JPS61101106A - Operation start characteristic improving circuit of agc circuit - Google Patents
Operation start characteristic improving circuit of agc circuitInfo
- Publication number
- JPS61101106A JPS61101106A JP59223188A JP22318884A JPS61101106A JP S61101106 A JPS61101106 A JP S61101106A JP 59223188 A JP59223188 A JP 59223188A JP 22318884 A JP22318884 A JP 22318884A JP S61101106 A JPS61101106 A JP S61101106A
- Authority
- JP
- Japan
- Prior art keywords
- voltage
- agc
- circuit
- switching
- turned
- 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.)
- Granted
Links
Abstract
Description
【発明の詳細な説明】
（イ）産業上の利用分野
本発明は、電子機器の自動利得制御（ＡＧＣ）回路に係
り、特に電源電圧投入時のＡＧＣ検波回路の立上り時間
を少くしたＡＧＣ回路の動作開始特性改善回路に関する
。Detailed Description of the Invention (a) Field of Industrial Application The present invention relates to an automatic gain control (AGC) circuit for electronic equipment, and in particular to an AGC circuit that reduces the rise time of the AGC detection circuit when the power supply voltage is turned on. This invention relates to an operation start characteristic improvement circuit.
（ロ）従来の技術
一般にＡＧＣ回路は、増幅器の出力端から入力端に対し
、前記増幅器の出力信号のレベルを検出するＡＧＣ検波
回路と、該検波回路の出力レベルに応じてＡＧＣ駆動回
路を動作させ、これにより前記増幅器の利得を制御する
ＡＧＣループが設げられている。(B) Prior art In general, an AGC circuit includes an AGC detection circuit that detects the level of the output signal of the amplifier from the output end of the amplifier to the input end, and an AGC drive circuit that operates according to the output level of the detection circuit. An AGC loop is provided to control the gain of the amplifier.
その−例として東京三洋電機株半導体事業部発行の「三
洋半導体二一−ズＪＡ１１３９Ａに掲載されているＩＣ
，ＬＡ７０４０の応用回路例が上げられ、要部を第２図
に示す。An example of this is the IC listed in "Sanyo Semiconductor 21-S JA1139A" published by the Semiconductor Division of Tokyo Sanyo Electric Co., Ltd.
, an example of an applied circuit for LA7040 is given, and the main part is shown in FIG.
第２図において、（１）は増幅器、（２）はコンデンサ
ｆ３）（４）及びダイオード（５１（６）より成る検波
回路、（７）はＡＧＣ駆動回路、（８）は入力端子、（
９）は出力端子、０■υは結合コンデンサを示し、入力
端子（８）に入力信号を加えると結合コンデンサα■を
介して増幅器（１）にて信号増幅され、出力端子（９）
からは結合コンデンサ（１１）を介して出力端子（９）
から出力信号が得られる。In Fig. 2, (1) is an amplifier, (2) is a detection circuit consisting of a capacitor f3) (4) and a diode (51 (6), (7) is an AGC drive circuit, (8) is an input terminal, (
9) is an output terminal, and 0■υ is a coupling capacitor. When an input signal is applied to the input terminal (8), the signal is amplified by the amplifier (1) via the coupling capacitor α■, and the signal is output to the output terminal (9).
from the output terminal (9) via the coupling capacitor (11)
The output signal is obtained from
このとき入力信号のレベルの大小に応じてＡＧＣ検波回
路（２）のコンデンサ＋３）ｆ４）及びダイオード（５
）（６）によって倍圧整流し、ＡＧＣｉ駆勲回路（力か
ら前記増幅器（１）に帰還を施し、その利得制御を行い
、テープレコーダの音声記録時は記録信号レベルを一定
範囲内にするためＡＬＣと呼ばれるレベル制御が行われ
る。At this time, depending on the level of the input signal, the capacitor +3)f4) and diode (5) of the AGC detection circuit (2)
)(6), the AGCi drive circuit (power is fed back to the amplifier (1), its gain is controlled, and the recording signal level is kept within a certain range when recording audio on a tape recorder. Level control called ALC is performed.
ところが前記ＡＧＣ検波回路（２）は、電源スィッチが
オフの状態では不動作であり、従って充放電用のコンデ
ンサ（４）の充電電荷はゼロの状態となっている。そこ
で、電源電圧投入と同時に入力端子（８）に大入力信号
が加えられると、前記コンデンサ（４）が充電されるま
でに時間を要し、第３図（イ）に示すように電源電圧投
入時、増幅器（１）の出力が大振幅になったり、増幅器
（１）は飽和した場合出力端子（９）からは歪んだ信号
が現われる。However, the AGC detection circuit (2) is inoperative when the power switch is off, and therefore the charge in the charging/discharging capacitor (4) is zero. Therefore, if a large input signal is applied to the input terminal (8) at the same time as the power supply voltage is turned on, it will take time for the capacitor (4) to be charged, and as shown in Figure 3 (a), the power supply voltage will be turned on. When the output of the amplifier (1) becomes large in amplitude or the amplifier (1) becomes saturated, a distorted signal appears from the output terminal (9).
（ハ）発明が解決しようとする問題点
前述の従来例では、電源投入時大入力信号が増幅器に加
わった場合、出力が大振幅となったり増幅器が飽和し、
出力信号が歪んでしまう欠点があったのを、本発明は前
記欠点を除去するものである。(c) Problems to be solved by the invention In the conventional example described above, when a large input signal is applied to the amplifier when the power is turned on, the output becomes large in amplitude or the amplifier becomes saturated.
The present invention eliminates the drawback that the output signal is distorted.
に）問題点を解決するための手段
本発明は、ＡＧＣループを構成するＡＧＣ検波回路の出
力端にスイッチングトランジスタとショットキーダイオ
ードを接続し、該スイッチングトランジスタのベースて
電源電圧投入と同時にオンさせるだめのパルスを印加す
る構成である。B) Means for solving the problem The present invention connects a switching transistor and a Schottky diode to the output terminal of an AGC detection circuit constituting an AGC loop, and turns on the base of the switching transistor at the same time as the power supply voltage is turned on. This is a configuration that applies pulses of .
（ホ）作用
本発明の構成において、前記スイッチングトランジスタ
を電源電圧投入時該スイッチングトランジスタのベース
に制御用のパルスを印加するので、該スイッチングトラ
ンジスタはオンになり、それに伴ってＡＧＣ検波回路の
出力端は前記ショットキーダイオードの順方向電圧分だ
けが前記ＡＧＣ駆動回路に加わり、ＡＧＣ検波回路の動
作開始に先立ち、入力端子（８）大入力信号印加時ＡＧ
Ｃルーズの動作開始が早められる。(E) Effect In the configuration of the present invention, a control pulse is applied to the base of the switching transistor when the power supply voltage is turned on, so the switching transistor is turned on, and accordingly, the output terminal of the AGC detection circuit Only the forward voltage of the Schottky diode is applied to the AGC drive circuit, and prior to the start of operation of the AGC detection circuit, when a large input signal is applied to the input terminal (8), the AG
The start of C-loose operation is brought forward.
（へ）実施例
図面に従って本発明を説明すると、第１図は本発明回路
を示し、第２図と同一素子については同一図番を付して
あり、α２は電源トランジスタ、αＪは駆動用トランジ
スタ、（１４１はリップルフィルタ用コンデンサ、ａ５
はスイッチングトランジスタ、ａＱはショットキーダイ
オ−、ドである。(f) To explain the present invention according to the drawings, Figure 1 shows the circuit of the present invention, and the same elements as in Figure 2 are given the same figure numbers, α2 is a power transistor, αJ is a drive transistor , (141 is a ripple filter capacitor, a5
is a switching transistor, and aQ is a Schottky diode.
次に本発明回路の動作について説明すると、電源スィッ
チ（図示せず）オフ時、ＡＧＣ検波回路（２）の充放電
用コンデンサ（４）は、全く電圧が加わっていないので
、充電電荷はゼロの状態である。Next, to explain the operation of the circuit of the present invention, when the power switch (not shown) is off, no voltage is applied to the charging/discharging capacitor (4) of the AGC detection circuit (2), so the charging charge is zero. state.
そこで前記電源スィッチを閉じ、電源電圧投入により、
端子（１７１に所定電圧（ＶＣ，、）が加わると、これ
に伴って、抵抗Ｑ８）を通して流れる充電電流による抵
抗αＱの電圧降下によりトランジスタα９が光電期間の
ある時間だけオンして、スイッチングトランジスタ（１
５１のベースに正電圧が加わってバイアスされ、該スイ
ッチングトランジスタ叫がオンするので、該スイッチン
グトランジスタａ９のエミッタを介してショットキーダ
イオードαＱに流れる電流によるダイオードａ５の立上
り電圧Ｖｓｔ（例えば０．４ボルト）がスイッチングト
ランジスタ■のコレクタに現われ、この電圧がＡＧＣ検
波回路（２）のコンデンサ（４）に加わり、該コンデン
サ（４）は充電されるので、ＡＧＣ駆動回路（力の入力
端電圧はＶｓｆに等しくなる。Then, by closing the power switch and turning on the power supply voltage,
When a predetermined voltage (VC, , ) is applied to the terminal (171), the voltage drop across the resistor αQ due to the charging current flowing through the resistor Q8 turns on the transistor α9 for a certain period of time during the photoelectric period, and the switching transistor ( 1
A positive voltage is applied to the base of the switching transistor a9 to bias it and turn on the switching transistor, so that the rising voltage Vst of the diode a5 (for example, 0.4 volts) due to the current flowing to the Schottky diode αQ through the emitter of the switching transistor a9. ) appears at the collector of the switching transistor ■, and this voltage is applied to the capacitor (4) of the AGC detection circuit (2), and the capacitor (4) is charged, so that the input terminal voltage of the AGC drive circuit (power input terminal voltage becomes Vsf). be equal.
このとき前記スイッチングトランジスタα５のコレクタ
・エミッタ間電圧（ＶｃｍｏＷ）はほぼゼロであり、無
視するものとする。At this time, the collector-emitter voltage (VcmoW) of the switching transistor α5 is approximately zero and is ignored.
次にリップルフィルタを構成するコンデンサ圓が徐々に
抵抗時を介して充電され充電が完了すると、トランジス
タＯ３は通常のリップルフィルタの動作を行い、リップ
ルフィルタ用のコンデンサα４の両端電圧は上昇し、ト
ランジスタ（１３１はオフ、ｕｚはオンとなり、増幅器
（１）へはトランジスタα力を介して定電圧が与えられ
、入力端子（８）Ｋ加えられた入力信号は、結合コンデ
ンサαＱを介して増幅器（１）に入力され、結合コンデ
ンサαυを介して出力端子（９）から出力信号が得られ
る。このときＡＧＣ検波回路（７）は、前記増幅器（１
）の出力信号の大きさに応じて検波出力がＡＧＣ駆動回
路（７）に加わり、該ＡＧＣ駆動回路（力の出力端は前
記結合コンデンサαυの一端に加わり、ＡＧＣ動作が行
われる。Next, the capacitor circle constituting the ripple filter is gradually charged through the resistor, and when charging is completed, the transistor O3 operates as a normal ripple filter, the voltage across the ripple filter capacitor α4 rises, and the transistor (131 is off, uz is on, a constant voltage is applied to the amplifier (1) via the transistor α, and the input signal applied to the input terminal (8) K is sent to the amplifier (1) via the coupling capacitor αQ. ), and an output signal is obtained from the output terminal (9) via the coupling capacitor αυ.At this time, the AGC detection circuit (7)
) is applied to the AGC drive circuit (7), the output terminal of which is applied to one end of the coupling capacitor αυ, and AGC operation is performed.
ここで前記入力信号が大振幅になったとしても、前記ス
イッチングトランジスタ叫及びショットキーダイオード
側を通してＡＧＣ検波回路（２）のコンデンサ（４）に
充電電流の流れ、電源電圧投入と同時にＡＧＣ駆動回路
は動作し得る。第１図において、増幅器（１）の入力側
にＡＧＣループが動作し始めるレベルよりも２０ｄＢ大
きい信号を加えておいて、電源電圧投入したとき、第３
図（ロ）に示すように、従来の場合（第３図（イ））に
比し、約１／２のレベルに抑制される。Even if the input signal has a large amplitude, a charging current flows to the capacitor (4) of the AGC detection circuit (2) through the switching transistor and the Schottky diode, and the AGC drive circuit is activated at the same time as the power supply voltage is turned on. It can work. In Figure 1, a signal 20 dB higher than the level at which the AGC loop starts operating is applied to the input side of the amplifier (1), and when the power supply voltage is turned on, the third
As shown in Figure (b), the level is suppressed to about 1/2 compared to the conventional case (Figure 3 (a)).
（ト）発明の効果
本発明によれば、電源電圧投入時に増幅器に大入力信号
が加わった場合でも、制御パルス発生回路からの制御パ
ルスにより、スイッチングトランジスタ及びショットキ
ーダイオードをオンになし、ＡＧＣ検波回路の出力端の
電位を上げておく構成であり、前記大入力信号に対して
もＡＧＣ駆動回路が応動でき、従来の様にＡＧＣ動作の
遅れによる増幅器の明相等の支障は防止できる。(G) Effects of the Invention According to the present invention, even if a large input signal is applied to the amplifier when the power supply voltage is turned on, the switching transistor and Schottky diode are turned on by the control pulse from the control pulse generation circuit, and the AGC detection The configuration is such that the potential at the output terminal of the circuit is raised, so that the AGC drive circuit can respond to the large input signal, and problems such as bright phase of the amplifier due to delay in AGC operation, which are conventional, can be prevented.
第１図は本発明のＡＧＣ回路の動作開始特性改善回路を
示す回路図、第２図は従来の同回路を示す回路図、第３
図は同回路の説明波形図を示す。
主な図番の説明
（１）・・・増幅器、 （２）・・・ＡＧＣ検波回路、
（７）・・・へ〇〇駆動回路、 （８）−入力端子、
（９）・・・出力端子、Ｑ２Ｑ３１・・・電源トラン
ジスタ、 ａ５・・・スイッチングトランジスタ、 （
１６１・・・ショットキーダイオード。
出願人 三洋電機株式会社 外１名
代理人 弁理士 佐 野 静 夫
第２ｒ４
第３図
電神股ト
１にＸFIG. 1 is a circuit diagram showing a circuit for improving the operation start characteristic of an AGC circuit according to the present invention, FIG. 2 is a circuit diagram showing a conventional circuit, and FIG.
The figure shows an explanatory waveform diagram of the same circuit. Explanation of main drawing numbers (1)...Amplifier, (2)...AGC detection circuit,
(7) ...〇〇drive circuit, (8) - input terminal,
(9)...Output terminal, Q2Q31...Power transistor, a5...Switching transistor, (
161...Schottky diode. Applicant Sanyo Electric Co., Ltd. and one other agent Patent attorney Shizuo Sano No. 2r4 Figure 3 Denjinmata to 1
Claims (1)
側に帰還ループを接続し、該増幅器の利得を自動制御す
るＡＧＣ回路において、前記ＡＧＣ検波回路の出力端に
スイッチングトランジスタのコレクタ・エミッタ路とシ
ョットキーダイオードを直列接続し、該スイッチングト
ランジスタのベースを電源電圧投入時に制御するパルス
発生回路を前記ベースに接続し、前記電源電圧投入と同
時に前記ＡＧＣ検波回路を動作開始せしめることを特徴
としたＡＧＣ回路の動作開始特性改善回路。(1) In an AGC circuit that automatically controls the gain of the amplifier by connecting a feedback loop from the output side of the amplifier to the input side via the AGC detection circuit, the collector-emitter path of the switching transistor is connected to the output end of the AGC detection circuit. and a Schottky diode are connected in series, a pulse generation circuit for controlling the base of the switching transistor when the power supply voltage is turned on is connected to the base, and the AGC detection circuit starts operating at the same time as the power supply voltage is turned on. A circuit for improving the operation start characteristics of an AGC circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59223188A JPS61101106A (en) | 1984-10-23 | 1984-10-23 | Operation start characteristic improving circuit of agc circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59223188A JPS61101106A (en) | 1984-10-23 | 1984-10-23 | Operation start characteristic improving circuit of agc circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61101106A true JPS61101106A (en) | 1986-05-20 |
| JPH047604B2 JPH047604B2 (en) | 1992-02-12 |
Family
ID=16794177
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP59223188A Granted JPS61101106A (en) | 1984-10-23 | 1984-10-23 | Operation start characteristic improving circuit of agc circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61101106A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0946614A (en) * | 1995-07-27 | 1997-02-14 | Nec Corp | Automatic gain control circuit and receiving front end device using the circuit |
| US7251933B2 (en) | 2002-03-08 | 2007-08-07 | Kayaba Industry Co., Ltd. | Flow rate control device for power steering |
-
1984
- 1984-10-23 JP JP59223188A patent/JPS61101106A/en active Granted
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0946614A (en) * | 1995-07-27 | 1997-02-14 | Nec Corp | Automatic gain control circuit and receiving front end device using the circuit |
| US7251933B2 (en) | 2002-03-08 | 2007-08-07 | Kayaba Industry Co., Ltd. | Flow rate control device for power steering |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH047604B2 (en) | 1992-02-12 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4254303A (en) | Automatic volume adjusting apparatus | |
| US4112384A (en) | Controlled recovery automatic gain control amplifier | |
| US3832627A (en) | Transistor circuit with slow voltage rise and fast voltage fall characteristic | |
| US3770984A (en) | Fast recovery low distortion limiter circuit | |
| JPH0750861B2 (en) | Pulse noise suppression device for FM receiver | |
| JPS622783A (en) | Agc wave detecting circuit | |
| US4319094A (en) | Three-terminal power supply circuit for telephone set | |
| US4264785A (en) | Voltage regulator circuitry for a telephone answering device | |
| JPS61101106A (en) | Operation start characteristic improving circuit of agc circuit | |
| JPH0420302B2 (en) | ||
| US4119801A (en) | Mode switching and voltage regulator circuitry for a telephone answering device | |
| EP0102660B1 (en) | Telephone circuit | |
| US4234892A (en) | AGC Circuit responsive to intermediate gray level in video signal | |
| US4751577A (en) | Gain control circuit | |
| US4639616A (en) | Circuit for controlling the base of a power transistor used in high tension switching | |
| US4051442A (en) | Gain control circuits for audio amplifiers | |
| JPS6338147B2 (en) | ||
| US2915650A (en) | Ramp wave generator | |
| KR890006328Y1 (en) | Video camera fade control signal generator | |
| JPS6329293Y2 (en) | ||
| JP3132103B2 (en) | Coil switching device | |
| JPH0417510B2 (en) | ||
| US4075513A (en) | Averaging and peak detection circuit | |
| JPS6012707B2 (en) | recording level control device | |
| JPH039380Y2 (en) |