JPS6325770Y2 - - Google Patents
Info
- Publication number
- JPS6325770Y2 JPS6325770Y2 JP7641380U JP7641380U JPS6325770Y2 JP S6325770 Y2 JPS6325770 Y2 JP S6325770Y2 JP 7641380 U JP7641380 U JP 7641380U JP 7641380 U JP7641380 U JP 7641380U JP S6325770 Y2 JPS6325770 Y2 JP S6325770Y2
- Authority
- JP
- Japan
- Prior art keywords
- voltage
- terminal
- current
- output
- circuit
- 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.)
- Expired
Links
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- Control Of Amplification And Gain Control (AREA)
- Amplifiers (AREA)
Description
【考案の詳細な説明】
本考案は可変増幅回路に係り、出力電圧のレベ
ル調整に応じて電圧−電流変換回路の変換率を可
変させ、特に低出力調整時に変換率を最小にして
許容入力電圧を最大とし、実装のSN比を大きく
とり得る可変増幅回路を提供することを目的とす
る。[Detailed Description of the Invention] The present invention relates to a variable amplifier circuit, in which the conversion rate of a voltage-to-current conversion circuit is varied according to the level adjustment of the output voltage, and the conversion rate is minimized especially when adjusting the output voltage to allow the allowable input voltage. The purpose of this invention is to provide a variable amplifier circuit that can maximize the SN ratio of the implementation.
一般の音量調整回路に用いられている可変増幅
回路は、増幅器出力の電圧レベルを可変抵抗器に
よる抵抗値の比で分割して信号減衰量を可変して
いた。このものは、増幅器そのものの利得を可変
しているのではなく、増幅器出力を分割している
だけであるので、増幅器自体のノイズ成分が出力
され、第１図の曲線（可変抵抗器の抵抗値が
100KΩで、最大出力時の回路利得が17dBの回路
の特性）に示す如く、SN比は比較的低く、特に
−6dB付近においてピークを生じる欠点があつ
た。 Variable amplifier circuits used in general volume adjustment circuits vary the amount of signal attenuation by dividing the voltage level of the amplifier output by the ratio of the resistance values of variable resistors. This device does not vary the gain of the amplifier itself, but only divides the amplifier output, so the noise component of the amplifier itself is output, and the curve shown in Figure 1 (resistance value of variable resistor but
As shown in the circuit characteristics (100KΩ, circuit gain of 17dB at maximum output), the S/N ratio was relatively low, and had the drawback of peaking especially around -6dB.
本考案は上記欠点を除去したものであり、以下
図面と共にその一実施例について説明する。 The present invention eliminates the above-mentioned drawbacks, and an embodiment thereof will be described below with reference to the drawings.
第２図は本考案になる可変増幅回路の一実施例
の回路図を示す。同図中、１は入力端子、２は電
圧−電流変換回路で、従来周知のものである。
VRは音量調整用の可変抵抗器で、可動接片Ｃは
アースされていて出力端子３′に接続されており、
端子Ａは電圧−電流変換回路２の電流出力端子４
及び出力端子３に接続されており、端子Ｂは抵抗
R10を介してトランジスタQ2，Q3のエミツタの接
続点Ｄに接続されている。 FIG. 2 shows a circuit diagram of an embodiment of the variable amplifier circuit according to the present invention. In the figure, 1 is an input terminal, and 2 is a voltage-current conversion circuit, which is conventionally known.
VR is a variable resistor for adjusting the volume, and the movable contact piece C is grounded and connected to the output terminal 3'.
Terminal A is the current output terminal 4 of the voltage-current conversion circuit 2
and output terminal 3, and terminal B is a resistor.
It is connected to a connection point D between the emitters of transistors Q 2 and Q 3 via R 10 .
入力端子１に入来した入力信号はFETQ1を介
してトランジスタQ2，Q3のベースに供給される。
FETQ1はソースホロワ、トランジスタQ2，Q3は
エミツタホロワであるため、点Ｄの電圧は入力信
号電圧に略等しくなる。トランジスタQ4，Q6、
抵抗R4，R6にて第１のカレントミラー回路、ト
ランジスタQ5，Q7、抵抗R5，R7にて第２のカレ
ントミラー回路が構成されており、点Ｄの電圧を
VD、可変抵抗器VRの可動接片Ｃと端子Ｂとの間
の抵抗値をR11とすると、VD／R10＋R11なる電流が
これら２つのカレントミラー回路に流れ、入力信
号電圧の大きさに応じた値の出力電流Ｉが出力端
子４よりとり出される。ここの場合、電圧−電流
変換率は、可変抵抗器VRの可動接片Ｃと端子Ｂ
との間の抵抗値R11と抵抗R10の抵抗値との和に
て決定される。 An input signal that has entered input terminal 1 is supplied to the bases of transistors Q 2 and Q 3 via FET Q 1 .
Since FET Q 1 is a source follower and transistors Q 2 and Q 3 are emitter followers, the voltage at point D is approximately equal to the input signal voltage. Transistors Q 4 , Q 6 ,
Resistors R 4 and R 6 constitute a first current mirror circuit, transistors Q 5 and Q 7 and resistors R 5 and R 7 constitute a second current mirror circuit, and the voltage at point D is
V D , and the resistance value between the movable contact piece C of the variable resistor VR and the terminal B is R 11 , a current of V D /R 10 + R 11 flows through these two current mirror circuits, and the input signal voltage An output current I having a value corresponding to the magnitude is taken out from the output terminal 4. In this case, the voltage-current conversion rate is between the movable contact C of the variable resistor VR and the terminal B.
It is determined by the sum of the resistance value R11 between and the resistance value of the resistor R10 .
ここで、最大音量を得るとき、可変抵抗器VR
の可動接片Ｃを端子Ｂに接続する。出力電流Ｉ
は、出力端子３，３′間に接続される負荷、可動
接片Ｃ、抵抗R10を介して点Ｄに流れる。この
際、可動接片Ｃと端子Ｂとの間の抵抗値は実質上
無視し得るので出力電流Ｉは最大値となり、一
方、可動接片Ｃと端子Ａとの間の抵抗値は最大
（R11＋R12）となり、かつ、出力電流Ｉは最大値
であるので、出力端子３，３′間には最大出力電
圧がとり出される。又、出力電流は最大であるの
で、電圧−電流変換率は高く、この時の利得を
20dB、最大出力電圧を20Vとすると、許容入力
電圧は2Vと比較的小になる。 Here, when getting the maximum volume, the variable resistor VR
Connect the movable contact piece C to the terminal B. Output current I
flows to point D via the load connected between output terminals 3 and 3', movable contact C, and resistor R10 . At this time, the resistance value between the movable contact piece C and the terminal B can be practically ignored, so the output current I becomes the maximum value, while the resistance value between the movable contact piece C and the terminal A becomes the maximum value (R 11 +R 12 ) and the output current I is at its maximum value, so the maximum output voltage is taken out between the output terminals 3 and 3'. Also, since the output current is maximum, the voltage-current conversion rate is high, and the gain at this time is
20dB, and the maximum output voltage is 20V, the allowable input voltage is 2V, which is relatively small.
一方、音量を小さくするとき、可動接片Ｃを端
子Ａ側に変位させる。これにより、可動接片Ｃと
端子Ｂとの間の抵抗値は上記最大出力時よりも大
きくなり、出力電流は可動接片Ｃと端子Ｂとの間
の抵抗R11及び抵抗R10を介して流れるので上記
最大出力よりも小さくなり、従つて、電圧−電流
変換率は小さくなり、許容入力電圧は大きくな
る。又、可動接片Ｃと端子Ａとの間の抵抗値は上
記最大出力時より小さくなり、かつ、出力電流は
上記最大出力時よりも小さくなるので、出力端子
３，３間の出力電圧は上記の場合よりも小さくな
る。 On the other hand, when reducing the volume, the movable contact piece C is displaced toward the terminal A side. As a result, the resistance value between the movable contact piece C and the terminal B becomes larger than that at the maximum output, and the output current flows through the resistance R11 and the resistance R10 between the movable contact piece C and the terminal B. Since the current flows, the output becomes smaller than the maximum output, so the voltage-to-current conversion ratio becomes smaller and the allowable input voltage becomes larger. In addition, the resistance value between the movable contact piece C and the terminal A is smaller than that at the above maximum output, and the output current is smaller than that at the above maximum output, so the output voltage between the output terminals 3 and 3 is smaller than that at the above maximum output. is smaller than in the case of .
この場合、本願考案は電圧−電流変換回路２の
電圧−電流変換率を可変することにより回路の利
得を可変して音量調整しているので、出力電圧を
小に調整する伴つて許容入力は大となり、単に増
幅器出力の電圧レベルを分圧して音量調整してい
た従来の回路に比して出力電圧に回路のノイズ成
分が含まれる割合は少なく、第１図の曲線（可
変抵抗器VRの抵抗値が10KΩで、最大出力時の
回路利得が17dBの回路の特性）に示す如く、従
来のものに比してSN比を比較的高くとり得る。 In this case, the present invention adjusts the volume by varying the gain of the circuit by varying the voltage-to-current conversion rate of the voltage-to-current conversion circuit 2, so as the output voltage is adjusted to a small value, the allowable input increases. Compared to conventional circuits that simply adjust the volume by dividing the voltage level of the amplifier output, the proportion of circuit noise components included in the output voltage is small. As shown in the characteristics of the circuit with a value of 10KΩ and a circuit gain of 17dB at maximum output, it is possible to achieve a relatively high SN ratio compared to conventional ones.
音量を最小にするとき、可動接片Ｃを端子Ａに
接続する。これにより、可動接片Ｃと端子Ｂとの
間の抵抗値は最大になつて出力電流は最小とな
り、一方、可動接片Ｃと端子Ａとの間の抵抗値は
最小となり、かつ、出力電流は最小であるので、
出力端子３，３′間の出力電圧は最小になる。こ
のとき、出力電流は最小であるので電圧−電流変
換率は低く、従つて、許容入力電圧は最大とな
り、例えば20V程度まで入力可能となる。 When minimizing the volume, connect movable contact piece C to terminal A. As a result, the resistance value between the movable contact piece C and the terminal B becomes the maximum, and the output current becomes the minimum, while the resistance value between the movable contact piece C and the terminal A becomes the minimum value, and the output current becomes the minimum value. is the minimum, so
The output voltage between output terminals 3 and 3' becomes minimum. At this time, since the output current is the minimum, the voltage-current conversion rate is low, and therefore the allowable input voltage is the maximum, for example, it is possible to input up to about 20V.
なお、電圧−電流変換回路は上記実施例のもの
に限定されることはなく、入力電圧をこれに応じ
た大きさの電流値としてとり出す回路であればよ
い。 Note that the voltage-current conversion circuit is not limited to that of the above embodiment, and may be any circuit that extracts the input voltage as a current value corresponding to the input voltage.
上述の如く、本考案になる可変増幅回路は、一
方の端子を一方の出力端子に接続され、可動接片
をアースされて他方の出力端子に接続された可変
抵抗器と、入力電圧に略等しい電圧をエミツタ共
通接続点に取出すエミツタホロワの一対のトラン
ジスタと、該一対のトランジスタの一方のトラン
ジスタのコレクタに接続された第１のカレントミ
ラー回路と、該一対のトランジスタの他方のトラ
ンジスタのコレクタに接続された第２のカレント
ミラー回路とにて構成され、上記第１のカレント
ミラー回路と第２のカレントミラー回路とを接続
して上記可変抵抗器の一方の端子に接続して上記
入力電圧に応じた大きさの電流を取出す電流出力
端子とし、上記エミツタ共通接続点を抵抗を介し
て上記可変抵抗器の他方の端子に接続し、該可変
抵抗器の可動接片と該可変抵抗器の他方の端子と
の間の抵抗を電圧−電流変換率を決定する素子と
して動作する電圧−電流変換回路とより構成した
ため、可動接片の変位によつて可動接片と上記他
方の端子との間の抵抗値を可変し得、これによ
り、電圧−電流変換率を可変して回路利得を可変
し得、特に、出力レベルを小に調整すべく可動接
片を変位せしめる操作に伴つて電圧−電流変換率
は低くなつて許容入力電圧は大きくなるので、例
えば、音量調整回路に適用した場合、単に増幅器
出力の電圧レベルを分圧して調整していた従来回
路に比して出力電圧に回路のノイズ成分が含まれ
る割合は少なく、従来のものに比して実装のSN
比を大きくとり得る等の特長を有する。 As mentioned above, the variable amplifier circuit according to the present invention includes a variable resistor whose one terminal is connected to one output terminal, whose movable contact piece is grounded and connected to the other output terminal, and whose input voltage is approximately equal to the input voltage. A pair of emitter follower transistors that take out voltage to a common emitter connection point, a first current mirror circuit connected to the collector of one transistor of the pair of transistors, and a first current mirror circuit connected to the collector of the other transistor of the pair of transistors. and a second current mirror circuit, and the first current mirror circuit and the second current mirror circuit are connected to one terminal of the variable resistor to adjust the voltage according to the input voltage. The emitter common connection point is connected to the other terminal of the variable resistor via a resistor, and the movable contact piece of the variable resistor and the other terminal of the variable resistor are connected to each other. Since the resistance between the movable contact piece and the other terminal is configured by a voltage-current conversion circuit that operates as an element that determines the voltage-current conversion rate, the resistance value between the movable contact piece and the other terminal is changed by the displacement of the movable contact piece. This makes it possible to vary the circuit gain by varying the voltage-to-current conversion rate. In particular, the voltage-to-current conversion rate changes as the movable contact piece is displaced to adjust the output level to a small level. For example, when applied to a volume adjustment circuit, the output voltage will contain noise components from the circuit, compared to conventional circuits that simply divide the voltage level of the amplifier output and adjust it. SN of implementation is small compared to conventional
It has the advantage of being able to take a large ratio.
第１図は従来回路及び本考案回路の回路利得対
SN比特性図、第２図は本考案回路の一実施例の
回路図である。
１……入力端子、２……電圧−電流変換回路、
３，３′……出力端子、４……電流出力端子、
VR……可変抵抗器、Q1〜Q7……トランジスタ、
R10〜R12……抵抗。
Figure 1 shows the circuit gain vs. of the conventional circuit and the circuit of the present invention.
FIG. 2 is a circuit diagram of an embodiment of the circuit of the present invention. 1...Input terminal, 2...Voltage-current conversion circuit,
3, 3'...Output terminal, 4...Current output terminal,
VR……variable resistor, Q1 to Q7 ……transistor,
R10 ~ R12 ...Resistance.
Claims (1)
接片をアースされて他方の出力端子に接続された
可変抵抗器と、 入力電圧に略等しい電圧をエミツタ共通接続点
に取出すエミツタホロワの一対のトランジスタ
と、該一対のトランジスタの一方のトランジスタ
のコレクタに接続された第１のカレントミラー回
路と、該一対のトランジスタの他方のトランジス
タのコレクタに接続された第２のカレントミラー
回路とにて構成され、上記第１のカレントミラー
回路と第２のカレントミラー回路とを接続して上
記可変抵抗器の一方の端子に接続して上記入力電
圧に応じた大きさの電流を取出す電流出力端子と
し、上記エミツタ共通接続点を抵抗を介して上記
可変抵抗器の他方の端子に接続し、上記可変抵抗
器の可動接片と上記可変抵抗器の他方の端子との
間の抵抗を電圧−電流変換率を決定する素子とし
て動作する電圧−電流変換回路とより構成してな
る可変増幅回路。[Claims for Utility Model Registration] A variable resistor whose one terminal is connected to one output terminal, whose movable contact piece is grounded and connected to the other output terminal, and a voltage approximately equal to the input voltage is commonly connected to the emitter. a pair of emitter follower transistors, a first current mirror circuit connected to the collector of one of the pair of transistors, and a second current mirror circuit connected to the collector of the other transistor of the pair of transistors; The first current mirror circuit and the second current mirror circuit are connected to one terminal of the variable resistor to generate a current having a magnitude corresponding to the input voltage. The common connection point of the emitter is connected to the other terminal of the variable resistor through a resistor, and the resistance between the movable contact piece of the variable resistor and the other terminal of the variable resistor is set as the current output terminal to be taken out. and a voltage-current conversion circuit that operates as an element to determine the voltage-current conversion rate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7641380U JPS6325770Y2 (en) | 1980-06-02 | 1980-06-02 |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7641380U JPS6325770Y2 (en) | 1980-06-02 | 1980-06-02 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS572720U JPS572720U (en) | 1982-01-08 |
| JPS6325770Y2 true JPS6325770Y2 (en) | 1988-07-13 |
Family
ID=29439047
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7641380U Expired JPS6325770Y2 (en) | 1980-06-02 | 1980-06-02 |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6325770Y2 (en) |
-
1980
- 1980-06-02 JP JP7641380U patent/JPS6325770Y2/ja not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS572720U (en) | 1982-01-08 |
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