JPH04167605A - Preamplifier circuit for photoelectric conversion - Google Patents
Preamplifier circuit for photoelectric conversionInfo
- Publication number
- JPH04167605A JPH04167605A JP2289480A JP28948090A JPH04167605A JP H04167605 A JPH04167605 A JP H04167605A JP 2289480 A JP2289480 A JP 2289480A JP 28948090 A JP28948090 A JP 28948090A JP H04167605 A JPH04167605 A JP H04167605A
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- optical
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- light receiving
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- 238000006243 chemical reaction Methods 0.000 title claims abstract description 22
- 230000003287 optical effect Effects 0.000 claims abstract description 33
- 229920006395 saturated elastomer Polymers 0.000 abstract description 3
- 230000003247 decreasing effect Effects 0.000 abstract 1
- 230000003321 amplification Effects 0.000 description 11
- 238000003199 nucleic acid amplification method Methods 0.000 description 11
- 239000003990 capacitor Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
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- Amplifiers (AREA)
- Optical Communication System (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、光フアイバ通信において、受光素子を用いて
、光信号を電気信号に変換して増幅する回路に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a circuit that converts an optical signal into an electrical signal and amplifies it using a light receiving element in optical fiber communication.
この種の光−電気変換前置増幅回路では、受光素子によ
って光−電気変換が行われた後、電気信号を一定の増幅
率にて増幅して出力する回路が一般的である。This type of optical-to-electrical conversion preamplifier circuit is generally a circuit that amplifies and outputs an electrical signal at a constant amplification factor after optical-to-electrical conversion is performed by a light receiving element.
このような光の一例が第２図に示されている。An example of such light is shown in FIG.
第２図によれば、受光素子２１に逆電圧ａを印加してお
く。この受光素子２１に光信号が入力されると、受光素
子２１のなだれ降下による現象によって光電変換が行わ
れる。受光素子２１によって生成された電気信号は、コ
ンデンサ２２を通り、バイアスｂの印加されているトラ
ンジスタ２３のベースに入力される。ここで、トランジ
スタ２３の増幅作用により、電圧ｄの加えられている一
定の負荷抵抗２４が接続されているトランジスタ２３の
コレクタ出力として、一定の増幅された電気信号Ｃが出
力される。According to FIG. 2, a reverse voltage a is applied to the light receiving element 21. When an optical signal is input to the light receiving element 21, photoelectric conversion is performed due to a phenomenon caused by the avalanche of the light receiving element 21. The electrical signal generated by the light receiving element 21 passes through the capacitor 22 and is input to the base of the transistor 23 to which bias b is applied. Here, due to the amplification effect of the transistor 23, a constant amplified electric signal C is outputted as the collector output of the transistor 23, which is connected to a constant load resistor 24 to which a voltage d is applied.
〔発明が解決しようとする課題〕
この従来の光−電気変換前置増幅回路では、負荷抵抗が
一定なため、光入力信号が過大入力の時には、光−電気
変換された電気信号が、トランジスタの一定の増幅率に
よって、一定に増幅される。[Problems to be Solved by the Invention] In this conventional optical-to-electrical conversion preamplifier circuit, the load resistance is constant, so when the optical input signal is excessively input, the optical-to-electrical converted electric signal is Constant amplification is achieved by a constant amplification factor.
このために、トランジスタが飽和領域での増幅となり、
結果として、出力信号として飽和するという問題点があ
る。For this reason, the transistor becomes amplified in the saturation region,
As a result, there is a problem that the output signal is saturated.
本発明の目的は、このような欠点を除去し、光信号が過
大入力時に、増幅回路の飽和現象を低減した光−電気変
換前置増幅回路を提供することにある。SUMMARY OF THE INVENTION An object of the present invention is to provide an optical-to-electrical conversion preamplifier circuit that eliminates such drawbacks and reduces the saturation phenomenon of the amplifier circuit when an excessive optical signal is input.
本発明の光−電気変換前置増幅回路は、入力された電気
信号に基づいて第１および第２の電気信号を生成する受
光部と、
受光部の第１の電気信号を増幅して、負荷に出力電気信
号を発生する増幅部と、
受光部の第２の電気信号を直流信号に変換する変換部と
、
変換部の直流信号と予め設定されている基準信号とを比
較して、比較結果を送り出す比較部と、増幅部の負荷に
並列に接続され、比較部の比較結果に基づいて大きさを
変える可動負荷とを有し、変換部からの直流信号が基準
信号より小さいときに、可動負荷の大きさを増幅部の負
荷の大きさより大きくし、変換部からの直流信号が基準
信号より大きいときに、可動負荷の大きさを増幅部の負
荷の大きさより小さくする。The optical-to-electrical conversion preamplifier circuit of the present invention includes a light receiving section that generates first and second electrical signals based on an input electrical signal, and a light receiving section that amplifies the first electrical signal of the light receiving section and loads the an amplification section that generates an output electrical signal; a conversion section that converts the second electrical signal of the light receiving section into a DC signal; and a comparison result that compares the DC signal of the conversion section with a preset reference signal. The movable load is connected in parallel to the load of the amplification section and changes its size based on the comparison result of the comparison section.When the DC signal from the conversion section is smaller than the reference signal, the movable load The magnitude of the load is made larger than the magnitude of the load on the amplification section, and when the DC signal from the conversion section is greater than the reference signal, the magnitude of the movable load is made smaller than the magnitude of the load on the amplification section.
また、本発明の光−電気変換前置増幅回路は、光信号を
電気信号に変換する受光素子と、受光素子の光順電流に
よって電圧を発生する受光素子のアノード側に接続され
る抵抗器と、この抵抗器の電圧を整流する整流器と、受
光素子で光信号から変換された電気信号を増幅するトラ
ンジスタと、
そのトランジスタのコレクタに直列に接続される負荷抵
抗器と、
整流器から発生する電圧と基準電圧とを比較する比較器
と、
負荷抵抗器に並列に接続され、比較器の制御電圧により
抵抗値が変動する可変負荷抵抗器とを有し、
光信号が過大に入力された場合に負荷抵抗器の変動によ
り、出力電気信号が飽和状態にならないように増幅する
。Further, the optical-to-electrical conversion preamplifier circuit of the present invention includes a light receiving element that converts an optical signal into an electrical signal, and a resistor connected to the anode side of the light receiving element that generates a voltage by the optical forward current of the light receiving element. , a rectifier that rectifies the voltage of this resistor, a transistor that amplifies the electrical signal converted from the optical signal by the photodetector, a load resistor connected in series to the collector of the transistor, and a voltage generated from the rectifier. It has a comparator that compares the voltage with a reference voltage, and a variable load resistor that is connected in parallel to the load resistor and whose resistance value changes depending on the control voltage of the comparator. Amplify the output electrical signal so that it does not reach saturation due to resistor fluctuations.
次に、本発明の実施例について図面を参照して説明する
。Next, embodiments of the present invention will be described with reference to the drawings.
第１図は、本発明の一実施例を示すブロック図である。FIG. 1 is a block diagram showing one embodiment of the present invention.
第１図に示される光−電気変換前置増幅回路は、光信号
を電気信号に変換する受光素子１と、受光素子１の光順
電流によって電圧を発生する、受光素子のアノード側に
接続される抵抗器３と、抵抗器３の電圧を整流する整流
器４と、光信号から電気信号に変換された電気信号の増
幅作用を持つトランジスタ８と、受光素子１のカソード
とトランジスタ８のベースとの間に接続されたカップリ
ングコンデンサ２と、トランジスタ８のコレクタに直列
に接続された負荷抵抗器７と、整流器４から発生する電
圧と基準電圧とを比較する比較器５と、負荷抵抗器７に
並列に接続され、比較器５の制御電圧により抵抗値が変
動する可変負荷抵抗器６とで構成されている。The optical-to-electrical conversion preamplifier circuit shown in FIG. 1 includes a light receiving element 1 that converts an optical signal into an electrical signal, and an anode side of the light receiving element that generates a voltage by the optical forward current of the light receiving element 1. a resistor 3, a rectifier 4 that rectifies the voltage of the resistor 3, a transistor 8 that has the function of amplifying the electrical signal converted from the optical signal to an electrical signal, and the cathode of the light receiving element 1 and the base of the transistor 8. a coupling capacitor 2 connected between them, a load resistor 7 connected in series to the collector of the transistor 8, a comparator 5 that compares the voltage generated from the rectifier 4 with a reference voltage, and a load resistor 7 connected in between. The variable load resistor 6 is connected in parallel and has a resistance value that varies depending on the control voltage of the comparator 5.
このような構成の光−電気変換前置増幅回路は、光信号
が過大入力された場合においても、負荷の変動により出
力信号が飽和状態にならないように、増幅機能を有する
。The optical-to-electrical conversion preamplifier circuit having such a configuration has an amplification function to prevent the output signal from becoming saturated due to load fluctuations even when an excessive amount of optical signal is input.
次に、本実施例の動作について説明する。Next, the operation of this embodiment will be explained.
受光素子１には、逆電圧ａが印加されている。A reverse voltage a is applied to the light receiving element 1 .
これによって、光信号が入力されると、光信号の強弱に
よって、光順電流ｆも光信号の強さによって比例し流れ
る。これによって、受光素子１のアノード側と抵抗３の
接続点において、電圧降下りが発生する。この電圧降下
りは受光素子１の光順電流ｆの強弱によって比例して電
圧が変わる。同時に、光信号から変換された電気信号ｇ
も、ある一定のバイアス電圧すの印加されたトランジス
タ１２のベースに人力される。Accordingly, when an optical signal is input, the optical forward current f flows in proportion to the strength of the optical signal depending on the strength of the optical signal. As a result, a voltage drop occurs at the connection point between the anode side of the light receiving element 1 and the resistor 3. This voltage drop changes in proportion to the strength of the optical forward current f of the light receiving element 1. At the same time, the electrical signal g converted from the optical signal
Also, a certain bias voltage is applied to the base of the transistor 12.
ここで、光信号入力の受光入力が低い場合、つまり、ト
ランジスタ８のコレクタ出力信号として飽和領域になら
ない光信号の場合には、電圧降下りも小さくなる。整流
器４を通過した直流電圧ｉは、基準電圧ｅと比較器５に
て比較される。この結果、電圧ｄの加えられている可変
負荷抵抗６の抵抗値を太き（するように、比較器９は、
制御電圧ｊを出力する。これによって、トランジスタ８
の負荷は負荷抵抗７と可変負荷抵抗６の並列で決まるた
め、負荷抵抗７が可変負荷抵抗６よりも充分に小さい場
合には、はぼ負荷抵抗７の大きさが一定となり、トラン
ジスタ８の増幅率は一定となり、出力信号Ｃはある一定
の増幅倍された出力となる。Here, when the light reception input of the optical signal input is low, that is, when the optical signal does not fall into the saturation region as the collector output signal of the transistor 8, the voltage drop is also small. The DC voltage i that has passed through the rectifier 4 is compared with a reference voltage e in a comparator 5. As a result, the comparator 9 increases the resistance value of the variable load resistor 6 to which the voltage d is applied.
Outputs control voltage j. As a result, transistor 8
The load is determined by the parallel load resistance 7 and the variable load resistance 6, so if the load resistance 7 is sufficiently smaller than the variable load resistance 6, the size of the load resistance 7 will be constant, and the amplification of the transistor 8 will be The ratio is constant, and the output signal C becomes an output amplified by a certain constant.
次に、光信号入力が高い場合、つまり、トランジスタ８
のコレクタ出力信号が飽和領域となる場合には、電圧り
は電圧降下が太き（なり、整流器４を通過した直流電圧
ｉも高い電圧が発生する。Next, if the optical signal input is high, that is, transistor 8
When the collector output signal of is in the saturation region, the voltage drop becomes large, and the DC voltage i passing through the rectifier 4 is also high.
ここで、比較器５の入力にて基準電圧ｅと比較される。Here, it is compared with the reference voltage e at the input of the comparator 5.
比較器５は、可変負荷抵抗６の抵抗値を小さくするよう
に制御電圧ｊを出力する。これにより、トランジスタ８
の負荷抵抗値は下がり、増幅率も低くなり、出力信号Ｃ
は飽和領域から線形領域にて増幅された出力となる。Comparator 5 outputs control voltage j to reduce the resistance value of variable load resistor 6. As a result, transistor 8
The load resistance value of C decreases, the amplification factor also decreases, and the output signal C
is the output amplified from the saturation region to the linear region.
以上説明したように、本発明によれば、光入力信号の強
弱にかかわりなく、飽和することのない出力信号を得ら
れるという効果を有する。As described above, the present invention has the effect that an output signal that does not saturate can be obtained regardless of the strength of the optical input signal.
第１図は、本発明の一実施例を示すブロック図、第２図
は、従来の光−電気変換前置増幅回路の一例を示すブロ
ック図である。
１・・・・・受光素子
２・・・・・カップリングコンデンサ
３・・・・・抵抗器
４・・・・・整流器
５・・・・・比較器
６・・・・・可変負荷抵抗器
７・・・・・負荷抵抗器
８・・・・・トランジスタ
代理人 弁理士 岩 佐 義 幸
第１図FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing an example of a conventional optical-to-electrical conversion preamplifier circuit. 1... Light receiving element 2... Coupling capacitor 3... Resistor 4... Rectifier 5... Comparator 6... Variable load resistor 7... Load resistor 8... Transistor representative Patent attorney Yoshiyuki Iwasa Figure 1
Claims (2)
電気信号を生成する受光部と、 受光部の第１の電気信号を増幅して、負荷に出力電気信
号を発生する増幅部と、 受光部の第２の電気信号を直流信号に変換する変換部と
、 変換部の直流信号と予め設定されている基準信号とを比
較して、比較結果を送り出す比較部と、増幅部の負荷に
並列に接続され、比較部の比較結果に基づいて大きさを
変える可動負荷とを有し、変換部からの直流信号が基準
信号より小さいときに、可動負荷の大きさを増幅部の負
荷の大きさより大きくし、変換部からの直流信号が基準
信号より大きいときに、可動負荷の大きさを増幅部の負
荷の大きさより小さくする光−電気変換前置増幅回路。(1) A light receiving section that generates first and second electrical signals based on an input electrical signal; and an amplifying section that amplifies the first electrical signal of the light receiving section and generates an output electrical signal to a load. , a conversion section that converts the second electrical signal of the light receiving section into a DC signal, a comparison section that compares the DC signal of the conversion section with a preset reference signal and sends out the comparison result, and a load of the amplifier section. It has a movable load that is connected in parallel to the converter and whose magnitude changes based on the comparison result of the comparator. An optical-to-electrical conversion preamplifier circuit that makes the size of the movable load smaller than the load of the amplifier section when the DC signal from the conversion section is larger than the reference signal.
子の光順電流によって電圧を発生する受光素子のアノー
ド側に接続される抵抗器と、この抵抗器の電圧を整流す
る整流器と、 受光素子で光信号から変換された電気信号を増幅するト
ランジスタと、 そのトランジスタのコレクタに直列に接続される負荷抵
抗器と、 整流器から発生する電圧と基準電圧とを比較する比較器
と、 負荷抵抗器に並列に接続され、比較器の制御電圧により
抵抗値が変動する可変負荷抵抗器とを有し、 光信号が過大に入力された場合に負荷抵抗器の変動によ
り、出力電気信号が飽和状態にならないように増幅する
光−電気変換前置増幅回路。(2) a light receiving element that converts an optical signal into an electrical signal, a resistor connected to the anode side of the light receiving element that generates a voltage by the optical forward current of the light receiving element, and a rectifier that rectifies the voltage of this resistor; A transistor that amplifies the electrical signal converted from the optical signal by the photodetector, a load resistor connected in series to the collector of the transistor, a comparator that compares the voltage generated from the rectifier with a reference voltage, and a load resistor. It has a variable load resistor that is connected in parallel to the comparator and whose resistance value fluctuates depending on the control voltage of the comparator.If an excessive amount of optical signal is input, the output electrical signal will reach saturation due to fluctuations in the load resistor. An optical-to-electrical conversion preamplifier circuit that amplifies the signal so that it does not
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2289480A JPH04167605A (en) | 1990-10-26 | 1990-10-26 | Preamplifier circuit for photoelectric conversion |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2289480A JPH04167605A (en) | 1990-10-26 | 1990-10-26 | Preamplifier circuit for photoelectric conversion |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH04167605A true JPH04167605A (en) | 1992-06-15 |
Family
ID=17743823
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2289480A Pending JPH04167605A (en) | 1990-10-26 | 1990-10-26 | Preamplifier circuit for photoelectric conversion |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH04167605A (en) |
-
1990
- 1990-10-26 JP JP2289480A patent/JPH04167605A/en active Pending
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