JPH0614647B2 - Optical receiver circuit - Google Patents
Optical receiver circuitInfo
- Publication number
- JPH0614647B2 JPH0614647B2 JP60187296A JP18729685A JPH0614647B2 JP H0614647 B2 JPH0614647 B2 JP H0614647B2 JP 60187296 A JP60187296 A JP 60187296A JP 18729685 A JP18729685 A JP 18729685A JP H0614647 B2 JPH0614647 B2 JP H0614647B2
- Authority
- JP
- Japan
- Prior art keywords
- output
- phase
- circuit
- amplifier
- main amplifier
- 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 - Fee Related
Links
- 230000003287 optical effect Effects 0.000 title claims description 19
- 238000001514 detection method Methods 0.000 description 9
- 238000010586 diagram Methods 0.000 description 5
- 239000003990 capacitor Substances 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000000903 blocking effect Effects 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
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- Electronic Switches (AREA)
- Amplifiers (AREA)
- Dc Digital Transmission (AREA)
- Optical Communication System (AREA)
Description
【発明の詳細な説明】 ［産業上の利用分野］ 本発明は交流結合形の光受信回路に係り、特に符合形式
によらず安定した識別・再生を行なうことができる光受
信回路に関する。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC coupling type optical receiving circuit, and more particularly to an optical receiving circuit capable of performing stable identification / reproduction regardless of the code format.
［従来の技術］ 従来、10Ｍｂ／ｓ以上の高速のディジタル伝送には、第
３図に示すような光受信回路が知られており、この光受
信回路においては平均デューティ比が50％となる符号形
式が用いられることが多い。このような符合にしては、
第４図に示すＣＭＩ（Code Mark Inversion），ＤＭＩ
（Differrential Mark Inversion）符号などがある。[Prior Art] Conventionally, an optical receiving circuit as shown in FIG. 3 is known for high-speed digital transmission of 10 Mb / s or more, and in this optical receiving circuit, a code having an average duty ratio of 50% is used. Format is often used. With such a sign,
CMI (Code Mark Inversion) and DMI shown in FIG.
(Differrential Mark Inversion) code etc.
光受信回路は、基本的には、受光素子１とプリアンプ２
とメインアンプ３と比較回路４とからなり、プリアンプ
２とメインアンプ３との間には直流成分を遮断するコン
デンサ５が設けられると共に、メインアンプ３にはその
出力の低周波成分を負帰還させるＣ・Ｒからなる負帰還
ループが形成されている。なお、Ｒ１＋Ｒ２とＲ３の抵
抗値は等しく選定されている。The light receiving circuit basically comprises a light receiving element 1 and a preamplifier 2
And a main amplifier 3 and a comparison circuit 4, a capacitor 5 for blocking a direct current component is provided between the preamplifier 2 and the main amplifier 3, and the low frequency component of its output is negatively fed back to the main amplifier 3. A negative feedback loop composed of C and R is formed. The resistance values of R 1 + R 2 and R 3 are selected to be equal.
この光受信回路における帰還方式は、メインアンプ３の
同相・逆相の２相出力の低周波成分のみを帰還するの
で、メインアンプ３の同相・逆相出力の平均レベルを等
しくするように働く。したがって、平均デューティ比が
50％の信号入力があるときは、第５図（ａ）のようにメ
インアンプ３の同相・逆相の平均値は等しくなり、同図
（ｂ）に示すように比較回路４からはパルス幅の歪が小
さくデューティ比50％のディジタル信号が得られる。ま
た、こうした低周波帰還によりメインアンプ３の差動入
力端子間のオフセット電圧をキャンセルできる利点もあ
る。この光受信回路では、例えば64Ｍｂ／ｓのディジタ
ル伝送において、パルス幅の歪を2ns以下に保つことは
容易である。Since the feedback system in this optical receiving circuit feeds back only the low-frequency components of the in-phase and anti-phase two-phase outputs of the main amplifier 3, it works so as to make the average levels of the in-phase and anti-phase outputs of the main amplifier 3 equal. Therefore, the average duty ratio is
When 50% of the signal is input, the average values of the in-phase and anti-phase of the main amplifier 3 become equal as shown in FIG. 5 (a), and the pulse width from the comparator circuit 4 becomes as shown in FIG. 5 (b). A digital signal with a small duty ratio of 50% can be obtained. There is also an advantage that the offset voltage between the differential input terminals of the main amplifier 3 can be canceled by such low frequency feedback. In this optical receiving circuit, it is easy to maintain the pulse width distortion at 2 ns or less in, for example, 64 Mb / s digital transmission.
［発明が解決しようとする問題点］ ところが、上記の低周波を帰還する方式の光受信回路で
は、メインアンプ３の２相出力の平均値を等しくするよ
うに働くので、デューティ比が50％以外の符号方式で用
いると、パルス幅が大きく歪んでしまう問題がある。第
５図（ｃ）には平均デューティ比30％の信号入力のとき
のメインアンプ３の同相・逆相出力を、同図（ｂ）には
そのときの比較回路４の出力を示す。[Problems to be Solved by the Invention] However, in the above-described optical receiver circuit that feeds back the low frequency, the duty ratios other than 50% work because they make the average values of the two-phase outputs of the main amplifier 3 equal. When used in the coding method of 1, there is a problem that the pulse width is greatly distorted. FIG. 5 (c) shows the in-phase and anti-phase outputs of the main amplifier 3 when a signal having an average duty ratio of 30% is input, and FIG. 5 (b) shows the output of the comparison circuit 4 at that time.
［発明の目的］ 本発明は以上の従来技術の問題点を解消すべく創案され
たものであり、本発明の目的は入力信号のデューティ比
によることなく、パルス幅の歪が少なく安定した識別・
再生を行なうことができる光受信回路を提供することに
ある。[Object of the Invention] The present invention was devised to solve the above-mentioned problems of the prior art, and the object of the present invention is not to depend on the duty ratio of the input signal, but stable identification with less distortion of the pulse width.
It is to provide an optical receiving circuit capable of reproducing.
［発明の概要］ 本発明の要旨は、光信号を電気信号に変換する受光素子
と、受光素子の出力を増幅する増幅器と、増幅器と交流
結合されその交流出力を増幅して180゜位相の異なる２相
出力を出力する差動増幅器と、差動増幅器の２相出力を
比較してディジタル信号を出力する比較回路とを備え、
上記差動増幅器にその２相出力のハイレベルを一致させ
るべく２相出力のハイレベル電圧を各差動入力端に負帰
還する帰還回路を設けたことにある。[Summary of the Invention] The gist of the present invention is to provide a light receiving element that converts an optical signal into an electric signal, an amplifier that amplifies the output of the light receiving element, and an AC output that is AC-coupled with the amplifier and amplifies the AC output so that the phase difference is 180 °. A differential amplifier that outputs a two-phase output and a comparison circuit that compares the two-phase outputs of the differential amplifier and outputs a digital signal,
The differential amplifier is provided with a feedback circuit for negatively feeding back the high-level voltage of the two-phase output to each differential input terminal in order to match the high level of the two-phase output.
［実施例］ 以下に本発明の実施例を添付図面に従って詳述する。Embodiments Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
第１図に示す如く、光受信回路は、入力される光信号を
電気信号に変換する受光素子１と、受光素子１の出力を
増幅する増幅器としてのプリアンプ２と、プリアンプ２
にコンデンサ５を介して交流結合されプリアンプ２の交
流出力を増幅して位相の180゜異なる２相出力を出力する
差動増幅器としてのメインアンプ３と、メインアンプ３
の２相出力を比較してディジタル信号を出力する比較回
路４と、メインアンプ３の２相出力をそれぞれ差動入力
端に負帰還する積分回路で構成された帰還ループとを有
する。更に本回路では上記構成に鎖線Ａで示す回路が付
加されている。即ち、メインアンプ３の帰還ループ入力
側にはハイレベル検出回路６，７がそれぞれ挿設される
と共に、メインアンプ３の利得調整端子にはメインアン
プ３の出力振幅を一定に保つためのＡＧＣ回路が接続さ
れている。ＡＧＣ回路は、メインアンプ３の出力のロー
レベルを検出するローレベル検出回路８と、ローレベル
検出回路８が出力するローレベルの信号とハイレベル検
出回路７が出力するハイレベルの信号との電圧差に比例
する電圧を出力する差動アンプ９とからなる。As shown in FIG. 1, the optical receiving circuit includes a light receiving element 1 for converting an input optical signal into an electric signal, a preamplifier 2 as an amplifier for amplifying an output of the light receiving element 1, and a preamplifier 2
A main amplifier 3 as a differential amplifier that is AC-coupled via a capacitor 5 to amplify the AC output of the preamplifier 2 and outputs a two-phase output having a phase difference of 180 °;
Of the main amplifier 3 and a feedback loop composed of an integrating circuit for negatively feeding back the two-phase outputs of the main amplifier 3 to the differential input terminals. Further, in this circuit, a circuit indicated by a chain line A is added to the above configuration. That is, the high level detection circuits 6 and 7 are respectively inserted on the feedback loop input side of the main amplifier 3, and the AGC circuit for keeping the output amplitude of the main amplifier 3 constant at the gain adjustment terminal of the main amplifier 3. Are connected. The AGC circuit includes a low level detection circuit 8 for detecting a low level of the output of the main amplifier 3, a voltage of a low level signal output by the low level detection circuit 8 and a high level signal output by the high level detection circuit 7. The differential amplifier 9 outputs a voltage proportional to the difference.
なお、ハイレベル検出回路６，７としては、第６図に示
すように、例えば特開昭５７−１８１２３６号公報にピ
ーク検波器として示されている一般的によく知られた回
路を用いればよい。As the high level detection circuits 6 and 7, as shown in FIG. 6, for example, a generally well-known circuit shown as a peak detector in JP-A-57-181236 may be used. .
上記のように構成されているので、本回路のメインアン
プ３には帰還ループによりメインアンプ３の出力のハイ
レベルに比例する電圧が帰還される。この結果、メイン
アンプ３の同相・逆相出力のハイレベルが一致するよう
に制御される。With the above configuration, the voltage proportional to the high level of the output of the main amplifier 3 is fed back to the main amplifier 3 of this circuit by the feedback loop. As a result, the in-phase and anti-phase outputs of the main amplifier 3 are controlled so that the high levels thereof match.
同相・逆相成分の振幅は等しいので、同相・逆相のハイ
レベルだけでなくローレベルも等しく設定される。この
ため、比較回路４のしきい値は信号の中心に一致するこ
ととなり、平均デューティ比によらずに、歪のないパル
スが得られることになる。第２図（ａ）は平均デューテ
ィ比50％の信号入力のときメインアンプ３の２相出力
を、同図（ｂ）はそのときの比較回路４の出力を示す。
また第２図（ｃ）は平均デューティ比30％の信号入力の
ときのメインアンプ３の２相出力を、同図（ｄ）はその
ときの比較回路４の出力を示すもので、パルス幅の歪が
ない。Since the amplitudes of the in-phase and anti-phase components are the same, not only the high level of the in-phase and anti-phase components but also the low level are set to the same level. Therefore, the threshold value of the comparison circuit 4 coincides with the center of the signal, and a pulse without distortion is obtained regardless of the average duty ratio. 2A shows the two-phase output of the main amplifier 3 when a signal input with an average duty ratio of 50%, and FIG. 2B shows the output of the comparison circuit 4 at that time.
Further, FIG. 2 (c) shows the two-phase output of the main amplifier 3 when a signal having an average duty ratio of 30% is input, and FIG. 2 (d) shows the output of the comparison circuit 4 at that time. There is no distortion.
またＡＧＣ回路によりメインアンプ３の出力振幅が一定
に保たれるので、メインアンプ３出力にパルス幅歪が発
生しない。ＡＧＣ回路がない場合には、入力レベルが大
きいとき、メインアンプ３の出力の段階でパルス幅に歪
が生じ、ハイレベルの帰還が無意味になっしまう。な
お、ハイレベル検出回路６，７のホールド時間は長くと
ってあるので、その時間内の信号パターンの変化の影響
を受けず、デューティ比によることなく本方式を適用す
ることができる。Moreover, since the output amplitude of the main amplifier 3 is kept constant by the AGC circuit, pulse width distortion does not occur in the output of the main amplifier 3. If there is no AGC circuit, when the input level is high, the pulse width is distorted at the output stage of the main amplifier 3, and high-level feedback becomes meaningless. Since the hold time of the high level detection circuits 6 and 7 is long, the present method can be applied without being affected by the change in the signal pattern within that time and without depending on the duty ratio.
尚、上記実施例では、メインアンプ３の出力をＡＧＣ回
路により一定に保ち、光受信回路のダイナミックレンジ
を拡大しているが、例えば、受光素子１にＰＩＮフォト
ダイオードではなくアバランシェフォトダイオード（Ａ
ＰＤ）を使用し、ＡＰＤのバイアスを変化させることに
よってメインアンプ３の出力を一定に保つようにしても
よい。この場合にもＡＧＣ回路を設けた場合と同様な効
果が得られる。In the above embodiment, the output of the main amplifier 3 is kept constant by the AGC circuit to expand the dynamic range of the light receiving circuit. However, for example, the light receiving element 1 is not a PIN photodiode but an avalanche photodiode (A
PD) may be used and the output of the main amplifier 3 may be kept constant by changing the bias of the APD. In this case as well, the same effect as when the AGC circuit is provided can be obtained.
［発明の効果］ 以上要するに本発明によれば、差動増幅器の出力のハイ
レベルに比例する電圧を各差動入力端に負帰還して差動
増幅器の同相・逆相出力のハイレベル一致させているた
め、入力される光信号のパターンを変化すなわちデュー
ティ比の変化による信号の平均値レベルの変動の影響を
受けることなく、歪の少ないパルスが得られ、安定した
識別・再生を行なうことができる。[Effects of the Invention] In summary, according to the present invention, the voltage proportional to the high level of the output of the differential amplifier is negatively fed back to each differential input terminal so that the in-phase and anti-phase outputs of the differential amplifier are matched with each other. Therefore, a pulse with little distortion can be obtained and stable identification / reproduction can be performed without being affected by the change in the pattern of the input optical signal, that is, the change in the average value level of the signal due to the change in the duty ratio. it can.
第１図は本発明に係る光受信回路の一実施例を示す回路
図、第２図は同光受信回路の応答波形の一例を示す波形
図、第３図は従来の光受信回路を示す回路図、第４図は
平均デューティ比50％の符号形式を示す図、第５図は第
３図の光受信回路の応答波形の一例を示す波形図、第６
図はハイレベル検出回路の回路図である。 図中、１は受光素子、２はプリアンプ、３はメインアン
プ、４は比較回路、５はコンデンサ、６，７はハイレベ
ル検出回路、８はローレベル検出回路、９は差動アンプ
である。FIG. 1 is a circuit diagram showing an embodiment of an optical receiving circuit according to the present invention, FIG. 2 is a waveform diagram showing an example of a response waveform of the optical receiving circuit, and FIG. 3 is a circuit showing a conventional optical receiving circuit. FIG. 4 is a diagram showing a code format with an average duty ratio of 50%, FIG. 5 is a waveform diagram showing an example of a response waveform of the optical receiver circuit of FIG.
The figure is a circuit diagram of a high-level detection circuit. In the figure, 1 is a light receiving element, 2 is a preamplifier, 3 is a main amplifier, 4 is a comparison circuit, 5 is a capacitor, 6 and 7 are high level detection circuits, 8 is a low level detection circuit, and 9 is a differential amplifier.
フロントページの続き (51)Int.Cl.5 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｈ０４Ｂ 10/00 10/04 10/06 Ｈ０４Ｌ 25/06 8226−5Ｋ Continuation of the front page (51) Int.Cl. 5 Identification number Office reference number FI technical display location H04B 10/00 10/04 10/06 H04L 25/06 8226-5K
Claims (1)
受光素子の出力を増幅する増幅器と、増幅器と交流結合
されその交流出力を増幅して180゜位相の異なる２相出力
を出力する差動増幅器と、差動増幅器の２相出力を比較
してディジタル信号を出力する比較回路とを備え、上記
差動増幅器にその２相出力のハイレベルを一致させるべ
く２相出力のハイレベル電圧を各差動入力端に負帰還す
る帰還回路を設けたことを特徴とする光受信回路。1. A light receiving element for converting an optical signal into an electric signal,
An amplifier that amplifies the output of the light receiving element, a differential amplifier that is AC-coupled with the amplifier and that amplifies the AC output to output a two-phase output with a 180 ° phase difference, and a digital amplifier that compares the two-phase outputs of the differential amplifier And a feedback circuit for negatively feeding back the high-level voltage of the two-phase output to each differential input terminal in order to match the high-level of the two-phase output to the differential amplifier. Characteristic optical receiver circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60187296A JPH0614647B2 (en) | 1985-08-28 | 1985-08-28 | Optical receiver circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60187296A JPH0614647B2 (en) | 1985-08-28 | 1985-08-28 | Optical receiver circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6248839A JPS6248839A (en) | 1987-03-03 |
| JPH0614647B2 true JPH0614647B2 (en) | 1994-02-23 |
Family
ID=16203513
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP60187296A Expired - Fee Related JPH0614647B2 (en) | 1985-08-28 | 1985-08-28 | Optical receiver circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0614647B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009177516A (en) * | 2008-01-24 | 2009-08-06 | Sumitomo Electric Ind Ltd | Optical receiver |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01205610A (en) * | 1988-02-12 | 1989-08-18 | Nec Corp | Optical reception circuit |
| JPH01222512A (en) * | 1988-03-01 | 1989-09-05 | Fujitsu Ten Ltd | Waveform shaping circuit |
| JPH08223228A (en) * | 1994-03-17 | 1996-08-30 | Fujitsu Ltd | Equalizing amplifier, receiver using the same, and preamplifier |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57181236A (en) * | 1981-04-30 | 1982-11-08 | Fujitsu Ltd | Waveform amplification detecting system |
-
1985
- 1985-08-28 JP JP60187296A patent/JPH0614647B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009177516A (en) * | 2008-01-24 | 2009-08-06 | Sumitomo Electric Ind Ltd | Optical receiver |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6248839A (en) | 1987-03-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |