JPH0750862B2 - Optical receiver circuit - Google Patents
Optical receiver circuitInfo
- Publication number
- JPH0750862B2 JPH0750862B2 JP61217678A JP21767886A JPH0750862B2 JP H0750862 B2 JPH0750862 B2 JP H0750862B2 JP 61217678 A JP61217678 A JP 61217678A JP 21767886 A JP21767886 A JP 21767886A JP H0750862 B2 JPH0750862 B2 JP H0750862B2
- Authority
- JP
- Japan
- Prior art keywords
- circuit
- band
- equalizing
- gain
- 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 - Lifetime
Links
Landscapes
- Optical Communication System (AREA)
- Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、光通信装置の光受信回路の構成に関し、特
に、高速のPCM光中継器の光受信回路に関する。Description: TECHNICAL FIELD The present invention relates to a configuration of an optical receiving circuit of an optical communication device, and particularly to an optical receiving circuit of a high-speed PCM optical repeater.
本発明は、受光素子と、この受光素子の出力を等化増幅
する等化増幅回路と、受光素子の出力変動に対応して等
化出力の振幅を一定にする自動利得制御回路とを備えた
光受信回路において、 上記受光素子が増倍領域に入り電流増倍率が高くなり帯
域幅が減少した場合に、上記等化増幅回路の周波数特性
の帯域補償を自動的に行うことにより、 等化波形の符号間干渉を軽減したものである。The present invention includes a light receiving element, an equalizing amplifier circuit that equalizes and amplifies the output of the light receiving element, and an automatic gain control circuit that keeps the amplitude of the equalized output constant in response to the output fluctuation of the light receiving element. In the optical receiving circuit, when the light receiving element enters the multiplication area and the current multiplication factor becomes high and the bandwidth decreases, band compensation of the frequency characteristics of the equalizing and amplifying circuit is performed automatically to obtain an equalized waveform. This reduces the intersymbol interference of.
従来の光受信回路は、受光レベルの変動に対してもその
出力振幅が一定となるよう自動利得制御回路を有してお
り、受光素子としてのアバランシェホトダイオード（AP
D）の電流増倍率と、等化増幅回路の利得とを制御し、
振幅のみ制御するのが一般的であった。The conventional optical receiver circuit has an automatic gain control circuit so that its output amplitude is constant even if the received light level fluctuates, and the avalanche photodiode (AP
The current multiplication factor of D) and the gain of the equalization amplification circuit are controlled,
It was common to control only the amplitude.
ところが、最近の情報量の増加に伴い伝送するビットレ
ートも増加し、１キガビットを超える光通信システムの
実現が必要となりつつある。このような、高速の光通信
装置の光受信回路の受光素子としてアバランシェホトダ
イオードを使用した場合には、アバランシェホトダイオ
ードの増倍領域において、その帯域が変化し受信等化波
形が劣化を生じる欠点がある。However, with the recent increase in the amount of information, the bit rate for transmission also increases, and it is becoming necessary to realize an optical communication system exceeding 1 gigabit. When an avalanche photodiode is used as the light receiving element of the optical receiving circuit of such a high-speed optical communication device, there is a drawback that the band changes in the multiplication region of the avalanche photodiode, and the reception equalized waveform deteriorates. .
すなわち、アバランシェホトダイオードの利得・帯域幅
積（Ｇ・Ｂ積）が一定であるため、アバランシェホトダ
イオードの電流増倍率Ｍの上昇に従い帯域幅が減少す
る。一方高ビットレートの光受信回路においては、等化
増幅回路が必要とする周波数帯域も広帯域であるため、
このアバランシェホトダイオードの帯域幅が等化増幅回
路の所要帯域以下になった場合に、受信等化波形に符号
間干渉を生じる。このため、符号間干渉の量が大きい場
合には、伝送器の符号誤り率に対する影響が雑音制限よ
りも支配的となり符号誤り率が劣化する。That is, since the gain-bandwidth product (GB product) of the avalanche photodiode is constant, the bandwidth decreases as the current multiplication factor M of the avalanche photodiode increases. On the other hand, in a high bit rate optical receiving circuit, the frequency band required by the equalizing and amplifying circuit is wide,
When the bandwidth of the avalanche photodiode becomes equal to or less than the required bandwidth of the equalization amplifier circuit, intersymbol interference occurs in the reception equalization waveform. Therefore, when the amount of intersymbol interference is large, the influence of the transmitter on the code error rate becomes more dominant than the noise limitation, and the code error rate deteriorates.
本発明の目的は、上記の欠点を除去することにより、等
化波形の符号間干渉を軽減できる光受信回路を提供する
ことにある。An object of the present invention is to provide an optical receiving circuit that can reduce intersymbol interference of equalized waveforms by eliminating the above drawbacks.
本発明は、入力光信号を受光する受光素子と、利得可変
手段を有する等化増幅回路と、この等化増幅回路の等化
出力に対応して上記受光素子の電流増倍率および上記等
化増幅回路の利得を自動的に制御する自動利得制御回路
とを含み光受信回路において、上記等化増幅回路内に設
けられ、外部からの制御により上記等化増幅回路の周波
数特性の帯域補償を行う帯域補償手段と、上記受光素子
のバイアス電圧の変化に対応して上記帯域補償手段を自
動的に制御する自動帯域補償制御手段とを含むことを特
徴とする。The present invention relates to a light receiving element for receiving an input optical signal, an equalizing amplifier circuit having a gain varying means, and a current multiplication factor of the light receiving element and the equalizing amplifier circuit corresponding to the equalized output of the equalizing amplifier circuit. A band that is provided in the equalizing amplifier circuit in the optical receiving circuit including an automatic gain control circuit that automatically controls the gain of the circuit and performs band compensation of the frequency characteristic of the equalizing amplifier circuit by external control. Compensation means and automatic band compensation control means for automatically controlling the band compensation means in response to changes in the bias voltage of the light receiving element are included.
等化増幅回路の帯域補償手段として、例えば、可変フィ
ルタ回路を有する前置増幅回路を設け、自動帯域補償手
段として、例えば、自動利得制御回路として、受光素子
としてのアバランシェホトダイオードにバイアス電圧を
供給する高電圧発生回路（DC・DCコンバータ）と上記前
置増幅回路の可変フィルタ回路とを接続する。For example, a preamplifier circuit having a variable filter circuit is provided as a band compensating means of the equalizing amplifier circuit, and a bias voltage is supplied to an avalanche photodiode as a light receiving element as an automatic band compensating means, for example, as an automatic gain control circuit. The high voltage generation circuit (DC / DC converter) is connected to the variable filter circuit of the preamplification circuit.
かくして、入力光信号が小さくなりアバランシェホトダ
イオードが、そのバイアス電圧が高くなりアバランシェ
増倍領域に入ると、上記可変フィルタ回路が高域特性を
強調するように制御され、等化出力の高域補償が行われ
る。Thus, when the input optical signal becomes small and the avalanche photodiode has a high bias voltage and enters the avalanche multiplication region, the variable filter circuit is controlled so as to emphasize the high frequency characteristic, and the high frequency compensation of the equalized output is performed. Done.
従って、アバランシェホトダイオードがアバランシェ増
倍領域に入りその帯域幅が減少しても、等化出力の帯域
幅は自動的に補償され、等化波形の符号間干渉を軽減す
ることが可能となる。Therefore, even if the avalanche photodiode enters the avalanche multiplication region and its bandwidth is reduced, the bandwidth of the equalized output is automatically compensated, and the intersymbol interference of the equalized waveform can be reduced.
以下、本発明の実施例について図面を参照して説明す
る。Hereinafter, 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構成図であ
る。本実施例は、入力光信号10を受光して電気信号に変
換する受光素子としてのアバランシェホトダイオード７
と、外部より制御可能な可変フィルタ回路を有し、アバ
ランシェホトダイオード７の出力を入力する前置増幅回
路２と、この前置増幅回路の出力を入力する、外部より
利得制御可能な可変利得増幅回路３と、ピーク検出回路
4aを有し、可変利得増幅回路の出力を入力し等化出力11
を出力する主増幅回路４と、ピーク検出回路4aの出力を
入力し二つの制御出力を出力し、その一つの制御出力が
可変利得増幅回路３に接続された制御回路５と、制御回
路５の他の制御出力を入力し、アバランシェホトダイオ
ード７のバイアス電圧および前置増幅回路２の可変フィ
ルタ回路の制御信号12を出力するDC・DCコンバータ６と
をふくんでいる。ここで、前置増幅回路２、可変利得増
幅回路３および主増幅回路４は等化増幅回路１を構成
し、制御回路５およびDC・DCコンバータは自動利得制御
回路を構成する。FIG. 1 is a block diagram showing an embodiment of the present invention. In this embodiment, an avalanche photodiode 7 as a light receiving element for receiving an input optical signal 10 and converting it into an electric signal is provided.
And a preamplifier circuit 2 that has a variable filter circuit that can be controlled from the outside and that inputs the output of the avalanche photodiode 7, and a variable gain amplifier circuit that inputs the output of this preamplifier circuit and that can control the gain from the outside. 3 and peak detection circuit
Equipped with 4a, the output of the variable gain amplifier circuit is input and the equalized output 11
Of the main detection circuit 4 which outputs the output of the peak detection circuit 4a and outputs two control outputs, one control output of which is connected to the variable gain amplification circuit 3 and the control circuit 5 It includes a DC / DC converter 6 which receives another control output and outputs the bias voltage of the avalanche photodiode 7 and the control signal 12 of the variable filter circuit of the preamplifier circuit 2. Here, the preamplifier circuit 2, the variable gain amplifier circuit 3, and the main amplifier circuit 4 constitute the equalizing amplifier circuit 1, and the control circuit 5 and the DC / DC converter constitute an automatic gain control circuit.
本発明の特徴は、第１図において外部より制御可能な可
変フィルタ回路を有する前置増幅回路２と、その制御信
号12を出力するDC・DCコンバータ６とを設けたことにあ
る。The feature of the present invention resides in that in FIG. 1, a preamplifier circuit 2 having a variable filter circuit which can be controlled from the outside and a DC / DC converter 6 for outputting a control signal 12 thereof are provided.
可変フィルタ回路は、前置増幅回路２の負帰還回路に設
けたコンデンサを可変容量ダイオードで構成し、これを
制御信号12により制御することにより実現できる。The variable filter circuit can be realized by configuring a capacitor provided in the negative feedback circuit of the preamplifier circuit 2 with a variable capacitance diode and controlling this with a control signal 12.
次に、本実施例の動作を第２図に示す特性図を参照して
説明する。Next, the operation of this embodiment will be described with reference to the characteristic diagram shown in FIG.
ピーク検出回路4aの出力は、制御回路５およびDC・DCコ
ンバータ６によって構成される自動利得制御回路（AGC
回路）により、アバランシェホトダイオード７のバイア
ス電圧を変化させ、その電流増倍率の制御および可変利
得増幅回路３の利得の制御を行い、等化出力11の振幅を
一定に保つとともに、アバランシェホトダイオードの増
倍領域では、前置増幅回路２の帯域補償を行う。The output of the peak detection circuit 4a is an automatic gain control circuit (AGC composed of the control circuit 5 and the DC / DC converter 6).
Circuit) to change the bias voltage of the avalanche photodiode 7 to control the current multiplication factor and the gain of the variable gain amplifier circuit 3 to keep the amplitude of the equalized output 11 constant and to multiply the avalanche photodiode. In the area, band compensation of the preamplifier circuit 2 is performed.
すなわち、受光レベルが比較的大きくアバランシェホト
ダイオード７が増倍しない非増倍領域で動作する領域で
は、等化増幅回路１の周波数特性は第２図に示すよう
に、通常用いられる５次トムソンフィルタの特性を近似
する。次に、受光レベルが低下し、可変利得増幅回路３
の利得が最大となり、アバランシェホトダイオード７が
増倍領域に達すると、前置増幅回路２の帯域補償により
第２図９に示すように、等化増幅回路１の周波数特性の
高域をアバランシェホトダイオード７の帯域劣化に対応
して補償し、アバランシェホトダイオード７の帯域劣化
による等化波形の符号間干渉の量を抑圧する。That is, in the region where the received light level is relatively high and the avalanche photodiode 7 operates in the non-multiplied region where the multiplication is not performed, the frequency characteristic of the equalization amplifier circuit 1 is as shown in FIG. Approximate the characteristics. Next, the light receiving level decreases, and the variable gain amplifier circuit 3
When the avalanche photodiode 7 reaches the multiplication region, the preamplification circuit 2 band-compensates and the avalanche photodiode 7 increases the frequency range of the equalization amplification circuit 1 as shown in FIG. Compensation is made corresponding to the band deterioration of (1) and the amount of intersymbol interference of the equalized waveform due to band deterioration of the avalanche photodiode 7 is suppressed.
第３図に前置増幅回路２の回路構成の一例を示す図を示
す。ここで、トランジスタTR1はエミッタ接地型増幅
器、トランジスタTR2は出力バッファ回路を構成してい
る。トランジスタTR1の増幅度をＧとすると、 で表される。Zc＝Rcであり、可変容量ダイオードＤの容
量をCxとするとき、Zeは となり、この（２）式により、（１）式は、 となり、 となる。Cxは、DC・DCコンバータ６よりの制御信号12に
より印加される逆バイアス電圧により変化されるため、
第２図の特性図に示すように周波数特性の高域の利得を
補償することができる。FIG. 3 shows a diagram showing an example of the circuit configuration of the preamplifier circuit 2. Here, the transistor TR 1 constitutes a grounded-emitter amplifier, and the transistor TR 2 constitutes an output buffer circuit. If the amplification of the transistor TR 1 is G, It is represented by. When Z c = R c and the capacitance of the variable capacitance diode D is C x , Z e is From this equation (2), equation (1) becomes Next to Becomes Since C x is changed by the reverse bias voltage applied by the control signal 12 from the DC / DC converter 6,
As shown in the characteristic diagram of FIG. 2, it is possible to compensate the high frequency gain of the frequency characteristic.
また、本実施例では前置増幅回路２で帯域補償を行った
が、他のブロックでも例えば、可変利得制御回路３で行
っても同様であり、等化増幅回路１全体で第２図のよう
に周波数特性を補償すればよい。Further, in the present embodiment, the band compensation is performed by the preamplification circuit 2, but the same applies to other blocks, for example, the variable gain control circuit 3, and the equalization amplification circuit 1 as a whole is as shown in FIG. It is sufficient to compensate the frequency characteristic.
以上、説明したように、本発明は、アバランシェホトダ
イオードの増倍領域での帯域劣化を等化増幅回路の周波
数特性を自動的に帯域補償を行うことにより、等化波形
の歪による符号間干渉を軽減できる効果がある。As described above, according to the present invention, the band deterioration in the multiplication region of the avalanche photodiode is automatically band-compensated for the frequency characteristic of the equalizing amplifier circuit, so that the intersymbol interference due to the distortion of the equalized waveform is prevented. There is an effect that can be reduced.
第１図は本発明の一実施例を示すブロック構成図。 第２図はこの実施例回路の周波数特性の一例を示す特性
図。 第３図は前置増幅回路の一例を示す回路図。 １……等化増幅回路、２……前置増幅回路、３……可変
利得増幅回路、４……主増幅回路、4a……ピーク検出回
路、５……制御回路、６……DC・DCコンバータ、７……
アバランシェホトダイオード（APD）、８……利得周波
数特性（APD非増倍領域）、９……利得周波数特性（APD
増倍領域）、10……入力光信号、11……等化出力、12…
…制御信号。FIG. 1 is a block diagram showing an embodiment of the present invention. FIG. 2 is a characteristic diagram showing an example of frequency characteristics of this embodiment circuit. FIG. 3 is a circuit diagram showing an example of a preamplifier circuit. 1 ... Equalization amplification circuit, 2 ... Preamplification circuit, 3 ... Variable gain amplification circuit, 4 ... Main amplification circuit, 4a ... Peak detection circuit, 5 ... Control circuit, 6 ... DC / DC Converter, 7 ...
Avalanche photodiode (APD), 8 ... Gain frequency characteristic (APD non-multiplication region), 9 ... Gain frequency characteristic (APD)
Multiplication area), 10 ... Input optical signal, 11 ... Equalized output, 12 ...
…Control signal.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｈ０４Ｂ 10/26 10/28 ─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 6 Identification code Office reference number FI technical display location H04B 10/26 10/28
Claims (1)
（７）と、利得可変手段を有する等化増幅回路（１）
と、この等化増幅回路の等化出力に対応して上記受光素
子の電流増倍率および上記等化増幅回路の利得を自動的
に制御する自動利得制御回路（５、６）とを含む光受信
回路において、 上記等化増幅回路内に設けられ、外部からの制御により
上記等化増幅回路の周波数特性の帯域補償を行う帯域補
償手段と、上記受光素子のバイアス電圧の変化に対応し
て上記帯域補償手段を自動的に制御する自動帯域補償制
御手段と を含むことを特徴とする光受信回路。1. An equalizing amplifier circuit (1) having a light receiving element (7) for receiving an input optical signal (10) and a gain varying means.
And an automatic gain control circuit (5, 6) for automatically controlling the current multiplication factor of the light receiving element and the gain of the equalizing and amplifying circuit corresponding to the equalized output of the equalizing and amplifying circuit. In the circuit, a band compensating unit is provided in the equalizing amplifier circuit, which performs band compensation of the frequency characteristic of the equalizing amplifier circuit under external control, and the band corresponding to the change in the bias voltage of the light receiving element. And an automatic band compensation control means for automatically controlling the compensation means.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61217678A JPH0750862B2 (en) | 1986-09-16 | 1986-09-16 | Optical receiver circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61217678A JPH0750862B2 (en) | 1986-09-16 | 1986-09-16 | Optical receiver circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6373723A JPS6373723A (en) | 1988-04-04 |
| JPH0750862B2 true JPH0750862B2 (en) | 1995-05-31 |
Family
ID=16708004
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP61217678A Expired - Lifetime JPH0750862B2 (en) | 1986-09-16 | 1986-09-16 | Optical receiver circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0750862B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3947865B2 (en) | 2000-03-06 | 2007-07-25 | 富士通株式会社 | Preamplifier |
| JP4315165B2 (en) * | 2006-04-28 | 2009-08-19 | 住友電気工業株式会社 | Station side device and optical receiving circuit |
| JP2011171812A (en) * | 2010-02-16 | 2011-09-01 | Yokogawa Electric Corp | Optical receiver |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61177832A (en) * | 1985-02-04 | 1986-08-09 | Nippon Telegr & Teleph Corp <Ntt> | Automatic gain controlling system of optical receiver |
-
1986
- 1986-09-16 JP JP61217678A patent/JPH0750862B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6373723A (en) | 1988-04-04 |
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