WO2002089320A1 - High efficiency power amplifier - Google Patents

High efficiency power amplifier Download PDF

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Publication number
WO2002089320A1
WO2002089320A1 PCT/KR2002/000747 KR0200747W WO02089320A1 WO 2002089320 A1 WO2002089320 A1 WO 2002089320A1 KR 0200747 W KR0200747 W KR 0200747W WO 02089320 A1 WO02089320 A1 WO 02089320A1
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WO
WIPO (PCT)
Prior art keywords
voltage
signal
power amplifier
vcc
trigger signal
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Application number
PCT/KR2002/000747
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French (fr)
Inventor
Bum-Jong Ko
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Bum-Jong Ko
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Publication of WO2002089320A1 publication Critical patent/WO2002089320A1/en

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Classifications

    • 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
    • H03F1/02—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation
    • H03F1/0205—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in transistor amplifiers
    • H03F1/0211—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in transistor amplifiers with control of the supply voltage or current
    • H03F1/0244—Stepped control
    • H03F1/025—Stepped control by using a signal derived from the input signal
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
    • H03F3/21—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers with semiconductor devices only
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2201/00—Indexing scheme relating to details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements covered by H03F1/00
    • H03F2201/32—Indexing scheme relating to modifications of amplifiers to reduce non-linear distortion
    • H03F2201/3215—To increase the output power or efficiency

Definitions

  • the present invention relates to a power amplifier. More particularly, this invention relates to a power amplifier, having power sources that are separated into multiple levels and providing highly efficient amplification performance by enabling a necessary level of the power source to selectively operate according to the amplified output level.
  • a power amplifier includes class-A, -AB, -B, -C, and -D, according to the amplification manner.
  • output signal distortion is the lowest in class-A
  • amplification performance is the best in class-D. Therefore, a lot of high-end power amplifiers use class-AB amplification.
  • the efficiency rate is about 55% at maximum output level and, in addition, the substantial efficiency is only 30%.
  • FIG. 1A shows a waveform depicting the relationships between the output level and the supply voltage in a conventional power amplifier.
  • FIG. IB shows the heated power dissipation in a power amplifier of the present invention.
  • a power amplifier having power source parts that are separated into multiple stages and providing highly efficient amplification performance by enabling necessary magnitude voltage of the power source part to selectively operate according to the amplified output level.
  • a power amplifier comprises: input means for receiving a signal from a voltage amplifying stage; output means for power-amplifying the signal received by the input means; a plurality of power source means, for providing a voltage to the output means, each of which provides different voltages and is selected according to the level of amplified signal; detection means for detecting voltage as a trigger signal from the power-amplified signal at the output means; comparison means for comparing a trigger signal from the detection means with a predetermined threshold value; and control means for selecting one out of a plurality of power source means, according to the compared result from the comparison means.
  • a power amplifier comprises: input means for receiving a signal from a voltage amplifying stage; output means for power-amplifying the signal received by the input means, the output means being supplied with a (+) voltage and (-) voltage; a plurality of (+) power source means and (-) power source means, for providing a voltage to the output means, each of which provides different voltages and is selected according to the level of amplified signal, each of the power source means including a first, a second, and a third (+)Vcc, a first, a second, and a third (-)Vcc, and a GROUND;
  • (+) detection means for detecting (+) voltage as a trigger signal from the power- amplified signal at the output means; (-) detection means for detecting (-) voltage as a trigger signal from the power- amplified signal at the output means; first, second, and third (+) comparison means for comparing a trigger signal detected by the (+) detection means with a predetermined threshold value, each of which has different threshold value and is dedicatedly supplied with voltage from the first, second, and third (+)Vcc; first, second, and third (-) comparison means for comparing a trigger signal detected by the (-) detection means with a predetermined threshold value, each of which has different threshold value and is dedicatedly supplied with voltage from the first, second, and third (- )Ncc; first, second, and third (+) control means for selecting, according to the compared result from the (+) comparison means, one out of a plurality of power source means, each of which is dedicatedly supplied with voltage from the first, second, and third (+)Vcc; and first, second, and third (-) control
  • threshold values of the first (+) and (-) comparison means is determined such that the first (+)Vcc and the first (-)Vcc operates to provide voltage, if the (+) and (-) detection means do not detect any signal. If a trigger signal is greater than the threshold value set to the second (+) comparison means, the second (+) control means is enabled such that the second (+)Vcc operates to provide voltage. If a trigger signal is greater than the threshold value set to the third (+) comparison means, the third (+) control means is enabled such that the third (+)Vcc operates to provide voltage, and the second (+)Vcc is disabled.
  • FIG. 1A and FIG. IB are waveform diagrams showing the relationships between the output level and the supply voltage, respectively in a conventional power amplifier and that of the present invention
  • FIG. 2 is a block diagram of a power amplifier according to the present invention
  • FIG. 3A and FIG. 3B are more specific circuit diagrams of a power amplifier according to the present invention
  • FIG. 3A and FIG. 3B are more specific circuit diagrams of a power amplifier according to the present invention
  • FIGs. 4 to 9 are circuit diagrams showing various embodiment of a power amplifier according to the present invention. Preferred Embodiment for Carrying out the Invention
  • FIG. 2 is a block diagram showing a power amplifier embodying the above inventive concept.
  • the power amplifier is roughly similar to the conventional one, which includes an input part 13 for receiving a signal from a voltage amplifying stage 11 and an output part 15 for amplifying.
  • the output part 15 is supplied with both (+) and (-) voltage. Accordingly, a detection part is divided into a (+) detection part 17 and a (-) detection part 17', and a comparison part and a control part are respectively divided into a (+) part and a (-) part.
  • FIG. 2 shows that a power source part is divided into 7 different- voltage-providing parts. Specifically, a power source part includes 3 (+)Ncc's, 3 (-)Vcc's, and a GROUND.
  • Each of the power source part is dedicatedly connected with each the comparison part 19a ⁇ 19c, 19a' ⁇ 19c' and the control part 21a ⁇ 21c, 21a' ⁇ 21c ⁇
  • the different threshold values are set to each the comparison part.
  • Each the comparison part 19a ⁇ 19c, 19a' ⁇ 19c' compares the threshold value with the signals detected by the (+) detection part 17 or the (-) detection part 17', enabling the control part 21a ⁇ 21c, 21a' ⁇ 21c' to select the appropriate power source part to provide the output part 15 with the power source.
  • the threshold values are set to the first comparison part 19a and the second comparison part 19b such that the first (+)Vcc and the first (-)Vcc operates to provide voltage.
  • a trigger signal the detected signal by the detection part will be referred to as "a trigger signal”.
  • the second (+) control part 21b is enabled such that the second (+)Vcc operates to provide voltage.
  • the third (+) control part 21c is enabled such that the third (+)Vcc operates to provide voltage, and the second (+)Vcc is disabled.
  • the second (-) control part 21b' is enabled such that the second (-)Vcc operates to provide voltage.
  • the third (-) control part 21c' is enabled such that the third (-)Vcc operates to provide voltage, and the second (-)Vcc is disabled.
  • the power source part is divided into 7 levels in FIG. 2, the number of the power source part is properly chosen by those who skilled in the art to which this invention pertains.
  • the diodes Dl and D2 are connected to the GROUND, this may be modified that a cathode of Dl is connected to the first (+)Vcc, and an anode of D2 is connected to the first (-)Vcc.
  • the detection parts 17, 17' may detect a trigger signal from an output terminal of the output part 15 instead of the input part 13 as above. However, it is more preferable that a trigger signal is detected from the input part 13 because almost all characteristics of an amplifier depend on the power supply's switching rate.
  • FIG. 3A is a circuit diagram of a power amplifier specified form the brief block diagram in FIG. 2;
  • FIG. 3B is a circuit diagram simplified from FIG. 3A.
  • FETs are used as the comparison parts, and a power source part is divided into 5 levels. The operation of this circuit will be described.
  • threshold values are set to the cutoff voltage of Q15 and Q32. If there is no input signal, the input voltage of Q15 is greater than the threshold value and the input voltage of Q32 is less than the threshold value. Therefore, control transistors Q9 and Q36 are turned on and D7 and Dll are turned off, enabling the first (+)Vcc and the first (-)Vcc to provide voltage.
  • the negative power source is provided from the second (- )Vcc because Q46 is turned on; while the first (-)Vcc is disabled because Q36 is turned off. If the voltage of input signal plus D5 becomes less than the threshold value of Q15, the positive power source is provided, through D7, from the GROUND because Q39 is turned off.
  • FIG. 3 A shows an emitter-follower stage 23 inserted between the voltage amplifying stage 11 (see FIG. 2) and the output part 15.
  • the emitter- follower stage 23 is located to protect the voltage amplifying stage 11 from the variation of input impedance according to the variation of output, and from the switching noise arising during the power supply switching operation.
  • FIG. 3B is a drawing, which is simplified from FIG. 3A by eliminating constant current sources CD2, CD5 and Q23, Q26. Among these, FIG. 3A is preferable to FIG. 3B, because the former is capable of preventing the co-interference during switching.
  • FIG. 4 exemplarily shows that the circuit of the present invention is adapted to a conventional amplifying circuit.
  • FIGs. 3A, 3B, and 4 exemplarily show that a trigger signal for comparison is detected from the input signal of the output part 15; while FIGs. 5 and 6 show that the trigger signal is detected from the output signal of the output part 15. (4) Description of comparison part
  • FIGs. 3A to 6 show the case that FETs Q7, 8, 15, 16, 32, 33, 40, 41, 54, 55, 62, 63,
  • FIG. 7 shows the case that OP-amps Ul to 4 are used for the comparison part. OP- amp whose input impedance is greater and response speed is faster can provide greater efficiency. Even though the OP -amp circuit in FIG. 7 adopts a dual-powered configuration, it may be adopt a single-power configuration, of course.
  • FIG. 8 shows the case that comparators Ul to 4 are used for the comparison part.
  • the comparator type "LM311" may be substituted by the equivalents.
  • FIG. 9 shows the example that comparators for general use are utilized. A comparator whose input impedance is greater and response speed is faster can provide greater efficiency.
  • control part is constructed by transistors
  • the other power control devices such as FET, IGBT, SSR, SCR, etc., may be used for the control part.
  • the power source part having more levels gives greater efficiency.
  • the number of levels of the power source part is decided according to the economic conditions.
  • Dl and D2 are connected to the GROUND, to protect the output device. Therefore, if the output device's withstand voltage is high enough, Dl may be connected to the first (+)Vcc and D2 may be connected to the first (-)Vcc.
  • an audio-grade output device transistor of 230V withstand voltage
  • the power amplifier can make up to 2600W output at 8 ⁇ load.
  • the power amplifier according to the present invention has an advantage of providing its substantial efficiency greater than 80%, regardless of the output level. Therefore, it has the efficiency being a match for class-D amplifiers, and also has the performance standing comparison with class-AB amplifiers.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Amplifiers (AREA)

Abstract

Disclosed is a high efficiency power amplifier, which comprises inpput part receiving signal from a voltage amplifying stage; output part which output the inputted signal after power amplification; a plurality of power sources which selectively supplies the output part with a voltage according to the level of amplified signal. The level of amplified signal is detected by a detection part, and the signal detected by the detection part is compared to the threshold value, by a comparison part. A control part slectively connects on of the power source parts to the output part, according to the comparison result through the comparison part.

Description

HIGH EFFICIENCY POWER AMPLIFIER
Technical Field The present invention relates to a power amplifier. More particularly, this invention relates to a power amplifier, having power sources that are separated into multiple levels and providing highly efficient amplification performance by enabling a necessary level of the power source to selectively operate according to the amplified output level.
Background Art
In general, a power amplifier includes class-A, -AB, -B, -C, and -D, according to the amplification manner. Among them, output signal distortion is the lowest in class-A, while amplification performance is the best in class-D. Therefore, a lot of high-end power amplifiers use class-AB amplification. In a conventional power amplifier, most of the characteristics are satisfactory, however, in a class-AB amplifier, the efficiency rate is about 55% at maximum output level and, in addition, the substantial efficiency is only 30%. In a conventional power amplifier, because supply voltage is fixed regardless of the amount of output level, the efficiency rate farther decreases at less output level rather than at maximum output level. FIG. 1A shows a waveform depicting the relationships between the output level and the supply voltage in a conventional power amplifier. Whereas, FIG. IB shows the heated power dissipation in a power amplifier of the present invention.
Disclosure of Invention
To solve the above problems, there is provided a power amplifier, having power source parts that are separated into multiple stages and providing highly efficient amplification performance by enabling necessary magnitude voltage of the power source part to selectively operate according to the amplified output level.
According to an aspect of the present invention, a power amplifier comprises: input means for receiving a signal from a voltage amplifying stage; output means for power-amplifying the signal received by the input means; a plurality of power source means, for providing a voltage to the output means, each of which provides different voltages and is selected according to the level of amplified signal; detection means for detecting voltage as a trigger signal from the power-amplified signal at the output means; comparison means for comparing a trigger signal from the detection means with a predetermined threshold value; and control means for selecting one out of a plurality of power source means, according to the compared result from the comparison means. According to another aspect of this invention, a power amplifier comprises: input means for receiving a signal from a voltage amplifying stage; output means for power-amplifying the signal received by the input means, the output means being supplied with a (+) voltage and (-) voltage; a plurality of (+) power source means and (-) power source means, for providing a voltage to the output means, each of which provides different voltages and is selected according to the level of amplified signal, each of the power source means including a first, a second, and a third (+)Vcc, a first, a second, and a third (-)Vcc, and a GROUND;
(+) detection means for detecting (+) voltage as a trigger signal from the power- amplified signal at the output means; (-) detection means for detecting (-) voltage as a trigger signal from the power- amplified signal at the output means; first, second, and third (+) comparison means for comparing a trigger signal detected by the (+) detection means with a predetermined threshold value, each of which has different threshold value and is dedicatedly supplied with voltage from the first, second, and third (+)Vcc; first, second, and third (-) comparison means for comparing a trigger signal detected by the (-) detection means with a predetermined threshold value, each of which has different threshold value and is dedicatedly supplied with voltage from the first, second, and third (- )Ncc; first, second, and third (+) control means for selecting, according to the compared result from the (+) comparison means, one out of a plurality of power source means, each of which is dedicatedly supplied with voltage from the first, second, and third (+)Vcc; and first, second, and third (-) control means for selecting, according to the compared result from the (-) comparison means, one out of a plurality of power source means, each of which is dedicatedly supplied with voltage from the first, second, and third (-)Vcc.
In operation, threshold values of the first (+) and (-) comparison means is determined such that the first (+)Vcc and the first (-)Vcc operates to provide voltage, if the (+) and (-) detection means do not detect any signal. If a trigger signal is greater than the threshold value set to the second (+) comparison means, the second (+) control means is enabled such that the second (+)Vcc operates to provide voltage. If a trigger signal is greater than the threshold value set to the third (+) comparison means, the third (+) control means is enabled such that the third (+)Vcc operates to provide voltage, and the second (+)Vcc is disabled. When an input signal is positive, if a trigger signal is greater than the threshold value set to the first (-) comparison means, the voltage provided to the first (-) control means is stopped such that the GROUND provides voltage. If a trigger signal is less than the threshold value set to the second (-) comparison means, the second (-) control means is enabled such that the second (-)Vcc operates to provide voltage. If a trigger signal is greater than the threshold value set to the third (-) comparison means, the third (-) control means is enabled such that the third (-)Vcc operates to provide voltage, and the second (-)Vcc is disabled. When an input signal is negative, if a trigger signal is less than the threshold value set to the first (+) comparison means, the voltage provided to the first (+) control means is stopped such that the GROUND provides voltage.
Brief Description of Drawings The above and other objects, features and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings, in which: FIG. 1A and FIG. IB are waveform diagrams showing the relationships between the output level and the supply voltage, respectively in a conventional power amplifier and that of the present invention,
FIG. 2 is a block diagram of a power amplifier according to the present invention, FIG. 3A and FIG. 3B are more specific circuit diagrams of a power amplifier according to the present invention, and
FIGs. 4 to 9 are circuit diagrams showing various embodiment of a power amplifier according to the present invention. Preferred Embodiment for Carrying out the Invention
Preferred embodiment for carrying out the present invention will be described herein below with reference to the accompanying drawings.
FIG. 2 is a block diagram showing a power amplifier embodying the above inventive concept. The power amplifier is roughly similar to the conventional one, which includes an input part 13 for receiving a signal from a voltage amplifying stage 11 and an output part 15 for amplifying.
In the power amplifier shown in FIG. 2, the output part 15 is supplied with both (+) and (-) voltage. Accordingly, a detection part is divided into a (+) detection part 17 and a (-) detection part 17', and a comparison part and a control part are respectively divided into a (+) part and a (-) part. FIG. 2 shows that a power source part is divided into 7 different- voltage-providing parts. Specifically, a power source part includes 3 (+)Ncc's, 3 (-)Vcc's, and a GROUND. Each of the power source part is dedicatedly connected with each the comparison part 19a~19c, 19a'~19c' and the control part 21a~21c, 21a'~21c\ The different threshold values are set to each the comparison part. Each the comparison part 19a~19c, 19a'~19c' compares the threshold value with the signals detected by the (+) detection part 17 or the (-) detection part 17', enabling the control part 21a~21c, 21a'~21c' to select the appropriate power source part to provide the output part 15 with the power source.
The operation of the power amplifier the present invention will be described, with regard to FIG. 2.
If the (+) detection part 17 or the (-) detection part 17' does not detect any signal, i.e., there is no signal on the input part 13, the threshold values are set to the first comparison part 19a and the second comparison part 19b such that the first (+)Vcc and the first (-)Vcc operates to provide voltage. Hereinafter, the detected signal by the detection part will be referred to as "a trigger signal".
If a trigger signal is greater than the threshold value set to the second (+) comparison part 19b, the second (+) control part 21b is enabled such that the second (+)Vcc operates to provide voltage. Successively, if a trigger signal is greater than the threshold value set to the third (+) comparison part 19c, the third (+) control part 21c is enabled such that the third (+)Vcc operates to provide voltage, and the second (+)Vcc is disabled.
Further, when an input signal is positive, if the voltage level of a signal on the input part 13 is greater than the threshold value set to the first (-) comparison part 19a', the voltage provided to the first (-) control part 21a' is stopped and a diode D2 is turned on, such that the GROUND provides voltage.
If a trigger signal is less than the threshold value set to the second (-) comparison part 19b', the second (-) control part 21b' is enabled such that the second (-)Vcc operates to provide voltage. Successively, if a trigger signal is greater than the threshold value set to the third (-) comparison part 19c', the third (-) control part 21c' is enabled such that the third (-)Vcc operates to provide voltage, and the second (-)Vcc is disabled.
Further, when an input signal is negative, if a trigger signal is less than the threshold value set to the first (+) comparison part 19a, the voltage provided to the first (+) control part 21a is stopped and a diode Dl is turned on, such that the GROUND provides voltage.
Even though the power source part is divided into 7 levels in FIG. 2, the number of the power source part is properly chosen by those who skilled in the art to which this invention pertains. In addition, even though the diodes Dl and D2 are connected to the GROUND, this may be modified that a cathode of Dl is connected to the first (+)Vcc, and an anode of D2 is connected to the first (-)Vcc. In addition, the detection parts 17, 17' may detect a trigger signal from an output terminal of the output part 15 instead of the input part 13 as above. However, it is more preferable that a trigger signal is detected from the input part 13 because almost all characteristics of an amplifier depend on the power supply's switching rate.
(1) Specified Circuitry
FIG. 3A is a circuit diagram of a power amplifier specified form the brief block diagram in FIG. 2; FIG. 3B is a circuit diagram simplified from FIG. 3A. In FIG. 3A, FETs are used as the comparison parts, and a power source part is divided into 5 levels. The operation of this circuit will be described.
1) In the case of no input signal
Since the reference potential points of Q15 and Q32 are connected to the GROUND, threshold values are set to the cutoff voltage of Q15 and Q32. If there is no input signal, the input voltage of Q15 is greater than the threshold value and the input voltage of Q32 is less than the threshold value. Therefore, control transistors Q9 and Q36 are turned on and D7 and Dll are turned off, enabling the first (+)Vcc and the first (-)Vcc to provide voltage.
2) In the case of positive input signal
If the voltage of input signal plus D5 (a trigger signal) is greater than the threshold value of Q7 (first (+)Vcc + cutoff voltage of Q32), the positive power source is provided from the second (+)Vcc because Q 1 is turned on; while the first (+)Vcc is disabled because
Q9 is turned off. If the voltage of input signal plus D13 becomes greater than the threshold value of Q32, the negative power source is provided, through Dll, from the GROUND because Q36 is turned off. 3) In the case of negative input signal
If the voltage of input signal plus D13 is less than the threshold value of Q40 (first (- )Vcc + cutoff voltage of Q40), the negative power source is provided from the second (- )Vcc because Q46 is turned on; while the first (-)Vcc is disabled because Q36 is turned off. If the voltage of input signal plus D5 becomes less than the threshold value of Q15, the positive power source is provided, through D7, from the GROUND because Q39 is turned off.
(2) Description of input part FIG. 3 A shows an emitter-follower stage 23 inserted between the voltage amplifying stage 11 (see FIG. 2) and the output part 15. The emitter- follower stage 23 is located to protect the voltage amplifying stage 11 from the variation of input impedance according to the variation of output, and from the switching noise arising during the power supply switching operation. FIG. 3B is a drawing, which is simplified from FIG. 3A by eliminating constant current sources CD2, CD5 and Q23, Q26. Among these, FIG. 3A is preferable to FIG. 3B, because the former is capable of preventing the co-interference during switching. FIG. 4 exemplarily shows that the circuit of the present invention is adapted to a conventional amplifying circuit.
(3) Description of detection part
FIGs. 3A, 3B, and 4 exemplarily show that a trigger signal for comparison is detected from the input signal of the output part 15; while FIGs. 5 and 6 show that the trigger signal is detected from the output signal of the output part 15. (4) Description of comparison part
Transistors, FETs, OP-amps, or comparators are used for the comparison part, however, the efficiency of the present invention is dependent upon the response speed of a device used for the comparison part. FIGs. 3A to 6 show the case that FETs Q7, 8, 15, 16, 32, 33, 40, 41, 54, 55, 62, 63,
75, 76, 83, 84 are used for the comparison part. An FET can be used when economical conditions are required because of simple structure of FET. Transistors may be used instead of FETs. In this case, it is needed to heighten the input impedance of a transistor by using the Darlington configuration. FIG. 7 shows the case that OP-amps Ul to 4 are used for the comparison part. OP- amp whose input impedance is greater and response speed is faster can provide greater efficiency. Even though the OP -amp circuit in FIG. 7 adopts a dual-powered configuration, it may be adopt a single-power configuration, of course.
FIG. 8 shows the case that comparators Ul to 4 are used for the comparison part. The comparator type "LM311" may be substituted by the equivalents. FIG. 9 shows the example that comparators for general use are utilized. A comparator whose input impedance is greater and response speed is faster can provide greater efficiency.
(5) Description of control part In all the drawings, even though the control part is constructed by transistors, the other power control devices, such as FET, IGBT, SSR, SCR, etc., may be used for the control part.
(6) Description of power source According to the power amplifier of this invention, the power source part having more levels gives greater efficiency. However, it is preferable that the number of levels of the power source part is decided according to the economic conditions. In FIG. 2 Dl and D2 are connected to the GROUND, to protect the output device. Therefore, if the output device's withstand voltage is high enough, Dl may be connected to the first (+)Vcc and D2 may be connected to the first (-)Vcc. When using the conventional power amplifier, an audio-grade output device (transistor of 230V withstand voltage) cannot make more than 600W output at 8 Ω load, because the power source can only be applied up to ±115V maximum. However, when using the power amplifier according to the present invention, since the power source can be applied up to +230 V, the power amplifier can make up to 2600W output at 8 Ω load.
From the foregoing, the power amplifier according to the present invention has an advantage of providing its substantial efficiency greater than 80%, regardless of the output level. Therefore, it has the efficiency being a match for class-D amplifiers, and also has the performance standing comparison with class-AB amplifiers.
While the invention has been shown and described with reference to a certain embodiment to carry out this invention, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

What Is Claimed Is:
1. A power amplifier comprising: input means for receiving a signal from a voltage amplifying stage; output means for power-amplifying the signal received by the input means; a plurality of power source means, for providing a voltage to the output means, each of which provides different voltages and is selected according to the level of amplified output signal.
2. The power amplifier of claim 1, further comprising: detection means for detecting voltage as a trigger signal from the power-amplified signal at the output means; comparison means for comparing a trigger signal from the detection means with a predetermined threshold value; control means for selecting one out of a plurality of power source means, according to the compared result from the comparison means.
3. The power amplifier of claim 2, wherein the detection means detects a trigger signal from the input signal of the output means.
4. The power amplifier of claim 2, wherein the detection means detects a trigger signal from the output signal of the output means.
5. The power amplifier of claim 2, wherein the input means is an emitter-follower.
6. The power amplifier of claim 2, wherein the comparison means is selected from the group consisting of a transistor, FET, OP-amp, and a comparator.
7. The power amplifier of claim 2, wherein the control means is selected from the group consisting of a transistor, FET, IGBT, SSR, and SCR.
8. A power amplifier comprising: input means for receiving a signal from a voltage amplifying stage; output means for power-amplifying the signal received by the input means, the output means being supplied with a (+) voltage and (-) voltage; and a plurality of (+) power source means and (-) power source means, for providing a voltage to the output means, each of which provides different voltages and is selected according to the level of amplified signal.
9. The power amplifier of claim 8, wherein the power source means includes a first, a second, and a third (+)Vcc, a first, a second, and a third (-)Vcc, and a GROUND, and the power amplifier further comprising:
(+) detection means for detecting (+) voltage as a trigger signal from the power- amplified signal at the output means;
(-) detection means for detecting (-) voltage as a trigger signal from the power- amplified signal at the output means; first, second, and third (+) comparison means for comparing a trigger signal detected by the (+) detection means with a predetermined threshold value, each of which has different threshold value and is dedicatedly supplied with voltage from the first, second, and third (+)Vcc; first, second, and third (-) comparison means for comparing a trigger signal detected by the (-) detection means with a predetermined threshold value, each of which has different threshold value and is dedicatedly supplied with voltage from the first, second, and third (-)Vcc; first, second, and third (+) control means for selecting, according to the compared result from the (+) comparison means, one out of a plurality of power source means, each of which is dedicatedly supplied with voltage from the first, second, and third (+)Vcc; and first, second, and third (-) control means for selecting, according to the compared result from the (-) comparison means, one out of a plurality of power source means, each of which is dedicatedly supplied with voltage from the first, second, and third (-
)Vcc, wherein threshold values of the first (+) and (-) comparison means is determined such that the first (+)Vcc and the first (-)Vcc operates to provide voltage, if the (+) and (-) detection means do not detect any signal, if a trigger signal is greater than the threshold value set to the second (+) comparison means, the second (+) control means is enabled such that the second (+)Vcc operates to provide voltage, if a trigger signal is greater than the threshold value set to the third (+) comparison means, the third (+) control means is enabled such that the third (+)Ncc operates to provide voltage, and the second (+)Vcc is disabled. when an input signal is positive, if a trigger signal is greater than the threshold value set to the first (-) comparison means, the voltage provided to the first (-) control means is stopped such that the GROUND provides voltage. if a trigger signal is less than the threshold value set to the second (-) comparison means, the second (-) control means is enabled such that the second (-)Vcc operates to provide voltage, if a trigger signal is greater than the threshold value set to the third (-) comparison means, the third (-) control means is enabled such that the third (-)Vcc operates to provide voltage, and the second (-)Vcc is disabled. when an input signal is negative, if a trigger signal is less than the threshold value set to the first (+) comparison means, the voltage provided to the first (+) control means is stopped such that the GROUND provides voltage.
10. The power amplifier of claim 9, wherein the (+) and (-) detection means detect a trigger signal from the input signal of the output means.
11. The power amplifier of claim 9, wherein the (+) and (-) detection means detect a trigger signal from the output signal of the output means.
12. The power amplifier of claim 9, wherein the input means is an emitter-follower.
13. The power amplifier of claim 9, wherein the (+) and (-) comparison means are selected from the group consisting of a transistor, FET, OP-amp, and a comparator.
14. The power amplifier of claim 9, wherein the (+) and (-) control means are selected from the group consisting of a transistor, FET, IGBT, SSR, and SCR.
PCT/KR2002/000747 2001-04-30 2002-04-23 High efficiency power amplifier WO2002089320A1 (en)

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KR1020010023337A KR20020083735A (en) 2001-04-30 2001-04-30 High efficency power amplifier

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WO2004019486A1 (en) * 2002-08-21 2004-03-04 Siemens Aktiengesellschaft A power amplifier system

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Publication number Priority date Publication date Assignee Title
KR100592767B1 (en) 2003-12-26 2006-06-26 한국전자통신연구원 The dual antenna diversity transmitter and system with improved power amplifier efficiency

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JPH11214936A (en) * 1998-01-26 1999-08-06 Mitsubishi Electric Corp Analog signal amplifier and solid-state image-pickup element containing the same
US5936464A (en) * 1997-11-03 1999-08-10 Motorola, Inc. Method and apparatus for reducing distortion in a high efficiency power amplifier
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EP0837559A1 (en) * 1996-10-18 1998-04-22 Matsushita Electric Industrial Co., Ltd. High efficiency linear power amplifier of plural frequency bands and high efficiency power amplifier
US5936464A (en) * 1997-11-03 1999-08-10 Motorola, Inc. Method and apparatus for reducing distortion in a high efficiency power amplifier
JPH11214936A (en) * 1998-01-26 1999-08-06 Mitsubishi Electric Corp Analog signal amplifier and solid-state image-pickup element containing the same
US6157253A (en) * 1999-09-03 2000-12-05 Motorola, Inc. High efficiency power amplifier circuit with wide dynamic backoff range

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WO2004019486A1 (en) * 2002-08-21 2004-03-04 Siemens Aktiengesellschaft A power amplifier system

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