JPH02149139A - Optical receiver - Google Patents
Optical receiverInfo
- Publication number
- JPH02149139A JPH02149139A JP63303067A JP30306788A JPH02149139A JP H02149139 A JPH02149139 A JP H02149139A JP 63303067 A JP63303067 A JP 63303067A JP 30306788 A JP30306788 A JP 30306788A JP H02149139 A JPH02149139 A JP H02149139A
- Authority
- JP
- Japan
- Prior art keywords
- voltage
- apd
- output
- optical
- multiplication factor
- 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
- 230000003287 optical effect Effects 0.000 title claims abstract description 40
- 238000001514 detection method Methods 0.000 claims abstract description 16
- 230000006866 deterioration Effects 0.000 abstract description 6
- 230000002542 deteriorative effect Effects 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 1
Landscapes
- Optical Communication System (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は光通信装置に関し、特にＡＰＤ （アバランシ
ェフォトダイオード）を受光素子としてアナログ変調さ
れた光信号を受信する光受信装置に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical communication device, and more particularly to an optical receiving device that receives an analog modulated optical signal using an APD (avalanche photodiode) as a light receiving element.
一般に、ＡＰＤを受光素子とする光受信装置では、ＡＰ
ＤＯ増倍率によって信号対雑音比（ＳＮ比）が変化し、
ＳＮ比を最大にする最適な増倍率が存在する。一方、Ｓ
Ｎ比が最大となる増倍率は光受信電力によって変化し、
ＳＮ比を最大にするＡＰＤの最適増倍率Ｍ ６ ｐｔ、
は、入力光電力Ｐ、−に対して次式で与えられるため、
入力光電力の増加に対してＭを小さくする必要がある。Generally, in an optical receiving device that uses an APD as a light receiving element, the AP
The signal-to-noise ratio (SN ratio) changes depending on the DO multiplication factor,
There is an optimal multiplication factor that maximizes the signal-to-noise ratio. On the other hand, S
The multiplication factor at which the N ratio is maximum varies depending on the optical reception power,
The optimal multiplication factor M 6 pt of APD that maximizes the SN ratio,
is given by the following equation for the input optical power P,-, so
It is necessary to reduce M as the input optical power increases.
Ｍ 、、、 −Ｍ、 Ｐ 、 −１／！＋翼ここで、Ｍ
ｏ ：ＡＰＤ及び増幅回路によって決まる定数
Ｘ ：ＡＰＤの過剰増倍雑音指数
このため、従来のこの種の光受信装置は、第２図に示す
ように構成されている。即ち、図において、ＡＰＤから
なる受光素子１へ入力された光信号はここで電気信号に
変換され、増幅回路２で所要レベルまで増幅された後、
出力信号として出力される。ピーク検出回路３は増幅回
路２の出力信号のピーク値電圧を検出し、差動増幅回路
４により基準電圧５と比較され、差に比例した電圧が増
幅回路２に加えられ、出力信号が一定レベルとなるよう
に増幅回路２の利得が制御される。M,,, -M, P, -1/! + Tsubasa here, M
o: Constant determined by APD and amplifier circuit X: Excess multiplication noise figure of APD Therefore, a conventional optical receiver of this type is configured as shown in FIG. That is, in the figure, an optical signal input to a light receiving element 1 consisting of an APD is converted into an electrical signal, and after being amplified to a required level by an amplifier circuit 2,
Output as an output signal. The peak detection circuit 3 detects the peak value voltage of the output signal of the amplifier circuit 2, which is compared with the reference voltage 5 by the differential amplifier circuit 4, and a voltage proportional to the difference is applied to the amplifier circuit 2, so that the output signal is at a constant level. The gain of the amplifier circuit 2 is controlled so that .
また、同時にピーク検出回路３で検出されたピーク値電
圧を差動増幅器８において基準電圧７と比較し、差に比
例した電圧をバイアス電圧発生回路９に加えられ、前記
受光素子１の増倍率を制御する。At the same time, the peak value voltage detected by the peak detection circuit 3 is compared with the reference voltage 7 in the differential amplifier 8, and a voltage proportional to the difference is applied to the bias voltage generation circuit 9 to determine the multiplication factor of the light receiving element 1. Control.
ここで、入力光電力の増加に対してはＭを小さくし、減
少に対してはＭを大きくすることで、ＳＮ比の劣化を抑
えると共に、一定の出力信号レベルを得ている。Here, by decreasing M in response to an increase in input optical power and increasing M in response to a decrease, deterioration of the SN ratio is suppressed and a constant output signal level is obtained.
上述した従来の光受信装置は、入力光信号がアナログ光
信号の場合には、入力光電力が一定でも変調度が変化し
たときに出力信号レベルが一定となるように増倍率を変
化制御する。このため、変調度が変化する光信号に対し
ては、該入力光電力に対して最適の増倍率に設定するこ
とができなくなり、出力信号のＳＮ比が劣化するという
問題がある。In the conventional optical receiver described above, when the input optical signal is an analog optical signal, the multiplication factor is controlled to change so that the output signal level becomes constant when the modulation degree changes even if the input optical power is constant. Therefore, for an optical signal whose modulation degree changes, it is no longer possible to set the optimum multiplication factor for the input optical power, resulting in a problem that the S/N ratio of the output signal deteriorates.
本発明は変調度が変化する光信号に対しても出力信号の
ＳＮ比の劣化を抑えることができる光受信装置を提供す
ることを目的とする。SUMMARY OF THE INVENTION An object of the present invention is to provide an optical receiver capable of suppressing deterioration of the S/N ratio of an output signal even for an optical signal whose modulation degree changes.
〔課題を解決するたφの手段］
本発明の光受信装置は、出力信号のピーク値を検出する
ピーク検出回路の出力電圧を基準電圧と比較して増幅器
の利得を制御する電気的ＡＧＣ（自動利得制御）ループ
と、受光素子としてのＡＰＤの出力電流の平均値に比例
した電圧を発生する検出回路の出力電圧を基準電圧と比
較してＡＰＤの増倍率を制御する光学的ＡＧＣループと
を備えている。[Means for solving the problem] The optical receiving device of the present invention uses an electric AGC (automatic AGC) that controls the gain of an amplifier by comparing the output voltage of a peak detection circuit that detects the peak value of an output signal with a reference voltage. and an optical AGC loop that controls the multiplication factor of the APD by comparing the output voltage of a detection circuit that generates a voltage proportional to the average value of the output current of the APD as a light receiving element with a reference voltage. ing.
上述した構成では、ＡＰＤの出力電流の平均値に比例し
た電圧に基づいてＡＰＤのバイアス電圧を制御してその
増倍率を制御用シ、変調度の変化に対しても増倍率が変
化されることはなく、人力光信号のＳＮ比の劣化を防止
するのに好適な増倍率を維持できる。In the above configuration, the bias voltage of the APD is controlled based on a voltage proportional to the average value of the output current of the APD to control the multiplication factor, and the multiplication factor is also changed in response to a change in the modulation degree. Therefore, it is possible to maintain a multiplication factor suitable for preventing deterioration of the S/N ratio of the human-powered optical signal.
次に、本発明を図面を参照して説明する。 Next, the present invention will be explained with reference to the drawings.
第１図は本発明による光受信装置の一実施例のブロック
構成図である。図において、ＡＰＤからなる受光素子１
へ入力された光信号はここで電気信号に変換され、増幅
回路２で所要レベルまで増幅された後、出力信号として
出力される。ピーク検出回路３は増幅回路２の出力信号
のピーク値電圧を検出し、差動増幅回路４により基準電
圧５と比較され、差に比例した電圧が増幅回路２に加え
られ、出力信号が一定レベルとなるように増幅回路２の
利得が制御される。即ち、電気的ＡＧＣループが構成さ
れる。FIG. 1 is a block diagram of an embodiment of an optical receiver according to the present invention. In the figure, a light receiving element 1 consisting of an APD
The input optical signal is converted into an electrical signal here, and after being amplified to a required level by the amplifier circuit 2, it is output as an output signal. The peak detection circuit 3 detects the peak value voltage of the output signal of the amplifier circuit 2, which is compared with the reference voltage 5 by the differential amplifier circuit 4, and a voltage proportional to the difference is applied to the amplifier circuit 2, so that the output signal is at a constant level. The gain of the amplifier circuit 2 is controlled so that . That is, an electrical AGC loop is constructed.
一方、検出回路６は受光素子１の出力電流を検出してそ
の平均値を求め、この平均値に比例した電圧を発生する
。そして、この平均比例電圧を差動増幅器８において基
準電圧７と比較し、差に比例した電圧をバイアス電圧発
生回路９に加える。On the other hand, the detection circuit 6 detects the output current of the light receiving element 1, calculates its average value, and generates a voltage proportional to this average value. Then, this average proportional voltage is compared with a reference voltage 7 in a differential amplifier 8, and a voltage proportional to the difference is applied to a bias voltage generation circuit 9.
このバイアス電圧発生回路９は、入力された電圧を電圧
変換して前記前記受光素子ｌのバイアス電圧として印加
し、前記検出回路６の出力電圧が一定となるように受光
素子１の増倍率Ｍを制御する。This bias voltage generation circuit 9 converts the input voltage into a voltage and applies it as a bias voltage to the light receiving element 1, and adjusts the multiplication factor M of the light receiving element 1 so that the output voltage of the detection circuit 6 is constant. Control.
即ち、光学的ＡＧＣループが構成される。That is, an optical AGC loop is constructed.
したがって、この構成では、入力光電力の平均値に対し
てＡＰＩ）の増倍率Ｍの制御を行うことになるため、入
力光信号の変調度の変化に対してはＡＰＤＯ増倍率増倍
率化されることはない。これにより、光受信電力に対し
て好適な増倍率に設定でき、ＳＮ比の劣化を防止する。Therefore, in this configuration, since the multiplication factor M of API is controlled with respect to the average value of the input optical power, the APDO multiplication factor is changed in response to a change in the modulation degree of the input optical signal. Never. Thereby, a suitable multiplication factor can be set for the optical reception power, and deterioration of the SN ratio can be prevented.
なお、変調度の変化による出力信号レベルの変化は、ピ
ーク検出回路３．差動増幅回路４．基準電圧５からなる
電気的ＡＧＣループにより抑制できる。Note that changes in the output signal level due to changes in the modulation degree are detected by the peak detection circuit 3. Differential amplifier circuit 4. This can be suppressed by an electrical AGC loop consisting of a reference voltage 5.
以上説明したように本発明は、受光素子としてのＡＰＤ
の出力電流の平均値に比例した電圧を発生する検出回路
の出力電圧を基準電圧と比較してＡＰＤの増倍率を制御
する光学的ＡＧＣループを備えているので、出力信号を
一定の出力レベルに維持できるのはもとより、変調度の
変化に対してもＡＰＤの増倍率が変化されることはなく
、変調度が変化される入力光信号に対しても出力信号の
ＳＮ比の劣化を抑えることができる効果がある。As explained above, the present invention provides an APD as a light receiving element.
It is equipped with an optical AGC loop that controls the multiplication factor of the APD by comparing the output voltage of the detection circuit, which generates a voltage proportional to the average value of the output current of the detector, with a reference voltage, so the output signal can be kept at a constant output level. Not only can it be maintained, but the multiplication factor of the APD does not change even when the modulation degree changes, and the deterioration of the S/N ratio of the output signal can be suppressed even for input optical signals whose modulation degree changes. There is an effect that can be achieved.
第１図は本発明による光受信装置の一実施例のブロック
構成図、第２図は従来の光受信装置のブロック構成図で
ある。
ｌ・・・受光素子（ＡＰＤ）、２・・・増幅器、３・・
・ピーク検出回路、４・・・差動増幅回路、５・・・基
準電圧、６・・・検出回路、７・・・基準電圧、８・・
・差動増幅回路、９・・・バイアス電圧発生回路。
８ｉ會力漕係回路FIG. 1 is a block diagram of an embodiment of an optical receiver according to the present invention, and FIG. 2 is a block diagram of a conventional optical receiver. l...Photodetector (APD), 2...Amplifier, 3...
・Peak detection circuit, 4...Differential amplifier circuit, 5...Reference voltage, 6...Detection circuit, 7...Reference voltage, 8...
- Differential amplifier circuit, 9...bias voltage generation circuit. 8i power rowing circuit
Claims (1)
ナログ光変調信号を受信する光受信装置において、出力
信号のピーク値を検出するピーク検出回路の出力電圧を
基準電圧と比較して増幅器の利得を制御する電気的自動
利得ループと、前記受光素子の出力電流の平均値に比例
した電圧を発生する検出回路の出力電圧を基準電圧と比
較して前記受光素子の増倍率を制御する光学的自動利得
制御ループとを備えたことを特徴とする光受信装置。1. In an optical receiver that receives an analog optical modulation signal using an avalanche photodiode as a light receiving element, an electrical circuit that controls the gain of the amplifier by comparing the output voltage of a peak detection circuit that detects the peak value of the output signal with a reference voltage. an automatic gain loop; and an automatic optical gain control loop that controls the multiplication factor of the light receiving element by comparing the output voltage of a detection circuit that generates a voltage proportional to the average value of the output current of the light receiving element with a reference voltage. An optical receiving device comprising:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63303067A JPH02149139A (en) | 1988-11-30 | 1988-11-30 | Optical receiver |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63303067A JPH02149139A (en) | 1988-11-30 | 1988-11-30 | Optical receiver |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH02149139A true JPH02149139A (en) | 1990-06-07 |
Family
ID=17916502
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63303067A Pending JPH02149139A (en) | 1988-11-30 | 1988-11-30 | Optical receiver |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH02149139A (en) |
-
1988
- 1988-11-30 JP JP63303067A patent/JPH02149139A/en active Pending
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