JPH0145783B2 - - Google Patents
Info
- Publication number
- JPH0145783B2 JPH0145783B2 JP57079360A JP7936082A JPH0145783B2 JP H0145783 B2 JPH0145783 B2 JP H0145783B2 JP 57079360 A JP57079360 A JP 57079360A JP 7936082 A JP7936082 A JP 7936082A JP H0145783 B2 JPH0145783 B2 JP H0145783B2
- Authority
- JP
- Japan
- Prior art keywords
- voltage
- photoelectric conversion
- conversion circuit
- receiving element
- light receiving
- 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
Links
- 238000006243 chemical reaction Methods 0.000 claims description 17
- 230000005669 field effect Effects 0.000 claims description 2
- 230000003287 optical effect Effects 0.000 description 6
- 101150073536 FET3 gene Proteins 0.000 description 5
- 238000010586 diagram Methods 0.000 description 5
- 230000003321 amplification Effects 0.000 description 3
- 238000003199 nucleic acid amplification method Methods 0.000 description 3
- 230000003071 parasitic effect Effects 0.000 description 3
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
- H04B10/691—Arrangements for optimizing the photodetector in the receiver
- H04B10/6911—Photodiode bias control, e.g. for compensating temperature variations
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Optical Communication System (AREA)
Description
【発明の詳細な説明】
本発明は光通信システムにおいて光信号を電気
信号に変換する光電変換回路に関し、詳細には受
信信号帯域が受光素子の寄生容量によつて制限を
受けずかつ電源電圧の大きさにほゞ等しい出力振
幅を有する電気信号が得られる光電変換回路に関
する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photoelectric conversion circuit that converts an optical signal into an electrical signal in an optical communication system. The present invention relates to a photoelectric conversion circuit that can obtain an electrical signal having an output amplitude approximately equal to the magnitude.
第１図は従来の光電変換回路を例示する図であ
る。この光電変換回路は光信号を受光素子である
フオトダイオード１を流れる電流に変換し、この
フオトダイオード１の電流を直列に設けた負荷抵
抗Ｒ１に流しこの負荷抵抗Ｒ１の両端に発生した
電圧を電気信号出力として取り出すものである。
この方式の光電変換回路はフオトダイオード１の
寄生容量と、直列に設けられた負荷抵抗Ｒ１によ
る回路時定数により受信信号帯域が制限されると
いう欠点がある。 FIG. 1 is a diagram illustrating a conventional photoelectric conversion circuit. This photoelectric conversion circuit converts an optical signal into a current flowing through a photodiode 1 which is a light receiving element, and the current of this photodiode 1 is passed through a load resistor R1 provided in series, and the voltage generated across this load resistor R1 is converted into an electric current. It is taken out as a signal output.
This type of photoelectric conversion circuit has the disadvantage that the received signal band is limited by the parasitic capacitance of the photodiode 1 and the circuit time constant caused by the load resistor R1 provided in series.
第２図は従来の別の光電変換回路を例示する図
である。この光電変換回路はフオトダイオード１
に直列に逆相増幅器２を接続し、負荷抵抗Ｒ２を
逆相増幅器２ａ負帰還抵抗として用いた電流・電
圧変換器である。逆相増幅器２は帯域が十分広く
増幅度の大きいものが用いられているので、この
方式の光電変換回路は受信信号帯域が広い。しか
し、この光電変換回は十分な受信信号帯域と利得
とを持つた逆相増幅器２が必要であり、これを安
定に動作させることは困難である。 FIG. 2 is a diagram illustrating another conventional photoelectric conversion circuit. This photoelectric conversion circuit consists of photodiode 1
This is a current/voltage converter in which an anti-phase amplifier 2 is connected in series with the anti-phase amplifier 2a and a load resistor R2 is used as a negative feedback resistor of the anti-phase amplifier 2a. Since the anti-phase amplifier 2 has a sufficiently wide band and a high degree of amplification, this type of photoelectric conversion circuit has a wide reception signal band. However, this photoelectric conversion circuit requires an anti-phase amplifier 2 having a sufficient reception signal band and gain, and it is difficult to operate this in a stable manner.
本発明の目的は、デプレツシヨン形FETを用
いてバイアスを簡素化し、受光素子の寄生容量を
打ち消して受信信号帯域を広帯域化し、しかも
ほゞ電源電圧に等しい出力信号振幅が得られる光
電変換回路を提供することである。 An object of the present invention is to provide a photoelectric conversion circuit that uses a depletion type FET to simplify the bias, cancel out the parasitic capacitance of the light receiving element, widen the received signal band, and obtain an output signal amplitude approximately equal to the power supply voltage. It is to be.
以下に図面を参照して本発明について詳細に説
明する。 The present invention will be described in detail below with reference to the drawings.
第３図は本発明の光電変換回路の実施例を示す
図である。この光電変換回路はデプレツシヨン形
FETのソースホロワー増幅器であり、受光素子
１はソース・ゲート間に接続されている。この回
路は電圧増幅率が１であり、その入力インピーダ
ンスが非常に高いのでフオトダイオード等の受光
素子１の負荷抵抗となる抵抗Ｒ３が十分大きく設
定できる。FET３はデプレツシヨン形FETであ
りバイアス電圧は負の電圧であつて、受光素子１
にはFET３の逆バイアス電圧がそのままかゝる。 FIG. 3 is a diagram showing an embodiment of the photoelectric conversion circuit of the present invention. This photoelectric conversion circuit is a depletion type
It is a FET source follower amplifier, and the light receiving element 1 is connected between the source and gate. Since this circuit has a voltage amplification factor of 1 and an extremely high input impedance, the resistor R3 serving as the load resistance of the light receiving element 1 such as a photodiode can be set sufficiently large. FET3 is a depletion type FET, and the bias voltage is a negative voltage.
The reverse bias voltage of FET3 is applied as is.
光信号がない場合には、負荷抵抗Ｒ３に流れる
電流は受光素子１の暗電流とFET３のゲート漏
れ電流とである。従つて、FET３のゲート電圧
VGはほとんどOVとなり、FET３のソース電圧は
この回路に必要な逆バイアス電圧となる。この逆
バイアス電圧が受光素子１の逆バイアス電圧とな
る。光信号が入力された場合には、受光素子１に
生じる受光電流が負荷抵抗Ｒ３に流れてゲート電
圧VGが変動する。この回路は電圧増幅率が１で
あるから、出力端であるバイアス抵抗Ｒ４の電圧
もゲート電圧VGに追従して変動する。つまり、
受光素子１の逆バイアス電圧は一定のまゝ出力信
号電圧が取り出せることになり、受光素子１の寄
生容量に対する充放電は行なわれない。そのため
信号帯域は受光素子１の負荷抵抗Ｒ３とその漂遊
容量によつて決まる時定数で制限されるだけであ
り、光電変換回路の広帯域化が実現できる。ま
た、出力電圧の振幅は電源電圧から光信号がない
場合の逆バイアス電圧とFET３のソース・ドレ
イン間の飽和電圧とを差し引いた電圧となり、
ほゞ電源電圧と同じ振幅が得られ電源電圧を有効
に利用できる。更に、この回路はFET３をゲー
ト入力を２つもつものに替えることにより出力バ
イアスの設定が容易にできる。 When there is no optical signal, the current flowing through the load resistor R3 is the dark current of the light receiving element 1 and the gate leakage current of the FET 3. Therefore, the gate voltage of FET3
V G is almost OV, and the source voltage of FET3 becomes the reverse bias voltage required for this circuit. This reverse bias voltage becomes the reverse bias voltage of the light receiving element 1. When an optical signal is input, a light-receiving current generated in the light-receiving element 1 flows through the load resistor R3, and the gate voltage V G changes. Since this circuit has a voltage amplification factor of 1, the voltage of the bias resistor R4, which is the output terminal, also fluctuates following the gate voltage VG . In other words,
The output signal voltage can be extracted while the reverse bias voltage of the light receiving element 1 remains constant, and the parasitic capacitance of the light receiving element 1 is not charged or discharged. Therefore, the signal band is limited only by the time constant determined by the load resistance R3 of the light receiving element 1 and its stray capacitance, and a wide band of the photoelectric conversion circuit can be realized. Also, the amplitude of the output voltage is the voltage obtained by subtracting the reverse bias voltage when there is no optical signal and the saturation voltage between the source and drain of FET3 from the power supply voltage,
Almost the same amplitude as the power supply voltage can be obtained and the power supply voltage can be used effectively. Furthermore, in this circuit, the output bias can be easily set by replacing the FET 3 with one having two gate inputs.
第１図及び第２図はそれぞれ従来の光電変換回
路を例示する図、第３図は本発明の光電変換回路
の実施例を示す図である。
１：受光素子、２：逆相増幅器、３：電界効果
トランジスタ、Ｒ１，Ｒ２，Ｒ３：負荷抵抗、Ｒ
４：バイアス抵抗。
1 and 2 are diagrams each illustrating a conventional photoelectric conversion circuit, and FIG. 3 is a diagram illustrating an embodiment of the photoelectric conversion circuit of the present invention. 1: Photodetector, 2: Negative phase amplifier, 3: Field effect transistor, R1, R2, R3: Load resistance, R
4: Bias resistance.
Claims (1)
るソースホロワー増幅器のソースーゲート端子間
に該トランジスタのソース電圧が逆バイアス電圧
となる向きに受光素子を接続して成ることを特徴
とする光電変換回路。 ２ １において、前記受光素子がフオトダイオー
ドからなることを特徴とする光電変換回路。[Scope of Claims] 1. A photoelectric conversion circuit characterized in that a light receiving element is connected between the source and gate terminals of a source follower amplifier using a depletion type field effect transistor in such a direction that the source voltage of the transistor becomes a reverse bias voltage. 2. The photoelectric conversion circuit according to item 1, wherein the light receiving element is composed of a photodiode.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57079360A JPS58196734A (en) | 1982-05-12 | 1982-05-12 | Photoelectric converting circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57079360A JPS58196734A (en) | 1982-05-12 | 1982-05-12 | Photoelectric converting circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS58196734A JPS58196734A (en) | 1983-11-16 |
| JPH0145783B2 true JPH0145783B2 (en) | 1989-10-04 |
Family
ID=13687723
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP57079360A Granted JPS58196734A (en) | 1982-05-12 | 1982-05-12 | Photoelectric converting circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS58196734A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS593650U (en) * | 1982-06-30 | 1984-01-11 | ソニー株式会社 | Light receiving device |
| US4958500A (en) * | 1989-04-20 | 1990-09-25 | Hitachi, Ltd. | Air conditioner and air conditioning method |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4921049A (en) * | 1972-04-17 | 1974-02-25 |
-
1982
- 1982-05-12 JP JP57079360A patent/JPS58196734A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4921049A (en) * | 1972-04-17 | 1974-02-25 |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS58196734A (en) | 1983-11-16 |
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