a plurality of (for example, 'n') digital variable resistor parts 21-1 to 21-n, and a plurality (for example, 'n' resonators 22-1 to 22-n are required. For example, when 'n' is 5, the frequencies of five bands can be adjusted. That is, the case corresponds to five slide bars of the equalizers 20-1 and 20-2.

The first operational amplifier OP1 performs an amplification function of the audio signal applied from the processor 10 among the two operational amplifiers OP1 and OP2 positioned on the audio signal path. OP2) attenuates the audio signal output to the audio amplifier 30.

At this time, the audio signal is amplified or attenuated in one frequency band depending on the position of the center tap of the digital variable resistors 21-1 to 21-n. When the tap connected to the center is positioned in the center, the audio signal is flattened and neither amplified nor attenuated, whereas the tap connected to the resonators 22-1 to 22-n moves to the 'H' display position. The more the audio signal is amplified, the more the audio signal is attenuated.

Using this principle, the amplification and attenuation of the audio signal is performed in the resonators 22-1 to 22-n corresponding to each frequency. The amplified amount and the attenuated amount are determined by the processor 10 or the controller ( It depends on the resistance value of the digital variable resistor parts 21-1 to 21-n set under the control of 23).

On the other hand, the operation of the digital variable resistors 21-1 to 21-n will be described in more detail with reference to FIG. 3 as follows.

The digital variable resistors 21-1 to 21-n perform similar operations in terms of their operation with general mechanical variable resistors, but control them electrically instead of mechanically in terms of control. The signal level of each corresponding resonator 22-1 to 22-n is adjusted.

First, the up / down counter 24 in the digital variable resistors 21-1 to 21-n has an m-th decoder connected to itself under control from the processor 10 or the controller 23. By increasing or decreasing the value of 26, the position of the center tap of the digital variable resistors 21-1 to 21-n is actually adjusted.

At this time, the position information on the center tap of the digital variable resistors 21-1 to 21-n is stored in an inactive memory 25 such as, for example, EEPROM. It is controlled by the processor 10 or the control from the controller 23, and thus information on the center tap position is stored in the inactive memory 25.

Thus, the m-th decoder 26 controls the opening and closing of each switch (S1 ~ Sm) according to the decoder value adjustment of the up / down counter 24, at this time whether the respective switches (S1 ~ Sm) are open or closed The center tap position of the 'm' stage can be set, and as a result, the signal levels of the resonators 22-1 to 22-n can be adjusted to the 'm' stage.

In this principle, when the 'n' of the resonators 22-1 to 22-n is used, the audio signal can be adjusted at 'n' frequencies, and thus, the digital variable resistor 21-1 at the 'm' stage. ~ 21-n), it is possible to set the signal size of the 'm' step for each frequency.

Alternatively, the stereo implementation may be performed using two equalizers 20-1 and 20-2 which perform the above-described operation, and the control of the two equalizers 20-1 and 20-2 may be controlled. Since it is performed by the processor 10, it is possible to implement a digital graphic equalizer.

As described above, the graphic equalizer circuit in the mobile communication terminal according to an embodiment of the present invention can process the sound when the mobile communication terminal user listens to an audio signal such as an MP3 file, and according to the type of sound source You can apply other settings (e.g., rock, jazz, classic, etc.), allowing you to listen to lively audio that was only possible with regular audio devices.

In addition, by creating icons such as the actual slide bar on the LCD of the mobile communication terminal can be used properly, such as the arrow keys on the keypad, the user can feel the control of the equalizer directly, and several settings (eg For example, Rock, Jazz, Classic, etc.) are stored in memory in advance and the menu tree is constructed on the LCD so that the user can select the desired setting value among the menus.

In addition, the graphic equalizer circuit in the mobile communication terminal according to an embodiment of the present invention significantly reduces the amount of computation of the processor by processing the hardware rather than the software, thereby securing a large amount of resources of the processor. Processor resources can be applied to other applications, and current consumption can also be reduced by reducing the computational complexity of the processor.

At this time, in the IC of the graphic equalizer circuit in the mobile communication terminal according to an embodiment of the present invention, by eliminating the elements that are constrained to IC, and at the same time to reduce the size of each component, the area of the entire circuit is greatly reduced In addition, it can be inserted as a part in a multi-function chip such as an MSM chip, further reducing its area, and the amount of current consumed by the hardware is not large.

As described above, in the mobile communication terminal capable of playing MP3 files according to the present invention, by implementing the core elements to perform the stereo graphic equalizer function in hardware and only the control of the hardware to perform the processor, the role of the processor significantly It is possible to reduce the current consumption and reduce the memory capacity by reducing the current, and at the same time, it is very easy to IC by removing the elements constrained by the IC.

Claims (7)

A mobile communication terminal having an audio amplifier for amplifying and outputting an audio signal, A processor for giving a setting value for controlling a signal size of a specific frequency band; A first operational amplifier for amplifying an audio signal applied through the processor; A second operational amplifier for attenuating the audio signal output to the audio amplifier; A digital variable resistor unit configured to set a resistance value according to a set value provided by the processor and adjust a level of an audio signal applied through the first op amp according to the set resistance value; And a resonator configured to resonate an audio signal by controlling a signal size according to the signal level of the digital variable resistor unit. delete delete delete The method of claim 1, And the digital variable resistor unit is programmable and is implemented to digitize the variable resistor unit so as to be controlled by the processor. The method of claim 1, The digital variable resistor unit includes a plurality of switches for setting the center tap position of the digital variable resistor unit in a plurality of stages to adjust the signal level of each resonator unit in a plurality of stages; A multiplex decoder for controlling opening and closing of each switch; An up / down counter for adjusting a center tap position of the digital variable resistor unit by increasing or decreasing a multiplicity decoder value connected thereto according to the control of the processor; And a nonvolatile memory configured to store information about a center tap position of the digital variable resistor unit. The method of claim 1, The resonator unit is implemented in a plurality of frequency bands for each frequency band by using the op amp graphic equalizer circuit in a mobile communication terminal, characterized in that for controlling the plurality of frequencies connected to each of the digital variable resistor.

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