JPH0326332B2 - - Google Patents
Info
- Publication number
- JPH0326332B2 JPH0326332B2 JP57117966A JP11796682A JPH0326332B2 JP H0326332 B2 JPH0326332 B2 JP H0326332B2 JP 57117966 A JP57117966 A JP 57117966A JP 11796682 A JP11796682 A JP 11796682A JP H0326332 B2 JPH0326332 B2 JP H0326332B2
- Authority
- JP
- Japan
- Prior art keywords
- photodetector
- resistor
- optical
- circuit
- power supply
- 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
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J1/00—Photometry, e.g. photographic exposure meter
- G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
- G01J1/44—Electric circuits
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Spectrometry And Color Measurement (AREA)
- Photometry And Measurement Of Optical Pulse Characteristics (AREA)
Description
【発明の詳細な説明】 本発明は光検波回路に関する。[Detailed description of the invention] The present invention relates to a photodetector circuit.
光通信方式は、従来の電気通信方式に比較し
て、広帯域の長距離伝送が可能であるという利点
を持ち、かつ、光フアイバの特異性のため外部か
らのじよう乱を受けにくく、より品質の高い伝送
システムを構成することができる。 Compared to conventional telecommunication systems, optical communication systems have the advantage of being able to transmit broadband over long distances, and because of the uniqueness of optical fibers, they are less susceptible to external disturbances and have higher quality. A high transmission system can be constructed.
一方、光フアイバの軽量、細心および安価（材
量が豊富）等の利点により、上記の高品質伝送シ
ステム以外にも、ローカルな光通信が急速に普及
する傾向にあり、このため、より汎用性のあるシ
ステムが要求されるようになつてきている。例え
ば、工場内通信や同一建造物内通信のように伝送
距離の短いシステムから、加入者系システムや主
幹線通信網から分岐される中距離システムまでそ
の需要はさまざまである。このような多様なシス
テムに対応するには、伝送路長の違いにより生ず
る光受信レベルの違いに対応できなけれならな
い。 On the other hand, in addition to the above-mentioned high-quality transmission systems, local optical communications are rapidly becoming popular due to the advantages of optical fibers, such as their light weight, fineness, and low cost (available in large amounts of materials). Increasingly, a certain system is required. For example, the demands vary from systems with short transmission distances, such as communication within a factory or within the same building, to medium-distance systems branched from subscriber systems and main trunk communication networks. In order to support such a variety of systems, it is necessary to be able to handle differences in optical reception levels caused by differences in transmission path length.
これの対応策としては、システム毎に機器を変
更する第１の方法、短距離伝送システムの場合に
は光減衰器を用いて光受信レベルを強制的に下げ
る第２の方法および全ての光受信レベルで動作す
るような機器を実現する第３の方法がある。 As a countermeasure for this, the first method is to change the equipment for each system, the second method is to forcibly lower the optical reception level using an optical attenuator in the case of a short-distance transmission system, and the There is a third way to realize a device that operates at the level.
多様な伝送システムに安価でより汎用性のある
機器を提供するには伝送システム毎の変更がなく
かつ、高価な光減衰器を使用しない第３の方法が
優れており、光受信レベルの低いときに動作（受
信感度が高い）し、かつ光受信レベルの高いとき
でも安定して動作する機器の使用は非常に有効で
ある。 In order to provide inexpensive and more versatile equipment for various transmission systems, the third method is superior because it does not require changes for each transmission system and does not use expensive optical attenuators. It is very effective to use equipment that operates stably (high reception sensitivity) and operates stably even when the optical reception level is high.
この受信感度は、主に光検波回路とそれに続く
増幅回路とに大きく依存している。光検波器は電
気回路的には電流源として働くため、受信感度は
光検波器の負荷抵抗すなわち光検波器の電源供給
用抵抗（以下、バイアス抵抗と言う）と増幅回路
の帰還抵抗とで決められる。 This receiving sensitivity largely depends on the optical detection circuit and the subsequent amplifier circuit. Since a photodetector works as a current source in an electrical circuit, the receiving sensitivity is determined by the photodetector's load resistance, that is, the photodetector's power supply resistance (hereinafter referred to as bias resistance) and the feedback resistance of the amplifier circuit. It will be done.
増幅回路の帰還抵抗の値は伝送信号の周波数帯
域によつて一義的に決められるため、光検波器の
バイアス抵抗の値はその帰還抵抗の値より十分大
きく選び、光検波器の負荷抵抗値が下らないよう
にしている。 Since the value of the feedback resistance of the amplifier circuit is uniquely determined by the frequency band of the transmission signal, the value of the bias resistance of the photodetector should be selected to be sufficiently larger than the value of the feedback resistance, so that the load resistance value of the photodetector is I'm trying not to let it go down.
一般に、光受信レベル変動の補正を行なう自動
可変利得回路や振幅制限回路を使用することによ
り光受信レベルの比較的高いときにも機器が動作
するよう考慮されている。しかしながら、、光受
信レベルが非常に高いときには、例えば半導体接
合型の光検波器を使用したときには、光信号を検
出して流れる光電流により光検出器のバイアス抵
抗で大きな電圧降下が生じ、この結果、光検波器
の電源電圧不足を招く。この電源電圧の不足は、
半導体接合型光検波器の空乏層幅を狭くしたり、
その端子間容量を増大させて、周波数応答特性を
劣化させるため、正常な光検波が行なえなくな
る。 Generally, it is considered that devices can operate even when the optical reception level is relatively high by using an automatic variable gain circuit or an amplitude limiting circuit that corrects fluctuations in the optical reception level. However, when the optical reception level is very high, for example when a semiconductor junction photodetector is used, the photocurrent that flows when detecting the optical signal causes a large voltage drop in the bias resistance of the photodetector, resulting in , leading to insufficient power supply voltage for the photodetector. This lack of power supply voltage causes
Narrowing the depletion layer width of semiconductor junction photodetectors,
Since the capacitance between the terminals is increased and the frequency response characteristics are deteriorated, normal optical detection cannot be performed.
この電圧降下は、光検波器のバイアス抵抗の大
きさに比例しているため、光受信レベルの高いと
きには、そのバイアス抵抗値を小さくして周波数
応答特性の劣化を防ぐことができる。しかしなが
ら、上述したように、光受信レベルが低いとき
に、十分な特性を得るにはその光検波器のバイア
ス抵抗を大きくして光受信感度の劣化を押える必
要があり、この相反する特性により、広範囲の光
受信レベルで動作する光検波回路を実現すること
は困難であつた。 Since this voltage drop is proportional to the magnitude of the bias resistance of the photodetector, when the optical reception level is high, the bias resistance value can be reduced to prevent deterioration of the frequency response characteristics. However, as mentioned above, in order to obtain sufficient characteristics when the optical reception level is low, it is necessary to increase the bias resistance of the optical detector to suppress deterioration of optical reception sensitivity, and due to these contradictory characteristics, It has been difficult to realize an optical detection circuit that operates over a wide range of optical reception levels.
本発明の目的は上述の欠点を除去した光検波回
路を提供することにある
本発明の光検波回路は、光信号を受信する光検
波手段と該光検波手段と接続され大きな抵抗値を
有する第１の抵抗と光検波手段にバイアス電圧を
供給する第１の電源との直列接続からなる第１の
直列回路と、該第１の直列回路と並列に接続され
第１の抵抗より小さな抵抗値を有する第２の抵抗
とダイオードと光検波手段に第１の電源より小さ
いバイアス電圧を供給する第２の電源との直列接
続からなる第２の直列回路とから構成されてい
る。信号レベルの変動はこの光検波回路の後段の
増幅回路や自動可変利得回路または振幅制限回路
で補償するものとする。 SUMMARY OF THE INVENTION An object of the present invention is to provide a photodetector circuit which eliminates the above-mentioned drawbacks. a first series circuit consisting of a series connection of a first resistor and a first power source that supplies a bias voltage to the optical detection means; a first series circuit connected in parallel with the first series circuit and having a resistance value smaller than the first resistor; A second series circuit includes a second resistor, a diode, and a second power supply that supplies a bias voltage lower than that of the first power supply to the optical detection means. It is assumed that fluctuations in signal level are compensated for by an amplifier circuit, an automatic variable gain circuit, or an amplitude limiting circuit after the optical detection circuit.
次に本発明について図面を参照して詳細に説明
する。 Next, the present invention will be explained in detail with reference to the drawings.
第１図は本発明の一実施例を示す回路図であ。
図において、本実施例は、光信号を受信する半導
体接合型光検波器１と、検波器１と接続され抵抗
値RB1を有する第１のバイアス抵抗器２と、正極
側が接地され負極側が抵抗器２と接続された電源
電が−VB1の第１の電源３と、検波器１と接続さ
れ抵抗値RB2を有する第２の抵抗器４と、アノー
ドが抵抗器４と接続されたダイオード５と、正極
側が接地され負極側がダイオード５のカソードと
接続された電源電圧が−VB2の第２の電源と、
増幅回路８と、増幅回路８の帰還抵抗７とから構
成されている。 FIG. 1 is a circuit diagram showing one embodiment of the present invention.
In the figure, this embodiment includes a semiconductor junction type photodetector 1 that receives an optical signal, a first bias resistor 2 connected to the detector 1 and having a resistance value R B1 , and a resistor whose positive electrode side is grounded and whose negative electrode side is a resistor. a first power supply 3 whose power supply voltage is -V B1 connected to the detector 2; a second resistor 4 connected to the detector 1 and having a resistance value R B2 ; and a diode whose anode is connected to the resistor 4. 5, a second power supply whose positive pole side is grounded and whose negative pole side is connected to the cathode of the diode 5 and whose power supply voltage is -VB2 , an amplifier circuit 8, and a feedback resistor 7 of the amplifier circuit 8.
ここで、−VB1＜VB2（｜VB1｜＞｜VB2｜）と仮
定すると、光検波器のバイアス電圧VBは、光受
信レベルが小さくて光電流が少ない場合には(1)式
で与えられ、光受信レベルが大きく光電流が多い
場合には(2)式で与えられる。 Here, assuming −V B1 <V B2 (|V B1 |> | V B2 |), the bias voltage V B of the photodetector is (1) when the optical reception level is low and the photocurrent is small. When the optical reception level is high and the photocurrent is large, it is given by equation (2).
VB＝VB1＋I0×RB1 ……(1)
VB＝VB2＋Vf＋I0×RB2 ……(2)
ここで、I0は光電流、Vfは半導体５の順方向電
圧降下である。 V B = V B1 + I 0 × R B1 ... (1) V B = V B2 + V f + I 0 × R B2 ... (2) Here, I 0 is the photocurrent, and V f is the forward voltage of the semiconductor 5. It is a descent.
すなわち、第２図に示すように、光電流がある
値IXより少ないときには、(1)式のVB1とRB1とI0と
でバイアス電圧VBが決まる。このとき、第２の
電源電圧VB2がそのバイアス電VBより高いためダ
イオード５には逆電圧がかかり、この結果、等価
的に光検波バイアス回路は、RB1とVB1だけで構
成したものと同一となり、負荷抵抗の減少による
る光受信感度の劣化はない。 That is, as shown in FIG. 2, when the photocurrent is less than a certain value IX , the bias voltage VB is determined by VB1 , RB1 , and I0 in equation (1). At this time, since the second power supply voltage V B2 is higher than the bias voltage V B , a reverse voltage is applied to the diode 5, and as a result, the optical detection bias circuit is equivalently made up of only R B1 and V B1 . is the same, and there is no deterioration in optical reception sensitivity due to a decrease in load resistance.
また、光電流がIXより大きいときには、(2)式の
VB2，Vf，RB2およびI0でバイアス電圧が決まる。
これは、光電流の増加にともない、RB1での電圧
降下が大きくなり、バイアス電圧VBが第２の電
源電圧VB2より高くなるためダイオード５には順
方向の電圧がかかり、光電流が第２の電源６方向
に流れ出すためである。 Also, when the photocurrent is larger than I
The bias voltage is determined by V B2 , V f , R B2 and I 0 .
This is because as the photocurrent increases, the voltage drop at R B1 increases and the bias voltage V B becomes higher than the second power supply voltage V B2 , so a forward voltage is applied to the diode 5 and the photo current increases. This is because it flows out in the 6 directions of the second power source.
具体的な数値例を以下に示す。 Specific numerical examples are shown below.
VB1＝−20（Ｖ），VB2＝−５（Ｖ），RB1＝100
（KΩ），RB2＝１（KΩ），RB2＝１（KΩ）およびVf
＝0.7（Ｖ）とすると、IX＝0.36（mA）となり、光
の波長が1.3（μm）帯の光検波器を使用したとき
には、平均光受信レベルにおいて約−５（dBm）
以上で第２の電源６が働くことになる。 V B1 = -20 (V), V B2 = -5 (V), R B1 = 100
(KΩ), R B2 = 1 (KΩ), R B2 = 1 (KΩ) and V f
= 0.7 (V), I
With the above steps, the second power supply 6 becomes operational.
以上、本発明には煩雑な調整や高価な光減衰器
が不要で、広範囲な光受信レベルで動作する光検
波回路を提供できるという効果がある。 As described above, the present invention has the advantage of being able to provide an optical detection circuit that operates at a wide range of optical reception levels without requiring complicated adjustments or expensive optical attenuators.
第１図は本発明の一実施例を示す回路図および
第２図は実施例の光検波回路バイアス電圧VB光
電流I0との関係を示す図である。
図において、１……半導体接合型光検波器、２
……抵抗器、３……電源、４……抵抗器、５……
ダイオード、６……電源、７……抵抗器、８……
増幅回路。
FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing the relationship between the photodetector circuit bias voltage V B and the photocurrent I 0 of the embodiment. In the figure, 1... semiconductor junction type photodetector, 2
...Resistor, 3...Power supply, 4...Resistor, 5...
Diode, 6...Power supply, 7...Resistor, 8...
Amplification circuit.
Claims (1)
段と接続され大きな抵抗値を有する第１の抵抗と
前記光検波手段にバイアス電圧を供給する第１の
電源との直列接続からなる第１の直列回路と、該
第１の直列回路と並列に接続され前記第１の抵抗
より小さな抵抗値を有する第２の抵抗とダイオー
ドと前記光検波手段に前記第１の電源より小さい
バイアス電圧を供給する第２の電源との直列接続
からなる第２の直列回路とから構成されたことを
特徴とする光検波回路。1. A first resistor that is connected in series with a photodetector that receives an optical signal, a first resistor that is connected to the photodetector and has a large resistance value, and a first power supply that supplies a bias voltage to the photodetector. a series circuit, a second resistor and diode connected in parallel with the first series circuit and having a resistance value smaller than that of the first resistor, and a bias voltage smaller than the first power source is supplied to the photodetecting means. and a second series circuit connected in series with a second power supply.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11796682A JPS599524A (en) | 1982-07-07 | 1982-07-07 | Photodetector circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11796682A JPS599524A (en) | 1982-07-07 | 1982-07-07 | Photodetector circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS599524A JPS599524A (en) | 1984-01-18 |
| JPH0326332B2 true JPH0326332B2 (en) | 1991-04-10 |
Family
ID=14724669
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11796682A Granted JPS599524A (en) | 1982-07-07 | 1982-07-07 | Photodetector circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS599524A (en) |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54131981A (en) * | 1978-04-03 | 1979-10-13 | Nippon Telegr & Teleph Corp <Ntt> | Automatic control circuit of photo detecting sensitivity |
-
1982
- 1982-07-07 JP JP11796682A patent/JPS599524A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS599524A (en) | 1984-01-18 |
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