JPH077335A - Optical receiver circuit - Google Patents
Optical receiver circuitInfo
- Publication number
- JPH077335A JPH077335A JP74794A JP74794A JPH077335A JP H077335 A JPH077335 A JP H077335A JP 74794 A JP74794 A JP 74794A JP 74794 A JP74794 A JP 74794A JP H077335 A JPH077335 A JP H077335A
- Authority
- JP
- Japan
- Prior art keywords
- input terminal
- phase output
- receiving element
- output terminal
- circuit
- 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
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- Amplifiers (AREA)
Abstract
(57)【要約】
【目的】受光素子の接合容量による帯域制限を受けず、
周波数ゼロ近辺から広い周波数にわたり、フラットなゲ
イン特性が得られる。
【構成】入力端子、正相出力端子、逆相出力端子を有す
る増幅器と、前記入力端子に接続された受光素子と、前
記入力端子と逆相出力端子間に接続された帰還抵抗とを
具備した光受信回路であって、前記受光素子は、前記正
相出力端子電圧を分圧する分圧回路の電圧分圧点と前記
入力端子間に接続されており、前記受光素子の接合容量
に流れる周波数劣化要因の電流をゼロとすべく、前記分
圧回路の抵抗値、前記増幅器のオープンループゲインが
決められている。
(57) [Abstract] [Purpose] No band limitation due to the junction capacitance of the photo detector,
A flat gain characteristic can be obtained from around zero frequency to a wide range of frequencies. [Structure] An amplifier having an input terminal, a positive-phase output terminal, and a negative-phase output terminal, a light-receiving element connected to the input terminal, and a feedback resistor connected between the input terminal and the negative-phase output terminal. In the optical receiving circuit, the light receiving element is connected between the voltage dividing point of the voltage dividing circuit for dividing the voltage of the positive phase output terminal and the input terminal, and the frequency deterioration flowing in the junction capacitance of the light receiving element is caused. The resistance value of the voltage dividing circuit and the open loop gain of the amplifier are determined so that the factor current is zero.
Description
【０００１】[0001]
【産業上の利用分野】本発明は光受信回路に関し、特に
光ファイバを使って光信号を電気信号に変換する光受信
モジュールに使用されるものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical receiver circuit, and more particularly to an optical receiver module for converting an optical signal into an electric signal by using an optical fiber.
【０００２】[0002]
【従来の技術】従来の光受信回路は、図３に示す並列帰
還形増幅器により構成されていた（例えば特開昭５８−
１６５０２０号、特開昭５８−１４３６４６号、特開昭
５８−１４２６４７号、特開昭６０−１３４６１１号公
報参照）。即ち入力端子２、逆送出力端子３を持つ増幅
器１と、入力端子２と電源Ｖｃｃ間に接続された受光素
子４と、入力端子２と逆相出力端子３間に接続された帰
還抵抗５とによる構成である。この回路の動作は、論理
的に次のように表される。増幅器１の入力電圧をｖi、
出力電圧をｖo 、オープンループゲインを−Ａとする
と、2. Description of the Related Art A conventional optical receiving circuit is composed of a parallel feedback type amplifier shown in FIG.
165020, JP-A-58-143646, JP-A-58-142647, and JP-A-60-134611). That is, an amplifier 1 having an input terminal 2 and a reverse transmission output terminal 3, a light receiving element 4 connected between the input terminal 2 and the power supply Vcc, and a feedback resistor 5 connected between the input terminal 2 and the negative phase output terminal 3. It is a structure by. The operation of this circuit is logically expressed as follows. The input voltage of the amplifier 1 is v i ,
If the output voltage is v o and the open loop gain is -A,
【０００３】[0003]
【数１】 また受光素子４からの信号電流をｉ、受光素子４の接合
容量をＣJ とすると、[Equation 1] When the signal current from the light receiving element 4 is i and the junction capacitance of the light receiving element 4 is C J ,
【０００４】[0004]
【数２】 （１）式および（２）式からｖi を消去すると[Equation 2] Eliminating v i from equations (1) and (2)
【０００５】[0005]
【数３】 通常はＡ>>１なので、[Equation 3] Usually A >> 1, so
【０００６】[0006]
【数４】 とすると[Equation 4] And
【０００７】[0007]
【数５】 となり、−３ｄＢダウンの高域遮断周波数ｆc は、[Equation 5] And the high cutoff frequency f c of -3 dB down is
【０００８】[0008]
【数６】 となる。またｆc より充分低い周波数での変換ゲインは
ＲF となる。従って広い周波数帯域にわたって充分なゲ
インを得ようとすると、ＲF とＡは極力大きく、ＣJ は
極力小さくする必要がある。[Equation 6] Becomes The conversion gain at a frequency sufficiently lower than f c is R F. Therefore, in order to obtain a sufficient gain over a wide frequency band, it is necessary to make R F and A as large as possible and C J as small as possible.
【０００９】[0009]
【発明が解決しようとする課題】しかるに受光素子１の
接合容量ＣJ を小さくしようとしても、できないことが
ある。例えば、使用するファイバの関係から、受光面積
を大きくしなければならない場合とか、増幅器１と受光
素子４を集積化させるために、受光素子４をｐｉｎ構造
でなく、ｐｎ構造で作らなければならない場合等であ
る。この場合には、目標とするゲインで充分な周波数帯
域を得られないことがあるという問題があった。そこで
本発明の目的とするところは、受光素子の接合容量ＣJ
が大きくても、充分な周波数帯域が得られる光受信回路
を提供することにある。However, even if the junction capacitance C J of the light receiving element 1 is made small, it may not be possible. For example, when the light receiving area needs to be increased due to the relationship of the fiber to be used, or in order to integrate the amplifier 1 and the light receiving element 4, the light receiving element 4 has to be formed by a pn structure instead of a pin structure. Etc. In this case, there is a problem that a sufficient frequency band may not be obtained with the target gain. Therefore, the object of the present invention is to provide a junction capacitance C J of the light receiving element.
An object of the present invention is to provide an optical receiving circuit that can obtain a sufficient frequency band even if the value is large.
【００１０】[0010]
【課題を解決するための手段と作用】本発明は、入力端
子、正相出力端子、逆相出力端子を有する増幅器と、前
記入力端子に接続された受光素子と、前記入力端子と逆
相出力端子間に接続された帰還抵抗とを具備した光受信
回路であって、前記受光素子は、前記正相出力端子電圧
を分圧する分圧する分圧回路の電圧分圧点と前記入力端
子間に接続されており、前記受光素子の接合容量に流れ
る周波数劣化要因の電流をゼロとすべく、前記分圧回路
の抵抗値、前記増幅器のオープンループゲインが決めら
れていることを特徴とする光受信回路である。According to the present invention, an amplifier having an input terminal, a positive phase output terminal and a negative phase output terminal, a light receiving element connected to the input terminal, and an opposite phase output from the input terminal. An optical receiving circuit comprising a feedback resistor connected between terminals, wherein the light receiving element is connected between a voltage dividing point of a voltage dividing circuit for dividing the voltage of the positive phase output terminal and the input terminal. The light receiving circuit is characterized in that the resistance value of the voltage dividing circuit and the open loop gain of the amplifier are determined so that the current of the frequency deterioration factor flowing in the junction capacitance of the light receiving element is set to zero. Is.
【００１１】すなわち本発明では、周波数劣化の原因と
なる受光素子の接合容量ＣJ が、増幅器の出力電圧に関
与しない回路構成とすることにより、接合容量ＣJ に係
わらず、高周波数帯域にわたり、フラットなゲイン特性
が得られるようにしたものである。[0011] That is, in the present invention, the junction capacitance C J of the light receiving element which causes the frequency deterioration, with a circuit arrangement which is not involved in the output voltage of the amplifier, regardless of junction capacitance C J, over a high frequency band, This is to obtain a flat gain characteristic.
【００１２】[0012]
【実施例】以下図面を参照して本発明の実施例を説明す
る。図１は、本発明に至る前の回路構成例であるが、こ
れは図３のものと対応させた場合の例であるから、対応
箇所には同一符号を付し、特徴とする点の説明を行う。
本構成の特徴は、増幅器１の正相出力端子１０と接地間
には、抵抗Ｒ1 、Ｒ2 からなる電圧分圧回路１１が接続
され、分圧点１２と入力端子２間には、コンデンサＣo
が接続されている点である。この図１の光受信回路の動
作は、理論的に次のように表せる。Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of a circuit configuration before reaching the present invention, but since this is an example in the case where it corresponds to that of FIG. I do.
The characteristic of this configuration is that a voltage divider circuit 11 composed of resistors R 1 and R 2 is connected between the positive phase output terminal 10 of the amplifier 1 and the ground, and a capacitor is provided between the voltage dividing point 12 and the input terminal 2. C o
Is connected. The operation of the optical receiving circuit of FIG. 1 can be theoretically expressed as follows.
【００１３】[0013]
【数７】 [Equation 7]
【００１４】[0014]
【数８】 （６）、（７）式からｖi を消去すると[Equation 8] If v i is eliminated from equations (6) and (7),
【００１５】[0015]
【数９】 ここで[Equation 9] here
【００１６】[0016]
【数１０】 となるように（９）式の各値を決める。即ち（８）式の
ｊω（角周波数）のついた項がゼロとなり、周波数がゼ
ロから広い周波数帯域に至るまでフラットなゲインが得
られるようにする。つまり（８）式は、[Equation 10] Each value of the equation (9) is determined so that That is, the term with jω (angular frequency) in the equation (8) becomes zero, so that a flat gain can be obtained from zero frequency to a wide frequency band. That is, equation (8) is
【００１７】[0017]
【数１１】 となり、受光素子４の接合容量ＣJ による帯域劣化をお
さえ、高周波帯域にわたりフラットなゲイン特性の光受
信回路が得られる。なおこの理由は、（７）式におい
て、接合容量ＣJ を流れる周波数劣化要因の電流（−ｊ
ωＣJ ｖi ）を、コンデンサＣo に流れる電流[Equation 11] Therefore, the band deterioration due to the junction capacitance C J of the light receiving element 4 can be suppressed, and an optical receiving circuit having a flat gain characteristic over a high frequency band can be obtained. Incidentally, this is because, in equation (7), the junction capacitance C J Frequency degradation factor of the current through the (-j
ωC J v i ) is the current flowing through the capacitor C o
【００１８】[0018]
【数１２】 でキャンセルしたためといえる。[Equation 12] It can be said that it was canceled at.
【００１９】図２は本発明の一実施例を示す。これは、
分圧点１２から入力端子２に接続される図１のコンデン
サＣo の代わりに、受光素子４の接合容量ＣJ を使用し
たものであり、分圧回路１１の分圧点１２が、受光素子
４のカソードに接続されている。この図２の回路は、図
１の場合と同様な方法により、FIG. 2 shows an embodiment of the present invention. this is,
Instead of the capacitor C o in Figure 1 connected from the voltage dividing point 12 to the input terminal 2 is obtained by using the junction capacitance C J of the light receiving element 4, the voltage dividing point 12 of the voltage dividing circuit 11, the light-receiving element 4 cathodes. The circuit of FIG. 2 is obtained by the same method as that of FIG.
【００２０】[0020]
【数１３】 と表わされ、[Equation 13] Is expressed as
【００２１】[0021]
【数１４】 とすることにより（上記（９）式でＣo とＣJ は等価と
したものと考えてよい）、接合容量ＣJ による帯域劣化
をおさえることができるものである。尚図１では、信号
電流ｉ以外に、受光素子４に流れる周波数劣化要因の電
流を、コンデンサＣo に流れる電流でキャンセルするよ
うにしたが、図２では接合容量ＣJ には、周波数劣化要
因の電流は流れないようにされ、等価的に該電流はキャ
ンセルされたものと考えることができる。[Equation 14] By setting the above (it may be considered that C o and C J are equivalent in the above equation (9)), it is possible to suppress the band deterioration due to the junction capacitance C J. In Naozu 1, in addition to the signal current i, the current of the frequency deterioration factors flowing through the light-receiving element 4, it has been adapted to cancel the current flowing through the capacitor C o, FIG. 2, the junction capacitance C J, the frequency deterioration factor The current is prevented from flowing, and it can be considered that the current is equivalently canceled.
【００２２】[0022]
【発明の効果】以上説明したごとく本発明によれば、受
光素子の接合容量による帯域制限を受けず、周波数ゼロ
近辺から広い周波数にわたり、フラットなゲイン特性が
得られる光受信回路が提供できるものである。As described above, according to the present invention, it is possible to provide an optical receiving circuit which can obtain a flat gain characteristic over a wide frequency range from around zero frequency without being subject to band limitation by the junction capacitance of the light receiving element. is there.
【図１】本発明に至る前の回路例を示す回路構成図。FIG. 1 is a circuit configuration diagram showing a circuit example before reaching the present invention.
【図２】本発明の一実施例の回路図。FIG. 2 is a circuit diagram of an embodiment of the present invention.
【図３】従来の光受信回路図。FIG. 3 is a conventional optical receiver circuit diagram.
１…増幅器、２…入力端子、３…逆相出力端子、４…受
光素子、５…帰還抵抗、１０…正相出力端子、１１…電
圧分圧回路、１２…分圧点、Ｃｏ…コンデンサ。DESCRIPTION OF SYMBOLS 1 ... Amplifier, 2 ... Input terminal, 3 ... Negative phase output terminal, 4 ... Light receiving element, 5 ... Feedback resistance, 10 ... Positive phase output terminal, 11 ... Voltage dividing circuit, 12 ... Voltage dividing point, Co ... Capacitor.
Claims (1)
有する増幅器と、前記入力端子に接続された受光素子
と、前記入力端子と逆相出力端子間に接続された帰還抵
抗とを具備した光受信回路であって、前記受光素子は、
前記正相出力端子電圧を分圧する分圧回路の電圧分圧点
と前記入力端子間に接続されており、前記受光素子の接
合容量に流れる周波数劣化要因の電流をゼロとすべく、
前記分圧回路の抵抗値、前記増幅器のオープンループゲ
インが決められていることを特徴とする光受信回路。1. An amplifier having an input terminal, a positive-phase output terminal, and a negative-phase output terminal, a light-receiving element connected to the input terminal, and a feedback resistor connected between the input terminal and the negative-phase output terminal. A light receiving circuit comprising: the light receiving element,
It is connected between the voltage dividing point of the voltage dividing circuit for dividing the voltage of the positive-phase output terminal and the input terminal, so that the current of the frequency deterioration factor flowing in the junction capacitance of the light receiving element is zero,
An optical receiving circuit, wherein a resistance value of the voltage dividing circuit and an open loop gain of the amplifier are determined.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP74794A JPH077335A (en) | 1994-01-10 | 1994-01-10 | Optical receiver circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP74794A JPH077335A (en) | 1994-01-10 | 1994-01-10 | Optical receiver circuit |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1311334A Division JPH0654852B2 (en) | 1989-11-30 | 1989-11-30 | Optical receiver circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH077335A true JPH077335A (en) | 1995-01-10 |
Family
ID=11482295
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP74794A Pending JPH077335A (en) | 1994-01-10 | 1994-01-10 | Optical receiver circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH077335A (en) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS56107654A (en) * | 1980-01-31 | 1981-08-26 | Nec Corp | Light receiving circuit |
| JPH02246602A (en) * | 1989-03-20 | 1990-10-02 | Sumitomo Electric Ind Ltd | Amplifier for optical reception |
-
1994
- 1994-01-10 JP JP74794A patent/JPH077335A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS56107654A (en) * | 1980-01-31 | 1981-08-26 | Nec Corp | Light receiving circuit |
| JPH02246602A (en) * | 1989-03-20 | 1990-10-02 | Sumitomo Electric Ind Ltd | Amplifier for optical reception |
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