KR20130011234A - Analog class ab amplifier for audio - Google Patents

Analog class ab amplifier for audio Download PDF

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Publication number
KR20130011234A
KR20130011234A KR1020110072235A KR20110072235A KR20130011234A KR 20130011234 A KR20130011234 A KR 20130011234A KR 1020110072235 A KR1020110072235 A KR 1020110072235A KR 20110072235 A KR20110072235 A KR 20110072235A KR 20130011234 A KR20130011234 A KR 20130011234A
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KR
South Korea
Prior art keywords
output
output node
amplifier
input terminal
transistor
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KR1020110072235A
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Korean (ko)
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이승제
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제이에이취엔지니어링주식회사
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Priority to KR1020110072235A priority Critical patent/KR20130011234A/en
Publication of KR20130011234A publication Critical patent/KR20130011234A/en

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/32—Modifications of amplifiers to reduce non-linear distortion
    • H03F1/3217—Modifications of amplifiers to reduce non-linear distortion in single ended push-pull amplifiers
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/32—Modifications of amplifiers to reduce non-linear distortion
    • H03F1/3241—Modifications of amplifiers to reduce non-linear distortion using predistortion circuits
    • H03F1/3276—Modifications of amplifiers to reduce non-linear distortion using predistortion circuits using the nonlinearity inherent to components, e.g. a diode
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/26—Push-pull amplifiers; Phase-splitters therefor
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/45—Differential amplifiers
    • H03F3/45071—Differential amplifiers with semiconductor devices only
    • H03F3/45076—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier
    • H03F3/4508—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier using bipolar transistors as the active amplifying circuit
    • H03F3/45174—Mirror types

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Amplifiers (AREA)

Abstract

The present invention relates to an analog class AB amplifier for audio. According to one aspect of the present invention, an analog class AB amplifier comprising a biasing circuit for minimizing cross distortion of an output signal outputted from a complementary push-pull transistor and a push-pull transistor and output from an output terminal (Vout). The push-pull transistor comprises: a first end connected to an electrostatic source input terminal and a base or gate electrode connected to a first output node and connected to an emitter or source electrode side in response to a change in voltage level at the first output node. A first transistor for outputting to an output terminal; A second transistor connected to a sub-power input terminal and having a base or gate electrode connected to a second output node and output to an output terminal connected to an emitter or source electrode in response to a change in voltage level at the second output node; ; The biasing circuit includes: a bias voltage provided between the first output node and the second output node and configured to compensate for a voltage drop between the base or gate electrode and the emitter or source electrode of each of the first and second transistors. A first diode and a second diode to produce; An upper current mirror circuit for flowing the current output from the electrostatic source input terminal to an output side opposite to the output side connected to the first output node; A lower current mirror circuit configured to mirror the current flowing from the second output node to the negative power input terminal and the current flowing from the opposite output side of the upper current mirror circuit to the negative power input terminal and to be discharged to the negative power input terminal; There is proposed an analog class AB amplifier comprising a.

Description

ANALOG CLASS AB AMPLIFIER FOR AUDIO

The present invention relates to an analog class AB amplifier for audio. Specifically, it relates to an audio class AB amplifier having a current mirror circuit in order to minimize cross distortion of an output signal.

In general, an analog amplification circuit is widely used as an audio amplifier. Analog amplifier circuits include amplifier circuits such as class A, class B, and class AB. For audio amplifiers, linearity has been emphasized more than high efficiency. Analog amplifiers have the disadvantage of having poor linearity at the expense of good linearity.

In particular, class A amplifiers have a loss that is greater than the amplifier's maximum output, resulting in an efficiency that does not exceed 25%. Push-pull Class B amplifiers are adopted to overcome this problem by combining two transistors, eg BJTs in the form of emitter followers, to reduce energy loss. However, the efficiency is relatively higher than Class A, but crossover distortion occurs at a small signal level. In addition, the two transistors present in the class B amplifier are alternately turned on and off, and since the bias current does not flow at all times in general, fast on / off is difficult especially in a large current region, and thus harmonic distortion (Total) Harmonic Distortion (THD) worsens.

The class AB amplifier (Class AB), which combines the advantages and disadvantages of class A and class B, allows a certain amount of current to flow even in a static state, thereby solving crossover distortion at a small signal level. Doing.

Fig. 1 is a circuit diagram showing a conventional analog class AB amplifier for audio.

Referring to FIG. 1, the first and second diodes D 1 and D 2 are provided to compensate for the crossover distortion at a small level of the signal to compensate for the voltage drop between the base and the emitters, thereby providing cross distortion. I'm solving it. On the other hand, at this time, since the sound quality is excellent as the voltages of the input terminal Vin and the output terminal Vout are the same, it is necessary to make the voltages of the input terminal Vin and the output terminal Vout the same.

In addition, referring to the conventional analog class AB amplifier for audio as shown in FIG. 1, when the temperature increases, the base-emitter voltage Vbe decreases, and the base current Ib increases accordingly. As Ib) increases, the collector current Ic also increases, generating more heat in the bipolar transistor, repeatedly lowering the base-emitter voltage Vbe, and increasing Ic, resulting in thermal runaway of the transistor. Is damaged, so that the thermal runaway prevention transistor 70 is provided. Q 21 and the thermal runaway prevention transistor 70 of the Q 22 of Figure 1 also, as the base the temperature rises Q 21 and Q 22 - is already as teogan voltage (Vbe) is lowered, by lowering the bias voltage to prevent thermal runaway.

In the present invention, in configuring a biasing circuit for solving cross distortion in an analog class AB amplifier that can be used for audio, the voltage at the input terminal and the output terminal can be equalized more precisely. The company aims to provide an analog class AB amplifier for audio that can be biased easily without the need.

To this end, in the present invention, by configuring a biasing circuit using a current mirror circuit to minimize the cross-distortion of the output signal, to provide an analog class AB amplifier for audio that can be more precise biasing control.

In addition, in one aspect of the present invention, it is intended to enable precise biasing control without having to provide a separate thermal runaway circuit.

In order to achieve the above object, according to one aspect of the present invention, a complementary push-pull transistor and a biasing circuit for minimizing the cross-distortion of the output signal is output from the output terminal combined with the push-pull transistor For analog class AB amplifiers, the push-pull transistors are: a first stage connected to the electrostatic input terminal, a base or gate electrode connected to the first output node, and in response to a change in voltage level at the first output node; A first transistor for outputting to an output terminal connected to the source electrode side; A second transistor connected to a sub-power input terminal and having a base or gate electrode connected to a second output node and output to an output terminal connected to an emitter or source electrode in response to a change in voltage level at the second output node; ; The biasing circuit includes: a bias voltage provided between the first output node and the second output node and configured to compensate for a voltage drop between the base or gate electrode and the emitter or source electrode of each of the first and second transistors. A first diode and a second diode to produce; An upper current mirror circuit for flowing the current output from the electrostatic source input terminal to an output side opposite to the output side connected to the first output node; A lower current mirror circuit configured to mirror the current flowing from the second output node to the negative power input terminal and the current flowing from the opposite output side of the upper current mirror circuit to the negative power input terminal and to be discharged to the negative power input terminal; There is proposed an analog class AB amplifier comprising a.

Preferably, according to another aspect of the present invention, the upper and lower current mirror circuit is characterized in that the current mirror circuit laminated at least two stages, respectively.

Also preferably, in accordance with another aspect of the present invention, a resistor is provided between each emitter or source electrode of the first and second transistors and the output terminal.

Preferably, according to yet another aspect of the present invention, the first diode and the first transistor, and the second diode and the second transistor are each thermally coupled on one wafer.

Preferably, according to another aspect of the present invention, the first and second transistors are BJTs.

Further preferably, according to another aspect of the present invention, the upper and lower current mirror circuits are made using BJT.

Although not explicitly mentioned as one preferred aspect of the present invention, it is apparent that embodiments of the present invention according to various possible combinations of the above-mentioned technical features can be obviously implemented to those skilled in the art.

According to the aspect of the present invention, the voltage of the input terminal and the output terminal can be exactly the same, and furthermore, the analog class AB amplifier used for the audio which can be easily biased control without the conventional thermal runaway prevention circuit is provided. It became.

According to the present invention, by constructing a biasing circuit using a current mirror circuit, an analog class AB amplifier for audio capable of minimizing cross distortion of an output signal and enabling more precise biasing control is provided. In addition, according to the aspect of the present invention, precise biasing control is possible without having to provide a separate thermal runaway circuit.

It is apparent that various effects not directly referred to in accordance with various embodiments of the present invention can be derived by those of ordinary skill in the art from the various configurations according to the embodiments of the present invention.

Fig. 1 is a circuit diagram showing a conventional analog class AB amplifier for audio.
2 is a circuit diagram illustrating an analog class AB amplifier for audio according to an embodiment of the present invention.
3 is a circuit diagram illustrating an analog class AB amplifier for audio according to another embodiment of the present invention.

Embodiments of the present invention for achieving the above object are described with reference to the accompanying drawings. In describing the embodiments, the same reference numerals refer to the same configuration, and additional descriptions that may overlap or limit the meaning of the invention may be omitted in describing the embodiments of the present invention.

Prior to the detailed description, unless a component is referred to herein as being 'directly connected' or 'directly connected' to another component, one component is simply referred to as 'connected' or 'connected'. The elements may be connected or connected 'directly' to other components, and furthermore in the form in which another component is connected or connected between them unless contradictory to the description or contrary to the inventive concept. It should be understood that it can exist.

Although described in the singular form in this specification, it is not contrary to the concept of the invention in light of the environment in which the singular / plural is used without distinction between the singular and plural forms and the ordinary terminology used in the art. It is used in the sense that it includes plural expressions unless otherwise contradicted or clearly different from each other. It is to be understood that the term 'comprises', 'haves', 'comprises', 'comprises', etc., in the present specification does not preclude the existence or addition of one or more other features or components or combinations thereof in advance. .

FIG. 2 is a circuit diagram showing an analog class AB amplifier for audio according to an embodiment of the present invention, and FIG. 3 is a circuit diagram showing a class AB amplifier for audio according to another embodiment of the present invention.

2 and 3, an analog class AB amplifier for audio according to an embodiment of the present invention will be described.

2 and 3, the analog class AB amplifier for audio according to one embodiment of the present invention is complementary to the push-pull transistors 10 and 20 and the push-pull transistors 10 and 20, like the conventional class AB amplifier. And a biasing circuit for minimizing cross-distortion of the output signal outputted at the output terminal) and output at the output terminal (Vout).

2 or 3, the complementary push-pull transistors 10 and 20 include a first transistor Q 11 10 and a second transistor Q 12 20. The current is pushed by the first transistor Q 11 (10) and pulled by the second transistor Q 12 (20). The first transistor Q 11 10 has a first end connected to the electrostatic source input terminal Vcc and a base or gate electrode connected to the first output node 11. The first transistor Q 11 10 outputs to the output terminal Vout connected to the emitter or source electrode side in response to the change of the voltage level at the first output node 11. The second transistor Q 12 (20) has a first end connected to a negative power input terminal (Vss), a base or gate electrode connected to a second output node 21, and a voltage level at the second output node 21. In response to the change, the output is output to the output terminal Vout connected to the emitter or source electrode side. At the output terminal Vout, the output value through the first transistor Q 11 (10) and the output value through the second transistor Q 12 (20) are summed and output. In the present exemplary embodiment, the first and second transistors 10 and 20 may be bipolar transistors BJT or field effect transistors (FETs). Preferably, in another embodiment, the first and second transistors 10, 20 are bipolar transistors BJT. Although only bipolar transistors are shown as examples of the first and second transistors 10 and 20 in FIG. 2 or 3, it will be obvious to change to FETs such as MOSFETs, which are not shown by those skilled in the art.

A biasing circuit, which is a characteristic configuration of the present invention, is for minimizing cross distortion of an output signal in an analog analog AB amplifier for audio. In this embodiment, the first and second diodes 30 and 40 and the upper current mirror circuit 50 are provided. 50 '), and lower current mirror circuits 60 and 60'.

In this case, the first and second diodes 30 and 40 are provided between the first output node 11 and the second output node 21. The first and second diodes 30 and 40 generate bias voltages to compensate for the voltage drop between the base or gate electrode and the emitter or source electrode of each of the first and second transistors 10, 20. By doing so, the first and second diodes 30 and 40 compensate for the cross-distortion of the output signal and furthermore, the voltage drop, e.g., between base and emitter, as the temperature of the first and second transistors 10 and 20 increases. It compensates for the voltage drop. Preferably, the first and second diodes 30 and 40 respectively enhance thermal coupling with the first and second transistors 10 and 20 to more effectively compensate for voltage drops, such as voltage drop between base and emitter. Can be.

The upper current mirror circuits 50 and 50 'mirror the current output from the electrostatic source input terminal Vcc to the output side opposite to the output side connected to the first output node 11 to flow. That is, the current flowing through the output side opposite to the output side connected to the first output node 11 of the upper current mirror circuits 50 and 50 'is equal, and at this time, the output current becomes the current source I 3 . .

In addition, the lower current mirror circuits 60 and 60 'exit from the second output node 21 and the current flowing to the negative power input terminal Vss and the opposite output side of the upper current mirror circuits 50 and 50'. The current flowing to the negative power supply input terminal Vss is mirrored and is drawn out to the negative power supply input terminal Vss.

Preferably, the upper and lower current mirror circuits 50, 50 ′, 60, 60 ′ may be current mirror circuits using bipolar transistors BJT or current mirror circuits using field effect transistors (FETs). Preferably, according to another embodiment of the present invention, the upper and lower current mirror circuits 50, 50 ', 60, 60' are bipolar transistors BJT Q 1 as shown in Figs. , Q 2 , Q 3 , Q 4 , Q 5 , Q 6 , Q 7 , and Q 8 ). Although only the bipolar transistor BJT is shown as a transistor constituting the current mirror circuit in FIGS. 2 and 3, it will be obvious to change to an FET, for example, a MOSFET, which is not shown by those skilled in the art.

By configuring the upper current mirror circuits 50 and 50 'and the lower current mirror circuits 60 and 60' as described above, a constant current flows through the first and second diodes 30 and 40 so that the first and second It is possible to more accurately compensate for cross distortion of the output signal in the two diodes (30, 40). As a result, the voltage at the input terminal Vin and the output terminal Vout is kept the same, so that good sound quality can be obtained.

3, another embodiment of the present invention will be described.

Referring to FIG. 3, the upper and lower current mirror circuits 50 'and 60' are at least two stacked current mirror circuits, respectively. 3 shows current mirror circuits 50 'and 60' stacked in two stages. At this time, the upper and lower current mirror circuits 50 ', 60' are bipolar transistors BJT (Q 1 , Q 2 , Q 3 , Q 4 , Q 5 , Q 6 , Q 7 , Q 8 ) (51, 52). , 53, 54, 61, 62, 63, 64, or a current mirror circuit using a field effect transistor (FET), and preferably, as shown in FIG. BJT) is a mirror circuit.

As shown in FIG. 3, the two-stage current mirror circuits 50 'and 60' are disposed up and down, so as to provide a precise current source function, and output signals from the first and second diodes 30 and 40. FIG. It is possible to compensate more precisely the cross distortion of.

2 and 3, another embodiment of the present invention will be described.

2 and 3, resistors R 11 and R 12 are provided between each emitter or source electrode and output terminal of the first and second transistors 10 and 20, respectively.

Referring to FIG. 2, a load L is connected to the output terminal, and the load L is illustrated as a resistor in FIG. 3.

Looking at another embodiment of the present invention, although not shown, the first diode and the first transistor 10, and the second diode and the second transistor 20 are each thermally coupled on one wafer. Accordingly, the thermal coupling may be enhanced to more effectively compensate for voltage drops in the first and second transistors 10 and 20, for example, the base-emitter voltage drop Vbe in the case of a bipolar transistor BJT. .

In the foregoing, the present invention has been described with reference to the preferred embodiments thereof with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings and the foregoing embodiments are provided by way of illustration for purposes of clarity of understanding to those skilled in the art to which the present invention pertains. It is, therefore, to be understood that the various embodiments of the present invention may be embodied in various forms without departing from the essential characteristics thereof, and the above-described embodiments are to be considered as illustrative and not restrictive. Accordingly, the scope of the present invention should be construed in accordance with the invention as set forth in the appended claims rather than the foregoing embodiments, and various changes, alternatives, and equivalents by those skilled in the art may be made by the inventions It is obvious that it is included in the range of.

10: first transistor 11: first output node
20: second transistor 21: second output node
30: first diode 40: second diode
50, 50 ': upper current mirror circuit 60, 60': lower current mirror circuit

Claims (6)

An analog class AB amplifier comprising a biasing circuit for minimizing cross distortion of a complementary push-pull transistor and an output signal outputted from the push-pull transistor and output at an output terminal (Vout),
The push-pull transistor includes: a first terminal connected to an electrostatic source input terminal, a base or gate electrode connected to a first output node, and connected to an emitter or source electrode side in response to a change in voltage level at the first output node; A first transistor for outputting to an output terminal; A first terminal connected to a sub-power input terminal, a base or gate electrode connected to a second output node, and outputting to the output terminal connected to an emitter or source electrode side in response to a change in voltage level at the second output node; 2 transistors; Including,
The biasing circuit may include: a bias voltage provided between the first output node and the second output node and configured to compensate for a voltage drop between the base or gate electrode and the emitter or source electrode of each of the first and second transistors. A first diode and a second diode to produce; An upper current mirror circuit for flowing the current output from the electrostatic source input terminal to an output side opposite to an output side connected to the first output node; A lower current that mirrors the current flowing from the second output node toward the negative power input terminal and the current flowing from the opposite output side of the upper current mirror circuit to the negative power input terminal and mirrors and exits the negative power input terminal. Mirror circuits; Analog class AB amplifier, characterized in that comprises a.
The method according to claim 1,
The upper and lower current mirror circuit is an analog class AB amplifier, characterized in that each of the at least two stacked current mirror circuit.
The method according to claim 1,
An analog class AB amplifier, characterized in that a resistor is provided between each emitter or source electrode of the first and second transistors and the output terminal.
The method according to claim 1,
Wherein said first diode and said first transistor, and said second diode and said second transistor are each thermally coupled on a single wafer.
5. The method according to any one of claims 1 to 4,
The analog class AB amplifier, characterized in that the first and second transistors using BJT.
5. The method according to any one of claims 1 to 4,
The upper and lower current mirror circuit is an analog class AB amplifier, characterized in that using the BJT.
KR1020110072235A 2011-07-21 2011-07-21 Analog class ab amplifier for audio KR20130011234A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101694242B1 (en) * 2015-12-15 2017-01-09 현대오트론 주식회사 Power amplifier including a protection circuit

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101694242B1 (en) * 2015-12-15 2017-01-09 현대오트론 주식회사 Power amplifier including a protection circuit

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