JPH02164226A - Light-receiving element protection circuit - Google Patents
Light-receiving element protection circuitInfo
- Publication number
- JPH02164226A JPH02164226A JP31847988A JP31847988A JPH02164226A JP H02164226 A JPH02164226 A JP H02164226A JP 31847988 A JP31847988 A JP 31847988A JP 31847988 A JP31847988 A JP 31847988A JP H02164226 A JPH02164226 A JP H02164226A
- Authority
- JP
- Japan
- Prior art keywords
- receiving element
- voltage
- light
- current
- 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.)
- Pending
Links
- 238000012544 monitoring process Methods 0.000 claims abstract description 32
- 230000003287 optical effect Effects 0.000 claims description 18
- 230000007423 decrease Effects 0.000 claims description 6
- 230000003321 amplification Effects 0.000 abstract description 7
- 238000003199 nucleic acid amplification method Methods 0.000 abstract description 7
- 238000010586 diagram Methods 0.000 description 12
- 238000001514 detection method Methods 0.000 description 5
- 239000003990 capacitor Substances 0.000 description 3
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
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- Emergency Protection Circuit Devices (AREA)
Abstract
Description
【発明の詳細な説明】
〔概 要〕
受光素子を備えて光信号を受信する光信号受信回路にお
いて、該受光素子を過大な光入力による過大電流から保
護する受光素子保護回路に関し、光信号受信回路におい
て受光素子を過大な光入力による過大電流から保護する
ことを目的とし、供給電源電圧と受光量とに依存して増
減する通電電流に応じた信号を出力する受光素子を備え
てなる光信号受信回路において、制御に応じて前記受光
素子に供給する電源電圧を変化させる可変電圧電源と、
該受光素子に流れる電流を監視して該電流が所定の値を
超えないように前記可変電圧電源が供給する電源電圧を
制御する電流監視手段とを備えてなるように構成する。[Detailed Description of the Invention] [Summary] This invention relates to a light-receiving element protection circuit that protects the light-receiving element from excessive current due to excessive light input in an optical signal receiving circuit that includes a light-receiving element and receives an optical signal. An optical signal that is intended to protect the light receiving element from excessive current caused by excessive light input in a circuit, and is equipped with a light receiving element that outputs a signal according to the current that increases or decreases depending on the supply voltage and the amount of light received. In the receiving circuit, a variable voltage power supply that changes the power supply voltage supplied to the light receiving element according to control;
and current monitoring means for monitoring the current flowing through the light receiving element and controlling the power supply voltage supplied by the variable voltage power supply so that the current does not exceed a predetermined value.
本発明は、受光素子を備えて光信号を受信する光信号受
信回路において、該受光素子を過大な光入力による過大
電流から保護する受光素子保護回路に関する。The present invention relates to a light-receiving element protection circuit that protects the light-receiving element from excessive current due to excessive light input in an optical signal receiving circuit that includes a light-receiving element and receives optical signals.
光伝送装置の受信装置等においては、光信号を受信する
光信号受信回路において、例えば、バイアス電圧と受光
量に応じた電流特性を有するアバランシェホトダイオー
ド（ＡＰＤ）等が受光素子として使用される。ところで
、このような受光素子に、もし、過大な光入力が与えら
れると、該受光素子に過大な電流が流れることにより、
信号エラーを生じたり、あるいは、その電流レベルによ
っては、素子破壊という事態が発生することもあり得る
。したがって、上記のような光信号受信回路においては
、受光素子を過大な光入力による過大電流から保護する
保護回路が必要になる。BACKGROUND ART In a receiving device of an optical transmission device, an avalanche photodiode (APD) or the like having current characteristics depending on a bias voltage and an amount of received light is used as a light receiving element in an optical signal receiving circuit that receives an optical signal. By the way, if an excessive light input is given to such a light receiving element, an excessive current will flow through the light receiving element, causing
A signal error may occur, or depending on the current level, element destruction may occur. Therefore, in the optical signal receiving circuit as described above, a protection circuit is required to protect the light receiving element from excessive current due to excessive optical input.
従来、光信号受信回路においては受光素子の保護自体を
目的とする回路は全く設けられていなかった。Conventionally, optical signal receiving circuits have not been provided with any circuit for the purpose of protecting the light receiving element itself.
そのため、受光素子に、過大な光入力が与えられると、
過大な電流が流れて信号エラーを生じたり、素子を破壊
したりする恐れがあるという問題があった。Therefore, if excessive light input is given to the photodetector,
There is a problem in that an excessive current flows, which may cause signal errors or destroy the device.
本発明は上記の問題点に鑑み、なされたもので、光信号
受信回路において受光素子を過大な光入力による過大電
流から保護する受光素子保護回路を提供することを目的
とするものである。The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a light-receiving element protection circuit that protects a light-receiving element from excessive current due to excessive light input in an optical signal receiving circuit.
第１図は本発明の第１の形態の基本構成を示す図である
。本図において、１は受光素子、３は可変電圧電源、４
は信号増幅手段であり、さらに、２が、本発明の第１の
形態により設けられた電流監視手段である。FIG. 1 is a diagram showing the basic configuration of a first embodiment of the present invention. In this figure, 1 is a light receiving element, 3 is a variable voltage power supply, and 4 is a light receiving element.
2 is a signal amplification means, and 2 is a current monitoring means provided according to the first aspect of the present invention.
受光素子１は、供給電源電圧と受光量とに依存して増減
する通電電流に応した信号を出力するものである。The light-receiving element 1 outputs a signal corresponding to a current that increases or decreases depending on the supply voltage and the amount of light received.
第１図の構成は、上記受光素子ｌを備えてなる光信号受
信回路であって、該受光素子ｌの出力信号のレベルを所
定のレベルに変換するために設けられた、破線で示され
る信号増幅手段４を除く構成が本発明の第１の形態の受
光素子保護回路を形成する。The configuration of FIG. 1 is an optical signal receiving circuit comprising the above-mentioned light-receiving element 1, in which a signal indicated by a broken line is provided for converting the level of the output signal of the light-receiving element 1 to a predetermined level. The configuration excluding the amplifying means 4 forms the light receiving element protection circuit of the first embodiment of the present invention.
可変電圧電源３は、前記受光素子ｌ電源電圧を供給する
ものであって、制御に応じて該受光素子１に供給する電
源電圧を変化させる。The variable voltage power supply 3 supplies the power supply voltage to the light receiving element 1, and changes the power supply voltage supplied to the light receiving element 1 according to control.
電流監視手段、２は、上記受光素子１に流れる電流を監
視して該電流が所定の値を超えないように前記可変電圧
電源３が出力する電源電圧を制御する。Current monitoring means 2 monitors the current flowing through the light receiving element 1 and controls the power supply voltage output by the variable voltage power supply 3 so that the current does not exceed a predetermined value.
第２図は本発明の第２の形態の基本構成を示す図である
。本図においても、１は受光素子、３は可変電圧電源、
４は信号増幅手段であり、これらは、上述の第１図のも
のと同様のものである。FIG. 2 is a diagram showing the basic configuration of the second embodiment of the present invention. Also in this figure, 1 is a light receiving element, 3 is a variable voltage power supply,
Reference numeral 4 denotes signal amplification means, which are similar to those shown in FIG. 1 above.
さらに、５が、本発明の第２の形態により設けられた電
圧監視手段である。Furthermore, 5 is a voltage monitoring means provided according to the second embodiment of the present invention.
第２図の構成も、上記受光素子１を備えてなる光信号受
信回路であって、破線で示される信号増幅手段４を除く
構成が本発明の第２の形態の受光素子保護回路を形成す
る。The configuration shown in FIG. 2 is also an optical signal receiving circuit including the light receiving element 1 described above, and the configuration excluding the signal amplifying means 4 indicated by the broken line forms the light receiving element protection circuit of the second embodiment of the present invention. .
電圧監視手段５は、上記受光素子１が出力する信号電圧
を監視して該信号電圧が所定の値を超えないように前記
可変電圧電源５が出力する電源電圧を制御する。The voltage monitoring means 5 monitors the signal voltage output from the light receiving element 1 and controls the power supply voltage output from the variable voltage power supply 5 so that the signal voltage does not exceed a predetermined value.
本発明の第１の形態によれば、可変電圧電源３から受光
素子１に流れる電流は、電流監視手段２によって監視さ
れ、電流監視手段２は、該電流が所定の値を超えないよ
うに前記可変電圧電源３が受光素子１に対して供給する
電源電圧を制御するので、受光素子１に上記所定の値を
超える過大な電流が流れることがなくなる。According to the first embodiment of the present invention, the current flowing from the variable voltage power supply 3 to the light receiving element 1 is monitored by the current monitoring means 2, and the current monitoring means 2 is configured to monitor the current flowing from the variable voltage power supply 3 to the light receiving element 1 so that the current does not exceed a predetermined value. Since the variable voltage power supply 3 controls the power supply voltage supplied to the light receiving element 1, an excessive current exceeding the predetermined value does not flow through the light receiving element 1.
本発明の第２の形態によれば、受光素子１が受光量に応
じて出力する信号電圧は電圧監視手段５によって監視さ
れ、該電圧監視手段５は、該信号電圧が所定の値を超え
ないように前記可変電圧電源３が受光素子ｌに対して供
給する電源電圧を制御する。受光素子ｌが出力する信号
電圧は、受光量に応じて増減すると共に、可変電圧電源
３から供給される電源電圧にも応じて増減する、該受光
素子１の通電電流に応じて出力される。すなわち、該信
号電圧を監視することにより、間接的に受光素子１の通
電電流を監視することになるので、電圧監視手段５によ
る上述の制御により、受光素子１に上記所定の値を超え
る過大な電流が流れることがなくなる。According to the second embodiment of the present invention, the signal voltage output by the light receiving element 1 according to the amount of light received is monitored by the voltage monitoring means 5, and the voltage monitoring means 5 is configured to ensure that the signal voltage does not exceed a predetermined value. The variable voltage power supply 3 controls the power supply voltage supplied to the light receiving element 1 in this manner. The signal voltage output by the light receiving element 1 increases or decreases depending on the amount of light received, and also increases or decreases depending on the power supply voltage supplied from the variable voltage power supply 3, and is output in accordance with the current flowing through the light receiving element 1. That is, by monitoring the signal voltage, the current passing through the light-receiving element 1 is indirectly monitored, so that the above-mentioned control by the voltage monitoring means 5 causes the light-receiving element 1 to receive an excessive voltage exceeding the predetermined value. Current will no longer flow.
第３図は、本発明の第１の形態の実施例の概略構成を示
すものである。FIG. 3 shows a schematic configuration of an embodiment of the first form of the present invention.
また、第４図は、本発明の第２の形態の実施例の概略構
成を示すものである。Further, FIG. 4 shows a schematic configuration of an embodiment of the second form of the present invention.
第３図および第４図において、１０は受光素子、２０は
電流監視回路、３０はＤＣ−ＤＣコンバータ、５０は電
圧監視回路であって、それぞれ、第１図および／または
第２図の受光素子１、電流監視手段２、可変電圧電源３
、および電圧監視手段５に対応する。また、第３図およ
び第４図において、４０は増幅器、４１は自動利得制御
回路であって、第１図および第２図の信号増幅手段４に
対応する。3 and 4, 10 is a light receiving element, 20 is a current monitoring circuit, 30 is a DC-DC converter, and 50 is a voltage monitoring circuit, which are the light receiving elements of FIG. 1 and/or 2, respectively. 1. Current monitoring means 2. Variable voltage power supply 3
, and corresponds to the voltage monitoring means 5. Further, in FIGS. 3 and 4, 40 is an amplifier, and 41 is an automatic gain control circuit, which corresponds to the signal amplification means 4 in FIGS. 1 and 2.
増幅器４０は、受光素子１０が出力する信号電圧を増幅
する。The amplifier 40 amplifies the signal voltage output by the light receiving element 10.
自動利得制御回路４１は、上記増幅器４ｏの出力電圧を
検出して該出力電圧が所定のレベルの範囲に収まるよう
に、該増幅器４０の増幅率を制御する他、本実施例にお
いては、受光素子１ｏに電源電圧を供給するＤＣ−ＤＣ
コンバータ３０が出力する電源電圧（バイアス電圧）を
下げるように制御する。The automatic gain control circuit 41 detects the output voltage of the amplifier 4o and controls the amplification factor of the amplifier 40 so that the output voltage falls within a predetermined level range. DC-DC supplying power supply voltage to 1o
The power supply voltage (bias voltage) output by converter 30 is controlled to be lowered.
ＤＣ−ＤＣコンバータ３０は、周知のように、外部から
与える制御（基ｉｎ）電圧に応じて出力する電圧を変化
させ得るものである。As is well known, the DC-DC converter 30 can change the output voltage according to a control (base in) voltage applied from the outside.
第５図は、第３図の電流監視回路２０の構成例を示すも
のである。FIG. 5 shows an example of the configuration of the current monitoring circuit 20 shown in FIG. 3. In FIG.
第５図において、２１は差動増幅器、２２は比較器、そ
して、２３は電流検出抵抗であり、これらが、第３図の
電流監視回路２０を構成する。In FIG. 5, 21 is a differential amplifier, 22 is a comparator, and 23 is a current detection resistor, which constitute the current monitoring circuit 20 in FIG.
電流検出抵抗２３は、ＤＣ−ＤＣコンバータ３０から受
光素子ｌＯに電源電圧（バイアス電圧）を供給する経路
に直列に挿入される一定の、電力損失を少なくすべく充
分小さい抵抗値を有するものであって、該電流検出抵抗
２３の両端の電圧は差動増幅器２１によって増幅され、
該増幅された出力が比較器２２において所定の基準電圧
と比較される。The current detection resistor 23 is inserted in series in the path for supplying the power supply voltage (bias voltage) from the DC-DC converter 30 to the light receiving element IO, and has a resistance value sufficiently small to reduce power loss. Then, the voltage across the current detection resistor 23 is amplified by the differential amplifier 21,
The amplified output is compared with a predetermined reference voltage in a comparator 22.
該基準電圧は、前述の、電流監視手段２の機能を実現す
るために定められるものであって、受光素子に流れる電
流を監視して該電流が所定の値を超えないように前記可
変電圧電源３ （ＤＣ−ＤＣコンバータ３０）が出力す
る電源電圧（バイアス電圧）を制御する。The reference voltage is determined in order to realize the function of the current monitoring means 2 described above, and is used to monitor the current flowing through the light receiving element and to prevent the current from exceeding a predetermined value. 3 (DC-DC converter 30) controls the power supply voltage (bias voltage) output.
例えば、該基準電圧は、上記電流の所定の僅に対応する
ように定めておけば、該所定の値を超える電流がＤＣ−
ＤＣコンバータ３０から受光素子１０に電源電圧（バイ
アス電圧）を供給する経路に流れたとき、すなわち、受
光素子１０を流れたときにのみ、比較器２２より有効な
信号が出力され、ＤＣ−ＤＣコンバータ３０の出力電圧
を制御コ■、例えば、出力電圧を接地レヘルにすること
ができる。For example, if the reference voltage is set to correspond to a predetermined value of the current, the current exceeding the predetermined value will be
Only when the power supply voltage (bias voltage) flows from the DC converter 30 to the light receiving element 10, that is, when it flows through the light receiving element 10, a valid signal is output from the comparator 22, and the DC-DC converter For example, the output voltage can be set to the ground level.
こうして、受光素子１０に所定の値以上の電流が流れる
始めると、直ちに上記の制御が行なわれるので、受光素
子１０に過大な電流が流れることが防止できる。In this way, as soon as a current of a predetermined value or more starts flowing through the light receiving element 10, the above control is performed, so that it is possible to prevent an excessive current from flowing through the light receiving element 10.
なお、前述のように、自動利得制御回路４１も、ＤＣ−
ＤＣコンバータ３０が出力する電源電圧（バイアス電圧
）を下げるように制御するが、該自動利得制御回路４１
の制御によって増幅率が変化する増幅器４０の出力を検
出することによる制御であるので、受光素子ＩＯに過大
な電流が流れても、これに対応して増大した受光素子１
０の信号出力の振幅は、自動利得制御を受ける増幅器４
０によって該信号出力の振幅の増大に応じた（相対的な
）減衰を受けるので、受光素子１０に流れた電流値の増
大を検出するためには適当でない。Note that, as described above, the automatic gain control circuit 41 also has a DC-
The automatic gain control circuit 41 controls to lower the power supply voltage (bias voltage) output by the DC converter 30.
Since the control is based on detecting the output of the amplifier 40 whose amplification factor changes according to the control of
The amplitude of the signal output at 0 is determined by the amplifier 4 which is subject to automatic gain control.
0, it is attenuated (relatively) according to the increase in the amplitude of the signal output, so it is not suitable for detecting an increase in the value of the current flowing through the light receiving element 10.
第６図は、第４図の電圧監視回路５０の構成例を示すも
のである。FIG. 6 shows an example of the configuration of the voltage monitoring circuit 50 shown in FIG. 4. In FIG.
第６図において、５１は差動増幅器、５２は比較器、５
３および５４は分圧用抵抗、そして、５５はコンデンサ
であり、これらが、第４図の電圧監視回路５０を構成す
る。In FIG. 6, 51 is a differential amplifier, 52 is a comparator, and 5
3 and 54 are voltage dividing resistors, and 55 is a capacitor, which constitute the voltage monitoring circuit 50 in FIG.
分圧用抵抗５３および５４ば、受光素子１０の出力信号
のレベルを取り出して所定の比に分圧するものであって
、該信号出力レベルの低下を少なくすべく、両抵抗の抵
抗値の和は充分大きいものとする。また、両抵抗の接続
点と接地レベルとの間に接続されたコンデンサ５５は、
受光素子１０の出力信号のレベルの高周波成分を吸収す
るためのものである。The voltage dividing resistors 53 and 54 take out the level of the output signal of the light receiving element 10 and divide it into a predetermined ratio, and the sum of the resistance values of both resistors is sufficient to reduce the drop in the signal output level. Let's make it big. In addition, a capacitor 55 connected between the connection point of both resistors and the ground level is
This is for absorbing high frequency components of the level of the output signal of the light receiving element 10.
上記の抵抗５３の両端の電圧は、差動増幅器５１によっ
て増幅され、該増幅された出力が比較器５２において所
定の基準電圧と比較される。The voltage across the resistor 53 is amplified by a differential amplifier 51, and the amplified output is compared with a predetermined reference voltage in a comparator 52.
該基準電圧は、前述の、電圧監視手段５の機能を実現す
るために定められるものであって、受光素子が出力する
信号電圧を監視して該信号電圧が所定の値を超えないよ
うに前記可変電圧電源３（ＤＣ−ＤＣコンバータ３０）
が出力するバイアス電圧を制御する。The reference voltage is determined in order to realize the function of the voltage monitoring means 5 described above, and is used to monitor the signal voltage output from the light receiving element and to prevent the signal voltage from exceeding a predetermined value. Variable voltage power supply 3 (DC-DC converter 30)
Controls the bias voltage output by
例えば、該基準電圧は、上記信号電圧の所定の値に対応
するように定めておけば、該所定の値を超える信号電圧
が受光素子１０の出力として検出されたとき、すなわち
、受光素子ＩＯに該所定の値を超える信号電圧に対応す
る電流が流れたときにのみ、比較器５２より有効な信号
が出力され、ＤＣ−ＤＣコンバータ３０の出力電圧を制
御、例えば、出力電圧を接地レベルにすることができる
。For example, if the reference voltage is set to correspond to a predetermined value of the signal voltage, when a signal voltage exceeding the predetermined value is detected as the output of the light receiving element 10, that is, the reference voltage is set to correspond to the predetermined value of the signal voltage. Only when a current corresponding to a signal voltage exceeding the predetermined value flows, a valid signal is output from the comparator 52, and the output voltage of the DC-DC converter 30 is controlled, for example, the output voltage is set to the ground level. be able to.
こうして、受光素子１０に所定の値以上の電流が流れる
始めると、直ちに上記の制？Ｂが行なわれるので、受光
素子１０に過大な電流が流れることが防止できる。In this way, as soon as a current exceeding a predetermined value begins to flow through the light-receiving element 10, the above-mentioned restriction is applied. Since B is performed, excessive current can be prevented from flowing into the light receiving element 10.
なお、第６図に括弧付きで示される、■、検出回路とは
、ＤＣ−ＤＣコンバーク３０の出力電圧、すなわち、バ
イアス電圧を検出して、受光素子１０を損傷させること
のないように該バイアス電圧が所定の値以下になるよう
に、ＤＣ−ＤＣコンバータ３０を制’＜ＴＩするバイア
ス電圧検出回路であるが、これは、受光素子１０におけ
る、受光量の増大に対しては対応し得ないので、上述の
ような本発明による受光素子保護回路が必要である。Note that the detection circuit shown in parentheses in FIG. This is a bias voltage detection circuit that controls the DC-DC converter 30 so that the voltage is below a predetermined value, but this cannot cope with an increase in the amount of light received by the light receiving element 10. Therefore, the light receiving element protection circuit according to the present invention as described above is necessary.
本発明によれば、光信号受信回路において受光素子を過
大な光入力による過大電流から保護することができる。According to the present invention, a light receiving element in an optical signal receiving circuit can be protected from excessive current due to excessive optical input.
第１図は本発明の第１の形態の基本構成図、第２図は本
発明の第２の形態の基本構成図、第３図は本発明の第１
の形態の実施例の概略構成図、
第４図は本発明の第２の形態の実施例の概略構成図、
第５図は、第３図の電流監視回路の構成例を示す図、そ
して
第６図は、第４図の電流監視回路の構成例を示す図であ
る。
〔符号の説明〕
１・・・受光素子、 ２・・・電流監視手段、３・
・・可変電圧電源、 ４・・・信号増幅手段、５・・・
電圧監視手段、 １０・・・受光素子、２０・・・電
流監視回路、２１・・・差動増幅器、２２・・・比較器
、 ２３・・・電流ヰ★出抵抗、３０・・・ＤＣ−
ＤＣコンバータ、
４０・・・増幅器、 ４１・・・自動利得制御回路
、５０・・・電圧監視回路、５１・・・差動増幅器、５
２・・・比較器、 ５３．５４・・・分圧用抵抗、
５５・・・コンデンサ。
本発明のＮ１の形態の基本構成図
本発明の第１の形態の実施例概略ＩＩ戒図＄３回
本発明の第２の形態の実施例概略構戒図第４Ｇ
本発明の第２の形態の基本構成図
第
回
受光素子へ
第３図の電流監視回路の構成例を示す９第５回
第
回FIG. 1 is a basic configuration diagram of the first embodiment of the present invention, FIG. 2 is a basic configuration diagram of the second embodiment of the invention, and FIG. 3 is a basic configuration diagram of the first embodiment of the invention.
FIG. 4 is a schematic diagram of an embodiment of the second embodiment of the present invention; FIG. 5 is a diagram showing an example of the configuration of the current monitoring circuit of FIG. 3; FIG. 6 is a diagram showing an example of the configuration of the current monitoring circuit shown in FIG. 4. [Explanation of symbols] 1... Light receiving element, 2... Current monitoring means, 3...
...Variable voltage power supply, 4...Signal amplification means, 5...
Voltage monitoring means, 10... Light receiving element, 20... Current monitoring circuit, 21... Differential amplifier, 22... Comparator, 23... Current output resistance, 30... DC-
DC converter, 40... Amplifier, 41... Automatic gain control circuit, 50... Voltage monitoring circuit, 51... Differential amplifier, 5
2... Comparator, 53.54... Voltage dividing resistor,
55... Capacitor. Basic configuration diagram of form N1 of the present invention Embodiment of the first form of the present invention Outline II Precept diagram $3 times Example of the second form of the present invention Schematic structure diagram No. 4G Second form of the present invention Basic configuration diagram No. 9 Showing an example of the configuration of the current monitoring circuit shown in Figure 3 to the light-receiving element No. 9
Claims (1)
流に応じた信号を出力する受光素子（１）を備えてなる
光信号受信回路において、 制御に応じて前記受光素子（１）に供給する電源電圧を
変化させる可変電圧電源（３）と、該受光素子（１）に
流れる電流を監視して該電流が所定の値を超えないよう
に前記可変電圧電源（３）が供給する電源電圧を制御す
る電流監視手段（２）とを備えてなることを特徴とする
受光素子保護回路。 ２、供給電源電圧と受光量とに依存して増減する通電電
流に応じた信号を出力する受光素子（１）を備えてなる
光信号受信回路において、 制御に応じて前記受光素子（１）に供給する電源電圧を
変化させる可変電圧電源（３）と、該受光素子（１）が
出力する信号電圧を直接監視して該信号電圧が所定の値
を超えないように前記可変電圧電源（３）が供給する電
源電圧を制御する電圧監視手段（５）とを備えてなるこ
とを特徴とする受光素子保護回路。[Scope of Claims] 1. An optical signal receiving circuit comprising a light receiving element (1) that outputs a signal according to a energizing current that increases or decreases depending on the supply power voltage and the amount of received light, comprising: A variable voltage power supply (3) that changes the power supply voltage supplied to the light receiving element (1), and a variable voltage power supply (3) that monitors the current flowing through the light receiving element (1) so that the current does not exceed a predetermined value. 3) A current monitoring means (2) for controlling the power supply voltage supplied by the light receiving element protection circuit. 2. In an optical signal receiving circuit comprising a light-receiving element (1) that outputs a signal according to a current that increases or decreases depending on the supply voltage and the amount of light received, the light-receiving element (1) outputs a signal according to a control. A variable voltage power source (3) that changes the power supply voltage to be supplied, and a variable voltage power source (3) that directly monitors the signal voltage output by the light receiving element (1) so that the signal voltage does not exceed a predetermined value. 1. A light receiving element protection circuit comprising: voltage monitoring means (5) for controlling a power supply voltage supplied by the light receiving element protection circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31847988A JPH02164226A (en) | 1988-12-19 | 1988-12-19 | Light-receiving element protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31847988A JPH02164226A (en) | 1988-12-19 | 1988-12-19 | Light-receiving element protection circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH02164226A true JPH02164226A (en) | 1990-06-25 |
Family
ID=18099571
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP31847988A Pending JPH02164226A (en) | 1988-12-19 | 1988-12-19 | Light-receiving element protection circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH02164226A (en) |
-
1988
- 1988-12-19 JP JP31847988A patent/JPH02164226A/en active Pending
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