JPS6259822A - Photodetecting circuit - Google Patents
Photodetecting circuitInfo
- Publication number
- JPS6259822A JPS6259822A JP60201197A JP20119785A JPS6259822A JP S6259822 A JPS6259822 A JP S6259822A JP 60201197 A JP60201197 A JP 60201197A JP 20119785 A JP20119785 A JP 20119785A JP S6259822 A JPS6259822 A JP S6259822A
- Authority
- JP
- Japan
- Prior art keywords
- output
- current
- photodiode
- circuit
- amplifier
- 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
Landscapes
- Photometry And Measurement Of Optical Pulse Characteristics (AREA)
- Optical Recording Or Reproduction (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
この発明は、例えば光学方式の記録再生装置など（：用
いられる光検出回路（二関するものである。DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to, for example, a photodetection circuit used in an optical recording/reproducing device.
８３図は、従来より用いづれている光検出回路の一例で
、２つのフォトダイオードの入射量の差と高い感度で検
出ができる特徴を持つものである。FIG. 83 shows an example of a conventionally used photodetection circuit, which is characterized by the difference in the incident amount between two photodiodes and the ability to detect with high sensitivity.
図において、１１＋は検出光を電流に変換して出力電流
を発生する第１フオトダイオード、（２）は比較光を電
流に変換して比較電流を発生する第２フオトダイオード
、（１１，Ｑυは抵抗で、例えば負荷抵抗であり、抵抗
値は共にＲとする。ｑ７Ｊは増幅器、０３は増幅器＠の
出力端である。In the figure, 11+ is a first photodiode that converts the detection light into a current and generates an output current, (2) is a second photodiode that converts the comparison light into a current and generates a comparison current, and (11, Qυ is It is a resistor, for example a load resistance, and both resistance values are R. q7J is an amplifier, and 03 is the output terminal of the amplifier @.
次（−動作について説明する。Next (-Explain the operation.
第１１１Ｊ’２フオトダイオードｆｉｌ 、 ＋２１１
：、は共に逆バイアス電圧Ｖａが印加されている。111J'2 photodiode fil, +211
: and are both applied with a reverse bias voltage Va.
第１フオトダイオード（１）は増幅器Ｕの負入力と負荷
抵抗Ｒ（１１に接続され、第１フオトダイオード（１）
の検出光の入射光量に応じた出力電流工１は、増幅器α
りの負入力端子の電圧なＶｌ、増幅器０．２１の出力端
ａ階の電圧をＶ３とすると、次式（Ａｌで得られる。The first photodiode (1) is connected to the negative input of the amplifier U and the load resistor R (11).
The output current generator 1 according to the incident light amount of the detection light is the amplifier α
If the voltage at the negative input terminal of the amplifier 0.21 is V1, and the voltage at the output terminal a-th floor of the amplifier 0.21 is V3, the following equation (Al) is obtained.
１１＝ （Ｖｌ −Ｖ３） ／ Ｒ、−０−１−０−０
−＝−（Ａｌ一方、第２フオトダイオード（２１は、増
幅器Ｈの正入力と負荷抵抗Ｒ（ｌυｆ：接続されている
。この負荷抵抗Ｕυの他端はアースグランドに接地され
ている。第２フオトダイオード（２）の比較光の入射光
量に応じた出力電流工２は、増幅器（１７Ｊの正入力端
子の電圧Ｖ２より次式（Ｂｌで得られる。11=(Vl-V3)/R,-0-1-0-0
-=-(Al) On the other hand, the second photodiode (21 is connected to the positive input of the amplifier H and the load resistor R (lυf). The other end of this load resistor Uυ is grounded to the earth ground. The output current 2 corresponding to the amount of incident comparison light on the photodiode (2) is obtained from the voltage V2 at the positive input terminal of the amplifier (17J) using the following equation (Bl).
ｌ２＝Ｖ２／Ｒ・曲・曲四曲（Ｂｌ
今、実用上Ｖｌ ＝ Ｖ２として考えて良いから式（Ａ
）。l2=V2/R・Song・4 songs (Bl Now, in practical terms, you can think of Vl = V2, so the formula (A
).
（Ｂｌを用いて、次式（０）を得る。(Using Bl, the following formula (0) is obtained.
Ｖ３＝ （ｂ−Ｉ２） Ｒ・・・・・曲・曲・・・
・（Ｃ）この様に、従来の光検出回路の出力電圧ｖ３は
、第１．第２フオトダイオード１１１１２＋のそれぞれ
の出力電流工Ｉ、Ｉ２の差によって得られる。V3= (b-I2) R...Song/Song...
(C) In this way, the output voltage v3 of the conventional photodetection circuit is the first. It is obtained by the difference between the respective output currents I and I2 of the second photodiode 11112+.
従来の光検出回路は以上のように構成されているので、
増幅器の片側は、抵抗を経由して、或いは直接に、アー
スグランドに接地する必要がある。Since the conventional photodetection circuit is configured as described above,
One side of the amplifier must be grounded to earth ground, either through a resistor or directly.
ところが、普通、光検出回路の入力信号は微小であり、
一方、光検出回路の置かれる所は、アースグランドとし
ては非常に悪い条件の場合がちりアースグランドからの
雑音（二よる信号品質の劣化が従来より問題になってい
た。However, the input signal to the photodetector circuit is usually very small;
On the other hand, the location where the photodetector circuit is placed has been subject to noise from the earth ground under extremely poor conditions, and deterioration of signal quality due to noise from the earth ground has traditionally been a problem.
この発明は、上記のような問題点を解消するため（二な
されたもので、光検出回路をアースグランドより切り離
し、アークグランドからの雑音による信号品質の劣化を
減少させることを目的とする。This invention was made in order to solve the above-mentioned problems, and an object thereof is to separate the photodetection circuit from the earth ground and reduce the deterioration of signal quality due to noise from the arc ground.
この発明に係る光検出回路は、検出光を電流Ｃ：変換す
るフォトダイオード、このフォトダイオードからの出力
電流と、比較電流を差動入力し、それぞれ増幅してｍｌ
、第２出力信号を出力する差動増幅器、フォトダイオー
ドからの出力電流と第２出力信号間を第１抵抗を介して
負帰還させる第１回路、比較電流と第１出力信号間を第
２抵抗を介して負帰還させる第２回路を備えたものであ
る。The photodetection circuit according to the present invention includes a photodiode that converts detected light into a current C, an output current from this photodiode, and a comparison current that are differentially inputted, each amplified and converted into ml.
, a differential amplifier that outputs a second output signal, a first circuit that provides negative feedback between the output current from the photodiode and the second output signal via a first resistor, and a second resistor that connects the comparison current and the first output signal. The second circuit provides negative feedback via the second circuit.
この発明における光検出回路は、その構成上、信号は完
全にアースグランドから切り離されているので、アース
グランドからの雑音による信号品質の劣化が減少する様
（：なっている。Due to the structure of the photodetection circuit of the present invention, the signal is completely separated from the earth ground, so that deterioration of signal quality due to noise from the earth ground is reduced.
以下、この発明の一実施例を第１図について説明する。 An embodiment of the present invention will be described below with reference to FIG.
＋３１ 、 ［４１は第１．第２抵抗で、例えば負荷抵
抗でｓす、抵抗値は共にＲとする。＋５１は差動増幅器
で、第１フオトダイオード１１１からの出力電流と、第
２フオトダイオード（２１からの比較電流を差動入力し
て、それぞれ増幅し、出力端１６１ 、 ＋７１ ＋：
第１、第２出力信号を出力する。（８）は増幅器（５）
からの第２出力信号と第１フオトダイオード（１１から
の出力電流間を第１抵抗（３）を介して負帰還させる第
１回路、（９）は増幅器（５）からの第１出力信号と第
２フオトダイオード（２）からの比較電流間を第２抵抗
（４）を介して負帰還させる第２回路である。即ち、第
１．￥Ｊ２負荷抵抗１３１ 、１４１は増幅器（５）の
入力出力間１；互いに負帰還がかかるよう【：接続され
ている。+31, [41 is the 1st. The second resistor is, for example, a load resistor, and both resistance values are R. +51 is a differential amplifier, which differentially inputs the output current from the first photodiode 111 and the comparison current from the second photodiode (21), amplifies them respectively, and outputs terminals 161 and +71 +:
Output first and second output signals. (8) is an amplifier (5)
A first circuit that provides negative feedback between the second output signal from the amplifier (5) and the output current from the first photodiode (11) via the first resistor (3); This is a second circuit that provides negative feedback between the comparison currents from the second photodiode (2) via the second resistor (4).That is, the first J2 load resistors 131 and 141 are the inputs of the amplifier (5). The outputs are connected so that negative feedback is applied to each other.
第１．第２フオトダイオードｉｌ＋ 、 １２＋には、
それぞれ逆バイアス電圧ＶＢが印加されている。1st. The second photodiode il+, 12+ has
A reverse bias voltage VB is applied to each.
第１フオトダイオード＋１１の検出光の入射光量Ｉ：応
じた電流工１は、増幅器（５）の１つの入力端の電圧ｖ
１、増幅器（５）の１つの出力端の電圧ｖ４とすると、
次式（Ｄｌで得られる。The amount of incident light I of the detection light of the first photodiode +11: The corresponding current 1 is the voltage v at one input terminal of the amplifier (5)
1. Assuming that the voltage at one output terminal of the amplifier (5) is v4,
It is obtained by the following formula (Dl.
■ｒ＝ （Ｖ４−Ｖｌ） ／ Ｒ・曲曲曲・曲（Ｄｌ
同様にして、第２フオトダイオード（２）についても求
めると、
Ｉ２ ＝ （ｖａ −Ｖ２ ） ／ Ｒ−＝曲曲曲・・
（Ｅｌが得られる。■r= (V4-Vl) / R・Song・Song (Dl
Similarly, when calculating the second photodiode (2), I2 = (va - V2) / R- = music...
(El is obtained.
上記の例では、増幅器（５）の入力インピーダンスは充
分に負荷抵抗１３１ 、１４１の値よりも大きいものと
する。In the above example, it is assumed that the input impedance of the amplifier (5) is sufficiently larger than the values of the load resistors 131 and 141.
今、実用上よりＶｌ ＝ Ｖ２とすると、式（Ｄｌ 、
（Ｅ）より次式が得られる。Now, for practical reasons, if Vl = V2, then the formula (Dl,
The following formula is obtained from (E).
ｖ４二Ｖ３ ＝ （Ｉｔ −Ｉ２ ） Ｒ・−曲…−＝
−−−−−（Ｆ）以上の様に、この光検出回路あ場合に
は、第１、第２フオトダイオードｆｌ＋ 、 １２＋か
らの出力電流Ｉｔ、 Ｉ２の差が、増幅器（５）の差動
出力として得られる。v42V3 = (It −I2) R・−Song…−=
------- (F) As described above, in this photodetector circuit, the difference between the output currents It and I2 from the first and second photodiodes fl+ and 12+ is the differential output of the amplifier (5). obtained as output.
従って、検出光を検出することができる。Therefore, detection light can be detected.
上記の光検出回路では、アースグランドから切り離され
ているため、対雑音特性が向上し、従来よりＳ／Ｎ比の
良い光検出回路が実現できる。Since the above-mentioned photodetection circuit is separated from the earth ground, the noise resistance is improved, and a photodetection circuit with a better S/N ratio than the conventional one can be realized.
上記実施例では、第２フオトダイオード（２１を用い、
比較光を比較電流（＝変換する光検出回路の場合の例を
用いたが、少なくとも検出光を変換する第１フオトダイ
オード（１）があれば良く、又フォトダイオードは３個
以上あっても良い。In the above embodiment, the second photodiode (21) is used,
Although we have used an example of a photodetector circuit that converts comparison light into comparison current (=conversion), it is sufficient that there is at least a first photodiode (1) that converts detection light, and there may be three or more photodiodes. .
例えば、フォトダイオードが第１フオトダイオード（１
１のみで、１つの場合（二は、第２図の様に比較電流と
して、所定電流源αりの出力電流を増幅器＋５１１：入
力するようにすれば、上記実施例と同様の効果を奏する
。For example, the photodiode is the first photodiode (1
In the case of only 1 (2), if the output current of the predetermined current source α is inputted to the amplifier +511 as a comparison current as shown in FIG. 2, the same effect as in the above embodiment can be obtained.
以上のように、この発明によれば、光検出回路を、検出
光を電流（二変換するフォトダイオード、このフォトダ
イオードからの出力電流と、比較電流を差動入力し、そ
れぞれ増幅して第１．第２出力信号を出力する差動増幅
器、フォトダイオードからの出力電流と第２出力信号間
を第１抵抗を介して負帰還させる第１回路、比較電流と
第１出力信号間を第２抵抗を介して負帰還させる第２回
路を備えるようにしたので、完全にアースグランドから
分離でき、信号品質が良く、比較的ＳＺＮ比が良いもの
が得られる。As described above, according to the present invention, a photodetection circuit is connected to a photodiode that converts detected light into a current (two currents), an output current from this photodiode and a comparison current are differentially inputted, each is amplified, and a first .A differential amplifier that outputs a second output signal, a first circuit that provides negative feedback between the output current from the photodiode and the second output signal via a first resistor, and a second resistor that connects the comparison current and the first output signal. Since the second circuit is provided to provide negative feedback via the second circuit, it can be completely separated from the earth ground, and a signal with good signal quality and a relatively good SZN ratio can be obtained.
第１図はこの発明の一実施例による光検出回路を示す回
路図、第２凶はこの発明の他の実施例による光検出回路
を示す回路図、第３図は従来の光検出回路を示す回路図
である。
（１）・・・フォトダイオード、（３）・・・第１抵抗
、（４）・・・第２抵抗、；５）・・・差動増幅器、（
８）・・・第１回路、（９１・・・第２回路。
なお、図中同−付号は同一、又は相当部分を示す。Fig. 1 is a circuit diagram showing a photodetection circuit according to one embodiment of the present invention, Fig. 2 is a circuit diagram showing a photodetection circuit according to another embodiment of the invention, and Fig. 3 is a circuit diagram showing a conventional photodetection circuit. It is a circuit diagram. (1)...Photodiode, (3)...First resistor, (4)...Second resistor,;5)...Differential amplifier, (
8)...First circuit, (91...Second circuit. In addition, the same number in the figure indicates the same or equivalent part.
Claims (3)
フォトダイオードからの出力電流と、比較電流を差動入
力し、それぞれ増幅して第１、第２出力信号を出力する
差動増幅器、上記フォトダイオードからの出力電流と第
２出力信号間を第１抵抗を介して負帰還させる第１回路
、上記比較電流と第１出力信号間を第２抵抗を介して負
帰還させる第２回路を備えた光検出回路。(1) A photodiode that converts detection light into a current, a differential amplifier that inputs the output current from this photodiode and a comparison current differentially, amplifies each, and outputs a first and second output signal, and a differential amplifier that outputs the first and second output signals. A first circuit that provides negative feedback between the output current from the diode and the second output signal via the first resistor, and a second circuit that provides negative feedback between the comparison current and the first output signal via the second resistor. light detection circuit.
オードの出力電流である特許請求の範囲第１項記載の光
検出回路。(2) The photodetection circuit according to claim 1, wherein the comparison current is an output current of a photodiode that converts comparison light into a current.
求の範囲第１項記載の光検出回路。(3) The photodetection circuit according to claim 1, wherein the comparison current is an output current of a predetermined current source.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60201197A JPS6259822A (en) | 1985-09-10 | 1985-09-10 | Photodetecting circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60201197A JPS6259822A (en) | 1985-09-10 | 1985-09-10 | Photodetecting circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS6259822A true JPS6259822A (en) | 1987-03-16 |
Family
ID=16436954
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP60201197A Pending JPS6259822A (en) | 1985-09-10 | 1985-09-10 | Photodetecting circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6259822A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6768384B1 (en) * | 2001-11-15 | 2004-07-27 | Cypress Semiconductor Corporation | High-speed differential preamplifier |
| EP3404831A1 (en) * | 2017-05-16 | 2018-11-21 | Nokia Solutions and Networks Oy | Photoreceiver with pre-equalizing differential transimpedance amplifier |
-
1985
- 1985-09-10 JP JP60201197A patent/JPS6259822A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6768384B1 (en) * | 2001-11-15 | 2004-07-27 | Cypress Semiconductor Corporation | High-speed differential preamplifier |
| EP3404831A1 (en) * | 2017-05-16 | 2018-11-21 | Nokia Solutions and Networks Oy | Photoreceiver with pre-equalizing differential transimpedance amplifier |
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