JPS5913410A - Power amplifying circuit - Google Patents
Power amplifying circuitInfo
- Publication number
- JPS5913410A JPS5913410A JP12356382A JP12356382A JPS5913410A JP S5913410 A JPS5913410 A JP S5913410A JP 12356382 A JP12356382 A JP 12356382A JP 12356382 A JP12356382 A JP 12356382A JP S5913410 A JPS5913410 A JP S5913410A
- Authority
- JP
- Japan
- Prior art keywords
- resistors
- emitter
- output
- connection point
- output impedance
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
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
- H03F1/56—Modifications of input or output impedances, not otherwise provided for
Abstract
Description
【発明の詳細な説明】
産業上の利用分野
本発明は負帰還を利用した電力増幅器に係り、特に出力
インピーダンスの可変を簡単に実現するものである。DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a power amplifier using negative feedback, and in particular, to easily realize variable output impedance.
従来例の構成とその問題点
第１図に従来の電力増幅器を示す。第１図中、１は入力
端子、２は十電源端子、３は〜電源端子、４は出力端子
、６は負荷接地端子、６は電力増幅部、Ｒ１，Ｒ２は帰
還抵抗、Ｒ３，Ｒ４は分圧用抵抗、Ｒ５は負荷電流検出
用抵抗、ｖＲは出力インピーダンス可変用の可変抵抗で
ある。Conventional configuration and problems thereof FIG. 1 shows a conventional power amplifier. In Figure 1, 1 is an input terminal, 2 is a power supply terminal, 3 is a power supply terminal, 4 is an output terminal, 6 is a load ground terminal, 6 is a power amplification section, R1 and R2 are feedback resistors, and R3 and R4 are A resistor for voltage division, R5 is a resistor for detecting load current, and vR is a variable resistor for varying output impedance.
第１図は電力増幅器にブリッジ型と呼ばれる出力インピ
ーダンス可変回路を付加したものである。FIG. 1 shows a power amplifier to which a variable output impedance circuit called a bridge type is added.
この回路は、負荷抵抗ＲＬに流れる電流を負荷電流検出
用抵抗Ｒ６により検出し、それを電圧の形でとり出した
ものを帰還することにより、入力信号ｅｉに比例した電
流が負荷抵抗ＲＬに流れ、出力インピーダンスが無限大
となることを利用したものである。すなわち、可変抵抗
ｖＲを電圧帰還となる抵抗Ｒ４側にすれば出力インピー
ダンスは零となり、逆に可変抵抗ｖＲを電流帰還のみと
なる抵抗Ｒ６側にすれば出力インピーダンスは無限大と
なり、この間で電力増幅器の出力インピーダンスを自由
に可変することが出来る。This circuit detects the current flowing through the load resistor RL with the load current detection resistor R6, and feeds back the detected voltage in the form of a voltage, so that a current proportional to the input signal ei flows through the load resistor RL. , which takes advantage of the fact that the output impedance is infinite. In other words, if the variable resistor vR is set to the resistor R4 side that provides voltage feedback, the output impedance becomes zero, and conversely, if the variable resistor vR is set to the resistor R6 side that only provides current feedback, the output impedance becomes infinite, and during this time the power amplifier The output impedance can be freely varied.
しかし、第１図の回路はワット数の大きい電流検出用抵
抗Ｒ６を設けなければならず、配線も複雑になる欠点が
ある。また、このように電流検出用抵抗を利用すると、
負帰還電流が負荷抵抗ＲＬの影響を受けやすく、電流帰
還をかけすぎると不安定になることが多いという欠点も
ある。特にオーディオ用の電力増幅器として用いた場合
、負荷抵抗であるスピーカのインピーダンスがきわめて
不安定で、これが帰還電流に影響を及ぼすため、動作が
不安定になりやすい。However, the circuit shown in FIG. 1 requires the provision of a current detection resistor R6 having a large wattage, and has the drawback that the wiring becomes complicated. Also, if you use a current detection resistor like this,
Another disadvantage is that the negative feedback current is easily influenced by the load resistance RL, and if too much current feedback is applied, it often becomes unstable. Particularly when used as an audio power amplifier, the impedance of the speaker, which is the load resistance, is extremely unstable, and this affects the feedback current, resulting in unstable operation.
発明の目的
本発明は簡単な構成で、しかも安定に出力インピーダン
スを可変することのできる電力増幅器を提供するもので
ある。OBJECTS OF THE INVENTION The present invention provides a power amplifier that has a simple configuration and can stably vary its output impedance.
発明の構成
本発明は、プッシュプルの出力トランジスタのエミッタ
抵抗による降下電圧を分圧して負帰還をかけるようにし
だものである。このようにすれば、ワット数の大きい電
流検出用の抵抗を設ける必要がなく、シかもスピーカ等
の不安定なインピーダンスが帰還電流に影響を及ぼさな
いから、動作そのものもきわめて安定なものとなる。Structure of the Invention The present invention is designed to divide the voltage drop due to the emitter resistance of a push-pull output transistor and apply negative feedback. In this way, there is no need to provide a current detection resistor with a large wattage, and the unstable impedance of the speaker or the like will not affect the feedback current, so the operation itself will be extremely stable.
実施例の説明
本発明による一実施例を第２図に示す。第２図中、Ｑｌ
、Ｑ２はプッシュプル動作する相補型の出力トランジス
タ、Ｒ６，Ｒ７はそのエミッタ抵抗、その他は第１図中
の同一符号のものと同一である。DESCRIPTION OF THE EMBODIMENTS An embodiment according to the present invention is shown in FIG. In Figure 2, Ql
, Q2 are push-pull complementary output transistors, R6 and R7 are emitter resistors, and the other components are the same as those with the same symbols in FIG.
次に、この実施例の動作を説明する。通常、電力増幅器
において相補型トランジスタによるＢ級動作のプッシュ
プル出力段を用いた場合、出力トランジスタＱ１．Ｑ２
によるスイッチング歪を軽減するためにアイドリンク電
流を流すが、熱的安定性を得るために出力トランジスタ
Ｑ１．Ｑ２のエミッタにＱ１〜１９程度のエミッタ抵抗
Ｒ６，Ｒ７を挿入している。本発明はこのエミッタ抵抗
Ｒ６，Ｒ７を利用して負帰還電圧を得るものである。す
なわち、出力段より負帰還するポイントをエミッタ抵抗
Ｒ６とＲ６の接続点Ｏに選べば、出力インピーダンスは
零になるが、出力トランジスタＱ１．Ｑ２のエミッタ端
子に接続した分圧用抵抗Ｒ３，Ｒ４の接続点○゛に選べ
ば、各出力トランジスタＱ１．Ｑ２のエミッタ端子部分
の出力インピーダンスは零になるが、出力端子４におい
ては、エミッタ抵抗Ｒ６，Ｒ６が直列になるため、出力
インピーダンスはこのエミッタ抵抗Ｒ６，Ｒ６と同じ値
になる。従って、エミッタ抵抗Ｒ５，Ｒ６の接続点Ｏと
分圧用抵抗Ｒ３，Ｒ４の接続点０の間に可変抵抗ｖＲを
接続し、その摺動端子より帰還電圧をとり出すようにす
れば、出力インピーダンスを零からエミッタ抵抗までの
間で自由に可変することができる。しかも負荷抵抗ＲＬ
の影響を全く受けないから、動作もきわめて安定なもの
になる。Next, the operation of this embodiment will be explained. Normally, when a push-pull output stage of class B operation using complementary transistors is used in a power amplifier, the output transistor Q1. Q2
An idle link current is passed to reduce switching distortion caused by the output transistor Q1. Emitter resistors R6 and R7 of Q1 to Q19 are inserted into the emitter of Q2. The present invention utilizes these emitter resistors R6 and R7 to obtain a negative feedback voltage. That is, if the point of negative feedback from the output stage is selected as the connection point O between the emitter resistors R6 and R6, the output impedance becomes zero, but the output impedance of the output transistor Q1. If the connection point of the voltage dividing resistors R3 and R4 connected to the emitter terminal of Q2 is selected, each output transistor Q1. The output impedance of the emitter terminal portion of Q2 becomes zero, but at the output terminal 4, emitter resistors R6 and R6 are connected in series, so the output impedance has the same value as these emitter resistors R6 and R6. Therefore, by connecting a variable resistor vR between the connection point O of the emitter resistors R5 and R6 and the connection point 0 of the voltage dividing resistors R3 and R4, and taking out the feedback voltage from its sliding terminal, the output impedance can be reduced. It can be freely varied between zero and emitter resistance. Moreover, load resistance RL
Since it is completely unaffected by this, its operation is extremely stable.
また、第２図において、可縮抵抗ｖＲに直列または並列
にコンデンサを接続すれば、出力インピーダンスに周波
数特性をもたせることが可能となり、このようにすれば
、一層優れた負帰還をかけることができる。In addition, in Figure 2, if a capacitor is connected in series or parallel to the variable resistor vR, it is possible to give the output impedance a frequency characteristic, and in this way, even better negative feedback can be applied. .
発明の効果
以上のように本発明によれば、ワット数の大きい負荷型
棒検出用抵抗を用いることなく簡単に出力インピーダン
スを変化させることができる。しかも帰還電圧が負荷抵
抗の影響を受けないので、きわめて安定な動作が期待で
きる。Effects of the Invention As described above, according to the present invention, the output impedance can be easily changed without using a load-type rod detection resistor with a large wattage. Furthermore, since the feedback voltage is not affected by load resistance, extremely stable operation can be expected.
第１図は従来の電力増幅器の回路図、第２図は本発明の
一実施例の回路図である。
１・・・・・・入力端子、２，３・・・・・・電源端子
、４・・・・・・出力端子、５・・・・・・負荷接地端
子、６・・・・・・電力増幅部、Ｒ１，Ｒ２・・・・・
・帰還抵抗、Ｒ３，Ｒ４・・・・・・分圧用抵抗、Ｒ６
，Ｒ７・・・・・・エミッタ抵抗、ＲＬ・・・・・・負
荷抵抗、Ｑｌ、Ｑ２・・・・・・出力トランジスタ。FIG. 1 is a circuit diagram of a conventional power amplifier, and FIG. 2 is a circuit diagram of an embodiment of the present invention. 1... Input terminal, 2, 3... Power supply terminal, 4... Output terminal, 5... Load grounding terminal, 6... Power amplification section, R1, R2...
・Feedback resistor, R3, R4...Voltage dividing resistor, R6
, R7...Emitter resistance, RL...Load resistance, Ql, Q2...Output transistor.
Claims (3)
各エミッタに接続されたエミッタ抵抗と、上記各エミッ
タ抵抗による降下電圧を分圧する手段とを備え、上記分
圧された電圧で負帰還をかけるようにした電力増幅器。(1) Complementary push-pull output transistors, emitter resistors connected to their respective emitters, and means for dividing the voltage dropped by each of the emitter resistors, so as to apply negative feedback using the divided voltages. power amplifier.
を接続し、上記エミッタ抵抗同志の接続点と上記各分圧
用抵抗の他端同志の接続点の間に可変抵抗を接続し、上
記可変抵抗の摺動端子から負帰還電圧をとり出すように
した特許請求の範囲第１項記載の電力増幅器。(2) Connecting one end of a pair of voltage dividing resistors to the other end of each emitter resistor, and connecting a variable resistor between the connection point between the emitter resistors and the connection point between the other ends of each of the voltage dividing resistors, 2. A power amplifier according to claim 1, wherein a negative feedback voltage is taken out from a sliding terminal of said variable resistor.
たことを特徴とする特許請求の範囲第２項記載の電力増
幅器。(3) The power amplifier according to claim 2, characterized in that a capacitor is connected in series or in parallel with the variable resistor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12356382A JPS5913410A (en) | 1982-07-14 | 1982-07-14 | Power amplifying circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12356382A JPS5913410A (en) | 1982-07-14 | 1982-07-14 | Power amplifying circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS5913410A true JPS5913410A (en) | 1984-01-24 |
Family
ID=14863676
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP12356382A Pending JPS5913410A (en) | 1982-07-14 | 1982-07-14 | Power amplifying circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5913410A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6354808A (en) * | 1986-08-25 | 1988-03-09 | Yokogawa Electric Corp | Driver amplifier for parallel ad converter |
| EP0266919A2 (en) * | 1986-10-29 | 1988-05-11 | Eta Systems, Inc. | Integrated circuit output buffer |
-
1982
- 1982-07-14 JP JP12356382A patent/JPS5913410A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6354808A (en) * | 1986-08-25 | 1988-03-09 | Yokogawa Electric Corp | Driver amplifier for parallel ad converter |
| EP0266919A2 (en) * | 1986-10-29 | 1988-05-11 | Eta Systems, Inc. | Integrated circuit output buffer |
| EP0266919A3 (en) * | 1986-10-29 | 1989-08-30 | Eta Systems, Inc. | Integrated circuit output buffer |
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