JP2583476Y2 - Current-voltage conversion circuit - Google Patents
Current-voltage conversion circuitInfo
- Publication number
- JP2583476Y2 JP2583476Y2 JP1991098148U JP9814891U JP2583476Y2 JP 2583476 Y2 JP2583476 Y2 JP 2583476Y2 JP 1991098148 U JP1991098148 U JP 1991098148U JP 9814891 U JP9814891 U JP 9814891U JP 2583476 Y2 JP2583476 Y2 JP 2583476Y2
- Authority
- JP
- Japan
- Prior art keywords
- current
- operational amplifier
- measurement
- current detection
- measurement range
- 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 - Fee Related
Links
Landscapes
- Measurement Of Resistance Or Impedance (AREA)
- Control Of Amplification And Gain Control (AREA)
Description
【０００１】[0001]
【産業上の利用分野】この考案は電流−電圧変換回路に
関し、さらに詳しく言えば、ＬＣＲメータの入力段に適
用される電流−電圧変換回路に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current-to-voltage conversion circuit, and more particularly, to a current-to-voltage conversion circuit applied to an input stage of an LCR meter.
【０００２】[0002]
【従来の技術】ＬＣＲメータにおいては、被測定試料に
所定周波数の測定信号を供給し、同試料に流れる電流を
電圧に変換した後、その電圧をＡ／Ｄコンバータにてデ
ジタル信号に変換するようにしている。2. Description of the Related Art In an LCR meter, a measurement signal of a predetermined frequency is supplied to a sample to be measured, a current flowing through the sample is converted into a voltage, and the voltage is converted into a digital signal by an A / D converter. I have to.
【０００３】図３には演算増幅器Ａを利用した電流−電
圧変換回路の一例が示されている。すなわち、演算増幅
器Ａのイマジナリアースとされた入力端子と交流電源Ａ
Ｃとの間に被測定試料Ｚを接続し、交流電源ＡＣより同
試料Ｚに正弦波交流信号Ｖを印加する。FIG. 3 shows an example of a current-voltage conversion circuit using an operational amplifier A. That is, the imaginary earthed input terminal of the operational amplifier A and the AC power supply A
The sample Z to be measured is connected to the sample C, and a sine wave AC signal V is applied to the sample Z from the AC power supply AC.
【０００４】その際、同試料Ｚに流れる電流をＩとし、
電流検出抵抗をＲとすると、演算増幅器Ａの出力側に
は、 ＶＩ＝−Ｉ×Ｒ＝−Ｒ×Ｖ／Ｚ なる電圧が現われる。At this time, the current flowing through the sample Z is defined as I,
Assuming that the current detection resistor is R, a voltage of VI = −I × R = −R × V / Z appears on the output side of the operational amplifier A.
【０００５】[0005]
【考案が解決しようとする課題】ところで、抵抗Ｒ、イ
ンダクタンスＬもしくは静電容量Ｃを測定する場合、そ
の電流検出抵抗をインピーダンス｜Ｚ｜のレンジに合せ
て決めると、Ｌ，Ｃの場合、フルスケール時の出力電圧
ＶＩの値が異なったものとなる。By the way, when measuring the resistance R, inductance L or capacitance C, if the current detection resistance is determined according to the range of impedance | Z | The value of the output voltage VI at the time of the scale becomes different.
【０００６】その一例として、測定印加電圧１Ｖ、測定
周波数１ｋＨｚ、電流検出抵抗１ｋΩとした場合の｜Ｚ
｜とＲ，Ｌ，Ｃの関係を表１に示す。As one example, | Z when the applied voltage for measurement is 1 V, the frequency for measurement is 1 kHz, and the current detection resistance is 1 kΩ.
Table 1 shows the relationship between | and R, L, and C.
【０００７】[0007]
【表１】 このように、Ｌ，Ｃ，Ｒの各測定で、それぞれのレンジ
の検出値のフルスケールが一致しないため、測定精度に
バラツキが生じ信頼性の面で問題があった。[Table 1] As described above, in the L, C, and R measurements, the full scales of the detection values in the respective ranges do not match, and thus the measurement accuracy varies, and there is a problem in reliability.
【０００８】[0008]
【課題を解決するための手段】この考案は上記従来の事
情に鑑みなされたもので、その構成上の特徴は、ＬＣＲ
メータに適用される電流−電圧変換回路であって、所定
周波数の測定信号を発生する測定信号発生手段と、複数
の切換え可能な電流検出抵抗を有する演算増幅器とを備
え、同演算増幅器のイマジナリアースとされた入力端子
と上記測定信号発生手段との間に測定試料を接続して、
上記演算増幅器の出力側に同測定試料に流れる電流に対
応する出力電圧が現われるようにした電流−電圧変換回
路において、上記演算増幅器には、上記ＬＣＲメータの
抵抗測定レンジに対応して選択される第１の電流検出抵
抗群と、インダクタンス測定レンジに対応して選択され
る第２の電流検出抵抗群と、静電容量測定レンジに対応
して選択される第３の電流検出抵抗群とが設けられてい
て、上記各測定レンジのフルスケール時における上記演
算増幅器の出力電圧がほぼ一定となるようにしたことに
ある。SUMMARY OF THE INVENTION This invention has been made in view of the above conventional circumstances, features on its configuration, LCR
A current-voltage conversion circuit applied to a meter, comprising: a measurement signal generating means for generating a measurement signal of a predetermined frequency; and an operational amplifier having a plurality of switchable current detection resistors, wherein an imaginary earth of the operational amplifier is provided. Connecting the measurement sample between the input terminal and the measurement signal generating means,
A current-voltage conversion circuit in which an output voltage corresponding to the current flowing through the measurement sample appears at the output side of the operational amplifier.
In the circuit , the operational amplifier includes a first current detection resistor group selected according to the resistance measurement range of the LCR meter, and a second current detection resistor group selected according to the inductance measurement range. a third current detecting resistor group is provided which is selected to correspond to the capacitance measurement range, and the output voltage of the operational amplifier at the time of full scale of each measurement range is substantially constant It is in.
【０００９】なお、上記の本考案とは異なり、演算増幅
器の出力側に、ＬＣＲメータの抵抗測定レンジ、インダ
クタンス測定レンジおよび静電容量測定レンジに対応し
て増幅度が可変とされ、その各レンジのフルスケール時
における出力電圧をほぼ一定とするような可変利得型の
第２の演算増幅器を接続することも考えられるが、これ
によると、第２の演算増幅器をさらに必要とする分、コ
スト増となることは否めず、好ましくない。 It is to be noted that, unlike the above-described present invention, the operational amplification
The resistance measurement range of the LCR meter and the inductor
Compatibility with the capacitance measurement range and capacitance measurement range
The amplification degree is variable, and at the full scale of each range
Variable gain type that makes the output voltage at
It is conceivable to connect a second operational amplifier.
According to the above, since the second operational amplifier is further required,
It is unavoidable that the strike increases, which is not preferable.
【００１０】[0010]
【作用】上記構成のように、Ｌ，Ｃ，Ｒの各測定におい
て、そのパラメータに対応する電流検出抵抗を用いるこ
とにより、それぞれのレンジの検出値のフルスケールが
一致することになり、同一の分解能にて測定が行なわれ
る。As described above, in each measurement of L, C, and R, by using the current detection resistors corresponding to the parameters, the full scales of the detection values of the respective ranges match, and the same value is obtained. The measurement is performed at the resolution.
【００１１】[0011]
【実施例】図１にはこの考案の第１実施例が示されてい
る。同実施例においても先に説明の従来例と同様に演算
増幅器Ａが用いられるが、その電流検出抵抗としては次
のものが用意されている。FIG. 1 shows a first embodiment of the present invention. In this embodiment, the operational amplifier A is used similarly to the conventional example described above, but the following current detection resistors are prepared.
【００１２】すなわち、同演算増幅器Ａには、インピー
ダンス｜Ｚ｜の抵抗測定レンジに対応した系列の第１の
電流検出抵抗Ｒ１と、インダクタンスＬの測定レンジに
対応した系列の第２の電流検出抵抗Ｒ２と、静電容量Ｃ
の測定レンジに対応した系列の第３の電流検出抵抗Ｒ３
とが接続されている。図面上では詳しく示されていない
が、これらの各抵抗Ｒ１，Ｒ２およびＲ３は、それぞれ
所定数の抵抗群からなる。That is, the operational amplifier A has a first current detection resistor R1 in a series corresponding to a resistance measurement range of impedance | Z | and a second current detection resistor in a series corresponding to a measurement range of inductance L. R2 and capacitance C
Of the third current detection resistor R3 of the series corresponding to the measurement range of
And are connected. Although not shown in detail in the drawings, each of these resistors R1, R2 and R3 is composed of a predetermined number of resistor groups.
【００１３】例えば、測定印加電圧１Ｖ、測定周波数１
ｋＨｚとした場合において、第１の電流検出抵抗Ｒ１を
１０Ω，１００Ω，１ｋΩ，１０ｋΩ，１００ｋΩと
し、第２の電流検出抵抗Ｒ２を６．２８Ω，６２．８
Ω，６２８Ω，６．２８ｋΩ，６２．８ｋΩとし、ま
た、第３の電流検出抵抗Ｒ３を１５．９Ω，１５９Ω，
１．５９ｋΩ，１５．９ｋΩ，１５９ｋΩとして、各測
定レンジに応じて電流検出抵抗を使い分けることによ
り、各測定レンジのフルスケール相当における出力電圧
ＶＩがほぼ同じ値とされる。For example, a measurement applied voltage 1 V, a measurement frequency 1
When the frequency is set to kHz, the first current detection resistor R1 is set to 10Ω, 100Ω, 1kΩ, 10kΩ, 100kΩ, and the second current detection resistor R2 is set to 6.28Ω, 62.8.
, 628 Ω, 6.28 kΩ, 62.8 kΩ, and the third current detection resistor R3 is 15.9 Ω, 159 Ω,
By setting the current detection resistors to 1.59 kΩ, 15.9 kΩ, and 159 kΩ in accordance with each measurement range, the output voltage VI in each measurement range corresponding to the full scale is made substantially the same value.
【００１４】この出力電圧ＶＩは次段のＡ／Ｄ変換器の
入力となるため、各パラメータの測定に対してその分解
能が同じとなる。Since this output voltage VI is an input to the next-stage A / D converter, the resolution of each parameter measurement is the same.
【００１５】次に、参考までに図２を参照しながら、本
考案に対する参考例について説明する。この参考例は、
先に説明の図３に示されている電流−電圧変換回路の出
力側に第２の演算増幅器として可変利得型演算増幅器Ａ
２を接続したものからなる。 Next, for reference, FIG.
A reference example for the invention will be described. This reference example
On the output side of the current-voltage conversion circuit shown in FIG.
2 are connected.
【００１６】この可変利得型演算増幅器Ａ２は、インピ
ーダンス｜Ｚ｜の抵抗測定レンジにおいてはその増幅度
が１に固定されるが、インダクタンスＬの測定レンジお
よび静電容量Ｃの測定レンジの場合には、その増幅度が
次のように可変とされる。The gain of the variable gain operational amplifier A2 is fixed at 1 in the resistance measurement range of impedance | Z |, but is not in the measurement range of inductance L and capacitance C. , The degree of amplification of which is variable as follows.
【００１７】表１の場合を例にとって説明すると、イン
ダクタンス測定時においては、その増幅度が１／１．５
９とされる。また、静電容量測定時には、その増幅度が
１／０．６２８とされ、これによりこの可変利得型演算
増幅器Ａ２の出力電圧Ｖｉは、各測定レンジのフルスケ
ール相当時においてほぼ同一となる。Taking the case of Table 1 as an example, when the inductance is measured, the amplification factor is 1 / 1.5
9 is assumed. At the time of measuring the capacitance, the amplification factor is set to 1 / 0.628, so that the output voltage Vi of the variable gain operational amplifier A2 becomes substantially the same when the full scale of each measurement range is obtained.
【００１８】[0018]
【考案の効果】以上説明したように、この考案によれ
ば、ＬＣＲメータの各測定レンジにおいて、それらのフ
ルスケール電圧がほぼ同じとなるため、各パラメータを
同一の分解能をもってより正確に測定することができ
る。As described above, according to the present invention, in each measurement range of the LCR meter, their full-scale voltages are almost the same, so that each parameter can be measured more accurately with the same resolution. Can be.
【図１】この考案の第１実施例を示した回路図。FIG. 1 is a circuit diagram showing a first embodiment of the present invention.
【図２】この考案に対する参考例を示した回路図。FIG. 2 is a circuit diagram showing a reference example of the present invention.
【図３】従来例を示した回路図。FIG. 3 is a circuit diagram showing a conventional example.
Ａ 演算増幅器 Ａ２ 可変利得型演算増幅器 ＡＣ 交流電源 Ｒ，Ｒ１〜Ｒ３ 電流検出抵抗 Ｚ 被測定試料 A operational amplifier A2 variable gain operational amplifier AC AC power supply R, R1 to R3 Current detection resistor Z Sample to be measured
Claims (1)
換回路であって、所定周波数の測定信号を発生する測定
信号発生手段と、複数の切換え可能な電流検出抵抗を有
する演算増幅器とを備え、同演算増幅器のイマジナリア
ースとされた入力端子と上記測定信号発生手段との間に
測定試料を接続して、上記演算増幅器の出力側に同測定
試料に流れる電流に対応する出力電圧が現われるように
した電流−電圧変換回路において、 上記演算増幅器には、上記ＬＣＲメータの抵抗測定レン
ジに対応して選択される第１の電流検出抵抗群と、イン
ダクタンス測定レンジに対応して選択される第２の電流
検出抵抗群と、静電容量測定レンジに対応して選択され
る第３の電流検出抵抗群とが設けられていて、上記各測
定レンジのフルスケール時における上記演算増幅器の出
力電圧がほぼ一定となるようにしたことを特徴とする電
流−電圧変換回路。1. A current-voltage conversion circuit applied to an LCR meter, comprising: a measurement signal generating means for generating a measurement signal of a predetermined frequency; and an operational amplifier having a plurality of switchable current detection resistors. A measurement sample is connected between the imaginary earthed input terminal of the operational amplifier and the measurement signal generating means so that an output voltage corresponding to the current flowing through the measurement sample appears at the output side of the operational amplifier. In the current-voltage conversion circuit described above, the operational amplifier includes a first current detection resistor group selected according to the resistance measurement range of the LCR meter, and a second current detection resistor group selected according to the inductance measurement range. a current detection resistor group, and a third current detecting resistor group is provided which is selected to correspond to the capacitance measurement range, on at full scale of each measurement range Current, characterized in that the output voltage of the operational amplifier is in roughly a constant - voltage converting circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1991098148U JP2583476Y2 (en) | 1991-10-31 | 1991-10-31 | Current-voltage conversion circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1991098148U JP2583476Y2 (en) | 1991-10-31 | 1991-10-31 | Current-voltage conversion circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0540888U JPH0540888U (en) | 1993-06-01 |
| JP2583476Y2 true JP2583476Y2 (en) | 1998-10-22 |
Family
ID=14212102
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1991098148U Expired - Fee Related JP2583476Y2 (en) | 1991-10-31 | 1991-10-31 | Current-voltage conversion circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2583476Y2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007121125A (en) * | 2005-10-28 | 2007-05-17 | Hioki Ee Corp | Current detector and capacitance measurement device |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5926999B2 (en) * | 1977-06-20 | 1984-07-02 | タケダ理研工業株式会社 | Multi-point measuring device |
| JPS5972561U (en) * | 1982-11-08 | 1984-05-17 | 横河電機株式会社 | measuring device |
| JPH0652282B2 (en) * | 1987-06-04 | 1994-07-06 | 日置電機株式会社 | LCR meter |
-
1991
- 1991-10-31 JP JP1991098148U patent/JP2583476Y2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0540888U (en) | 1993-06-01 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 19980612 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
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| LAPS | Cancellation because of no payment of annual fees |