WO2013020265A1 - Output stage acceleration circuit of transistor audio power amplifier - Google Patents

Output stage acceleration circuit of transistor audio power amplifier Download PDF

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Publication number
WO2013020265A1
WO2013020265A1 PCT/CN2011/078104 CN2011078104W WO2013020265A1 WO 2013020265 A1 WO2013020265 A1 WO 2013020265A1 CN 2011078104 W CN2011078104 W CN 2011078104W WO 2013020265 A1 WO2013020265 A1 WO 2013020265A1
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WIPO (PCT)
Prior art keywords
transistor
power
output
power amplifier
stage
Prior art date
Application number
PCT/CN2011/078104
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French (fr)
Chinese (zh)
Inventor
胡章儒
Original Assignee
Hu Zhangru
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Publication date
Application filed by Hu Zhangru filed Critical Hu Zhangru
Priority to PCT/CN2011/078104 priority Critical patent/WO2013020265A1/en
Priority to CN201180001449.4A priority patent/CN102577109A/en
Publication of WO2013020265A1 publication Critical patent/WO2013020265A1/en

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/181—Low-frequency amplifiers, e.g. audio preamplifiers
    • H03F3/183—Low-frequency amplifiers, e.g. audio preamplifiers with semiconductor devices only
    • 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
    • H03F3/211—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers with semiconductor devices only using a combination of several amplifiers
    • 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
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
    • H03F2203/45—Indexing scheme relating to differential amplifiers
    • H03F2203/45362—Indexing scheme relating to differential amplifiers the AAC comprising multiple transistors parallel coupled at their gates and drains only, e.g. in a cascode dif amp, only those forming the composite common source transistor
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
    • H03F2203/45—Indexing scheme relating to differential amplifiers
    • H03F2203/45364—Indexing scheme relating to differential amplifiers the AAC comprising multiple transistors parallel coupled at their gates and sources only, e.g. in a cascode dif amp, only those forming the composite common source transistor

Definitions

  • the invention describes an acceleration method for an output stage of a transistor audio power amplifier, which utilizes the high conversion rate of a small power transistor to compensate for the defects of the high power transistor and accelerate the conversion rate of the output stage, thereby eliminating the transient intermodulation distortion of the transistor audio power amplifier.
  • Suitable for applications with transistor audio amplifiers such as stereos, amplifiers, DVD players and TVs.
  • the static indicator of the transistor audio amplifier is very good, but it is not good when actually playing music.
  • the accepted reason is that the transient intermodulation distortion of the transistor audio amplifier is very large. There are many factors that produce transient intermodulation distortion, the main ones are as follows:
  • the transient intermodulation distortion is basically solved. Then let's see how these problems are solved under the existing technical conditions.
  • the first one is the problem of the damping capacitor.
  • the main reason is that the high-frequency characteristics of the power amplifier transistor cause self-excited oscillation.
  • a vibration-absorbing capacitor is added to the circuit.
  • the high-frequency characteristics of the small-signal amplifying transistor of the power amplifier have been greatly improved, so the vibration-absorbing capacitor is used very small.
  • Transient intermodulation distortion caused by the snubber capacitor is much lower than before.
  • the second is the problem that the open loop gain is too large and the negative feedback is too deep.
  • the open-loop index of the transistor power amplifier is not high, it is necessary to rely on the deep negative feedback to improve the index, so that the open-loop gain of the transistor power amplifier is often made large, and the transient characteristics are also deteriorated.
  • the solution to this problem is to use a well-linear transistor and pair it up; add more local negative feedback; increase the open-loop specification of the transistor amplifier. Now, this problem has been solved very well. Then there is the last problem, that is, the problem that the conversion rate of the amplifier is not enough. Now, the conversion rate of small signal amplifiers has been done very well, achieving 2000V/US performance, which is more than enough in the audio field.
  • the high-power output stage slew rate of transistor audio amplifiers has not been able to go up.
  • the method of the invention utilizes the high slew rate of the small power transistor to compensate for the lack of conversion rate of the high power output transistor.
  • H-IN and L-IN in the figure are signals from the push stage, Q1 and Q2 are high power output tubes, and Q3 to Q8 are paralleled by the method of the present invention.
  • the current amplification factors of Q1 to Q8 are all equal. Due to the action of the B limit current resistor, the output power of Q3 is 1/2 of Q1 (one-sixth, the same below); the output power of Q5 is 1/2 of Q3; and so on. Assume that at some point, the rising signal rate from H-IN is too fast, so that the rate of Q1 cannot keep up. This shows that the voltage at the OUT terminal is lower than that at the H-IN terminal.
  • the task of Q3 is to compensate for the decrease in power due to the slow change of Q1.
  • the current is 1/2, and now, the actual compensation is less than 1/2, the current caused by the slow change of Q3 itself is reduced by 5% of Q5, and so on.
  • the right half of the drawing is the connection of the field effect transistor power amplifier circuit.
  • the method of the present invention has significant advantages over existing output stages with multiple high power transistor parallel circuits.
  • multiple high-power transistors are connected in parallel, multiple transistors are in the same direction of action rather than complementary, so that transient intermodulation distortion cannot be eliminated.
  • the conversion rate of high power transistors is not comparable to that of small power transistors. If it is in an integrated circuit, it is technically difficult to integrate multiple high-power transistors at the same time.
  • the method of the present invention is not only applicable to discrete original circuits, but also has advantages in integrated circuits.
  • the current amplification factor of the bipolar transistor can be controlled to distribute the output power of each of the smaller power transistors; if it is a field effect transistor, the transconductance coefficient can be controlled to distribute the output power of each of the smaller power transistors.
  • the method of the present invention also has several additional functions: Since the conversion rate of the output stage is accelerated, the high frequency characteristics of the transistor audio power amplifier are improved, so that the vibration damping capacitance can be reduced or even completely removed. The transient intermodulation distortion of the transistor audio power amplifier is further improved. At the same time, due to the improved small signal characteristics of the high-power output stage, the open-loop index of the circuit is improved, the open-loop gain can be reduced, and the negative feedback depth of the closed-loop state is reduced. This in turn can improve the transient intermodulation distortion of the circuit. The small signal characteristics of the high power output stage are improved, and the sound at a small volume is also better. Transistor audio amplifiers often work in a "small volume" state. Relative to the maximum output power, the transistor audio amplifiers in normal use operate at very small volume levels. For example, a maximum of 100W transistor audio amplifiers are often below 5W when actually listening.

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

Abstract

Disclosed is an output stage acceleration circuit of a transistor audio power amplifier. A plurality of low power transistors are connected in parallel at the end stage output tube of the output stage acceleration circuit, resistors are connected in series at the B stage of a bipolar transistor or the S stage of a field effect transistor, and the output power of each low power transistor is allocated. The circuit employs the high conversion rate feature of these low-power transistors to compensate for the defect of high-power transistors, accelerating the conversion rate of the output stage, improving the high frequency property of the transistor audio power amplifier, reducing oscillation damping capacitance, eliminating the transient intermodulation distortion of the transistor audio power amplifier, and at the same time improving the linearity of a small signal, thus reducing open loop gain. The circuit is applicable in fields such as combined sound equipment, loudspeakers, and DVD players with a transistor audio power amplifier.

Description

说 明 书  Description
晶体管音频功放输出级加速电路  Transistor audio power amplifier output stage acceleration circuit
本发明描述一种晶体管音频功放输出级的加速方法， 利用小功率晶体管转换速率高的特性来弥补大功 率晶体管的缺陷， 加速输出级的转换速率， 从而消除晶体管音频功放的瞬态互调失真。 适用于组合音响、 扩音机、 DVD机和电视机等有晶体管音频功放的领域。  The invention describes an acceleration method for an output stage of a transistor audio power amplifier, which utilizes the high conversion rate of a small power transistor to compensate for the defects of the high power transistor and accelerate the conversion rate of the output stage, thereby eliminating the transient intermodulation distortion of the transistor audio power amplifier. Suitable for applications with transistor audio amplifiers such as stereos, amplifiers, DVD players and TVs.
晶体管音频功放的静态指标很好， 但是， 实际放音乐时却不好听。 公认的原因是晶体管音频功放的瞬 态互调失真很大。 产生瞬态互调失真的因素有很多， 其中主要的有如下几种：  The static indicator of the transistor audio amplifier is very good, but it is not good when actually playing music. The accepted reason is that the transient intermodulation distortion of the transistor audio amplifier is very large. There are many factors that produce transient intermodulation distortion, the main ones are as follows:
①： 消振电容的影响；  1: the effect of the damping capacitor;
②： 开环增益过大， 负反馈过深；  2: The open loop gain is too large, and the negative feedback is too deep;
③： 放大器转换速率不够；  3: The amplifier conversion rate is not enough;
如果解决了以上 3个问题， 瞬态互调失真也就基本解决了。 那我们来看看在现有的技术条件下， 这些 问题解决得怎么样了。第①个是消振电容的问题， 主要是因为功放用晶体管的高频特性不好而引起自激振 荡， 为了消除自激振荡而在电路中加入了消振电容。现在的功放用小信号放大晶体管高频特性都有了很大 的改善， 所以消振电容都用得很小了。 由消振电容而产生的瞬态互调失真比以前降低了很多。第②个是开 环增益过大， 负反馈过深的问题。 由于晶体管功放的开环指标不高， 只得依靠深度的负反馈来改善指标， 使得晶体管功放的开环增益往往做得很大， 也使得瞬态特性变差。解决这个问题的方法是： 采用线性好的 晶体管， 而且配对使用； 多加局部负反馈； 提高晶体管功放的开环指标。 现在， 这个问题也已经解决得很 好了。那么还有最后一个问题， 就是放大器转换速率不够的问题。 现在， 小信号放大器的转换速率已经做 得很好， 能达到 2000V/ US的性能， 这在音频领域是綽綽有余了。 但是， 晶体管音频功放的大功率输出级 转换速率一直上不去。而且， 在现有技术条件下， 晶体管音频功放用的大功率输出晶体管转换速率还没有 更好的解决办法。本发明的方法就是利用小功率晶体管转换速率高的特点来弥补大功率输出晶体管转换速 率的不足。  If the above three problems are solved, the transient intermodulation distortion is basically solved. Then let's see how these problems are solved under the existing technical conditions. The first one is the problem of the damping capacitor. The main reason is that the high-frequency characteristics of the power amplifier transistor cause self-excited oscillation. In order to eliminate the self-oscillation, a vibration-absorbing capacitor is added to the circuit. Nowadays, the high-frequency characteristics of the small-signal amplifying transistor of the power amplifier have been greatly improved, so the vibration-absorbing capacitor is used very small. Transient intermodulation distortion caused by the snubber capacitor is much lower than before. The second is the problem that the open loop gain is too large and the negative feedback is too deep. Since the open-loop index of the transistor power amplifier is not high, it is necessary to rely on the deep negative feedback to improve the index, so that the open-loop gain of the transistor power amplifier is often made large, and the transient characteristics are also deteriorated. The solution to this problem is to use a well-linear transistor and pair it up; add more local negative feedback; increase the open-loop specification of the transistor amplifier. Now, this problem has been solved very well. Then there is the last problem, that is, the problem that the conversion rate of the amplifier is not enough. Now, the conversion rate of small signal amplifiers has been done very well, achieving 2000V/US performance, which is more than enough in the audio field. However, the high-power output stage slew rate of transistor audio amplifiers has not been able to go up. Moreover, under the prior art conditions, there is no better solution for the conversion rate of high power output transistors for transistor audio power amplifiers. The method of the invention utilizes the high slew rate of the small power transistor to compensate for the lack of conversion rate of the high power output transistor.
下面结合附图来说明本发明方法的具体实施： 图中的 H-IN和 L-IN都是来自推动级的信号， Q1和 Q2 是大功率输出管， Q3至 Q8是用本发明的方法并联的较小功率晶体管， Q1至 Q8的电流放大系数都是相等 的。 由于 B极限流电阻的作用， 使得 Q3的输出功率是 Q1的 1/2 ( 2分之 1， 下同）； Q5的输出功率是 Q3 的 1/2 ; 以此类推。 假设在某一时刻， 来自 H-IN的上升信号速率过快， 使得 Q1的速率跟不上， 这就表现 为 OUT端的电压相对于 H-IN端来说是降低了， 这个降低的电压使得 Q3的电流加大， Q3加大的部分只能 补偿因 Q1变化慢而减小的电流的 1/2， 没有补偿的那 1/2又使得 Q5的电流加大， 同样， Q5也只能补偿经 过 Q3补偿后剩下的那个 1/2 ; 以此类推。 那么到哪一级才会补偿完全呢？这要看具体的电路， 比如说： B 极是 64R输出功率为 1/2 W的小功率那一级， 确信不会出现转换速率的问题， 那么， 就在这一级用两只 B 极都串接 64R的同型号较小功率晶体管并联， 这样就能完全补偿因 Q1变化慢而减小的电流。 还有一个情 况要说明一下： Q3 自身也会出现转换速率不够的问题， 本来 Q3的任务是要补偿因 Q1变化慢而减小的电 流的 1/2的， 而现在， 实际补偿的不到 1/2， 由 Q3自身变化慢而引起的电流减小那部分还是由 Q5来补偿 其 1/2的， 以此类推。 附图的右半部分是场效应晶体管功放电路的接法。 The specific implementation of the method of the present invention will be described below with reference to the accompanying drawings: H-IN and L-IN in the figure are signals from the push stage, Q1 and Q2 are high power output tubes, and Q3 to Q8 are paralleled by the method of the present invention. For smaller power transistors, the current amplification factors of Q1 to Q8 are all equal. Due to the action of the B limit current resistor, the output power of Q3 is 1/2 of Q1 (one-sixth, the same below); the output power of Q5 is 1/2 of Q3; and so on. Assume that at some point, the rising signal rate from H-IN is too fast, so that the rate of Q1 cannot keep up. This shows that the voltage at the OUT terminal is lower than that at the H-IN terminal. This reduced voltage makes Q3 The current is increased. The part of Q3 is only compensated for 1/2 of the current that is reduced due to the slow change of Q1. The 1/2 without compensation makes the current of Q5 increase. Similarly, Q5 can only compensate for the current. The remaining 1/2 after Q3 compensation; and so on. So which level will it be fully compensated? This depends on the specific circuit, for example: B pole is 64W output power is 1/2 W low power level, I believe that there will be no conversion rate problem, then, at this level, use both B poles Connect the 64R's smaller power transistors of the same model in parallel, so that the current reduced by the slow change of Q1 can be fully compensated. There is another situation to explain: Q3 itself will also have a problem of insufficient conversion rate. The task of Q3 is to compensate for the decrease in power due to the slow change of Q1. The current is 1/2, and now, the actual compensation is less than 1/2, the current caused by the slow change of Q3 itself is reduced by 5% of Q5, and so on. The right half of the drawing is the connection of the field effect transistor power amplifier circuit.
和现有的输出级用多只大功率晶体管并联电路相比， 本发明的方法具有明显的优势。 多只大功率晶体 管并联时， 多只晶体管是同一个作用方向而不是互补的， 这样就不能消除瞬态互调失真。 而且， 大功率晶 体管的转换速率比不上小功率晶体管。如果是在集成电路里， 同时集成多只大功率晶体管在技术上也是难 以实现的。 本发明的方法不但适用于分立原件电路， 在集成电路里更加有优势。 在集成电路里， 可以控制 双极型晶体管的电流放大系数来分配各个较小功率晶体管的输出功率；如果是场效应晶体管，可以控制跨 导系数来分配各个较小功率晶体管的输出功率。  The method of the present invention has significant advantages over existing output stages with multiple high power transistor parallel circuits. When multiple high-power transistors are connected in parallel, multiple transistors are in the same direction of action rather than complementary, so that transient intermodulation distortion cannot be eliminated. Moreover, the conversion rate of high power transistors is not comparable to that of small power transistors. If it is in an integrated circuit, it is technically difficult to integrate multiple high-power transistors at the same time. The method of the present invention is not only applicable to discrete original circuits, but also has advantages in integrated circuits. In an integrated circuit, the current amplification factor of the bipolar transistor can be controlled to distribute the output power of each of the smaller power transistors; if it is a field effect transistor, the transconductance coefficient can be controlled to distribute the output power of each of the smaller power transistors.
本发明的方法还有附带的几个作用： 由于加速了输出级的转换速率， 该善了晶体管音频功放的高频特 性， 使得消振电容可以减小甚至完全去除。 进一步改善了晶体管音频功放的瞬态互调失真。 同时， 由于改 善了大功率输出级的小信号特性， 使得电路的开环指标提高， 开环增益可以降低， 减小了闭环状态的负反 馈深度。这又能使电路的瞬态互调失真得以改善。 改善了大功率输出级的小信号特性， 也使得小音量时的 音色更好。 晶体管音频功放往往都是工作在"小音量 "的状态。 相对与最大输出功率， 正常使用时的晶体 管音频功放都是工作在很小的音量状态。 比如， 最大 100W的晶体管音频功放， 实际听音时往往是在 5W 以下。  The method of the present invention also has several additional functions: Since the conversion rate of the output stage is accelerated, the high frequency characteristics of the transistor audio power amplifier are improved, so that the vibration damping capacitance can be reduced or even completely removed. The transient intermodulation distortion of the transistor audio power amplifier is further improved. At the same time, due to the improved small signal characteristics of the high-power output stage, the open-loop index of the circuit is improved, the open-loop gain can be reduced, and the negative feedback depth of the closed-loop state is reduced. This in turn can improve the transient intermodulation distortion of the circuit. The small signal characteristics of the high power output stage are improved, and the sound at a small volume is also better. Transistor audio amplifiers often work in a "small volume" state. Relative to the maximum output power, the transistor audio amplifiers in normal use operate at very small volume levels. For example, a maximum of 100W transistor audio amplifiers are often below 5W when actually listening.

Claims

权 利 要 求 书 Claim
1、 晶体管音频功放输出级加速电路， 其特征是： 在末级输出管位置并联多只较小功率的晶体管， 这 些较小功率的晶体管输出功率明显小于末级输出管。  1. Transistor audio power amplifier output stage acceleration circuit, which is characterized in that: a plurality of smaller power transistors are connected in parallel at the final output tube position, and the output power of these smaller power transistors is significantly smaller than the final output tube.
2、 如权利要求 1 所述的晶体管音频功放输出级加速电路， 其特征是： 这些并联的较小功率的晶体管 输出功率是按照如下组合排列： 1/2末级输出管功率； 1/4末级输出管功率； 1/8末级输出管功率； 1/16末 级输出管功率； 以此类推， 直到一个合适的数量为止。  2. The transistor audio power amplifier output stage acceleration circuit according to claim 1, wherein: the parallel output power of the smaller power transistors is arranged according to the following combination: 1/2 final stage output tube power; 1/4 end Stage output tube power; 1/8 final stage output tube power; 1/16 final stage output tube power; and so on, up to a suitable number.
3、 如权利要求 2所述的晶体管音频功放输出级加速电路， 其特征是： 按照如此组合排列的较小功率 的晶体管， 其最小输出管功率的晶体管是由两只输出功率相同的晶体管并联组合。  3. The transistor audio power amplifier output stage acceleration circuit according to claim 2, wherein: according to the combination of the smaller power transistors, the transistor having the smallest output tube power is connected in parallel by two transistors having the same output power. .
PCT/CN2011/078104 2011-08-08 2011-08-08 Output stage acceleration circuit of transistor audio power amplifier WO2013020265A1 (en)

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Application Number Priority Date Filing Date Title
PCT/CN2011/078104 WO2013020265A1 (en) 2011-08-08 2011-08-08 Output stage acceleration circuit of transistor audio power amplifier
CN201180001449.4A CN102577109A (en) 2011-08-08 2011-08-08 Transistor audio power amplifier output stage accelerated circuit

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Application Number Priority Date Filing Date Title
PCT/CN2011/078104 WO2013020265A1 (en) 2011-08-08 2011-08-08 Output stage acceleration circuit of transistor audio power amplifier

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WO2013020265A1 true WO2013020265A1 (en) 2013-02-14

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1356850A (en) * 2000-12-04 2002-07-03 杨云柳 Integrated power amplifier
CN200959590Y (en) * 2006-09-11 2007-10-10 沈锦成 Offset circuit of power amplifier
CN200973071Y (en) * 2006-06-09 2007-11-07 杨武 Audio power amplifier circuit

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1356850A (en) * 2000-12-04 2002-07-03 杨云柳 Integrated power amplifier
CN200973071Y (en) * 2006-06-09 2007-11-07 杨武 Audio power amplifier circuit
CN200959590Y (en) * 2006-09-11 2007-10-10 沈锦成 Offset circuit of power amplifier

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