JP2007189571A - Optical receiver - Google Patents

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JP2007189571A
JP2007189571A JP2006007029A JP2006007029A JP2007189571A JP 2007189571 A JP2007189571 A JP 2007189571A JP 2006007029 A JP2006007029 A JP 2006007029A JP 2006007029 A JP2006007029 A JP 2006007029A JP 2007189571 A JP2007189571 A JP 2007189571A
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frequency
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signals
band
pass filter
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JP2007189571A5 (en
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Kazumasa Kumamoto
一将 熊本
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DX Antenna Co Ltd
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DX Antenna Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To achieve a prescribed processing to a high-frequency signal of two frequency bands demodulated from an optical signal by a simple constitution, and inexpensively. <P>SOLUTION: A photodiode 2 light-receives the optical signal modulated by a mixed signal of the high-frequency signals of a first and a second frequency bands, and a signal corresponding to the mixed signal runs to tap-having high-frequency blocking coils 4 and 10 connected in series holding the photodiode 2. A high-pass filter 18 connected to the tap-having high-frequency blocking coil 4 extracts the high-frequency signal of the first frequency band from the mixed signal. The high-frequency signal of the second frequency band is extracted from the mixed signal generated in the tap-having high-frequency blocking coil 10. An amplification and frequency characteristic adjusting circuit 20 connected to the high-pass filter 18 processes the high-frequency signal of the first frequency band from the high-pass filter 18. The amplification and frequency characteristic adjusting circuit 36 connected to a low-pass filter 34 processes the high-frequency signal of the second frequency band from the low-pass filter 34. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、光受信機に関し、特に複数の高周波信号で変調された光信号を受信する光受信機に関する。   The present invention relates to an optical receiver, and more particularly to an optical receiver that receives an optical signal modulated by a plurality of high-frequency signals.

光受信機の一例が例えば特許文献１に開示されている。特許文献１の技術では、電源とアースとの間にツェナーダイオードとフォトダイオードと抵抗器とを直列に接続し、フォトダイオードにツェナーダイオードによってバイアスが印加されている。光ファイバ等から入力された光信号は、フォトダイオードで受光され、フォトダイオードに流れる光電流が光信号の強度に応じた大きさとなり、光信号が電気信号に変換される。この電気信号は、交流成分を抽出するコンデンサを介して増幅部に供給されて増幅される。   An example of an optical receiver is disclosed in Patent Document 1, for example. In the technique of Patent Document 1, a Zener diode, a photodiode, and a resistor are connected in series between a power supply and ground, and a bias is applied to the photodiode by the Zener diode. An optical signal input from an optical fiber or the like is received by a photodiode, a photocurrent flowing through the photodiode becomes a magnitude corresponding to the intensity of the optical signal, and the optical signal is converted into an electrical signal. This electric signal is supplied to the amplifying unit via a capacitor for extracting an AC component and amplified.

特開２００４−２３６２５９号公報JP 2004-236259 A

このような光受信機は、光ファイバによる光信号の伝送は幹線系のみとし、分配系は同軸網で行う光／同軸ハイブリッド方式の光共同受信システムにおいて、幹線系と分配系との接続部に設けられることがある。この場合、光信号は、異なる周波数帯の高周波信号で変調されている。例えば衛星放送信号及び衛星通信信号を衛星放送及び衛星通信受信用のアンテナで受信し、アンテナに付属するコンバータで変換した１ＧＨｚ〜２ＧＨｚ帯の衛星放送及び衛星通信中間周波信号（以下、衛星系中間周波信号と称する。）と、ＵＨＦ帯及びＶＨＦ帯の地上波テレビジョン放送信号とによって、変調されている。従って、この光信号を特許文献１に示されている光受信機において受信した場合、この光受信機に備えられている増幅部は、ＶＨＦ帯からＧＨｚ帯までの広い周波数帯域における高周波信号を増幅可能な広帯域のもので無ければならない。広帯域の増幅部を準備できたとしても、分配系での同軸ケーブルによる伝送を考慮した場合、ＶＨＦ帯及びＵＨＦ帯のテレビジョン放送信号及び衛星系中間周波信号には、それらの周波数に応じたチルト特性をそれぞれ持たせる必要がある。このようなことを１台の増幅部において行うことは実質的に不可能である。 In such an optical receiver, optical signal transmission by optical fiber is limited to the trunk line system, and the distribution system is an optical / coaxial hybrid type optical joint reception system that uses a coaxial network. May be provided. In this case, the optical signal is modulated with a high-frequency signal in a different frequency band. For example, satellite broadcast signals and satellite communication signals are received by a satellite broadcast and satellite communication reception antenna, and converted by a converter attached to the antenna, and 1 GHz to 2 GHz band satellite broadcast and satellite communication intermediate frequency signals (hereinafter referred to as satellite system intermediate frequency signals). And a terrestrial television broadcast signal in the UHF band and the VHF band. Therefore, when this optical signal is received by the optical receiver disclosed in Patent Document 1, the amplifying unit provided in this optical receiver amplifies a high-frequency signal in a wide frequency band from the VHF band to the GHz band. It must be possible broadband. Even if a wide-band amplifier is prepared, when transmission using a coaxial cable in the distribution system is considered, the TV broadcast signal in the VHF band and the UHF band and the satellite intermediate frequency signal are tilted according to their frequencies. Each must have its own characteristics. It is practically impossible to do this in a single amplification unit.

そこで、フォトダイオードの出力を２分配器に入力し、一方の分配出力から衛星系中間周波信号をフィルタによって抽出し、他方の分配出力からＶＨＦ帯及びＵＨＦ帯のテレビジョン放送信号をフィルタによって抽出し、衛星系中間周波信号にはその周波数に応じたチルト特性を持たせるように周波数特性を調整し、ＶＨＦ帯及びＵＨＦ帯のテレビジョン放送信号にはその周波数に応じたチルト特性を持たせるように周波数特性を調整する回路を設け、周波数特性が調整された衛星系中間周波信号とＶＨＦ帯及びＵＨＦ帯のテレビジョン放送信号とを合成器によって合成して、分配系に伝送することが考えられる。   Therefore, the output of the photodiode is input to the two distributors, the satellite intermediate frequency signal is extracted from one distribution output by a filter, and the television broadcast signals in the VHF band and the UHF band are extracted from the other distribution output by a filter. The frequency characteristic is adjusted so that the satellite system intermediate frequency signal has a tilt characteristic corresponding to the frequency, and the television broadcast signal in the VHF band and the UHF band has a tilt characteristic corresponding to the frequency. It is conceivable that a circuit for adjusting the frequency characteristics is provided, and the satellite system intermediate frequency signal and the television broadcast signals in the VHF band and the UHF band are synthesized by a synthesizer and transmitted to the distribution system.

しかし、このような構成では、分配器やフィルタが必要であり、増幅部の構成が複雑になる上に、コストが高くなる。更に、分配した上でフィルタによって衛星系中間周波信号とＶＨＦ帯及びＵＨＦ帯のテレビジョン放送信号とを抽出しているので、抽出された衛星系中間周波信号とＶＨＦ帯及びＵＨＦ帯のテレビジョン放送信号は、分配損失及びフィルタでの挿入損失の影響を受けて減衰されている。そのため、これら信号のＣ／Ｎ比が悪化する。これを改善するために、更に抽出された衛星系中間周波信号とＶＨＦ帯及びＵＨＦ帯のテレビジョン放送信号をそれぞれ増幅する必要があり、益々構成が複雑になる上に、コストが上昇する。   However, such a configuration requires a distributor and a filter, which makes the configuration of the amplification unit complicated and increases the cost. Further, since the satellite system intermediate frequency signal and the VHF band and UHF band television broadcast signals are extracted by the filter after being distributed, the extracted satellite system intermediate frequency signal and the VHF band and UHF band television broadcasts are extracted. The signal is attenuated under the influence of distribution loss and filter insertion loss. Therefore, the C / N ratio of these signals deteriorates. In order to improve this, it is necessary to amplify the satellite system intermediate frequency signal and the television broadcast signal in the VHF band and UHF band, respectively, which further increases the complexity and cost.

本発明は、簡単な構成で、かつ低コストで、復調した２つの異なる周波数帯の高周波信号に所定の処理を行うことができる光受信機を提供することを目的とする。   An object of the present invention is to provide an optical receiver capable of performing predetermined processing on a demodulated high-frequency signal in two different frequency bands with a simple configuration and at a low cost.

本発明の１実施形態の光受信機は、２端子の光受光素子を有している。この光受光素子は、光信号を受光すると、光信号に応じた信号が流れるもので、例えばフォトダイオードを使用することができる。受光する光信号は、第１及び第２の周波数帯の高周波信号の混合信号で変調されたものである。この光受光素子を挟んで直列に第１及び第２の負荷が接続されている。第１及び第２の負荷には、第１及び第２の周波数帯の高周波信号の混合信号が生じる。なお、光受光素子には、第１及び第２の負荷を介して適切なバイアスをバイアス回路によって与えることもできる。第１の負荷に第１の抽出手段が接続され、第１の抽出手段は、第１の負荷に生じた前記混合信号から第１の周波数帯の高周波信号を抽出する。第２の負荷に第２の抽出手段が接続され、第２の抽出手段は、第２の負荷に生じた前記混合信号から第２の周波数帯の高周波信号を抽出する。第１の抽出手段に第１の処理手段が接続され、第１の抽出手段から出力された第１の周波数帯の高周波信号を処理する。 第２の抽出手段に第２の処理手段が接続され、第２の抽出手段から出力された第２の周波数帯の高周波信号を処理する。第１及び第２の処理手段は、例えば増幅手段とすることができる。第１及び第２の処理手段の出力信号を合成手段が合成する。   The optical receiver of one embodiment of the present invention has a two-terminal light receiving element. The light receiving element receives a light signal and a signal corresponding to the light signal flows. For example, a photodiode can be used. The received optical signal is modulated with a mixed signal of high-frequency signals in the first and second frequency bands. First and second loads are connected in series with the light receiving element interposed therebetween. A mixed signal of high-frequency signals in the first and second frequency bands is generated in the first and second loads. Note that an appropriate bias can be applied to the light receiving element by a bias circuit via the first and second loads. A first extraction unit is connected to the first load, and the first extraction unit extracts a high-frequency signal in a first frequency band from the mixed signal generated in the first load. A second extraction unit is connected to the second load, and the second extraction unit extracts a high-frequency signal in a second frequency band from the mixed signal generated in the second load. The first processing means is connected to the first extraction means, and the high-frequency signal in the first frequency band output from the first extraction means is processed. The second processing means is connected to the second extraction means, and the high-frequency signal in the second frequency band output from the second extraction means is processed. The first and second processing means can be, for example, amplification means. The combining means combines the output signals of the first and second processing means.

このように構成された光受信機では、受光素子の両端に接続された第１及び第２の負荷からそれぞれ混合信号が取り出されている。従って、受光素子の一端に接続された負荷から取り出した混合信号を分配器によって分配する必要が無く、回路構成を簡略化することができ、かつコストを低減することができ、また各混合信号は分配損失の影響を受けない。なお、特開２００−２６１３８５号公報や特開２００５−５１５０４号公報には、フォトダイオードの両端からそれぞれ信号を取り出すことが開示されている。しかし、特開２００−２６１３８５号公報の技術では、両端から取り出した信号をそれぞれ増幅した後に、その差分を取り出して、入力換算雑音電流密度を小さくするものである。また、特開２００５−５１５０４号公報の技術では、フォトダイオードの両端からそれぞれ取り出した信号をプッシュプル増幅してＣ／Ｎ比を改善しようとするものである。即ち、フォトダイオードの両端から取り出した信号から周波数帯の異なる信号を抽出するという思想は開示されていない。   In the optical receiver configured as described above, mixed signals are respectively extracted from the first and second loads connected to both ends of the light receiving element. Therefore, it is not necessary to distribute the mixed signal taken out from the load connected to one end of the light receiving element by the distributor, the circuit configuration can be simplified, and the cost can be reduced. Not affected by distribution loss. JP-A Nos. 200-261385 and 2005-51504 disclose that signals are taken out from both ends of a photodiode. However, in the technique disclosed in Japanese Patent Laid-Open No. 200-261385, after the signals extracted from both ends are amplified, the difference is extracted to reduce the input equivalent noise current density. In the technique disclosed in Japanese Patent Application Laid-Open No. 2005-51504, signals extracted from both ends of the photodiode are push-pull amplified to improve the C / N ratio. That is, the idea of extracting signals having different frequency bands from signals extracted from both ends of the photodiode is not disclosed.

第１の処理手段は、第１の周波数帯の高周波信号の周波数特性を調整する第１の調整手段を含み、第２の処理手段は、第２の周波数帯の高周波信号の周波数特性を調整する第２の調整手段を含むものとすることができる。調整手段としては、例えばチルト回路やＢＯＮ回路を使用することができ、これに加えてレベル調整手段を設けることもできる。この場合、合成手段の後段に、伝送系が接続される。このように第１及び第２の周波数帯ごとに、所望の周波数特性に調整することができるので、伝送系を伝送される際に、第１及び第２の周波数帯の高周波信号がそれぞれ個別に受ける伝送系の影響を補償することができる。   The first processing means includes first adjusting means for adjusting the frequency characteristics of the high frequency signal in the first frequency band, and the second processing means adjusts the frequency characteristics of the high frequency signal in the second frequency band. Second adjustment means may be included. As the adjusting means, for example, a tilt circuit or a BON circuit can be used, and in addition to this, a level adjusting means can be provided. In this case, a transmission system is connected after the combining means. Thus, since it can be adjusted to a desired frequency characteristic for each of the first and second frequency bands, the high-frequency signals in the first and second frequency bands are individually transmitted when transmitted through the transmission system. It is possible to compensate for the influence of the transmission system.

更に、第１及び第２の周波数帯の高周波信号が、テレビジョン放送信号、例えば地上波テレビジョン放送信号と、衛星から送信されたテレビジョン放送信号を周波数変換した中間周波信号とすることができる。この場合、合成手段の出力信号が共同受信システムに伝送される。このように構成すると、共同受信システムの周波数特性によって第１及び第２の周波数帯の高周波信号が受ける影響を補償することができる。   Furthermore, the high-frequency signal in the first and second frequency bands can be a television broadcast signal, for example, a terrestrial television broadcast signal, and an intermediate frequency signal obtained by frequency-converting a television broadcast signal transmitted from a satellite. . In this case, the output signal of the combining means is transmitted to the joint reception system. If comprised in this way, the influence which the high frequency signal of a 1st and 2nd frequency band receives with the frequency characteristic of a joint reception system can be compensated.

以上のように、本発明による光受信機では、簡単な構成で、かつ低コストで、復調した２つの異なる周波数帯の高周波信号に所定の処理を行うことができる。   As described above, the optical receiver according to the present invention can perform predetermined processing on the demodulated high frequency signals in two different frequency bands with a simple configuration and at low cost.

本発明の１実施形態の光受信機は、光／同軸ハイブリッド方式の光共同受信システムにおいて、光系と同軸系との接合点に配置されている。例えばヘッドエンドから光ファイバで光信号を棟内ＣＡＴＶの入力側まで伝送し、この棟内ＣＡＴＶの入力側に、この光受信機が配置される。光受信機は、光信号を電気信号に変換して、同軸系、例えば棟内ＣＡＴＶの同軸ケーブルを介して棟内の各端末に伝送する。   An optical receiver according to an embodiment of the present invention is disposed at a junction between an optical system and a coaxial system in an optical / coaxial hybrid optical joint reception system. For example, an optical signal is transmitted from the head end to the input side of the in-building CATV by an optical fiber, and this optical receiver is arranged on the input side of the in-building CATV. The optical receiver converts an optical signal into an electric signal and transmits it to each terminal in the building via a coaxial system, for example, a coaxial cable of the in-building CATV.

この光信号は、例えばＵＨＦ帯及びＶＨＦ帯の地上波テレビジョン放送信号と、衛星放送及び衛星通信中間周波信号との混合信号で変調されている。ＵＨＦ帯及びＶＨＦ帯の地上波テレビジョン放送信号は、アナログ及びデジタル方式の双方または一方のものである。衛星放送及び衛星通信中間周波信号は、衛星放送及び衛星通信受信用アンテナで受信された衛星放送信号及び衛星通信信号を、このアンテナに付属するコンバータによって例えば１ＧＨｚ帯の中間周波信号に周波数変換したものである。   This optical signal is modulated by a mixed signal of, for example, a UHF band and a VHF band terrestrial television broadcast signal and a satellite broadcast and satellite communication intermediate frequency signal. The terrestrial television broadcast signals in the UHF band and the VHF band are analog and / or digital ones. The satellite broadcast and satellite communication intermediate frequency signal is obtained by converting the satellite broadcast signal and satellite communication signal received by the satellite broadcast and satellite communication receiving antenna into a frequency signal of, for example, 1 GHz band by a converter attached to the antenna. It is.

光受信機は、受光素子、例えばフォトダイオード２を有している。フォトダイオード２のカソードは、第１の負荷、例えば中間タップ付き高周波阻止コイル４と、バイアス用高周波阻止コイル６とを介してバイアス用電源の正極８に接続されている。また、フォトダイオード２のアノードは、第２の負荷、例えば中間タップ付き高周波阻止コイル１０、バイアス用高周波阻止コイル１２及びバイアス用抵抗器１４を介して基準電位、例えば接地電位に接続されている。バイアス用抵抗器１４には、並列にバイパスコンデンサ１６が接続されている。バイアス用高周波阻止コイル６、１２及びバイアス用抵抗器１４がバイアス回路を構成している。   The optical receiver has a light receiving element, for example, a photodiode 2. The cathode of the photodiode 2 is connected to the positive electrode 8 of the bias power source via a first load, for example, a high frequency blocking coil 4 with an intermediate tap and a bias high frequency blocking coil 6. The anode of the photodiode 2 is connected to a reference potential, for example, a ground potential, via a second load, for example, a high frequency blocking coil 10 with an intermediate tap, a high frequency blocking coil 12 for bias, and a resistor 14 for bias. A bypass capacitor 16 is connected to the bias resistor 14 in parallel. The bias high-frequency blocking coils 6 and 12 and the bias resistor 14 constitute a bias circuit.

フォトダイオード２に光信号が入光されると、フォトダイオード２には、上述した混合信号に対応する電流が流れる。   When an optical signal is incident on the photodiode 2, a current corresponding to the above-described mixed signal flows through the photodiode 2.

中間タップ付き高周波阻止コイル４の中間タップは、第１の抽出手段、例えばハイパスフィルタ１８に接続されている。ハイパスフィルタ１８は、中間タップに生じた混合信号から、衛星放送及び衛星通信中間周波信号を抽出するように、遮断周波数が選択されている。このハイパスフィルタ１８の出力信号は、処理手段、例えば増幅及び周波数特性調整回路２０に供給される。   The intermediate tap of the high frequency blocking coil 4 with the intermediate tap is connected to first extraction means, for example, a high-pass filter 18. In the high-pass filter 18, the cutoff frequency is selected so as to extract the satellite broadcast and satellite communication intermediate frequency signals from the mixed signal generated in the intermediate tap. The output signal of the high pass filter 18 is supplied to processing means, for example, an amplification and frequency characteristic adjustment circuit 20.

増幅及び周波数特性調整回路２０は、複数段、例えば２段の増幅段２２、２４が縦続接続されている。増幅段２２、２４は、衛星放送及び衛星通信中間周波信号を、ＶＨＦ帯及びＵＨＦ帯等に歪等を生じずに増幅可能なものである。増幅段２２、２４の間にレベル調整手段、例えばゲインコントロール回路２６が設けられている。ゲインコントロール回路２６は、自動ゲインコントロール回路とすることもできるし、手動ゲインコントロール回路とすることもできる。最終増幅段２４の出力側には、チルト回路２８が設けられている。このゲインコントロール回路２６とチルト回路２８とは、衛星放送及び衛星通信中間周波信号が、棟内ＣＡＴＶ３０の同軸ケーブルでの伝送によって蒙る、周波数特性を持つ減衰を補償するように、それぞれ調整されている。なお、ハイパスフィルタ１８、増幅段２２、ゲインコントロール回路２６、増幅段２４、チルト回路２８の間には、それぞれ直流阻止コンデンサ３２が設けられている。   The amplification and frequency characteristic adjustment circuit 20 has a plurality of stages, for example, two amplification stages 22 and 24 connected in cascade. The amplification stages 22 and 24 are capable of amplifying satellite broadcast and satellite communication intermediate frequency signals without causing distortion or the like in the VHF band and UHF band. Level adjusting means, for example, a gain control circuit 26 is provided between the amplification stages 22 and 24. The gain control circuit 26 can be an automatic gain control circuit or a manual gain control circuit. A tilt circuit 28 is provided on the output side of the final amplification stage 24. The gain control circuit 26 and the tilt circuit 28 are respectively adjusted so as to compensate for attenuation having frequency characteristics that satellite broadcasting and satellite communication intermediate frequency signals are affected by transmission through the coaxial cable of the in-building CATV 30. . A DC blocking capacitor 32 is provided between the high pass filter 18, the amplification stage 22, the gain control circuit 26, the amplification stage 24, and the tilt circuit 28.

同様に、中間タップ付き高周波阻止コイルの中間タップは、第２の抽出手段、例えばローパスフィルタ３４に接続されている。ローパスフィルタ３４は、中間タップに生じた混合信号から、ＵＨＦ帯及びＶＨＦ帯の地上波テレビジョン放送信号を抽出するように、遮断周波数が選択されている。このローパスフィルタ３４の出力信号は、処理手段、例えば増幅及び周波数特性調整回路３６に供給される。   Similarly, the intermediate tap of the high frequency blocking coil with the intermediate tap is connected to the second extraction means, for example, the low pass filter 34. The cut-off frequency is selected so that the low-pass filter 34 extracts the UHF band and VHF band terrestrial television broadcast signals from the mixed signal generated at the intermediate tap. The output signal of the low-pass filter 34 is supplied to processing means, for example, an amplification and frequency characteristic adjustment circuit 36.

増幅及び周波数特性調整回路３６は、複数段、例えば２段の増幅段３８、４０が縦続接続されている。増幅段３８、４０は、ＵＨＦ帯及びＶＨＦ帯の地上波テレビジョン放送信号を、衛星放送及び衛星通信中間周波信号に歪等を生じずに増幅可能なものである。増幅段３８、４０の間にレベル調整手段、例えばゲインコントロール回路４２が設けられている。ゲインコントロール回路４２は、自動ゲインコントロール回路とすることもできるし、手動ゲインコントロール回路とすることもできる。最終増幅段４０の出力側には、チルト回路４４が設けられている。このゲインコントロール回路４２とチルト回路４４とは、ＵＨＦ帯及びＶＨＦ帯の地上波テレビジョン放送信号が、棟内ＣＡＴＶ３０の同軸ケーブルでの伝送によって蒙る、周波数特性を持つ減衰を補償するように、それぞれ調整されている。なお、ローパスフィルタ３４、増幅段３８、ゲインコントロール回路４２、増幅段４０、チルト回路４４の間には、それぞれ直流阻止コンデンサ４６が設けられている。   The amplification and frequency characteristic adjustment circuit 36 includes a plurality of stages, for example, two amplification stages 38 and 40 connected in cascade. The amplification stages 38 and 40 can amplify terrestrial television broadcast signals in the UHF band and VHF band without causing distortion or the like in the satellite broadcast and satellite communication intermediate frequency signals. Level adjusting means, for example, a gain control circuit 42 is provided between the amplification stages 38 and 40. The gain control circuit 42 can be an automatic gain control circuit or a manual gain control circuit. A tilt circuit 44 is provided on the output side of the final amplification stage 40. The gain control circuit 42 and the tilt circuit 44 are respectively configured so as to compensate for attenuation having frequency characteristics, which is caused by transmission of the UHF band and VHF band terrestrial television broadcast signals through the coaxial cable of the in-building CATV 30. It has been adjusted. A DC blocking capacitor 46 is provided between the low-pass filter 34, the amplification stage 38, the gain control circuit 42, the amplification stage 40, and the tilt circuit 44, respectively.

これら２つの増幅及び周波数特性調整回路２０、３６の出力信号は、混合手段、例えば混合器４８によって混合される。混合器４８は、ハイパスフィルタ１８と同一のハイパスフィルタ５０によって、増幅及び周波数特性調整回路２０の出力信号から衛星放送及び衛星通信中間周波信号以外の信号を除去し、ローパスフィルタ３４と同一のローパスフィルタ５２によって、増幅及び周波数特性調整回路３６の出力信号からＵＨＦ帯及びＶＨＦ帯の地上波テレビジョン放送信号以外の信号を除去し、これらを合成し、棟内ＣＡＴＶ３０に伝送する。   The output signals of these two amplification and frequency characteristic adjusting circuits 20 and 36 are mixed by a mixing means, for example, a mixer 48. The mixer 48 removes signals other than satellite broadcast and satellite communication intermediate frequency signals from the output signal of the amplification and frequency characteristic adjustment circuit 20 by the same high pass filter 50 as the high pass filter 18, and the same low pass filter as the low pass filter 34. 52, signals other than the UHF band and VHF band terrestrial television broadcast signals are removed from the output signal of the amplification and frequency characteristic adjusting circuit 36, and these are synthesized and transmitted to the in-building CATV 30.

この光受信機では、フォトダイオード２の両端から、それぞれ混合信号を取り出し、ハイパスフィルタ１８及びローパスフィルタ３４によって、衛星放送及び衛星通信中間周波信号とＵＨＦ帯及びＶＨＦ帯地上波テレビジョン放送信号とを個別に取り出し、衛星放送及び衛星通信中間周波信号は、この信号専用の増幅及び周波数特性調整回路２０で、ＵＨＦ帯及びＶＨＦ帯地上波テレビジョン放送信号は、この信号専用の増幅及び周波数特性調整回路３６によってそれぞれ処理している。従って、フォトダイオード２の一端から混合信号を取り出して、その混合信号を２分配して、ハイパスフィルタ１８及びローパスフィルタ３４に供給する必要が無く、構成を簡略化することができる上に、分配器による分配損失が混合信号に生じず、Ｃ／Ｎ比を良好にすることができる。   In this optical receiver, the mixed signal is taken out from both ends of the photodiode 2, and the satellite broadcast and satellite communication intermediate frequency signals and the UHF band and VHF band terrestrial television broadcast signals are output by the high pass filter 18 and the low pass filter 34. Individually extracted satellite broadcasting and satellite communication intermediate frequency signals are amplified and frequency characteristic adjustment circuit 20 dedicated to this signal, and UHF band and VHF band terrestrial television broadcast signals are dedicated to this signal amplification and frequency characteristic adjustment circuit. 36 respectively. Therefore, it is not necessary to take out the mixed signal from one end of the photodiode 2 and distribute the mixed signal into two and supply the mixed signal to the high-pass filter 18 and the low-pass filter 34, and the configuration can be simplified. The distribution loss due to is not generated in the mixed signal, and the C / N ratio can be improved.

上記の実施の形態では、フォトダイオード２のカソード側の混合信号からハイパスフィルタ１８によって衛星放送及び衛星通信中間周波信号を取り出し、フォトダイオード２のアノード側の混合信号からＵＨＦ帯及びＶＨＦ帯の地上波テレビジョン放送信号をローパスフィルタ３４によって取り出したが、逆にフォトダイオード２のカソード側の混合信号からＵＨＦ帯及びＶＨＦ帯の地上波テレビジョン放送信号をローパスフィルタ３４によって取り出し、フォトダイオード２のアノード側の混合信号からハイパスフィルタ１８によって衛星放送及び衛星通信中間周波信号を取り出すこともできる。上記の実施の形態では、バイアス回路と負荷用の高周波阻止コイル６、１２を別途に設けたが、バイアス回路の一部の構成要素を負荷として使用することもできる。例えば中間タップ付き高周波阻止コイル４とバイアス用高周波阻止コイル６とに代えて抵抗器を設け、この抵抗器とフォトダイオード２のカソードとの接続点から混合信号を取り出し、中間タップ付き高周波阻止コイル１０、バイアス用高周波阻止コイル１２及びバイアス用抵抗器１４に代えて抵抗器を設け、この抵抗器とフォトダイオード２のアノードとの接続点から混合信号を取り出すことも可能である。上記の実施形態では、増幅及び周波数特性調整回路２０、３６ではチルト回路２８、４４を使用したが、これに代えてＢＯＮ回路を使用することもできるし、或いはチルト回路２８、４４を除去して、増幅のみ行うように構成することもできる。また、上記の実施の形態では、ハイパスフィルタ１８、５０、ローパスフィルタ３４、５２を使用したが、ハイパスフィルタ１８、５０に代えて、衛星放送及び衛星通信中間周波信号を通過させるバンドパスフィルタを使用し、ローパスフィルタ３４、５２に代えて、ＵＨＦ帯及びＶＨＦ帯地上波テレビジョン放送信号を通過させるバンドパスフィルタを使用することもできる。   In the above embodiment, satellite broadcast and satellite communication intermediate frequency signals are extracted from the mixed signal on the cathode side of the photodiode 2 by the high-pass filter 18, and UHF band and VHF band ground waves are extracted from the mixed signal on the anode side of the photodiode 2. The television broadcast signal was extracted by the low-pass filter 34, but the UHF band and VHF band terrestrial television broadcast signals were extracted from the mixed signal on the cathode side of the photodiode 2 by the low-pass filter 34, and the anode side of the photodiode 2 Satellite broadcast and satellite communication intermediate frequency signals can be extracted from the mixed signal by the high-pass filter 18. In the above embodiment, the bias circuit and the load high-frequency blocking coils 6 and 12 are separately provided. However, some components of the bias circuit may be used as a load. For example, a resistor is provided in place of the high frequency blocking coil 4 with intermediate tap and the high frequency blocking coil 6 for bias, and a mixed signal is taken out from the connection point between this resistor and the cathode of the photodiode 2, and the high frequency blocking coil 10 with intermediate tap is obtained. It is also possible to provide a resistor in place of the high frequency blocking coil 12 for bias and the resistor 14 for bias, and to extract a mixed signal from the connection point between this resistor and the anode of the photodiode 2. In the above embodiment, the tilt circuits 28 and 44 are used in the amplification and frequency characteristic adjustment circuits 20 and 36. However, a BON circuit can be used instead, or the tilt circuits 28 and 44 are removed. Alternatively, it may be configured to perform only amplification. In the above embodiment, the high-pass filters 18 and 50 and the low-pass filters 34 and 52 are used. However, instead of the high-pass filters 18 and 50, band-pass filters that pass satellite broadcast and satellite communication intermediate frequency signals are used. In place of the low-pass filters 34 and 52, band-pass filters that allow UHF band and VHF band terrestrial television broadcast signals to pass therethrough may be used.

本発明の１実施形態の光受信機のブロック図である。It is a block diagram of the optical receiver of one Embodiment of this invention.

符号の説明Explanation of symbols

２ フォトダイオード（受光素子）
４ 中間タップ付き高周波阻止コイル（第１の負荷）
１０ 中間タップ付き高周波阻止コイル（第２の負荷）
１８ ハイパスフィルタ（第１の抽出手段）
２０ 増幅及び周波数特性調整回路（第１の処理手段）
３４ ローパスフィルタ（第２の抽出手段）
３６ 増幅及び周波数特性調整回路（第２の処理手段） 2 Photodiode (light receiving element)
4 High frequency blocking coil with intermediate tap (first load)
10 High frequency blocking coil with intermediate tap (second load)
18 High pass filter (first extraction means)
20 Amplification and frequency characteristic adjustment circuit (first processing means)
34 Low-pass filter (second extraction means)
36 Amplification and frequency characteristic adjustment circuit (second processing means)

Claims (3)

第１及び第２の周波数帯の高周波信号の混合信号で変調された光信号を受光する２端子の光受光素子と、
この光受光素子を挟んで直列に接続され、第１及び第２の周波数帯の高周波信号の混合信号を生じる第１及び第２の負荷と、
第１の負荷に接続され、第１の負荷に生じた前記混合信号から第１の周波数帯の高周波信号を抽出する第１の抽出手段と、
第２の負荷に接続され、第２の負荷に生じた前記混合信号から第２の周波数帯の高周波信号を抽出する第２の抽出手段と、
第１の抽出手段に接続され、第１の抽出手段から出力された第１の周波数帯の高周波信号を処理する第１の処理手段と、
第２の抽出手段に接続され、第２の抽出手段から出力された第２の周波数帯の高周波信号を処理する第２の処理手段と、
第１及び第２の処理手段の出力信号を合成する合成手段とを、
具備する光受信機。 A two-terminal light-receiving element that receives an optical signal modulated by a mixed signal of high-frequency signals in the first and second frequency bands;
A first load and a second load connected in series with the light receiving element sandwiched therebetween to generate a mixed signal of high-frequency signals in the first and second frequency bands;
A first extraction unit connected to a first load and extracting a high-frequency signal in a first frequency band from the mixed signal generated in the first load;
A second extraction means connected to a second load for extracting a high-frequency signal in a second frequency band from the mixed signal generated in the second load;
A first processing means connected to the first extraction means for processing a high-frequency signal in the first frequency band output from the first extraction means;
A second processing means connected to the second extraction means for processing a high-frequency signal in the second frequency band output from the second extraction means;
Combining means for combining the output signals of the first and second processing means;
Optical receiver provided. 請求項１記載の光受信機において、第１の処理手段は、第１の周波数帯の高周波信号の周波数特性を調整する第１の調整手段を含み、第２の処理手段は、第２の周波数帯の高周波信号の周波数特性を調整する第２の調整手段を含み、前記合成手段は、伝送系に接続される光受信機。   2. The optical receiver according to claim 1, wherein the first processing means includes first adjusting means for adjusting a frequency characteristic of the high-frequency signal in the first frequency band, and the second processing means is the second frequency. An optical receiver including second adjusting means for adjusting a frequency characteristic of the high-frequency signal of the band, wherein the combining means is connected to a transmission system. 請求項２記載の光受信機において、第１及び第２の周波数帯の高周波信号が、テレビジョン放送信号であって、前記伝送系が伝送線路を使用した共同受信システムに伝送される光受信機。   3. The optical receiver according to claim 2, wherein the high-frequency signals in the first and second frequency bands are television broadcast signals, and the transmission system is transmitted to a joint reception system using a transmission line. .
JP2006007029A 2006-01-16 2006-01-16 Optical receiver Pending JP2007189571A (en)

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