JP4320691B2 - Transmission / reception switching circuit - Google Patents

Transmission / reception switching circuit Download PDF

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JP4320691B2
JP4320691B2 JP2000008603A JP2000008603A JP4320691B2 JP 4320691 B2 JP4320691 B2 JP 4320691B2 JP 2000008603 A JP2000008603 A JP 2000008603A JP 2000008603 A JP2000008603 A JP 2000008603A JP 4320691 B2 JP4320691 B2 JP 4320691B2
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transmission
frequency band
reception
antenna
received signal
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JP2001203601A (en
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剛志 武田
茂 釼持
裕之 但井
光弘 渡辺
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Hitachi Metals Ltd
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Hitachi Metals Ltd
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【０００１】
【発明の属する技術分野】
本発明は、デュアルバンド無線通信装置用送信・受信回路に関し、特に欧州のデュアルバンド携帯電話のアンテナ切り替え回路に関する。
【０００２】
【従来の技術】
近年の携帯電話の普及はめざましいものがあり、携帯端末機の機能の向上が図られている。その一つとして、一つの携帯端末機で二つの周波数帯での通話を可能とするデュアルバンド携帯電話が実用化されつつある。欧州では、無線周波数が異なる二つのシステム、900MHz帯のGSM（Global System for Mobil communications）と1.8GHz帯のDSC（Digital Cellular System）を一つのアンテナで送信・受信を行うデュアルバンド・ホンが実用化されている。
【０００３】
図１に、従来のデュアルバンド・ホンに使用されている送信・受信切り替え回路のブロック図を示す。送信・受信切り替え回路は、900MHz帯及び1.8GHz帯の送信信号及び受信信号を送信・受信するアンテナ１１，900MHz帯の送信信号及び受信信号を切り替えるスイッチ１２，1.8GHz帯の送信信号及び受信信号を切り替えるスイッチ１３，ならびに900MHz帯の送信・受信信号及び１.8GHz帯の送信・受信信号を分波・合成する分波器１４で構成される。図２に、図１に示した送信・受信切り替え回路の等価回路の一例を示す。この送信・受信切り替え回路では、900MHz帯及び1.8GHz帯の送信信号をオン・オフするダイオードがそれぞれ必要であり、例えば900MHz帯の送信・受信信号の切り替えスイッチ１２は送信信号をオン・オフするダイオード１２１と、900MHz帯の送信信号の周波数帯で凡そ９０度の位相差を持つ位相器１２２と、送信時にオンされ受信時オフされる受信側ダイオード１２３と、各々の前記ダイオード１２１，１２３に直流を印加する高周波チョーク回路１２４，１２５で構成されている。1.8GHz帯の送信・受信信号の切り替えスイッチ１３においても前記900MHz帯スイッチと同様に構成されている。また、送信・受信信号を分波・合成する分波器１４は、インダクタンス１４１とコンデンサ１４２からなる並列共振回路の後段に配置されるインダクタンス１４７、コンデンサ１４５，１４６からなるローパスフィルタ回路と、インダクタンス１４４とコンデンサ１４３からなる並列共振回路の後段に配置されるインダクタンス１４８，１４９、コンデンサ１５０からなるハイパスフィルタ回路とから構成されていた。
【０００４】
【本発明が解決しようとする課題】
従来の送信・受信信号の切り替え回路においては、前記のように送信信号をオン・オフするダイオードは各々一つ必要であり、又、分波器は900MHz帯の送信・受信信号及び1.8GHz帯の送信・受信信号を分波・合成するため、広帯域な伝送特性が要求されるため多くの回路素子を必要とし、送信・受信信号の切り替え回路の小型化が困難であった。
本発明は、このような問題点を解決し、小型の送信・受信信号の切り替え回路を提供することを目的とする。
【０００５】
【問題を解決するための手段】
本発明は、 送信信号及び受信信号を送信・受信するアンテナと、送信信号の経路に直列に配置された第１のダイオードによりアンテナへの送信信号をオン・オフする第１のスイッチと、前記アンテナに接続され、アンテナからの受信信号を第１の周波数帯域の受信信号と第２の周波数帯域の受信信号とに分離する分波器と、第１の周波数帯域の受信信号の経路に配置され、一端側が前記分波器と接続された第１の位相器と、第２の周波数帯域の受信信号の経路に配置され、一端側が前記分波器と接続された第２の位相器と、前記第１の位相器の他端側を接地する第２のダイオードと、前記第２の位相器の他端側を接地する第３のダイオードによって、第１の周波数帯域の受信信号、及び第２の周波数帯域の受信信号をオン・オフする第２のスイッチを有し、分波器のアンテナ側端子から第２のダイオードを介して接地までの経路の全位相は、第１の周波数帯域で略９０°であり、分波器の前記アンテナ側端子から第３のダイオードを介して接地までの経路の全位相は、第２の周波数帯域で略９０°であって、送信時に第１〜第３のダイオードをオンし、受信時に第１〜第３のダイオードをオフする送信・受信切り替え回路である。
本発明において、前記第１及び第２の位相器を、特性インピーダンス線路、ＬＣ集中定数回路から選ばれる少なくとも１つとするのが好ましい。
【０００６】
【発明の実施の形態】
以下、図面を参照して本発明に係る送信・受信切り替え回路を説明する。
図３に、本発明に係わる送信・受信切り替え回路の一実施例のブロック図を示す。
送信・受信切り替え回路３０は、送信信号及び受信信号を送信・受信するアンテナ３１、前記アンテナへ送信信号をオン・オフする第１のスイッチ３２，アンテナからの受信信号を第１の周波数帯域の受信信号と第２の周波数帯域の受信信号に分波する分波器３３，第１の周波数帯域の受信信号に対応した第１の位相器３４及び、第２の周波数帯域の受信信号に対応する第２の位相器３５、ならびに第１の周波数帯域の受信信号及び、第２の周波数帯域の受信信号をオン・オフする第２のスイッチ３６で構成される。
そして、第１のスイッチ３２及び分波器３３の第１の端子３２１、３３１がアンテナ３１に、分波器の第２の端子３３２が第１の位相器３４の第１の端子３４１に、分波器の第３の端子３３３が第２の位相器３５の第１の端子３５１に、第１の位相器３４の第２の端子３４２が第２のスイッチ３６の第１の端子３６１に、第２の位相器３５の第２の端子３５２が第２のスイッチ３６の第２の端子３６２にそれぞれ接続されている。第２のスイッチ３６の第３及び第４の端子３６３，３６４は、後段に配置される第１の周波数帯域の第１の受信フィルター３８，第２の周波数帯域の受信フィルター３９に、それぞれ接続される。
【０００７】
図４に、図３の送信・受信切り替え回路３０の一例の等価回路図を示す。
アンテナ３１からの受信信号を第１の周波数帯域及び第２の周波数帯域に分波する分波器３３はインダクタンス４３１〜４３３及びコンデンサ５３１〜５３３で構成され、第１の周波数帯域の受信信号が通過する第１及び第２の端子３３１，３３２間にインダクタンス４３１及びコンデンサ５３１とからなる共振回路、ならびに接地されたインダクタンス４３３が接続され、、第２の周波数帯域の受信信号が通過する第１及び第３の端子３３１、３３３間にインダクタンス４３２及びコンデンサ５３２からなる並列共振回路、並びに接地されたコンデンサ５３３が接続される。このとき、インダクタンス４３１及びコンデンサ５３１は第２の周波数帯域で共振し、インダクタンス４３２及びコンデンサ５３２は第１の周波数帯域で共振する定数を持つ。
第１及び第２の位相器３４，３５は特性インピーダンス線路で構成される。特性インピーダンス線路は通常５０Ωマイクロストリップラインが使用される。
第１のスイッチ３２はダイオード７０１、インダクタンス４２１，４２２、コンデンサ５２１〜５２３及び抵抗８２１、８２２で構成され、第１及び第２の端子３２１，３２２間にコンデンサ５２２、ダイオード７０１、コンデンサ５２３の順番に接続され、ダイオード７０１のカソード端子とコンデンサ５２２の接続点はインダクンス４２１及び抵抗８２１を介して接地され、ダイオード７０１のアノード端子とコンデンサ５２３の接続点はインダクタンス４２２及びコンデンサ５２１を介して接地される。このとき、インダクタンス４２２とコンデンサ５２１との接続点にはダイオード７０１のオン・オフを制御するための制御端子ＶＣ１が接続される。
第２のスイッチ３６はダイオード７０２，７０３、インダクタンス４６１，４６２、コンデンサ５６１〜５６５及び抵抗８６１、８６２で構成され、第１の周波数帯域の受信信号が通過する第１の端子３６１と第３の端子３６３との間にコンデンサ５６１、５６２が接続され、コンデンサ５６１とコンデンサ５６２との接続点はダイオード７０２を介して接地されるとともに、ダイオード７０２のオン・オフを制御するための制御端子ＶＣ２へインダクタンス４６１及び抵抗８６１を介して接続される。第２の周波数帯域の受信信号が通過する第２の端子３６２と第４の端子３６４との間にコンデンサ５６３，５６４が接続され、コンデンサ５６３と５６４との接続点は、ダイオード７０３を介して接地されるとともに、ダイオード７０３のオン・オフを制御するための制御端子ＶＣ２へインダクタンス４６２および抵抗８６２を介して接続される。
【０００８】
ここで、上記記載の送信・受信切り替え回路３０の動作について、第１及び第２の周波数帯域を1.8GHz（ＤＳＣ）及び900MHz（GSM）として説明する。
まず、受信の場合は、第１のスイッチ３２及び第２のスイッチ３６のダイオード７０１，７０２および７０３をオフ（ＶＣ１＝０Ｖ、ＶＣ２＝０Ｖ）にしておく。第１の周波数帯域の1.8GHz帯の受信信号は分波器３３の共振回路で分波され、分波器３３の第２の端子３３２へ出力される。この出力信号は、低損失なマイクロストリップ線路である第１の位相器を通過し第２のスイッチ３６の第１端子３６１へ現れる。第２のスイッチにおいてコンデンサ５６１及び５６２を十分に大きな容量を持つコンデンサ（例えば１００ｐＦ）をもちいることで、損失なく受信信号を第２のスイッチ３６の第３の端子３６３へと通過させる。一方、第２の周波数帯域の900MHz帯の受信信号も、分波器３３により分波され、第２のスイッチの第４の端子３６４へと通過していく。
送信時は、第１のスイッチ３２及び第２のスイッチ３６のダイオード７０１，７０２及び７０３をオン（ＶＣ１＝３Ｖ、ＶＣ２＝３Ｖ）にする。1.8GHz帯の第１の周波数帯域の送信信号が第１のスイッチ３２の第２の端子３２２へ入力すると、低損失で第１のスイッチ３２の第１の端子３２１へと通過し、アンテナ３１及び分波器３３の第１の端子３３１へと流れる。このとき、分波器３３のインダクタンス４３１及びコンデンサ５３１の共振回路、位相器３４及び第２のスイッチ３６のコンデンサ５６１の全位相を凡そ1.8GHz帯で９０度となるようにすることで、分波器３３の第１の端子３３１から受信フィルターをみたインピーダンスは高インピーダンスとなり分波器３３の第１の端子３３１へ流れてきた送信信号は全てアンテナへと流れる。
第２の周波数帯域の900MHz帯の送信信号においても、分波器３３のインダクタンス４３２及びコンデンサ５３２の共振回路、第２の位相器３５，及び第２のスイッチ３６のコンデンサ５６３の全位相を凡そ900MHz帯で９０度となるようにすることで、分波器３３の第１の端子３３１から受信フィルターをみたときのインピーダンスを高インピーダンスに出来、送信信号を受信フィルターへ流さないで、低損失にアンテナへと流せる。
【０００９】
【実施例】
前記図４に示した送信受信切り替え回路の伝送特性例を図５に、従来例の図２の切り替え回路の伝送特性例を図６に示す。
各々の回路素子の定数は、５２１＝１００ｐＦ、５２２＝１００ｐＦ、５２３＝１００ｐＦ、４２１＝６３ｎＨ、４２２＝６８ｎＨ、８２１＝３ＫΩ、８２２＝１ＫΩ、５３１＝３．５ｐＦ、５３２＝２ｐＦ、５３３＝１．５ｐＦ、４３１＝９ｎＨ、４３２＝４ｎＨ、４３３＝５ｎＨ、位相器３４は、1.8GHzで０．４波長となる５０Ωストリップライン、位相器３５は、900MHzで0.18波長となる５０Ωストリップライン、５６１＝１０ｐＦ、５６２＝１０ｐＦ、５６３＝１００ｐＦ、５６４＝１００ｐＦ、４６１＝３３ｎＨ，４６２＝６８ｎＨ、８６１＝１ＫΩ、８６２＝１ＫΩ、ダイオード７０１，７０２及び７０３はＰＩＮダイオードとした。
まず、送信信号の挿入損失は、従来の切り替え回路では900MHz帯及び1.8GHz帯で凡そ１ｄＢにあるのに対し、本発明による実施例では、900MHz帯及び1.8GHz帯の送信信号の挿入損失は凡そ０．５ｄＢである。これは、送信信号の挿入損失が、従来例では分波器の挿入損失を含むのに対し、本発明ではダイオードによる損失だけであるのによる。
送信信号の受信回路への挿入損失は、従来の切り替え回路は凡そ２５ｄＢ、本発明の実施例でも凡そ２５ｄＢと良好である。
次に受信信号のアンテナから受信フィルター間の挿入損失は、従来の切り替え回路では凡そ１ｄＢ、本発明の実施例も凡そ１ｄＢと良好である。
【００１０】
図７は、本発明に係る他の実施例の等価回路を示す。ここで第１及び第２の位相器３４，３５をＬＣの集中定数回路で構成し、受信スイッチ回路のダイオードをコンデンサを介して信号ラインに接続する構成とした。この場合であっても、低損失で小型の送信・受信切り替え回路を得ることができた。
【００１１】
【発明の効果】
本発明によれば、送信信号のスイッチを第１の送信信号と第２の送信信号との共用とすることが出来、共用とすることでスイッチをダイオード一つで構成でき、送信・受信切り替え回路を小型に出来る。さらには、送信・受信切り替え回路の分波器を受信信号の分波だけとすることで、送信信号の挿入損失を小さくでき、且つ、分波器を構成する回路素子数を削減できることにより送信・受信切り替え回路を小型に出来る。
【図面の簡単な説明】
【図１】従来のデュアルバンド・ホンに使用されている送信・受信切り替え回路のブロック図である。
【図２】従来の送信・受信切り替え回路の等価回路図である。
【図３】本発明に係る送信・受信切り替え回路の一実施例のブロック図である。
【図４】本発明に係る送信・受信切り替え回路の等価回路図である。
【図５】本発明に係る等価回路の伝送特性例を示す図である。
【図６】従来例の切り替え回路の伝送特性例を示す図である。
【図７】本発明に係る他の実施例の等価回路図である。
【符号の説明】
３１ アンテナ
３２ 第１のスイッチ
３３ 分波器
３４、３５ 位相器
３６ 第２のスイッチ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transmission / reception circuit for a dual-band wireless communication device, and more particularly to an antenna switching circuit for a European dual-band mobile phone.
[0002]
[Prior art]
In recent years, there has been a remarkable spread of mobile phones, and functions of mobile terminals have been improved. As one of them, a dual-band mobile phone capable of calling in two frequency bands with one mobile terminal is being put into practical use. In Europe, two systems with different radio frequencies, 900MHz band GSM (Global System for Mobil communications) and 1.8GHz band DSC (Digital Cellular System) dual-band phone that transmits and receives with one antenna are put into practical use. Has been.
[0003]
FIG. 1 shows a block diagram of a transmission / reception switching circuit used in a conventional dual-band phone. The transmission / reception switching circuit includes an antenna 11 for transmitting / receiving 900 MHz band and 1.8 GHz band transmission signals and reception signals, a switch 12 for switching between 900 MHz band transmission signals and reception signals, and 1.8 GHz band transmission signals and reception signals. It comprises a switch 13 for switching, and a demultiplexer 14 for demultiplexing and combining 900 MHz band transmission / reception signals and 1.8 GHz band transmission / reception signals. FIG. 2 shows an example of an equivalent circuit of the transmission / reception switching circuit shown in FIG. In this transmission / reception switching circuit, diodes for turning on and off transmission signals in the 900 MHz band and 1.8 GHz band are required. For example, the transmission / reception signal switching switch 12 in the 900 MHz band is a diode for turning on / off transmission signals. 121, a phase shifter 122 having a phase difference of about 90 degrees in the frequency band of a transmission signal in the 900 MHz band, a receiving-side diode 123 that is turned on during transmission and turned off during reception, and direct current is applied to each of the diodes 121 and 123. It comprises high frequency choke circuits 124 and 125 to be applied. The 1.8 GHz band transmission / reception signal selector switch 13 has the same configuration as the 900 MHz band switch. The demultiplexer 14 for demultiplexing / synthesizing the transmission / reception signals includes an inductance 147 disposed at a subsequent stage of the parallel resonance circuit including the inductance 141 and the capacitor 142, a low-pass filter circuit including the capacitors 145 and 146, and an inductance 144. And a high-pass filter circuit composed of the capacitors 150 and inductances 148 and 149 disposed in the subsequent stage of the parallel resonant circuit composed of the capacitor 143.
[0004]
[Problems to be solved by the present invention]
In the conventional transmission / reception signal switching circuit, one diode is required to turn on / off the transmission signal as described above, and the duplexer includes a 900 MHz band transmission / reception signal and a 1.8 GHz band transmission / reception signal. Since transmission / reception signals are demultiplexed / synthesized, a wide band transmission characteristic is required, so many circuit elements are required, and it is difficult to reduce the size of a transmission / reception signal switching circuit.
An object of the present invention is to solve such problems and provide a small transmission / reception signal switching circuit.
[0005]
[Means for solving problems]
The present invention includes an antenna that transmits and receives a transmission signal and a reception signal, a first switch that turns on and off a transmission signal to the antenna by a first diode arranged in series in a path of the transmission signal, and the antenna Is connected to the antenna, and is disposed in a path of the first frequency band received signal, and a duplexer that separates the received signal from the antenna into the first frequency band received signal and the second frequency band received signal , A first phase shifter having one end connected to the duplexer, a second phase shifter disposed on the path of the received signal in the second frequency band, and one end connected to the duplexer; The received signal in the first frequency band and the second frequency by the second diode that grounds the other end of the first phase shifter and the third diode that grounds the other end of the second phase shifter The second scan to turn on / off the received signal of the band The total phase of the path from the antenna side terminal of the duplexer to the ground via the second diode is approximately 90 ° in the first frequency band, and from the antenna side terminal of the duplexer. The total phase of the path from the third diode to the ground is approximately 90 ° in the second frequency band, the first to third diodes are turned on during transmission, and the first to third diodes are received during reception. This is a transmission / reception switching circuit for turning off the diode .
In the present invention, the first and second phase shifters are preferably at least one selected from a characteristic impedance line and an LC lumped constant circuit.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a transmission / reception switching circuit according to the present invention will be described with reference to the drawings.
FIG. 3 shows a block diagram of an embodiment of a transmission / reception switching circuit according to the present invention.
The transmission / reception switching circuit 30 includes an antenna 31 that transmits / receives a transmission signal and a reception signal, a first switch 32 that turns on / off the transmission signal to the antenna, and reception of a reception signal from the antenna in a first frequency band. A demultiplexer 33 for demultiplexing the signal into a received signal in the second frequency band, a first phase shifter 34 corresponding to the received signal in the first frequency band, and a first corresponding to the received signal in the second frequency band. 2 phase shifters 35, and a second switch 36 for turning on / off the reception signal of the first frequency band and the reception signal of the second frequency band.
The first terminals 321 and 331 of the first switch 32 and the duplexer 33 are connected to the antenna 31, and the second terminal 332 of the duplexer is connected to the first terminal 341 of the first phase shifter 34. The third terminal 333 of the correlator is connected to the first terminal 351 of the second phase shifter 35, the second terminal 342 of the first phase shifter 34 is connected to the first terminal 361 of the second switch 36, and The second terminal 352 of the second phase shifter 35 is connected to the second terminal 362 of the second switch 36. The third and fourth terminals 363 and 364 of the second switch 36 are respectively connected to the first reception filter 38 of the first frequency band and the reception filter 39 of the second frequency band, which are arranged at the subsequent stage. The
[0007]
FIG. 4 shows an equivalent circuit diagram of an example of the transmission / reception switching circuit 30 of FIG.
The demultiplexer 33 that demultiplexes the received signal from the antenna 31 into the first frequency band and the second frequency band is composed of inductances 431 to 433 and capacitors 531 to 533, and the received signal in the first frequency band passes therethrough. A resonance circuit including an inductance 431 and a capacitor 531 and a grounded inductance 433 are connected between the first and second terminals 331 and 332, and the first and second terminals through which a reception signal in the second frequency band passes are connected. A parallel resonant circuit including an inductance 432 and a capacitor 532 and a grounded capacitor 533 are connected between the three terminals 331 and 333. At this time, the inductance 431 and the capacitor 531 have a constant that resonates in the second frequency band, and the inductance 432 and the capacitor 532 have a constant that resonates in the first frequency band.
The first and second phase shifters 34 and 35 are constituted by characteristic impedance lines. As the characteristic impedance line, a 50Ω microstrip line is usually used.
The first switch 32 includes a diode 701, inductances 421 and 422, capacitors 521 to 523, and resistors 821 and 822, and the capacitor 522, the diode 701, and the capacitor 523 are arranged in this order between the first and second terminals 321 and 322. The connection point between the cathode terminal of the diode 701 and the capacitor 522 is grounded via the inductance 421 and the resistor 821, and the connection point between the anode terminal of the diode 701 and the capacitor 523 is grounded via the inductance 422 and the capacitor 521. At this time, a control terminal VC1 for controlling ON / OFF of the diode 701 is connected to a connection point between the inductance 422 and the capacitor 521.
The second switch 36 includes diodes 702 and 703, inductances 461 and 462, capacitors 561 to 565, and resistors 861 and 862, and a first terminal 361 and a third terminal through which a reception signal in the first frequency band passes. Capacitors 561 and 562 are connected to 363, and a connection point between the capacitors 561 and 562 is grounded via a diode 702, and an inductance 461 is connected to a control terminal VC2 for controlling on / off of the diode 702. And a resistor 861. Capacitors 563 and 564 are connected between the second terminal 362 and the fourth terminal 364 through which the received signal in the second frequency band passes, and the connection point between the capacitors 563 and 564 is grounded via the diode 703. At the same time, it is connected to a control terminal VC 2 for controlling on / off of the diode 703 via an inductance 462 and a resistor 862.
[0008]
Here, the operation of the transmission / reception switching circuit 30 described above will be described assuming that the first and second frequency bands are 1.8 GHz (DSC) and 900 MHz (GSM).
First, in the case of reception, the diodes 701, 702 and 703 of the first switch 32 and the second switch 36 are turned off (VC1 = 0V, VC2 = 0V). The reception signal in the 1.8 GHz band of the first frequency band is demultiplexed by the resonance circuit of the demultiplexer 33 and is output to the second terminal 332 of the demultiplexer 33. This output signal passes through the first phase shifter, which is a low-loss microstrip line, and appears at the first terminal 361 of the second switch 36. By using a capacitor (for example, 100 pF) having a sufficiently large capacity for the capacitors 561 and 562 in the second switch, the received signal is passed to the third terminal 363 of the second switch 36 without loss. On the other hand, the received signal in the 900 MHz band of the second frequency band is also demultiplexed by the demultiplexer 33 and passes to the fourth terminal 364 of the second switch.
During transmission, the diodes 701, 702 and 703 of the first switch 32 and the second switch 36 are turned on (VC1 = 3V, VC2 = 3V). When a transmission signal in the first frequency band of the 1.8 GHz band is input to the second terminal 322 of the first switch 32, it passes to the first terminal 321 of the first switch 32 with low loss, and the antenna 31 and The current flows to the first terminal 331 of the duplexer 33. At this time, the entire phase of the resonance circuit of the inductance 431 and the capacitor 531 of the branching filter 33, the capacitor 561 of the phase shifter 34 and the second switch 36 is set to 90 degrees in the 1.8 GHz band, so that the branching is performed. The impedance of the reception filter viewed from the first terminal 331 of the filter 33 becomes high impedance, and all transmission signals flowing to the first terminal 331 of the duplexer 33 flow to the antenna.
Even in the 900 MHz band transmission signal of the second frequency band, the total phase of the resonance circuit of the inductance 432 and the capacitor 532 of the duplexer 33, the second phase shifter 35, and the capacitor 563 of the second switch 36 is approximately 900 MHz. By setting the angle to 90 degrees in the band, the impedance when the reception filter is viewed from the first terminal 331 of the duplexer 33 can be made high impedance, and the antenna is reduced in loss without flowing the transmission signal to the reception filter. I can flow to.
[0009]
【Example】
FIG. 5 shows an example of transmission characteristics of the transmission / reception switching circuit shown in FIG. 4, and FIG. 6 shows an example of transmission characteristics of the switching circuit of FIG.
The constants of the respective circuit elements are 521 = 100 pF, 522 = 100 pF, 523 = 100 pF, 421 = 63 nH, 422 = 68 nH, 821 = 3 KΩ, 822 = 1 KΩ, 532 = 3.5 pF, 532 = 2 pF, 533 = 1. 5 pF, 431 = 9 nH, 432 = 4 nH, 433 = 5 nH, phase shifter 34 is a 50 Ω strip line with 0.4 wavelength at 1.8 GHz, phase shifter 35 is a 50 Ω strip line with 0.18 wavelength at 900 MHz, 561 = 10 pF 562 = 10 pF, 563 = 100 pF, 564 = 100 pF, 461 = 33 nH, 462 = 68 nH, 861 = 1 KΩ, 862 = 1 KΩ, and the diodes 701, 702 and 703 are PIN diodes.
First, in the conventional switching circuit, the insertion loss of the transmission signal is about 1 dB in the 900 MHz band and the 1.8 GHz band, whereas in the embodiment according to the present invention, the insertion loss of the transmission signal in the 900 MHz band and the 1.8 GHz band is about. 0.5 dB. This is because the insertion loss of the transmission signal includes the insertion loss of the duplexer in the conventional example, whereas in the present invention, it is only the loss due to the diode.
The insertion loss of the transmission signal into the receiving circuit is as good as about 25 dB in the conventional switching circuit and about 25 dB in the embodiment of the present invention.
Next, the insertion loss between the antenna and the reception filter of the received signal is as good as about 1 dB in the conventional switching circuit, and about 1 dB in the embodiment of the present invention.
[0010]
FIG. 7 shows an equivalent circuit of another embodiment according to the present invention. Here, the first and second phase shifters 34 and 35 are constituted by LC lumped constant circuits, and the diode of the reception switch circuit is connected to the signal line via a capacitor. Even in this case, a small transmission / reception switching circuit with low loss could be obtained.
[0011]
【The invention's effect】
According to the present invention, the switch of the transmission signal can be shared by the first transmission signal and the second transmission signal, and by using it in common, the switch can be configured with one diode, and the transmission / reception switching circuit Can be made smaller. Furthermore, the transmission / reception switching circuit demultiplexer is made only for demultiplexing of the received signal, so that the transmission signal insertion loss can be reduced and the number of circuit elements constituting the demultiplexer can be reduced. The reception switching circuit can be made small.
[Brief description of the drawings]
FIG. 1 is a block diagram of a transmission / reception switching circuit used in a conventional dual-band phone.
FIG. 2 is an equivalent circuit diagram of a conventional transmission / reception switching circuit.
FIG. 3 is a block diagram of an embodiment of a transmission / reception switching circuit according to the present invention.
FIG. 4 is an equivalent circuit diagram of a transmission / reception switching circuit according to the present invention.
FIG. 5 is a diagram showing an example of transmission characteristics of an equivalent circuit according to the present invention.
FIG. 6 is a diagram showing an example of transmission characteristics of a conventional switching circuit.
FIG. 7 is an equivalent circuit diagram of another embodiment according to the present invention.
[Explanation of symbols]
31 Antenna 32 First switch 33 Branching filter 34, 35 Phase shifter 36 Second switch

Claims (2)

送信信号及び受信信号を送信・受信するアンテナと、
送信信号の経路に直列に配置された第１のダイオードによりアンテナへの送信信号をオン・オフする第１のスイッチと、
前記アンテナに接続され、アンテナからの受信信号を第１の周波数帯域の受信信号と第２の周波数帯域の受信信号とに分離する分波器と、
第１の周波数帯域の受信信号の経路に配置され、一端側が前記分波器と接続された第１の位相器と、第２の周波数帯域の受信信号の経路に配置され、一端側が前記分波器と接続された第２の位相器と、
前記第１の位相器の他端側を接地する第２のダイオードと、前記第２の位相器の他端側を接地する第３のダイオードによって、第１の周波数帯域の受信信号、及び第２の周波数帯域の受信信号をオン・オフする第２のスイッチを有し、
分波器のアンテナ側端子から第２のダイオードを介して接地までの経路の全位相は、第１の周波数帯域で略９０°であり、分波器の前記アンテナ側端子から第３のダイオードを介して接地までの経路の全位相は、第２の周波数帯域で略９０°であって、
送信時に第１〜第３のダイオードをオンし、受信時に第１〜第３のダイオードをオフすることを特徴とする送信・受信切り替え回路。An antenna for transmitting and receiving transmission signals and reception signals;
A first switch for turning on and off a transmission signal to the antenna by a first diode arranged in series in a path of the transmission signal;
A duplexer connected to the antenna and separating a received signal from the antenna into a received signal in a first frequency band and a received signal in a second frequency band;
A first phase shifter arranged on the path of the received signal in the first frequency band, one end side connected to the duplexer, and a path of the received signal in the second frequency band, and one end side arranged on the path of the demultiplexing A second phaser connected to the device;
The second diode that grounds the other end of the first phase shifter and the third diode that grounds the other end of the second phase shifter , and the received signal in the first frequency band, and the second A second switch for turning on and off the received signal in the frequency band of
The total phase of the path from the antenna side terminal of the duplexer to the ground via the second diode is approximately 90 ° in the first frequency band, and the third diode is connected from the antenna side terminal of the duplexer. The total phase of the path through to ground is approximately 90 ° in the second frequency band,
A transmission / reception switching circuit characterized in that the first to third diodes are turned on during transmission and the first to third diodes are turned off during reception. 前記第１及び第２の位相器が、特性インピーダンス線路、ＬＣ集中定数回路から選ばれる少なくとも１つであることを特徴とする請求項１に記載の送信・受信切り替え回路。  The transmission / reception switching circuit according to claim 1, wherein the first and second phase shifters are at least one selected from a characteristic impedance line and an LC lumped constant circuit.
JP2000008603A 2000-01-18 2000-01-18 Transmission / reception switching circuit Expired - Lifetime JP4320691B2 (en)

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