JPS58206220A - Variable attenuating circuit - Google Patents
Variable attenuating circuitInfo
- Publication number
- JPS58206220A JPS58206220A JP9075082A JP9075082A JPS58206220A JP S58206220 A JPS58206220 A JP S58206220A JP 9075082 A JP9075082 A JP 9075082A JP 9075082 A JP9075082 A JP 9075082A JP S58206220 A JPS58206220 A JP S58206220A
- Authority
- JP
- Japan
- Prior art keywords
- resistance
- resistor
- value
- train
- 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.)
- Pending
Links
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
- H03H7/24—Frequency- independent attenuators
- H03H7/25—Frequency- independent attenuators comprising an element controlled by an electric or magnetic variable
Landscapes
- Attenuators (AREA)
Abstract
Description
【発明の詳細な説明】
本発明は、ラダー抵抗回路によるディジタル制従来のＲ
−２１ラダ一抵抗回路による可変減衰回路の例を第１図
に示す。DETAILED DESCRIPTION OF THE INVENTION The present invention provides a digital system using a ladder resistance circuit.
An example of a variable attenuation circuit using a -21 ladder-resistance circuit is shown in FIG.
第１図において、１は入力端、２は抵抗値Ｒの複数の抵
抗を寵列釦接続した第１の抵抗列、３は抵抗値２Ｒの複
数の抵抗を並列に接続した第２の抵抗列、４は第２の抵
抗列３の各抵抗を接地または出力端に切換えるための複
数のスイッチで構成されたスイッチ列、６は出力端であ
る。In Figure 1, 1 is an input terminal, 2 is a first resistor string in which a plurality of resistors with a resistance value R are connected in parallel, and 3 is a second resistor string in which a plurality of resistors with a resistance value 2R are connected in parallel. , 4 is a switch array composed of a plurality of switches for switching each resistor of the second resistor array 3 to ground or an output terminal, and 6 is an output terminal.
通常、第１図に示すＲ−２Ｒラダ一抵抗回路の出力端６
は、オペアンプの反転入力端で受けられ、電流が電圧に
変臭される。Usually, the output terminal 6 of the R-2R ladder-resistance circuit shown in FIG.
is received at the inverting input of the operational amplifier, converting the current into a voltage.
君１図に示すＲ−２Ｒラダ一抵抗回路では、入力端１に
流入する電流工は第２の抵抗列３へ入力側から順に−１
，−Ｉ、−Ｉ、・山・・ずつ分流して行２ ４
８
く。In the R-2R ladder-resistance circuit shown in Figure 1, the current flowing into the input terminal 1 is -1 in order from the input side to the second resistor string 3.
, -I, -I,・mountain・・divide each row 2 4
8.
そこで、スイッチ列４をある組合せで動作させることに
より、出力端５側に切換えられたスイッチに対応する分
流電流の和が出力端５へ流れ、そこで電圧に変臭される
ため、スイッチ列４の組合このようなＲ−２Ｒラダ一抵
抗回路の入力インピーダンスは、スイッチ列４の各スイ
ッチの状態に無関係に常に一定で、その値はＲとなる。Therefore, by operating the switch row 4 in a certain combination, the sum of the shunt currents corresponding to the switches switched to the output end 5 side flows to the output end 5, where it is converted into voltage. The input impedance of such a combined R-2R ladder-resistance circuit is always constant regardless of the state of each switch in the switch array 4, and its value is R.
ところで、このような可変減衰器をオーディオアンプの
音量制御等に用いる場合、入力側に接続される機器の出
力インピーダンスの関係から、入力インピーダンスをか
なり高く設定しなければならない。By the way, when such a variable attenuator is used for controlling the volume of an audio amplifier, the input impedance must be set quite high due to the output impedance of the equipment connected to the input side.
しかし、このようなＲ−２）１抵抗回格は普通ＩＣで構
成されるが、ＩＣで通常用いられる抵抗は拡散抵抗の場
合でも多結晶シリコン抵抗の場合でも、その直はかなり
低いため、入力インピーダンスを高くしようとすれば、
かなり広い面積を必要とし、コスト高になってしまうと
いう問題があった。However, such an R-2)1 resistor circuit is usually constructed with an IC, but the resistance normally used in an IC, whether it is a diffused resistor or a polycrystalline silicon resistor, is quite low in resistance, so the input If you try to increase the impedance,
This has the problem of requiring a fairly large area and resulting in high costs.
本発明は、Ｒ−２Ｒラダ一抵抗回路の性質を維持しなが
ら、同じ入力インピーダンスに対して、ＩＣ上の抵抗の
ための必要面１を大幅に減少させ千
ることのできる可変減衰回路を提供するものであ分流さ
れるように、君１の抵抗列の各抵抗の値を３ ３
３
入力端から順に、−Ｒ、−Ｒ、−Ｒ・・・・・と設定す
２ ４ ８
ることにより、全抵抗直を大巾項に減少させるようにし
たものである。The present invention provides a variable attenuation circuit that can significantly reduce the surface requirements for resistors on the IC for the same input impedance while maintaining the properties of an R-2R ladder resistor circuit. The value of each resistor in the resistor string of you 1 is 3 3
3 By setting -R, -R, -R, .
第２図に本発明の一実施例を示す、。第２図において第
１図と対応する部分には第１図と同一の符号を付してい
る。FIG. 2 shows an embodiment of the present invention. In FIG. 2, parts corresponding to those in FIG. 1 are given the same reference numerals as in FIG. 1.
第２図の実施例でｆ’ｌ： 、第２の抵抗列３の各抵抗
−Ｒとなるように設定したものである。In the embodiment shown in FIG. 2, f'l: and each resistance of the second resistor array 3 are set to -R.
このように抵抗値を設ポした場合でも、スイッチ列４に
流入する電流値は、第１図の場合と同様可変減衰器とし
ての動作は、第１図の場合と全く同じである。Even when the resistance value is set in this way, the current value flowing into the switch array 4 is the same as in the case of FIG. 1, and the operation as a variable attenuator is exactly the same as in the case of FIG.
また入力インピーダンスの値もＲとなり、第１図の場合
と全く同じである。Further, the value of the input impedance is also R, which is exactly the same as in the case of FIG.
例えば、スイッチ列４のスイッチ個数を１６個（１６ビ
ツト）とすると、第１図の例では、全抵抗値が４９１と
なるのに対し、第２図の実施例では、１１ 、３７５１
となり□に減少させられる。For example, if the number of switches in the switch row 4 is 16 (16 bits), the total resistance value is 491 in the example of FIG. 1, while it is 11,3751 in the example of FIG.
Therefore, it is reduced to □.
４．３
したがって、本発明によるラダー抵抗回路をＩＣに用い
れば、ＩＣ上の抵抗面積を大幅に減少させることができ
、大幅なコストダウンができるという効果がある。4.3 Therefore, if the ladder resistance circuit according to the present invention is used in an IC, the resistance area on the IC can be significantly reduced, resulting in a significant cost reduction.
第１図は従来例の回路図、第２図は本発明の一実、施例
の回路図である。
１・・・・・・入力端、２・・・・・・第１の抵抗列、
３・・・・・第２の抵抗列、４・・・・・・スイッチ列
、５・・・・・・出力端。FIG. 1 is a circuit diagram of a conventional example, and FIG. 2 is a circuit diagram of an embodiment of the present invention. 1...Input end, 2...First resistor string,
3... Second resistor string, 4... Switch string, 5... Output end.
Claims (1)
第２の抵抗列と、上記第２の抵抗列の各抵抗の他端を接
地および出力端に切換え接続する複数のスイッチから成
るスイッチ列とで構成され、上記第１の抵抗列の入力側
からＮ（但しＮは整数）（但しＲは単位抵抗値）、それ
以降の各抵抗の値を特徴とする可変減衰回路。A switch consisting of a second resistor string consisting of a first resistor made up of a plurality of resistors connected in series, and a plurality of switches that switch and connect the other end of each resistor of the second resistor string to ground and an output terminal. N (where N is an integer) (where R is a unit resistance value) from the input side of the first resistor array, and the variable attenuation circuit is characterized by a value of each resistor thereafter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9075082A JPS58206220A (en) | 1982-05-27 | 1982-05-27 | Variable attenuating circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9075082A JPS58206220A (en) | 1982-05-27 | 1982-05-27 | Variable attenuating circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS58206220A true JPS58206220A (en) | 1983-12-01 |
Family
ID=14007272
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP9075082A Pending JPS58206220A (en) | 1982-05-27 | 1982-05-27 | Variable attenuating circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS58206220A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4897599A (en) * | 1985-03-27 | 1990-01-30 | Createc Gesellschaft Fur Elektrotechnik Mbh | Signal processing device with a level adapter circuit |
-
1982
- 1982-05-27 JP JP9075082A patent/JPS58206220A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4897599A (en) * | 1985-03-27 | 1990-01-30 | Createc Gesellschaft Fur Elektrotechnik Mbh | Signal processing device with a level adapter circuit |
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