JP2558691B2 - AC light component amplifier - Google Patents
AC light component amplifierInfo
- Publication number
- JP2558691B2 JP2558691B2 JP62106700A JP10670087A JP2558691B2 JP 2558691 B2 JP2558691 B2 JP 2558691B2 JP 62106700 A JP62106700 A JP 62106700A JP 10670087 A JP10670087 A JP 10670087A JP 2558691 B2 JP2558691 B2 JP 2558691B2
- Authority
- JP
- Japan
- Prior art keywords
- current
- component
- operational amplifier
- voltage converter
- voltage
- 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 - Lifetime
Links
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- Photometry And Measurement Of Optical Pulse Characteristics (AREA)
Description
【発明の詳細な説明】 産業上の利用分野 本発明は、ホトダイオードを用いて入射光の交流成分
や変動光成分を取り出して増幅する光電変換回路に関す
るものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric conversion circuit that extracts and amplifies an alternating-current component or varying light component of incident light by using a photodiode.
従来の技術 測光分野や光センシング、光応用計測の分野におい
て、チョッピングした入射光の交流成分のみ測定した
り、あるいは入射光の不規則な変動成分のみを取り出し
て測定する場合がある。このような目的の回路として、
従来、第３図のような回路が使用されてきた。すなわ
ち、ホトダイオード１の出力を演算増幅器２で受け、電
流−電圧変換した後、抵抗R2とコンデンサC1より成る微
分回路により交流成分のみ取り出し、演算増幅器３によ
り電圧増幅を行なうというものである。演算増幅器２
は、ホトダイオードの直線性を保つため、R1とともに電
流−電圧変換器として構成し、入射光の時間的な平均光
量レベルに対応した直流成分に交流成分が重畳された信
号を出力する。そこで、微分回路により、その直流成分
を遮断し、交流成分のみを取り出す。演算増幅器２によ
る電流−電圧変換回路の増幅度（R1の値）は、入力信号
が最大の時でも演算増幅器２のダイナミックレンズを越
えないように設定される。したがって、入射光の直流成
分に対して交流成分が小さい場合は、微分回路の出力が
小さくなるため、演算増幅器３により電圧増幅を行なっ
て必要な振幅の出力信号を得る。2. Description of the Related Art In the field of photometry, optical sensing, and optical measurement, there are cases where only the AC component of chopped incident light is measured or only irregular fluctuation components of incident light are extracted and measured. As a circuit for such a purpose,
Conventionally, a circuit as shown in FIG. 3 has been used. That is, after the output of the photodiode 1 is received by the operational amplifier 2 and converted into current-voltage, only the AC component is taken out by the differentiating circuit composed of the resistor R2 and the capacitor C1, and the operational amplifier 3 performs voltage amplification. Operational amplifier 2
In order to maintain the linearity of the photodiode, is configured as a current-voltage converter together with R1, and outputs a signal in which an AC component is superimposed on a DC component corresponding to the temporal average light intensity level of incident light. Therefore, the differentiating circuit cuts off the direct current component and extracts only the alternating current component. The amplification degree (value of R 1 ) of the current-voltage conversion circuit by the operational amplifier 2 is set so as not to exceed the dynamic lens of the operational amplifier 2 even when the input signal is maximum. Therefore, when the AC component is small with respect to the DC component of the incident light, the output of the differentiating circuit becomes small, and therefore the operational amplifier 3 performs voltage amplification to obtain an output signal with a required amplitude.
発明が解決しようとする問題点 上記の従来の光電変換回路では、入射光の直流成分に
対して交流成分が微小な場合、初段の電流−電圧変換器
の増幅度が直流成分のレベルで制限されるため、微小な
交流信号に対しては、次段で電圧増幅を行なっても十分
なSN比が得られないという問題があった。また、自然光
にかかわる測定では、直流光レベルが予想外に高くなっ
て初段の電流−電圧変換器が飽和し、信号が得られなく
なるという問題があった。Problems to be Solved by the Invention In the above conventional photoelectric conversion circuit, when the AC component is small with respect to the DC component of the incident light, the amplification degree of the current-voltage converter in the first stage is limited by the level of the DC component. Therefore, for a small AC signal, there is a problem that a sufficient SN ratio cannot be obtained even if voltage amplification is performed in the next stage. In addition, in the measurement related to natural light, there was a problem that the DC light level unexpectedly increased and the current-voltage converter in the first stage was saturated, and a signal could not be obtained.
本発明は上記の従来の問題点を解決するもので、光電
変換の直線性がよく、かつ、微小な交流光成分に対する
SN比の高い光電変換回路を提供することを目的とする。The present invention solves the above-mentioned conventional problems, has good linearity of photoelectric conversion, and responds to minute AC light components.
It is an object to provide a photoelectric conversion circuit having a high SN ratio.
問題点を解決するための手段 本発明は、増幅度がG1［V/A］、時定数がτ１なる電
流−電圧変換器（２）と、G2≪G1なる関係の増幅度G
2（＝−R2）［V/A］を有し、τ２≫τ１なる関係の時定
数τ２を有する電流−電圧変換器（３）と、前記電流−
電圧変換器（2,3）それぞれの入力端子間に接続された
ホトダイオードと、前記電流−電圧変換器（３）の出力
信号の極性を反転する、増幅度G3（＝−R4/R3）の反転
増幅器（４）と、その反転増幅器（４）の出力端子と前
記電流−電圧変換器（２）の入力端子の間に接続され、
抵抗値がR2・R4/R3［Ω］に等しい抵抗素子とから構成
されることを特徴とする交流光成分増幅装置である。Means for Solving the Problems The present invention relates to a current-voltage converter (2) having an amplification degree of G 1 [V / A] and a time constant of τ 1, and an amplification degree G of a relationship of G 2 << G 1.
A current-voltage converter (3) having a time constant τ 2 of 2 (= −R 2 ) [V / A] and a relationship of τ 2 >> τ 1.
Voltage converter (2, 3) and photodiodes connected between respective input terminals, the current - inverting the polarity of the output signal of the voltage converter (3), the amplification degree G 3 (= -R 4 / R 3 ), An inverting amplifier (4) connected between the output terminal of the inverting amplifier (4) and the input terminal of the current-voltage converter (2),
It is an alternating-current optical component amplifying device characterized by comprising a resistance element having a resistance value equal to R 2 · R 4 / R 3 [Ω].
作用 本発明は、上記構成により、ホトダイオードの出力電
流の直流成分が電流−電圧変換器（３）により取り出さ
れ、反転増幅器と抵抗素子を通じて、電流−電圧変換器
（２）の入力端子に帰還されるので、電流−電圧変換器
（２）の入力端子では直流成分が相殺されて交流成分の
みが入力されるよう動作する。Action According to the present invention, the direct current component of the output current of the photodiode is taken out by the current-voltage converter (3) and is fed back to the input terminal of the current-voltage converter (2) through the inverting amplifier and the resistance element. Therefore, at the input terminal of the current-voltage converter (2), the DC component is canceled and only the AC component is input.
従って、電流−電圧変換器（３）が飽和しない限り、
電流−電圧変換器（２）が飽和することがなく、電流−
電圧変換器（２）の増幅度を大幅に高めてSN比の高い増
幅を行なうことができる。Therefore, as long as the current-voltage converter (3) does not saturate,
The current-voltage converter (2) does not saturate and current-
It is possible to significantly increase the amplification degree of the voltage converter (2) and perform amplification with a high SN ratio.
実施例 第１図は、本発明の交流光成分増幅装置の一実施例を
示す回路図である。第１図において、１はシリコンホト
ダイオード、２、３、および４は演算増幅器である。第
２図は、第１図の回路の各部の信号の波形を示したもの
で、（ａ）はシリコンホトダイオード１の出力、（ｂ）
は演算増幅器３の出力、（ｃ）は演算増幅器２の出力を
それぞれ表している。以下、本実施例の交流光成分増幅
回路について、その動作を説明する。Embodiment FIG. 1 is a circuit diagram showing an embodiment of an AC light component amplifying device of the present invention. In FIG. 1, 1 is a silicon photodiode, 2, 3 and 4 are operational amplifiers. FIG. 2 shows waveforms of signals at various parts of the circuit of FIG. 1, where (a) is the output of the silicon photodiode 1 and (b) is the output.
Represents the output of the operational amplifier 3, and (c) represents the output of the operational amplifier 2. The operation of the AC light component amplifier circuit of this embodiment will be described below.
第１図において、シリコンホトダイオード１は、ある
光環境の中に置かれ、ゆるやかに強度が変化する直流光
に、周波数のより高い、振幅の小さな交流光が重畳され
たものを受光し、第２図（ａ）のような電流を出力する
ものとする。シリコンホトダイオード１の出力電流は、
同じ値で極性の相異なる信号として演算増幅器２および
演算増幅器３に入力される。演算増幅器２は、抵抗R1と
ともに電流−電圧変換器を構成している。演算増幅器３
は、抵抗R2およびコンデンサC1とともに電流−電圧変換
器を構成し、τ２＝R2・C1なる時定数τ２を有し、この
時定数により交流成分を除去して直流成分のみを取り出
し、第２図（ｂ）のような信号を出力する。演算増幅器
４は、抵抗R3、R4とともに反転増幅器を構成し、第２図
（ｂ）の信号の極性を反転した信号を出力する。ここ
で、演算増幅器３による電流−電圧変換器の直流に対す
る増幅度G2は、 G2＝−R2［V/A］ ‥‥（１） 増幅演算器４による反転増幅器の増幅度G3は、 G3＝−R4/R3 ‥‥（２） で表される。つぎに、シリコンホトダイオード１から演
算増幅器２に流入する直流電流をi0とすると、R5から演
算増幅器の入力端子に流入する直流電流i1は、 i1＝−i0・R2・R4/（R3・R5） …（３） で表される。そこで、R5の値を、 R5＝G2・G3 ＝R2・R4/R3 ‥‥（４） のように決定すれば、（３）式、（４）式から、 i1＝−i0 ‥‥（５） が得られ、演算増幅器２の入力端子において、シリコン
ホトダイオード１の出力電流の直流成分が相殺され、演
算増幅器２は交流成分i2のみを増幅して、第２図（ｃ）
のような信号を出力する。In FIG. 1, a silicon photodiode 1 is placed in a certain light environment, receives direct current light whose intensity changes slowly, and superimposes alternating current light having a higher frequency and a smaller amplitude. It is assumed that the current as shown in FIG. The output current of the silicon photodiode 1 is
The signals having the same value but different polarities are input to the operational amplifier 2 and the operational amplifier 3. The operational amplifier 2 constitutes a current-voltage converter together with the resistor R 1 . Operational amplifier 3
Composes a current-voltage converter together with a resistor R 2 and a capacitor C 1 and has a time constant τ 2 such that τ 2 = R 2 · C 1. With this time constant, the AC component is removed and only the DC component is obtained. It is taken out and a signal as shown in FIG. 2 (b) is output. Operational amplifier 4, resistors with R 3, R 4 constitutes an inverting amplifier, and outputs a signal obtained by inverting the polarity of the signal of FIG. 2 (b). Here, the amplification degree G 2 of the current-voltage converter by the operational amplifier 3 with respect to direct current is G 2 = −R 2 [V / A] (1) The amplification degree G 3 of the inverting amplifier by the amplification operation unit 4 is , G 3 = −R 4 / R 3 (2) Next, assuming that the direct current flowing from the silicon photodiode 1 to the operational amplifier 2 is i 0 , the direct current i 1 flowing from R 5 to the input terminal of the operational amplifier is i 1 = −i 0 · R 2 · R 4 / (R 3 · R 5 ) ... It is expressed by (3). Therefore, if the value of R 5 is determined as R 5 = G 2 · G 3 = R 2 · R 4 / R 3 (4), then from equations (3) and (4), i 1 = −i 0 (5) is obtained, the DC component of the output current of the silicon photodiode 1 is canceled at the input terminal of the operational amplifier 2, and the operational amplifier 2 amplifies only the AC component i 2 , Figure (c)
Output a signal such as.
このように、演算増幅器２は、演算増幅器３の出力が
飽和しない限り、入射光の直流成分で飽和することなく
動作するので、演算増幅器２の増幅度を、演算増幅器３
の増幅度に比べて大幅に（10倍〜100倍）高く設定する
ことができる。As described above, the operational amplifier 2 operates without being saturated with the DC component of the incident light unless the output of the operational amplifier 3 is saturated.
It can be set significantly higher (10 to 100 times) than the amplification degree of.
シリコンホトダイオードの出力を演算増幅器により電
流−電圧変換する場合は、通常、シリコンホトダイオー
ドの電流源としての内部インピーダンスが極めて高く、
出力インピーダンスは直列のシャント抵抗だけで低くな
るため、演算増幅器の出力雑音電圧が電流電圧変換の増
幅度（フィードバック抵抗の値）に関係なくほとんど一
定となる。したがって、この電流電圧変換の段階で増幅
度を大幅に高めることにより、大幅なSN比の改善が実現
できる。When the output of a silicon photodiode is converted into a current-voltage by an operational amplifier, the internal impedance as a current source of the silicon photodiode is usually extremely high,
Since the output impedance is lowered only by the shunt resistance in series, the output noise voltage of the operational amplifier is almost constant regardless of the amplification degree of current-voltage conversion (value of feedback resistance). Therefore, by greatly increasing the degree of amplification at this current-voltage conversion stage, a significant improvement in the SN ratio can be realized.
発明の効果 以上のように、本発明によれば、比較的簡単な回路構
成で、入射光の微小な交流成分に対して、きわめてSN比
の良い、直線性の良い光電変換・増幅が可能となり、精
密測光や高感度の光応用センサなどの光電変換回路とし
て多方面に利用でき、その実用的効果は大きい。EFFECTS OF THE INVENTION As described above, according to the present invention, it is possible to perform photoelectric conversion / amplification with extremely good SN ratio and good linearity for a minute AC component of incident light with a relatively simple circuit configuration. It can be used in various fields as a photoelectric conversion circuit for precision photometry and high-sensitivity optical sensor, and its practical effect is great.
【図面の簡単な説明】 第１図は、本発明の実施例における交流光成分増幅装置
の回路図、第２図は、第１図の回路の各部の信号の波形
図、第３図は、従来例における交流光成分増幅装置の回
路図である。 １……シリコンホトダイオード、２……演算増幅器、３
……演算増幅器、４……演算増幅器BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram of an AC optical component amplifying device according to an embodiment of the present invention, FIG. 2 is a waveform diagram of signals at various parts of the circuit of FIG. 1, and FIG. It is a circuit diagram of the alternating-current light component amplifier in a prior art example. 1 ... Silicon photodiode, 2 ... Operational amplifier, 3
…… Operational amplifier, 4 …… Operational amplifier
Claims (1)
流−電圧変換器（２）と、 G2≪G1なる関係の増幅度G2（＝−R2）［V/A］を有し、
τ２≫τ１なる関係の時定数τ２を有する電流−電圧変
換器（３）と、 前記電流−電圧変換器（2,3）それぞれの入力端子間に
接続されたホトダイオードと、 前記電流−電圧変換器（３）の出力信号の極性を反転す
る、増幅度G3（＝−R4/R3）の反転増幅器（４）と、 その反転増幅器（４）の出力端子と前記電流−電圧変換
器（２）の入力端子の間に接続され、抵抗値がR2・R4/R
3［Ω］に等しい抵抗素子とから構成されることを特徴
とする交流光成分増幅装置。1. A current-voltage converter (2) having an amplification degree of G 1 [V / A] and a time constant of τ 1, and an amplification degree G 2 (= −R 2 ) having a relationship of G 2 << G 1. Has [V / A],
τ 2 >> τ 1 , a current-voltage converter (3) having a time constant τ 2 of the relationship, a photodiode connected between the input terminals of the current-voltage converters (2, 3), and the current- An inverting amplifier (4) having an amplification degree G 3 (= -R 4 / R 3 ) for inverting the polarity of the output signal of the voltage converter (3), the output terminal of the inverting amplifier (4) and the current-voltage. It is connected between the input terminals of the converter (2) and has a resistance of R 2 · R 4 / R.
An alternating current optical component amplifying device, which is composed of a resistance element having a resistance of 3 [Ω].
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62106700A JP2558691B2 (en) | 1987-04-30 | 1987-04-30 | AC light component amplifier |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62106700A JP2558691B2 (en) | 1987-04-30 | 1987-04-30 | AC light component amplifier |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63273021A JPS63273021A (en) | 1988-11-10 |
| JP2558691B2 true JP2558691B2 (en) | 1996-11-27 |
Family
ID=14440285
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62106700A Expired - Lifetime JP2558691B2 (en) | 1987-04-30 | 1987-04-30 | AC light component amplifier |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2558691B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5030925A (en) * | 1990-03-15 | 1991-07-09 | Triquint Semiconductor, Inc. | Transimpedance amplifier |
| US5592124A (en) * | 1995-06-26 | 1997-01-07 | Burr-Brown Corporation | Integrated photodiode/transimpedance amplifier |
| WO2004102168A1 (en) * | 2003-05-15 | 2004-11-25 | Niles Co., Ltd. | Signal detection circuit and signal detection method for rain sensor |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5363083A (en) * | 1976-11-18 | 1978-06-06 | Fujitsu Ltd | Detecting circuit for minute changing quantity |
-
1987
- 1987-04-30 JP JP62106700A patent/JP2558691B2/en not_active Expired - Lifetime
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5363083A (en) * | 1976-11-18 | 1978-06-06 | Fujitsu Ltd | Detecting circuit for minute changing quantity |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63273021A (en) | 1988-11-10 |
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