JP3601601B2

JP3601601B2 - Simultaneous bidirectional transmission system and method for adjusting phase difference between transmitted and received waveforms in simultaneous bidirectional transmission system

Info

Publication number: JP3601601B2
Application number: JP2003034991A
Authority: JP
Inventors: 孝之山
Original assignee: NEC Corp
Current assignee: NEC Corp
Priority date: 2003-02-13
Filing date: 2003-02-13
Publication date: 2004-12-15
Anticipated expiration: 2023-02-13
Also published as: JP2004247917A

Description

【０００１】
【発明の属する技術分野】
本発明は、同時双方向伝送システム、および同時双方向伝送システムにおける送受信波形の位相差調整方法に関する。
【０００２】
【従来の技術】
同時双方向伝送システムは、同一の伝送路の両端に接続された同時双方向伝送回路間で、該伝送路を介して自局の送信信号および対向局からの受信信号を同時に送受信するシステムである（例えば、特許文献１参照）。
【０００３】
この種の同時双方向伝送システムは、複数の信号を送受信する半導体集積回路（以下、ＬＳＩと称する）間の信号伝送に必要とされる伝送路の数を削減することができるため、ＬＳＩに特に有効に適用される。
【０００４】
【特許文献１】
特開２００２−３１４５１５号公報
【０００５】
【発明が解決しようとする課題】
しかしながら、従来の同時双方向伝送システムにおいては、対向局から伝送路を介して自局に送信されてくる受信信号の波形は、伝送路の損失によって波形鈍りが生じる。この対向局からの受信信号の波形と自局の送信信号の波形の遷移タイミング（信号が“０”から“１”に遷移するタイミング、または“１”から“０”に遷移するタイミング）が重なると、遷移時間の違いにより、データパターンによって対向局からの受信信号の波形にノイズ状の電圧変動が現れる。
【０００６】
そのため、ＬＳＩとしての同時双方向伝送回路や伝送路の特性ばらつきやノイズにより、受信信号の遷移タイミングに時間的変動が生じ、動作速度の上限が低くなったり、データ化けの原因となったりすることがあった。
【０００７】
そこで、本発明の目的は、高速伝送を行う場合でも安定した伝送を行うことができる同時双方向伝送システム、および同時双方向伝送システムにおける送受信波形の位相差調整方法を提供することにある。
【０００８】
【課題を解決するための手段】
上記目的を達成するために本発明の同時双方向伝送システムは、
同一の伝送路の両端に配置された同時双方向伝送回路の各々が前記伝送路に接続された送信回路および受信回路を有し、前記同時双方向伝送回路間で前記送信回路および前記受信回路により前記伝送路を介して送信信号および受信信号を同時に送受信する同時双方向伝送システムにおいて、
前記同時双方向伝送回路の少なくとも一方は、
前記送信回路の前段に配置され、外部入力される遅延設定値により設定された遅延量だけ自局の送信信号を遅延させて出力する遅延回路と、
前記遅延回路から出力された自局の送信信号に対して前記送信回路と同一の処理を施すことにより、自局と前記伝送路との接続点での自局の送信信号を擬似的に生成して出力する擬似送信回路と、
前記擬似送信回路から出力された自局の送信信号と前記受信回路から出力された対向局からの受信信号の位相を比較し、該位相比較結果を出力する位相比較回路と、
位相調整時に、前記遅延回路に出力する前記遅延設定値を変化させ、変化させた前記遅延設定値と前記位相比較回路から出力された前記位相比較結果との関係に基づいて、自局の送信信号の波形と対向局からの受信信号の波形の遷移タイミングが重ならないように前記遅延調整値を調整する遅延調整回路とを有することを特徴とするものである。
【０００９】
この構成によれば、自局の送信信号に遅延を与えることとし、その遅延量を自局の送信信号の波形と対向局からの受信信号の波形の遷移タイミングが重ならないように調整しているため、送受信波形の遷移タイミングが重なることを回避することが可能となる。
【００１０】
また、前記位相比較回路は、前記擬似送信回路から出力された自局の送信信号のエッジを用いて前記受信回路から出力された対向局からの受信信号をラッチしたものを前記位相比較結果として出力するか、または前記受信回路から出力された対向局からの受信信号のエッジを用いて前記擬似送信回路から出力された自局の送信信号をラッチしたものを前記位相比較結果として出力することとしても良い。
【００１１】
また、前記遅延調整回路は、位相調整時に、前記遅延回路に出力する前記遅延設定値を“０”から徐々に大きくし、前記位相比較回路から出力された前記位相比較結果が変化を開始した時点の前記遅延設定値と当該変化状態が元の状態に戻った時点の前記遅延設定値との中間値に前記遅延設定値を調整することとしても良い。
【００１２】
上記目的を達成するために本発明の同時双方向伝送システムにおける送受信波形の位相差調整方法は、
同一の伝送路の両端に接続された同時双方向伝送回路間で前記伝送路を介して送信信号および受信信号を同時に送受信する同時双方向伝送システムにおける送受信波形の位相差調整方法において、
前記同時双方向伝送回路の一方にて、
自局と前記伝送路との接続点に自局の送信信号が達する前段で、該自局の送信信号を遅延設定値により設定された遅延量だけ遅延させる第１のステップと、
前記第１のステップにて遅延した自局の送信信号を用いて、自局と前記伝送路との接続点での自局の送信信号を擬似的に生成する第２のステップと、
前記第２のステップにて擬似的に生成された自局の送信信号と対向局からの受信信号の位相を比較する第３のステップと、
前記遅延設定値を変化させ、変化させた前記遅延設定値と前記第３のステップにおける位相比較結果との関係に基づいて、自局の送信信号の波形と対向局からの受信信号の波形の遷移タイミングが重ならないように前記遅延調整値を調整する第４のステップとを実行することを特徴とするものである。
【００１３】
また、前記第３のステップでは、前記第２のステップにて擬似的に生成された自局の送信信号のエッジを用いて対向局からの受信信号をラッチしたものを前記位相比較結果とするか、または対向局からの受信信号のエッジを用いて前記第２のステップにて擬似的に生成された自局の送信信号をラッチしたものを前記位相比較結果とすることとしても良い。
【００１４】
また、前記第４のステップでは、前記遅延設定値を“０”から徐々に大きくし、前記位相比較結果が変化を開始した時点の前記遅延設定値と当該変化状態が元の状態に戻った時点の前記遅延設定値との中間値に前記遅延設定値を調整することとしても良い。
【００１５】
【発明の実施の形態】
以下に、本発明の実施の形態について図面を参照して説明する。
【００１６】
図１は、本発明の一実施形態の同時双方向伝送システムを示すブロック図である。
【００１７】
図１を参照すると、本発明の一実施形態の同時双方向伝送システムは、ｎ本のデータ信号線３および２本のストローブ信号線４の両端に接続された同時双方向伝送回路１，２を有しており、同時双方向伝送回路１，２間では、ｎビット幅のデータ信号をｎ本のデータ信号線３を介して同時に送受信するとともに、正補２種のストローブ信号を２本のストローブ信号線４を介して同時に送受信する。なお、ｎ本のデータ信号線３と２本のストローブ信号線４は等長配線とする。
【００１８】
同時双方向伝送回路１，２は、データ信号についての内部構成要素として、自局のデータ信号をデータ信号線３を介して対向局に送信する送信回路１０，２０と、自局のデータ信号と対向局からデータ信号線３を介して送信されてきたデータ信号とが合成された合成信号を受信し、受信した合成信号のうち対向局からのデータ信号のみを抽出して出力する受信回路１１，２１と、自局のデータ信号と対向局からのデータ信号との位相差調整を行う出力遅延調整回路１５，２５と、をそれぞれｎ個づつ有している。
【００１９】
さらに、同時双方向伝送回路１，２は、ストローブ信号についての内部構成要素として、自局のストローブ信号をストローブ信号線４を介して対向局に送信する送信回路１２，２２と、自局のストローブ信号と対向局からストローブ信号線４を介して送信されてきたストローブ信号とが合成された合成信号を受信し、受信した合成信号のうち対向局からのストローブ信号のみを抽出して出力する受信回路１３，２３と、自局のストローブ信号と対向局からのストローブ信号との位相差調整を行う出力遅延調整回路１６，２６と、をそれぞれ２個づつ有している。
【００２０】
その他、同時双方向伝送回路１，２は、データ信号についてのＦＦ（ＦｌｉｐＦｌｏｐ）１７，２７をｎ個づつ有し、ストローブ信号についてのＦＦ１８，２８を２個づつ有し、ストローブ信号を書込みクロックとしてデータ信号を書込むＦＩＦＯ（Ｆｉｒｓｔ−ＩｎＦｉｒｓｔ−Ｏｕｔ）１４，２４をｎ個づつ有している。
【００２１】
図２は、図１に示した出力遅延調整回路１５，１６，２５，２６の一構成例を示すブロック図である。
【００２２】
図２を参照すると、出力遅延調整回路１５，１６，２５，２６は、遅延回路１００と、擬似送信回路１０１と、位相比較回路（ＦＦ）１０２と、遅延調整回路１０３とを有している。
【００２３】
遅延回路１００は、外部入力される遅延量設定値により遅延量が可変し、遅延量設定値により設定された遅延量だけ自局の送信信号を遅延させて出力する。なお、遅延回路１００は、その遅延量の最大値を、対向局からの受信信号の遷移部分を必ず含むように伝送クロックの１周期分よりも大きくすることができる。
【００２４】
擬似送信回路１０１は、送信回路１０，１２，２０，２２の代わりに設けられたものであり、遅延回路１００から出力された自局の送信信号に対し、送信回路１０，１２，２０，２２と同様の処理を施すことにより自局の同時双方向伝送回路１，２と伝送路（データ信号線３、ストローブ信号線４）との接続点（Ｄ１点、Ｓ１点、Ｄ２点、Ｓ２点）での自局の送信信号を擬似的に生成して出力する。
【００２５】
本来、同時双方向伝送回路１，２では、自局の送信信号と対向局からの受信信号の位相差調整を行う場合、自局の同時双方向伝送回路１，２と伝送路との接続点での位相差について調整を行うべきである。しかしながら、この接続点に出力遅延調整回路１５，１６，２５，２６を組み込むことは、信号電圧レベルが内部論理回路と異なる等の理由により一般にできない。
【００２６】
そのため、本発明では、自局の同時双方向伝送回路１，２と伝送路との接続点での位相差について調整を行う代わりに、出力遅延調整回路１５，１６，２５，２６内の擬似送信回路１０１にて擬似的に生成された自局の送信信号と受信回路１１，１３，２１，２３から出力された対向局からの受信信号との位相差について調整を行うこととしている。
【００２７】
位相比較回路１０２は、ＦＦで構成され、擬似送信回路１０１から出力された自局の送信信号と受信回路１１，１３，２１，２３から出力された対向局からの受信信号の位相を比較し、その位相比較結果を出力する。なお、位相比較回路１０２は、擬似送信回路１０１から出力された自局の送信信号のエッジを用いて対向局からの受信信号をラッチしたものを位相比較結果として出力するか、あるいは対向局からの受信信号のエッジを用いて擬似送信回路１０１から出力された自局の送信信号をラッチしたものを位相比較結果として出力する。
【００２８】
遅延調整回路１０３は、位相調整時に、遅延回路１００に出力する遅延設定値を変化させ、変化させた遅延設定値と位相比較回路１０２から出力された位相比較結果との関係に基づいて、自局の送信信号の波形と対向局からの受信信号の波形の遷移タイミングが重ならないように遅延調整値を調整する。
【００２９】
以下、図１および図２に示した同時双方向伝送システムにおける送受信波形の位相差調整方法について説明する。ここでは、同時双方向伝送回路１側でデータ信号の送受信波形の位相差を調整する場合の位相差調整方法について説明する。
【００３０】
図３は、図１および図２に示した同時双方向伝送システムにおける送受信波形の位相差調整方法を説明するタイムチャートであり、（ａ）は同時双方向伝送回路１側でのデータ信号の位相差調整中に送受信波形の遷移タイミングが重なった場合の波形のタイムチャート、（ｂ）は同時双方向伝送回路１側でのデータ信号の位相差調整後の波形のタイムチャートである。
【００３１】
位相差調整時には、同時双方向伝送回路１，２の送信回路１０，２０では、“０”と“１”のデータ信号を繰返し同時に送信する。
【００３２】
このとき、対向局となる同時双方向伝送回路２の送信回路２０から出力された受信信号は、同時双方向伝送回路２とデータ信号線３との接続点Ｄ２では損失も遅延も殆ど無い状態であるが、データ信号線３を経て同時双方向伝送回路１とデータ信号線３との接続点Ｄ１に到達した時点ではデータ信号線３の損失のために波形鈍りや伝播遅延を伴った状態になっている。
【００３３】
一方、自局となる同時双方向伝送回路１の送信回路１０から出力された送信信号は、同時双方向伝送回路１とデータ信号線３との接続点Ｄ１では損失も遅延も殆ど無い状態になっている。
【００３４】
同時双方向伝送回路１とデータ信号線３との接続点Ｄ１では、送信回路１０の出力である自局の送信信号と同時双方向伝送回路２の送信回路２０の出力である対向局からの受信信号とが合成され、その合成信号が同時双方向伝送回路１の受信回路１１にて受信され、受信回路１１では、接続点Ｄ１での合成信号のうち対向局からの受信信号のみを抽出して出力遅延調整回路１５に出力する。
【００３５】
例えば、図３（ａ）に示すように、接続点Ｄ１において、送信回路１０の出力である自局の送信信号と、送信回路２０の出力である対向局からの受信信号の波形の遷移タイミングが重なった場合、ＦＩＦＯ１４に入力される受信データの波形は、ＬＳＩ（同時双方向伝送回路１，２）やデータ信号線３の特性ばらつきやノイズによる影響が非常に大きくなる。
【００３６】
ここで、遅延調整回路１０３は、遅延回路１００に出力する遅延設定値を初期値“０”から徐々に大きくしていく。すると、図４に示すように、位相比較回路１０２から出力された位相比較結果には、“０”から変化を開始する点と、当該変化状態から元の状態“０”に戻る点の２つの変化点が現れる。２つの変化点における遅延設定値をそれぞれＡ，Ｂとすると、遅延量設定値がＡからＢの間にある時は、接続点Ｄ１において自局の送信信号の波形と対向局からの受信信号の波形の遷移タイミングが重なる時であると考えられる。
【００３７】
そのため、遅延調整回路１０３は、自局の送信信号の波形と対向局からの受信信号の波形の遷移タイミングが重ならないように、遅延設定値を遅延設定値Ａ，Ｂの中間値に調整する。例えば、遅延設定値Ａ＝０．４Ｔ、遅延設定値Ｂ＝１．４Ｔである場合、遅延設定値Ａ，Ｂの中間値は、（０．４Ｔ＋１．４Ｔ）／２＝０．９Ｔとなる。
【００３８】
その後、遅延調整回路１０３は、上記で調整した遅延設定値を遅延回路１００に出力し、データ信号の送受信波形の位相差調整が完了する。
【００３９】
以降、図３（ｂ）に示すように、同時双方向伝送回路１では、自局の送信信号を上記で調整した遅延量だけ遅延させることで、同時双方向伝送回路１とデータ信号線３との接続点Ｄ１において送受信波形の遷移タイミングが重なることを回避することができる。それにより、ＦＩＦＯ１４に入力される受信データの波形は、ＬＳＩ（同時双方向伝送回路１，２）やデータ信号線３の特性ばらつきやノイズによる影響が小さくなる。
【００４０】
なお、本実施形態においては、同時双方向伝送回路２側で上記と同様にデータ信号の位相差調整を行っても同様の効果が得られるが、同時双方向伝送回路１，２のいずれか一方でデータ信号の位相差調整を行うことのみで、同時双方向伝送回路１，２の双方でデータ信号の送受信波形の遷移タイミングが重なることを回避できる。すなわち、同時双方向伝送回路１，２のいずれか一方にのみデータ信号の出力遅延回路を設けて位相差調整を行っても、同時双方向伝送回路１，２の双方でデータ信号の送受信波形の遷移タイミングが重なることを回避できる。
【００４１】
また、本実施形態においては、データ信号の送受信波形の位相差調整方法について説明したが、ストローブ信号の送受信波形の位相差を調整する場合も、同時双方向伝送回路１，２のいずれか一方で上記と同様にストローブ信号の位相差調整を行うことのみで、同時双方向伝送回路１，２の双方でストローブ信号の送受信波形の遷移タイミングが重なることを回避できる。すなわち、同時双方向伝送回路１，２のいずれか一方にのみストローブ信号の出力遅延回路を設けて位相差調整を行っても、同時双方向伝送回路１，２の双方でストローブ信号の送受信波形の遷移タイミングが重なることを回避できる。
【００４２】
また、本実施形態においては、出力遅延回路１５，１６，２５，２６の構成は図２の構成に限定されず、図５のような構成にすることが可能である。
【００４３】
図５に示した出力遅延調整回路１５，１６，２５，２６は、図２の構成に対して、遅延調整回路１０３を取り除き、遅延量設定値入力と位相比較結果出力を外部に引き出した点が異なる。
【００４４】
この場合、出力遅延調整回路１５，１６，２５，２６の外部で位相差調整機能を実現しなければならないが、本発明に含まれない他の機能、例えば、遅延回路１００の遅延量を手動で設定する機能、ビット間スキューを調整する機能などを自由に拡張することができるという利点がある。
【００４５】
【発明の効果】
以上説明したように本発明においては、自局の送信信号に遅延を与えることとし、その遅延量を自局の送信信号の波形と対向局からの受信信号の波形の遷移タイミングが重ならないように調整しているため、送受信波形の遷移タイミングが重なることを回避することができる。
【００４６】
したがって、ＬＳＩとしての同時双方向伝送回路や伝送路の特性ばらつきやノイズによる受信信号の時間的変動を抑えることができ、それにより、高速伝送でも安定した伝送を行うことができるようになる。
【図面の簡単な説明】
【図１】本発明の一実施形態の同時双方向伝送システムを示すブロック図である。
【図２】図１に示した出力遅延調整回路の一構成例を示すブロック図である。
【図３】図１および図２に示した同時双方向伝送システムにおける送受信波形の位相差調整方法を説明するタイムチャートであり、（ａ）は同時双方向伝送回路１側でのデータ信号の位相差調整中に送受信波形の遷移タイミングが重なった場合の波形のタイムチャート、（ｂ）は同時双方向伝送回路１側でのデータ信号の位相差調整後の波形のタイムチャートである。
【図４】図２に示した遅延調整回路における遅延量設定値の調整方法を説明する図である。
【図５】図１に示した出力遅延調整回路の他の構成例を示すブロック図である。
【符号の説明】
１，２同時双方向伝送回路
３データ信号線
４ストローブ信号線
１０，１２，２０，２２送信回路
１１，１３，２１，２３受信回路
１４，２４ＦＩＦＯ
１５，１６，２５，２６出力遅延調整回路
１７，１８，２７，２８ＦＦ
１００遅延回路
１０１擬似送信回路
１０２位相比較回路（ＦＦ）
１０３遅延調整回路[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a simultaneous bidirectional transmission system and a method for adjusting a phase difference between transmitted and received waveforms in the simultaneous bidirectional transmission system.
[0002]
[Prior art]
The simultaneous bidirectional transmission system is a system for simultaneously transmitting and receiving a transmission signal of the own station and a reception signal from the opposite station via the transmission path between simultaneous bidirectional transmission circuits connected to both ends of the same transmission path. (For example, see Patent Document 1).
[0003]
This type of simultaneous bidirectional transmission system can reduce the number of transmission paths required for signal transmission between semiconductor integrated circuits (hereinafter, referred to as LSI) that transmit and receive a plurality of signals. Effectively applied.
[0004]
[Patent Document 1]
JP-A-2002-314515
[Problems to be solved by the invention]
However, in the conventional simultaneous bidirectional transmission system, the waveform of the received signal transmitted from the opposite station to the own station via the transmission path is blunt due to the loss of the transmission path. The transition timing of the waveform of the reception signal from the opposite station and the transition timing of the waveform of the transmission signal of the own station (timing when the signal transitions from “0” to “1” or transition timing from “1” to “0”) overlap. Due to the difference in the transition time, a noise-like voltage fluctuation appears in the waveform of the signal received from the opposite station depending on the data pattern.
[0006]
As a result, due to variations in characteristics and noise of the simultaneous bidirectional transmission circuit and transmission line as an LSI, a temporal variation occurs in the transition timing of the received signal, thereby lowering the upper limit of the operation speed and causing data corruption. was there.
[0007]
Accordingly, an object of the present invention is to provide a simultaneous bidirectional transmission system capable of performing stable transmission even when performing high-speed transmission, and a method of adjusting a phase difference between transmitted and received waveforms in the simultaneous bidirectional transmission system.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a simultaneous two-way transmission system of the present invention comprises:
Each of the simultaneous bidirectional transmission circuits disposed at both ends of the same transmission line has a transmission circuit and a reception circuit connected to the transmission line, and the transmission circuit and the reception circuit are provided between the simultaneous bidirectional transmission circuits. In a simultaneous two-way transmission system for simultaneously transmitting and receiving a transmission signal and a reception signal via the transmission path,
At least one of the simultaneous bidirectional transmission circuits,
A delay circuit that is arranged in front of the transmission circuit and delays and outputs a transmission signal of its own station by a delay amount set by a delay setting value input externally,
By performing the same processing as that of the transmission circuit on the transmission signal of the own station output from the delay circuit, a transmission signal of the own station at a connection point between the own station and the transmission line is pseudo-generated. A pseudo transmission circuit for outputting
A phase comparison circuit that compares the phase of the transmission signal of the own station output from the pseudo transmission circuit and the phase of the reception signal from the opposite station output from the reception circuit, and outputs the phase comparison result,
At the time of phase adjustment, the delay setting value output to the delay circuit is changed, and based on the relationship between the changed delay setting value and the phase comparison result output from the phase comparison circuit, the transmission signal of the own station is changed. And a delay adjustment circuit for adjusting the delay adjustment value so that the transition timing of the waveform of the received signal from the opposite station does not overlap with the waveform of the received signal.
[0009]
According to this configuration, a delay is given to the transmission signal of the own station, and the delay amount is adjusted so that the transition timing of the waveform of the transmission signal of the own station does not overlap with the transition timing of the waveform of the reception signal from the opposite station. Therefore, it is possible to avoid overlapping of the transition timings of the transmission and reception waveforms.
[0010]
Further, the phase comparison circuit latches a reception signal from the opposite station output from the reception circuit using an edge of the transmission signal of the own station output from the pseudo transmission circuit and outputs the result as the phase comparison result. Or, by using the edge of the reception signal from the opposite station output from the reception circuit and latching the transmission signal of the own station output from the pseudo transmission circuit using the edge, and outputting the result as the phase comparison result. good.
[0011]
Further, at the time of phase adjustment, the delay adjustment circuit gradually increases the delay set value output to the delay circuit from “0”, and sets the time when the phase comparison result output from the phase comparison circuit starts to change. The delay set value may be adjusted to an intermediate value between the delay set value and the delay set value when the change state returns to the original state.
[0012]
In order to achieve the above object, a method for adjusting the phase difference of a transmission / reception waveform in a simultaneous two-way transmission system of the present invention includes:
In a simultaneous bidirectional transmission system for simultaneously transmitting and receiving a transmission signal and a reception signal via the transmission path between simultaneous bidirectional transmission circuits connected to both ends of the same transmission path, a phase difference adjustment method of a transmission / reception waveform,
In one of the simultaneous bidirectional transmission circuits,
A first step of delaying a transmission signal of the own station by a delay amount set by a delay setting value before a transmission signal of the own station reaches a connection point between the own station and the transmission line;
A second step of pseudo-generating a transmission signal of the own station at a connection point between the own station and the transmission line using the transmission signal of the own station delayed in the first step;
A third step of comparing the phase of the transmission signal of the own station pseudo-generated in the second step with the phase of the reception signal from the opposite station;
The delay setting value is changed, and the waveform of the transmission signal of the own station and the transition of the waveform of the reception signal from the opposite station are changed based on the relationship between the changed delay setting value and the phase comparison result in the third step. And a fourth step of adjusting the delay adjustment value so that the timings do not overlap.
[0013]
In the third step, whether a signal obtained by latching a reception signal from the opposite station using the edge of the transmission signal of the own station pseudo-generated in the second step is used as the phase comparison result or not. Alternatively, the phase comparison result may be obtained by latching the transmission signal of the own station which is pseudo-generated in the second step using the edge of the reception signal from the opposite station.
[0014]
In the fourth step, the delay set value is gradually increased from “0”, and the delay set value at the time when the phase comparison result starts to change and the time when the change state returns to the original state The delay setting value may be adjusted to an intermediate value with the delay setting value.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0016]
FIG. 1 is a block diagram showing a simultaneous bidirectional transmission system according to an embodiment of the present invention.
[0017]
Referring to FIG. 1, a simultaneous bidirectional transmission system according to one embodiment of the present invention includes simultaneous bidirectional transmission circuits 1 and 2 connected to both ends of n data signal lines 3 and two strobe signal lines 4. The simultaneous bidirectional transmission circuits 1 and 2 simultaneously transmit and receive an n-bit width data signal through n data signal lines 3 and transmit two types of strobe signals of two complementary types to two strobe signals. Transmission and reception are performed simultaneously via the signal line 4. The n data signal lines 3 and the two strobe signal lines 4 are of equal length.
[0018]
The simultaneous bidirectional transmission circuits 1 and 2 include, as internal components of the data signal, transmission circuits 10 and 20 for transmitting the data signal of the own station to the opposite station via the data signal line 3, and the data signals of the own station. A receiving circuit 11 for receiving a combined signal obtained by combining the data signal transmitted from the opposite station via the data signal line 3 and extracting and outputting only the data signal from the opposite station among the received combined signals; 21 and n output delay adjusting circuits 15 and 25 for adjusting the phase difference between the data signal of the own station and the data signal from the opposite station.
[0019]
Further, the simultaneous bidirectional transmission circuits 1 and 2 include, as internal components for the strobe signal, transmission circuits 12 and 22 for transmitting the strobe signal of the own station to the opposite station via the strobe signal line 4, and the strobe signal of the own station. A receiving circuit for receiving a combined signal obtained by combining a signal and a strobe signal transmitted from the opposite station via the strobe signal line 4 and extracting and outputting only a strobe signal from the opposite station in the received combined signal 13 and 23, and two output delay adjusting circuits 16 and 26 for adjusting the phase difference between the strobe signal of the own station and the strobe signal from the opposite station.
[0020]
In addition, the simultaneous bidirectional transmission circuits 1 and 2 have n flip-flops (FFs) 17 and 27 for data signals, two FFs 18 and 28 for strobe signals, and write strobe signals to write clocks. And n (first-in first-out) FIFOs 14 and 24 for writing data signals.
[0021]
FIG. 2 is a block diagram showing one configuration example of the output delay adjustment circuits 15, 16, 25, and 26 shown in FIG.
[0022]
Referring to FIG. 2, the output delay adjustment circuits 15, 16, 25, and 26 include a delay circuit 100, a pseudo transmission circuit 101, a phase comparison circuit (FF) 102, and a delay adjustment circuit 103.
[0023]
The delay circuit 100 varies the delay amount according to the delay amount setting value input from the outside, delays the transmission signal of the own station by the delay amount set by the delay amount setting value, and outputs the signal. The delay circuit 100 can make the maximum value of the delay amount larger than one cycle of the transmission clock so as to always include the transition portion of the signal received from the opposite station.
[0024]
The pseudo transmission circuit 101 is provided in place of the transmission circuits 10, 12, 20, and 22. The pseudo transmission circuit 101 receives the transmission signals of its own station output from the delay circuit 100 and transmits the pseudo signals to the transmission circuits 10, 12, 20, and 22. By performing similar processing, connection points (points D1, S1, D2, and S2) between the simultaneous bidirectional transmission circuits 1 and 2 of the own station and the transmission lines (data signal line 3, strobe signal line 4) are obtained. Pseudo-generates and outputs the transmission signal of its own station.
[0025]
Originally, when the simultaneous bidirectional transmission circuits 1 and 2 adjust the phase difference between the transmission signal of the own station and the reception signal from the opposite station, the connection point between the simultaneous bidirectional transmission circuits 1 and 2 of the own station and the transmission line Should be adjusted for the phase difference at. However, it is generally not possible to incorporate the output delay adjusting circuits 15, 16, 25, 26 at this connection point because the signal voltage level is different from that of the internal logic circuit.
[0026]
Therefore, in the present invention, instead of adjusting the phase difference at the connection point between the simultaneous bidirectional transmission circuits 1 and 2 of the own station and the transmission line, the pseudo transmission in the output delay adjustment circuits 15, 16, 25 and 26 is performed. The phase difference between the transmission signal of the own station simulated by the circuit 101 and the reception signal from the opposite station output from the reception circuits 11, 13, 21, and 23 is adjusted.
[0027]
The phase comparison circuit 102 is composed of an FF, compares the phase of the transmission signal of the own station output from the pseudo transmission circuit 101 with the phase of the reception signal output from the opposite station output from the reception circuits 11, 13, 21, and 23, The result of the phase comparison is output. Note that the phase comparison circuit 102 outputs a signal obtained by latching a reception signal from the opposite station using the edge of the transmission signal of the own station output from the pseudo transmission circuit 101 as a phase comparison result, or outputs the signal from the opposite station. It latches the transmission signal of its own station output from the pseudo transmission circuit 101 using the edge of the reception signal and outputs the result as a phase comparison result.
[0028]
The delay adjustment circuit 103 changes the delay setting value output to the delay circuit 100 at the time of phase adjustment, and based on the relationship between the changed delay setting value and the phase comparison result output from the phase comparison circuit 102, The delay adjustment value is adjusted so that the transition timing of the waveform of the transmission signal does not overlap with the transition timing of the waveform of the reception signal from the opposite station.
[0029]
Hereinafter, a method of adjusting the phase difference between the transmission and reception waveforms in the simultaneous bidirectional transmission system shown in FIGS. 1 and 2 will be described. Here, a method of adjusting the phase difference in the case where the phase difference of the transmission / reception waveform of the data signal is adjusted on the side of the simultaneous bidirectional transmission circuit 1 will be described.
[0030]
FIG. 3 is a time chart for explaining a method of adjusting the phase difference between the transmission and reception waveforms in the simultaneous bidirectional transmission system shown in FIGS. 1 and 2, wherein (a) shows the position of the data signal in the simultaneous bidirectional transmission circuit 1. FIG. 6B is a time chart of a waveform when the transition timing of the transmission / reception waveform overlaps during the phase difference adjustment, and FIG. 7B is a time chart of the waveform after the phase difference adjustment of the data signal on the side of the simultaneous bidirectional transmission circuit 1.
[0031]
At the time of the phase difference adjustment, the transmission circuits 10 and 20 of the simultaneous bidirectional transmission circuits 1 and 2 repeatedly and simultaneously transmit the data signals “0” and “1”.
[0032]
At this time, the reception signal output from the transmission circuit 20 of the simultaneous bidirectional transmission circuit 2 serving as the opposite station has almost no loss and no delay at the connection point D2 between the simultaneous bidirectional transmission circuit 2 and the data signal line 3. However, when the signal reaches the connection point D1 between the simultaneous bidirectional transmission circuit 1 and the data signal line 3 via the data signal line 3, the state is accompanied by waveform dulling and propagation delay due to the loss of the data signal line 3. ing.
[0033]
On the other hand, the transmission signal output from the transmission circuit 10 of the simultaneous bidirectional transmission circuit 1 serving as the local station has almost no loss or delay at the connection point D1 between the simultaneous bidirectional transmission circuit 1 and the data signal line 3. ing.
[0034]
At a connection point D 1 between the simultaneous bidirectional transmission circuit 1 and the data signal line 3, the transmission signal of the own station which is the output of the transmission circuit 10 and the reception from the opposite station which is the output of the transmission circuit 20 of the simultaneous bidirectional transmission circuit 2 The combined signal is received by the receiving circuit 11 of the simultaneous bidirectional transmission circuit 1, and the receiving circuit 11 extracts only the received signal from the opposite station from the combined signal at the connection point D1. Output to the output delay adjustment circuit 15.
[0035]
For example, as shown in FIG. 3A, at the connection point D1, the transition timing of the waveform of the transmission signal of the own station, which is the output of the transmission circuit 10, and the transition timing of the waveform of the reception signal from the opposite station, which is the output of the transmission circuit 20, If they overlap, the waveform of the received data input to the FIFO 14 is greatly affected by variations in the characteristics of LSIs (simultaneous bidirectional transmission circuits 1 and 2) and data signal lines 3 and noise.
[0036]
Here, the delay adjustment circuit 103 gradually increases the delay set value output to the delay circuit 100 from the initial value “0”. Then, as shown in FIG. 4, the phase comparison result output from the phase comparison circuit 102 includes two points, a point where the change starts from “0” and a point where the change state returns to the original state “0”. A change point appears. Assuming that the delay set values at the two change points are A and B, respectively, when the delay amount set value is between A and B, the waveform of the transmission signal of the own station and the waveform of the reception signal from the opposite station at the connection point D1. It is considered that the transition timings of the waveforms overlap.
[0037]
Therefore, the delay adjustment circuit 103 adjusts the delay setting value to an intermediate value between the delay setting values A and B so that the transition timing of the waveform of the transmission signal of the own station and the transition timing of the waveform of the reception signal from the opposite station do not overlap. For example, when the delay set value A = 0.4T and the delay set value B = 1.4T, the intermediate value between the delay set values A and B is (0.4T + 1.4T) /2=0.9T.
[0038]
Thereafter, the delay adjustment circuit 103 outputs the delay setting value adjusted as described above to the delay circuit 100, and the phase difference adjustment of the transmission / reception waveform of the data signal is completed.
[0039]
Thereafter, as shown in FIG. 3 (b), the simultaneous bidirectional transmission circuit 1 delays the transmission signal of the own station by the delay amount adjusted as described above, thereby connecting the simultaneous bidirectional transmission circuit 1 and the data signal line 3 to each other. At the connection point D1 of FIG. As a result, the waveform of the received data input to the FIFO 14 is less affected by variations in characteristics of the LSI (simultaneous bidirectional transmission circuits 1 and 2) and the data signal line 3 and noise.
[0040]
In this embodiment, the same effect can be obtained by adjusting the phase difference of the data signal on the side of the simultaneous bidirectional transmission circuit 2 in the same manner as described above. By simply adjusting the phase difference of the data signal, it is possible to avoid overlapping transition timings of the transmission and reception waveforms of the data signal in both the simultaneous bidirectional transmission circuits 1 and 2. That is, even if the output delay circuit for the data signal is provided only in one of the simultaneous bidirectional transmission circuits 1 and 2 to adjust the phase difference, the transmission / reception waveform of the data signal in both the simultaneous bidirectional transmission circuits 1 and 2 can be adjusted. Overlapping transition timings can be avoided.
[0041]
In the present embodiment, the method of adjusting the phase difference between the transmission and reception waveforms of the data signal has been described. However, when adjusting the phase difference between the transmission and reception waveforms of the strobe signal, one of the simultaneous bidirectional transmission circuits 1 and 2 may be used. Only by adjusting the phase difference of the strobe signal in the same manner as described above, it is possible to avoid overlapping transition timings of the transmission and reception waveforms of the strobe signal in both the simultaneous bidirectional transmission circuits 1 and 2. That is, even if the output delay circuit for the strobe signal is provided in only one of the simultaneous bidirectional transmission circuits 1 and 2 to adjust the phase difference, the transmission and reception waveform of the strobe signal is changed in both the simultaneous bidirectional transmission circuits 1 and 2. Overlapping transition timings can be avoided.
[0042]
Further, in the present embodiment, the configurations of the output delay circuits 15, 16, 25, and 26 are not limited to the configuration in FIG. 2, but can be configured as in FIG.
[0043]
The output delay adjustment circuits 15, 16, 25, and 26 shown in FIG. 5 are different from the configuration of FIG. 2 in that the delay adjustment circuit 103 is removed and the delay amount set value input and the phase comparison result output are extracted to the outside. different.
[0044]
In this case, the phase difference adjustment function must be realized outside the output delay adjustment circuits 15, 16, 25, and 26. However, other functions not included in the present invention, for example, the delay amount of the delay circuit 100 may be manually adjusted. There is an advantage that the setting function, the function of adjusting the skew between bits, and the like can be freely extended.
[0045]
【The invention's effect】
As described above, in the present invention, a delay is given to the transmission signal of the own station, and the amount of the delay is set so that the transition timing of the waveform of the transmission signal of the own station does not overlap with the transition timing of the waveform of the reception signal from the opposite station. Since the adjustment is performed, it is possible to prevent the transition timing of the transmission / reception waveform from overlapping.
[0046]
Therefore, it is possible to suppress a temporal variation of a received signal due to a variation in characteristics of a simultaneous bidirectional transmission circuit or a transmission line as an LSI or noise, thereby enabling stable transmission even at high speed transmission.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a simultaneous bidirectional transmission system according to an embodiment of the present invention.
FIG. 2 is a block diagram illustrating a configuration example of an output delay adjustment circuit illustrated in FIG. 1;
3A and 3B are time charts for explaining a method of adjusting a phase difference between transmission and reception waveforms in the simultaneous bidirectional transmission system shown in FIGS. 1 and 2; FIG. 3A shows a position of a data signal in the simultaneous bidirectional transmission circuit 1; FIG. 6B is a time chart of a waveform when the transition timing of the transmission / reception waveform overlaps during the phase difference adjustment, and FIG. 7B is a time chart of the waveform after the phase difference adjustment of the data signal on the side of the simultaneous bidirectional transmission circuit 1.
FIG. 4 is a diagram illustrating a method of adjusting a delay amount set value in the delay adjustment circuit shown in FIG. 2;
FIG. 5 is a block diagram illustrating another configuration example of the output delay adjustment circuit illustrated in FIG. 1;
[Explanation of symbols]
1, 2 simultaneous bidirectional transmission circuit 3 data signal line 4 strobe signal line 10, 12, 20, 22 transmission circuit 11, 13, 21, 23 reception circuit 14, 24 FIFO
15, 16, 25, 26 output delay adjusting circuits 17, 18, 27, 28 FF
REFERENCE SIGNS LIST 100 delay circuit 101 pseudo transmission circuit 102 phase comparison circuit (FF)
103 Delay adjustment circuit

Claims

Each of the simultaneous bidirectional transmission circuits disposed at both ends of the same transmission line has a transmission circuit and a reception circuit connected to the transmission line, and the transmission circuit and the reception circuit are provided between the simultaneous bidirectional transmission circuits. In a simultaneous two-way transmission system for simultaneously transmitting and receiving a transmission signal and a reception signal via the transmission path,
At least one of the simultaneous bidirectional transmission circuits,
A delay circuit that is arranged in front of the transmission circuit and delays and outputs a transmission signal of its own station by a delay amount set by a delay setting value input externally,
By performing the same processing as that of the transmission circuit on the transmission signal of the own station output from the delay circuit, a transmission signal of the own station at a connection point between the own station and the transmission line is pseudo-generated. A pseudo transmission circuit for outputting
A phase comparison circuit that compares the phase of the transmission signal of the own station output from the pseudo transmission circuit and the phase of the reception signal from the opposite station output from the reception circuit, and outputs the phase comparison result,
At the time of phase adjustment, the delay setting value output to the delay circuit is changed, and based on the relationship between the changed delay setting value and the phase comparison result output from the phase comparison circuit, the transmission signal of the own station is changed. And a delay adjusting circuit that adjusts the delay adjustment value so that the transition timing of the waveform of the received signal from the opposite station does not overlap with the waveform of the received signal.

The phase comparison circuit may output, as the phase comparison result, a signal obtained by latching a reception signal from the opposite station output from the reception circuit using an edge of the transmission signal of the own station output from the pseudo transmission circuit. Or latching the transmission signal of the own station output from the pseudo transmission circuit using the edge of the reception signal from the opposite station output from the reception circuit and outputting the latched result as the phase comparison result. A simultaneous two-way transmission system according to claim 1.

The delay adjustment circuit gradually increases the delay set value output to the delay circuit from “0” during phase adjustment, and sets the delay comparison value output from the phase comparison circuit when the phase comparison result starts changing. The simultaneous bidirectional transmission system according to claim 2, wherein the delay setting value is adjusted to an intermediate value between the delay setting value and the delay setting value at the time when the change state returns to the original state.

In a simultaneous bidirectional transmission system for simultaneously transmitting and receiving a transmission signal and a reception signal via the transmission path between simultaneous bidirectional transmission circuits connected to both ends of the same transmission path, a phase difference adjustment method of a transmission / reception waveform,
In one of the simultaneous bidirectional transmission circuits,
A first step of delaying a transmission signal of the own station by a delay amount set by a delay setting value before a transmission signal of the own station reaches a connection point between the own station and the transmission line;
A second step of pseudo-generating a transmission signal of the own station at a connection point between the own station and the transmission line using the transmission signal of the own station delayed in the first step;
A third step of comparing the phase of the transmission signal of the own station pseudo-generated in the second step with the phase of the reception signal from the opposite station;
The delay setting value is changed, and the waveform of the transmission signal of the own station and the transition of the waveform of the reception signal from the opposite station are changed based on the relationship between the changed delay setting value and the phase comparison result in the third step. And a fourth step of adjusting the delay adjustment value so that the timings do not overlap with each other.

In the third step, a signal obtained by latching a reception signal from the opposite station using an edge of the transmission signal of the own station pseudo-generated in the second step is used as the phase comparison result, or The method according to claim 4, wherein a result of latching a transmission signal of the own station which is artificially generated in the second step using an edge of a reception signal from the opposite station is used as the phase comparison result. A method for adjusting a phase difference between transmitted and received waveforms in the simultaneous bidirectional transmission system described in the above.

In the fourth step, the delay set value is gradually increased from "0", and the delay set value at the time when the phase comparison result starts to change and the delay set value at the time when the change state returns to the original state. The method according to claim 5, wherein the delay setting value is adjusted to an intermediate value with the delay setting value.