KR20240098312A - Volume Compressor Using Variable Gain Amplifier - Google Patents

Abstract

Disclosed is a volume compressor using a variable gain amplifier. A volume compressor using a variable gain amplifier of the present invention includes an input stage consisting of a variable gain amplifier; a compression stage that compresses the intermediate output whose gain is adjusted by the input stage using a predefined algorithm; and an output stage that outputs the sound compressed by the compression stage.

Description

Volume Compressor Using Variable Gain Amplifier}

The present invention relates to a volume compressor, and more specifically, to a volume compressor using a variable gain amplifier.

Reduction of the dynamic range of audio signals is an important topic in the fields of sound recording, sound reproduction, and broadcasting. The reduction in dynamic range may be relative to the adjustment of the characteristics of the audio signal in the physical capabilities used by the audio device.

A compressor may be used to reduce the dynamic range of the audio signal. The compression characteristics of a compressor can be adjusted with a number of compression parameters that have a significant impact on the perceived sound quality of the audio signal. Adjustment of these parameters can be difficult due to the complexity of human acoustic perception and is greatly influenced by the properties of the audio signal.

Adjustment of compressor parameters is usually performed manually by an experienced user. There is no intuitive mechanism to control the compression of the audio signal while maintaining high perceptual quality of the audio signal at the same time. When designing a compressor, there is a need to develop technology for compressing sound volume using a variable gain amplifier.

Patent Document 1: Korean Patent Publication No. 10-2016-0113224 (Publication date: 2016.09.28.) Patent Document 2: Korean Patent No. 10-1855969 (Announcement Date: 2018.06.25.) Patent Document 3: Korean Patent No. 10-1112565 (Announcement Date: 2012.02.15.) Patent Document 4: Korean Patent No. 10-1261212 (Publication Date: 2013.05.07)

The purpose of the present invention, which was created in response to the above-described necessity, is to provide a volume compressor using a VCA that compresses volume using a variable gain amplifier.

In order to achieve the above object, according to an embodiment of the present invention, the performance of the sound compressor can be improved by varying the gain according to the control voltage using a variable gain amplifier. Variable gain (VGA) or voltage control amplifier (VCA) ) is a type of electronic amplifier whose gain varies depending on the control voltage (often abbreviated as CV).

Voltage-controlled amplifiers have many applications, including audio level compression, synthesizers, and amplitude modulation. One example is the inverting configuration of a typical operational amplifier with a light dependent resistor (LDR) in the feedback loop. The gain of the amplifier then depends on the light falling on the LDR, which can be provided by an LED (optocoupler). The gain of the amplifier can then be controlled by the current passing through the LED. This is similar to the circuit used in optical audio compressors.

A voltage-controlled amplifier can be realized by first creating a voltage-controlled resistor (VCR), which is used to set the amplifier gain. A VCR is one of many interesting circuit elements that can be created using a junction field-effect transistor (JFET) with simple biasing. VCRs manufactured in this way can be obtained as individual devices. For example, there is VCR2N.

Another type of circuit uses an operating transconductance amplifier. In audio applications, logarithmic gain control is used to emulate how the ear hears sound. David E. Blackmer's dbx 202 voltage-controlled amplifier, based on the Blackmer gain cell, may have been one of the first successful implementations of a logarithmic voltage-controlled amplifier.

An analog multiplier is a type of voltage-controlled amplifier designed to have precise linear characteristics, both inputs are equal, and unlike most other voltage-controlled amplifiers, it can also operate in all four voltage quadrants.

A digitally controlled amplifier (DCA) is a digitally controlled variable gain amplifier. Digitally controlled amplifiers can use a stepwise approach to provide gradual gain selection increments to the circuit.

In its basic form, a toggle switch connected to a feedback resistor can provide two separate gain settings. This is not a computer-controlled function, but it describes the core functionality. If there are eight switches and eight resistors in the feedback loop, each switch can cause a specific resistor to control the amplifier's feedback. If each switch is converted to a relay, a microcontroller can be used to activate the relay to achieve the desired amount of gain.

The relay can be replaced with an appropriate type of field-effect transistor to reduce the mechanical characteristics of the design. Other devices such as the CD4053 bidirectional CMOS analog multiplexer integrated circuit and digital potentiometers (combined resistor string and MUX) can perform the switching function well. To minimize the number of switches and resistors, combinations of resistor values can be utilized by activating multiple switches.

According to various embodiments of the present invention, the dynamic range can be reduced while maintaining high perceptual quality of the audio signal.

1 is a diagram illustrating an example of a circuit diagram of a power supply unit of a sound compressor equipped with a variable gain amplifier according to an embodiment of the present invention;
Figure 2 is a diagram showing an example of an input circuit diagram of a sound compressor equipped with a variable gain amplifier according to an embodiment of the present invention;
FIG. 3 is a diagram illustrating an example of a main circuit diagram of a volume compressor equipped with a variable gain intensifier according to an embodiment of the present invention, and
Figure 4 is a diagram showing an example of a circuit diagram of the output stage of a sound compressor equipped with a variable gain amplifier according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. The preferred embodiments described below may be subject to various design changes within the scope of the technical idea of the present invention.

A volume compressor using a variable gain amplifier includes an input stage consisting of a variable gain amplifier, a compression stage that compresses the intermediate output whose gain is adjusted by the input stage using a predefined algorithm, and an output stage that outputs the sound compressed by the compression stage. do. The input terminal may further include a power supply unit that rectifies the applied voltage and outputs it as a two-terminal voltage.

The input stage operates by the power output from the power supply unit, and the gain can be varied and applied as an input to the compression stage. The compression stage applies the output signal from the input stage as an input and amplifies it. The amplified signals are mixed and applied to the input of another amplifier to output variable gain. The output stage may further include an amplifier that performs variable gain amplification by changing the variable gain using a variable resistor.

Figure 1 is a diagram illustrating an example of a circuit diagram of a power supply unit of a sound compressor equipped with a variable gain amplifier according to an embodiment of the present invention. Referring to Figure 1, for example, when 9 volts is applied as the applied voltage, the circuit diagram is configured in a ladder form so that the output voltage is +9V and -9V at the two terminals, and the diode (IN4001) and the first capacitor (100u) The output voltage can be adjusted using a switching voltage regulator (ICL 7660). A 1 microfarad capacitor can be connected between terminals 2 and 4 of the switching voltage regulator, and a 1 microfarad capacitor can also be connected between the 5th terminal and ground.

Figure 2 is a diagram illustrating an example of an input circuit diagram of a volume compressor equipped with a variable gain amplifier according to an embodiment of the present invention. Referring to Figure 2, an input capacitor is provided on the left side of the input terminal, and the voltage is divided by a resistor and is input as an applied voltage to the input voltage of the first amplifier. A switch may be provided at the output terminal of the first amplifier and may be applied as an input voltage to the amplification stage of the second stage. Voltage is applied to the second to fourth amplifiers, and the second amplifier outputs the output voltage of the input terminal. The output voltage of the third amplifier can be used as an applied voltage to the second amplifier, and the output voltage of the fourth amplifier can be configured to be used as an applied voltage to the third amplifier.

Figure 3 is a diagram illustrating an example of a circuit diagram of the main part of a volume compressor equipped with a variable gain intensifier according to an embodiment of the present invention. Referring to Figure 3, when applied to the fifth amplifier, two amplifiers are connected to the output terminal in a cascade manner. The sixth amplifier is configured to function as a filter, and the seventh amplifier adjusts the applied voltage according to the variable resistance to finally output an output voltage with a variable gain applied to the output stage.

Figure 4 is a diagram illustrating an example of a circuit diagram of the output stage of a volume compressor equipped with a variable gain amplifier according to an embodiment of the present invention. Referring to FIG. 4, the output stage circuit diagram can be configured to reduce the dynamic range when constructing a volume compressor by adopting a structure that can take variable gain by utilizing a plurality of amplifiers.

Claims (5)

In a volume compressor using a variable gain amplifier,
An input stage consisting of a variable gain amplifier;
a compression stage that compresses the intermediate output whose gain is adjusted by the input stage using a predefined algorithm; and
Including an output stage that outputs the sound compressed by the compression stage,
Loudness compressor using a variable gain amplifier.
According to claim 1,
The input terminal further includes a power supply unit that rectifies the applied voltage and outputs it as a two-terminal voltage.
Loudness compressor using a variable gain amplifier.
According to clause 2,
The input stage is operated by power output from the power supply unit, and the gain is varied and applied as an input to the compression stage,
Loudness compressor using a variable gain amplifier.
According to clause 3,
The compression stage applies the output signal of the input stage as an input and amplifies it, mixes the amplified signals, and applies them to the input of another amplifier to output the output with variable gain.
Loudness compressor using a variable gain amplifier.
According to clause 4,
The output stage further includes an amplifier that performs variable gain amplification by changing the variable gain with a variable resistor.
Loudness compressor using a variable gain amplifier.