JPS61237534A - Optical reception circuit - Google Patents
Optical reception circuitInfo
- Publication number
- JPS61237534A JPS61237534A JP60077548A JP7754885A JPS61237534A JP S61237534 A JPS61237534 A JP S61237534A JP 60077548 A JP60077548 A JP 60077548A JP 7754885 A JP7754885 A JP 7754885A JP S61237534 A JPS61237534 A JP S61237534A
- Authority
- JP
- Japan
- Prior art keywords
- resistor
- diode
- photoelectric conversion
- conversion element
- optical signal
- 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
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/60—Receivers
- H04B10/66—Non-coherent receivers, e.g. using direct detection
- H04B10/69—Electrical arrangements in the receiver
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Light Receiving Elements (AREA)
- Optical Communication System (AREA)
Abstract
Description
【発明の詳細な説明】
〔概要〕
ホトダイオード等の光電変換素子の出力信号を増幅男る
増幅素子の動作点を、入力ディジタル光信号レベルの変
化に対してもほぼ一定となるようにして、光受信回路の
動作を安定化させたものである。[Detailed Description of the Invention] [Summary] By amplifying the output signal of a photoelectric conversion element such as a photodiode, the operating point of the amplifying element is kept almost constant even with changes in the level of the input digital optical signal. This stabilizes the operation of the receiving circuit.
本発明は、光通信システムに於いて、伝送されたディジ
タル光信号を受信して電気信号に変換する光受信回路に
関するものである。The present invention relates to an optical receiving circuit that receives a transmitted digital optical signal and converts it into an electrical signal in an optical communication system.
光ファイバ等の光伝送路により伝送されたディジタル光
信号は、ホトダイオード等の光電変換素子により電気信
号に変換され、電界効果トランジスタ等の増幅素子によ
って増幅されて、後段のデータ処理回路に転送されるも
のである。A digital optical signal transmitted through an optical transmission line such as an optical fiber is converted into an electrical signal by a photoelectric conversion element such as a photodiode, amplified by an amplification element such as a field effect transistor, and then transferred to a subsequent data processing circuit. It is something.
ディジタル光信号を受信する従来の光受信回路は、例え
ば、第４図又は第５図に示す構成を有するものであった
。第４図に於いて、３１はホトダイオード等の光電変換
素子、３２は抵抗、３３は電界効果トランジスタ、３５
はバイポーラトランジスタ、３６は出力端子、Ｃ１，Ｃ
２は結合用及びバイパス用のコンデンサ、Ｒ１−Ｒ４は
抵抗、＋Ｖ、−ｙは電源電圧である。受信された光信号
は光電変換素子３１に加えられ、その光信号に対応した
電流が光電変換素子３１に流れるので、光信号を電気信
号に変換することができる。その電気信号は、トランジ
スタ３３．３５により増幅され、その増幅出力信号が出
力端子３６から後段の回路へ転送される。光電変換素子
３１と直列に一端が接続された抵抗３２の他端は出力端
子３６に接続され、帰還回路を構成している。A conventional optical receiving circuit for receiving a digital optical signal has a configuration shown in FIG. 4 or FIG. 5, for example. In FIG. 4, 31 is a photoelectric conversion element such as a photodiode, 32 is a resistor, 33 is a field effect transistor, and 35 is a photoelectric conversion element such as a photodiode.
is a bipolar transistor, 36 is an output terminal, C1, C
2 is a coupling and bypass capacitor, R1-R4 are resistors, +V and -y are power supply voltages. The received optical signal is applied to the photoelectric conversion element 31, and a current corresponding to the optical signal flows through the photoelectric conversion element 31, so that the optical signal can be converted into an electrical signal. The electrical signal is amplified by transistors 33 and 35, and the amplified output signal is transferred from output terminal 36 to a subsequent circuit. One end of the resistor 32 is connected in series with the photoelectric conversion element 31, and the other end of the resistor 32 is connected to an output terminal 36, forming a feedback circuit.
又第５図に於いて、４１は光電変換素子、４２は抵抗、
４３は電界効果トランジスタ、４５はバイポーラトラン
ジスタ、４６は出力端子、Ｒ１−Ｒ４は抵抗、ＣＩ、Ｃ
２は結合用及びバイパス用のコンデンサ、＋Ｖ、−Ｖは
電源電圧である。この回路は、光電変換素子４１と直列
に一端が接続された抵抗４２の他端は接地されているも
ので、受信された光信号は光電変換素子４１により電気
信号に変換され、トランジスタ４３．４５により増幅さ
れて出力端子４６から後段の回路へ転送される。Also, in FIG. 5, 41 is a photoelectric conversion element, 42 is a resistor,
43 is a field effect transistor, 45 is a bipolar transistor, 46 is an output terminal, R1-R4 are resistors, CI, C
2 is a coupling and bypass capacitor, +V and -V are power supply voltages. In this circuit, one end of a resistor 42 is connected in series with a photoelectric conversion element 41, and the other end is grounded.A received optical signal is converted into an electric signal by the photoelectric conversion element 41, and transistors 43, 45 The signal is amplified by the output terminal 46 and transferred to the subsequent circuit.
光伝送路を介して受信する光信号は、送信側の発光素子
や光伝送路の状態等により、レベルが変化する場合があ
る。従って、第４図に示す従来の光受信回路に於いては
、受信した光信号レベルが低いと、光電変換素子３１に
流れる電流の直流分も小さくなるから、抵抗３２による
電圧降下も僅かであって、ａ点とｂ点との間の電位差は
僅かなものとなるが、受信した光信号レベルが高くなる
と、光電変換素子３１に流れる電流の直流分が大きくな
り、抵抗３２による電圧降下が大きくなって、ａ、ｂ点
間の電位差が大きくなる。ｂ点は定電圧点となるもので
あるから、ａ、ｂ点間の電位差が大きくなると、ａ点の
電位が上昇することになる。即ち、フロントエンドの電
界効果トランジスタ３３のゲート電位が上昇し、最適値
からずれるので、信号の波形歪が大きくなる。The level of an optical signal received via an optical transmission line may change depending on the state of the light emitting element on the transmitting side, the optical transmission line, and the like. Therefore, in the conventional optical receiving circuit shown in FIG. 4, when the level of the received optical signal is low, the DC component of the current flowing through the photoelectric conversion element 31 is also small, so the voltage drop due to the resistor 32 is small. Therefore, the potential difference between point a and point b is small, but as the level of the received optical signal increases, the DC component of the current flowing through the photoelectric conversion element 31 increases, and the voltage drop due to the resistor 32 increases. As a result, the potential difference between points a and b increases. Since point b is a constant voltage point, when the potential difference between points a and b increases, the potential at point a increases. That is, the gate potential of the front-end field effect transistor 33 increases and deviates from the optimum value, resulting in increased waveform distortion of the signal.
又第５図に示す従来の光受信回路に於いても前述と同様
に、受信した光信号レベルに対応して、電界効果トラン
ジスタ４３のゲート電位が変化するから、その動作点が
最適点からずれることになり、信号の波形歪が大きくな
る。Furthermore, in the conventional optical receiving circuit shown in FIG. 5, the gate potential of the field effect transistor 43 changes in response to the level of the received optical signal, as described above, so its operating point deviates from the optimum point. As a result, the waveform distortion of the signal increases.
本発明は、光電変換素子の出力信号を増幅する増幅素子
の動作点を一定化することを目的とするものである。An object of the present invention is to stabilize the operating point of an amplification element that amplifies an output signal of a photoelectric conversion element.
本発明の光受信回路は、第１図の原理説明図を参照して
説明すると、受信した光信号を電気信号に変換するホト
ダイオード等の光電変換素子１と直列に抵抗２を接続し
、その抵抗２と並列にダイオード４を接続し、光電変換
素子１により変換された電気信号を電界効果トランジス
タ等の増幅素子３により増幅して、後段の回路へ転送す
るものである。The optical receiving circuit of the present invention will be explained with reference to the principle explanatory diagram of FIG. A diode 4 is connected in parallel with the photoelectric conversion element 1, and the electrical signal converted by the photoelectric conversion element 1 is amplified by an amplification element 3 such as a field effect transistor and transferred to a subsequent circuit.
光電変換素子１と直列に接続された抵抗２に並列にダイ
オード４を接続したことにより、光電変換素子１に流れ
る電流の直流分が増大して、抵抗２の両端の電圧が上昇
しようとしても、ダイオード４に分流するから、そのダ
イオード４の順方向電圧に抑制することができ、それに
よって、増幅素子３の動作点を受信光信号レベルの変化
に対してもほぼ一定化することができる。By connecting the diode 4 in parallel to the resistor 2 connected in series with the photoelectric conversion element 1, even if the DC component of the current flowing through the photoelectric conversion element 1 increases and the voltage across the resistor 2 attempts to rise, Since the current is shunted to the diode 4, the forward voltage of the diode 4 can be suppressed, thereby making it possible to keep the operating point of the amplifying element 3 almost constant even with changes in the level of the received optical signal.
以下図面を参照して本発明の実施例について詳細に説明
する。Embodiments of the present invention will be described in detail below with reference to the drawings.
第２図は、本発明の一実施例の回路図であり、１１はホ
トダイオード等の光電変換素子、１２は抵抗、１３は電
界効果トランジスタ、１４はダイオード、１５はバイポ
ーラトランジスタ、１６は出力端子、Ｒ１−Ｒ４は抵抗
、Ｃ１，Ｃ２は結合用及びバイパス用のコンデンサ、＋
Ｖ、−Ｖは電源電圧であって、光電変換素子１１と直列
に接続された抵抗１２と並列にダイオード１４が接続さ
れている。即ち、抵抗１２とダイオード１４の一端は、
ホトダイオード等の光電変換素子に適当なバイアス電圧
を与える点（図中のｂ点）に接続されている。FIG. 2 is a circuit diagram of an embodiment of the present invention, in which 11 is a photoelectric conversion element such as a photodiode, 12 is a resistor, 13 is a field effect transistor, 14 is a diode, 15 is a bipolar transistor, 16 is an output terminal, R1-R4 are resistors, C1 and C2 are coupling and bypass capacitors, +
V and -V are power supply voltages, and a diode 14 is connected in parallel with a resistor 12 connected in series with the photoelectric conversion element 11. That is, one end of the resistor 12 and the diode 14 is
It is connected to a point (point b in the figure) that applies an appropriate bias voltage to a photoelectric conversion element such as a photodiode.
ダイオード１４の順方向電圧は、通常０．６ｖであり、
光電変換素子１１に流れる電流による抵抗１２の電圧降
下が０．６Ｖ以下の場合は、ダイオード１４には電流が
殆ど流れない状態となる。又光電変換素子１１に流れる
電流による抵抗１２の電圧降下が、０．６Ｖ以上となる
と、ダイオード１４にも電流が流れて、ダイオード１４
の端子電圧はほぼ０．６■を維持することになるから、
光電変換素子１１に流れる電流が増加しても、抵抗１２
の両端の電圧は増加しないことになる。The forward voltage of the diode 14 is normally 0.6v,
When the voltage drop across the resistor 12 due to the current flowing through the photoelectric conversion element 11 is 0.6 V or less, almost no current flows through the diode 14 . Furthermore, when the voltage drop across the resistor 12 due to the current flowing through the photoelectric conversion element 11 becomes 0.6V or more, current also flows through the diode 14, causing the diode 14 to
Since the terminal voltage of will maintain approximately 0.6■,
Even if the current flowing through the photoelectric conversion element 11 increases, the resistance 12
The voltage across it will not increase.
従って、受信した光信号レベルが低いことにより、光電
変換素子１１に流れる電流の直流分が小さいと、ａ点と
ｂ点との間の電位差は抵抗１２の電圧降下による僅かな
値となる。又受信した光信号レベルが高いことにより、
光電変換素子ＩＩに流れる電流の直流分が大きいと、抵
抗１２の電圧降下は０．６Ｖ以上となるので、ダイオー
ド１４にも電流が流れることになる。それによって、ａ
点とｂ点との間の電位差は、ダイオード１４の順方向電
圧の値に抑制され、充電変換素子Ｉｆに流れる電流の直
流分、即ち、受信光信号レベルに関係なく、電界効果ト
ランジスタ１３の動作点を一定化することができる。な
お、ダイオード１４の直列接続数を選定することにより
、ａ点とｂ点との間の電位差を０．６Ｖ以外の所望の値
に設定することが可能である。即ち、増幅素子としての
電界効果トランジスタ１３の動作点は、ダイオード１４
の接続数により所望の点に設定することができるもので
ある。Therefore, if the DC component of the current flowing through the photoelectric conversion element 11 is small due to the low level of the received optical signal, the potential difference between points a and b will be a small value due to the voltage drop across the resistor 12. Also, due to the high level of the received optical signal,
If the direct current component of the current flowing through the photoelectric conversion element II is large, the voltage drop across the resistor 12 will be 0.6 V or more, so that current will also flow through the diode 14. Thereby, a
The potential difference between the point and the point b is suppressed to the value of the forward voltage of the diode 14, and the operation of the field effect transistor 13 is suppressed regardless of the direct current component of the current flowing through the charging conversion element If, that is, the level of the received optical signal. Points can be made constant. Note that by selecting the number of series-connected diodes 14, it is possible to set the potential difference between point a and point b to a desired value other than 0.6V. That is, the operating point of the field effect transistor 13 as an amplifying element is the diode 14.
It can be set at a desired point depending on the number of connections.
第３図は本発明の他の実施例の回路図であり、２１は光
電変換素子、２２は抵抗、２３は電界効果トランジスタ
、２４はダイオード、２５はバイポーラトランジスタ、
２６は出力端子であって、他の第２図と同一符号は同一
部分を示すものである。この実施例は、光電変換素子２
１と接地との間に抵抗２２が接続され、その抵抗２２と
並列にダイオード２４が接続されているものである。従
って、受信した光信号レベルが大きくなった時、流れる
電流の直流分が大きくなるが、抵抗２２の電圧降下が０
．６Ｖ以上となると、ダイオード２４の順方向電圧とな
るように分流されるから、電界効果トランジスタ２３の
動作点を一定化することができる。FIG. 3 is a circuit diagram of another embodiment of the present invention, in which 21 is a photoelectric conversion element, 22 is a resistor, 23 is a field effect transistor, 24 is a diode, 25 is a bipolar transistor,
26 is an output terminal, and the same reference numerals as in other parts of FIG. 2 indicate the same parts. In this example, the photoelectric conversion element 2
A resistor 22 is connected between the resistor 1 and the ground, and a diode 24 is connected in parallel with the resistor 22. Therefore, when the received optical signal level increases, the DC component of the flowing current increases, but the voltage drop across the resistor 22 becomes 0.
．． When the voltage exceeds 6V, the current is shunted to become the forward voltage of the diode 24, so that the operating point of the field effect transistor 23 can be made constant.
この実施例に於いても、抵抗２２と並列に接続するダイ
オード２４の直列接続数を選定することにより、増幅素
子としての電界効果トランジスタ２３の動作点を設定す
ることができる。又増幅素子としては、バイポーラトラ
ンジスタを用いることも勿論可能である。In this embodiment as well, the operating point of the field effect transistor 23 as an amplifying element can be set by selecting the number of series connections of the diodes 24 connected in parallel with the resistor 22. Furthermore, it is of course possible to use a bipolar transistor as the amplification element.
以上説明したように、本発明は、ホトダイオード等の光
電変換素子１と直列に接続された抵抗２に対して、並列
にダイオード４を接続したものであり、光電変換素子１
に流れる電流の直流分が光信号レベルに対応して変化し
ても、抵抗２の両端の電圧をダイオード４の順方向電圧
に抑制することができ、それによって電界効果トランジ
スタ等の増幅素子３の動作点を一定化することができる
ものである。従って、信号の波形歪を生じることもな（
、光受信回路の動作を安定化することができる。As explained above, in the present invention, a diode 4 is connected in parallel to a resistor 2 connected in series with a photoelectric conversion element 1 such as a photodiode.
Even if the DC component of the current flowing through the resistor 2 changes in response to the optical signal level, the voltage across the resistor 2 can be suppressed to the forward voltage of the diode 4. This allows the operating point to be made constant. Therefore, no signal waveform distortion occurs (
, the operation of the optical receiving circuit can be stabilized.
第１図は本発明の原理説明図、第２図及び第３図は本発
明のそれぞれ異なる実施例の回路図、第４図及び第５図
は従来例の回路図である。
１．１１．２１はホトダイオード等の光電変換素子、２
，１２．２２は抵抗、３は増幅素子、４．１４．２４は
ダイオード、１３．２３は電界効果トランジスタ、１５
．２５はバイポーラトランジスタ、１６．２６は出力端
子、Ｒ１−Ｒ４は抵抗、Ｃ１，Ｃ２は結合用及びバイパ
ス用のコンデンサである。FIG. 1 is a diagram explaining the principle of the present invention, FIGS. 2 and 3 are circuit diagrams of different embodiments of the present invention, and FIGS. 4 and 5 are circuit diagrams of a conventional example. 1.11.21 is a photoelectric conversion element such as a photodiode, 2
, 12.22 is a resistor, 3 is an amplification element, 4.14.24 is a diode, 13.23 is a field effect transistor, 15
．． 25 is a bipolar transistor, 16 and 26 are output terminals, R1-R4 are resistors, and C1 and C2 are coupling and bypass capacitors.
Claims (2)
て、 受信したディジタル光信号を電気信号に変換する光電変
換素子（１）と、 該光電変換素子（１）と直列に一端が接続された抵抗（
２）と、 該抵抗（２）と前記光電変換素子（１）との接続点を入
力端子に接続した増幅素子（３）と、前記抵抗（２）に
並列に接続したダイオード（４）とを備えた ことを特徴とする光受信回路。(1) In an optical receiving circuit that receives a digital optical signal, a photoelectric conversion element (1) that converts the received digital optical signal into an electrical signal, and one end connected in series with the photoelectric conversion element (1). resistance (
2), an amplifying element (3) whose input terminal is connected to a connection point between the resistor (2) and the photoelectric conversion element (1), and a diode (4) connected in parallel to the resistor (2). An optical receiving circuit characterized by comprising:
を所定のバイアス電位に接続したことを特徴とする特許
請求の範囲第１項記載の光受信回路。(2) The optical receiving circuit according to claim 1, characterized in that the other ends of the resistor (2) and the diode (4) are connected to a predetermined bias potential.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60077548A JPS61237534A (en) | 1985-04-13 | 1985-04-13 | Optical reception circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60077548A JPS61237534A (en) | 1985-04-13 | 1985-04-13 | Optical reception circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS61237534A true JPS61237534A (en) | 1986-10-22 |
Family
ID=13637063
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP60077548A Pending JPS61237534A (en) | 1985-04-13 | 1985-04-13 | Optical reception circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61237534A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6436087A (en) * | 1987-07-31 | 1989-02-07 | Hamamatsu Photonics Kk | Ic photodetector for photocoupler |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58168343A (en) * | 1982-03-29 | 1983-10-04 | Fujitsu Ltd | Optical agc circuit |
-
1985
- 1985-04-13 JP JP60077548A patent/JPS61237534A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58168343A (en) * | 1982-03-29 | 1983-10-04 | Fujitsu Ltd | Optical agc circuit |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6436087A (en) * | 1987-07-31 | 1989-02-07 | Hamamatsu Photonics Kk | Ic photodetector for photocoupler |
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