JP3613447B2

JP3613447B2 - Feedforward amplifier with double loop

Info

Publication number: JP3613447B2
Application number: JP16331499A
Authority: JP
Inventors: 恭宜鈴木; 俊雄野島
Original assignee: NTT Docomo Inc
Current assignee: NTT Docomo Inc
Priority date: 1999-06-10
Filing date: 1999-06-10
Publication date: 2005-01-26
Anticipated expiration: 2019-06-10
Also published as: JP2000353923A

Description

【０００１】
【発明の属する技術分野】
この発明は、主として高周波帯で使用される線形増幅器であるフィードフォワード増幅器、特に電力効率を高効率化したものに関する。
【０００２】
【従来の技術】
図５にフィードフォワード増幅器の構成を示す。フィードフォワード増幅器は、主増幅器の増幅伝達経路１１と線形信号伝達経路１２により構成される歪検出回路１３と、主信号伝達経路１４と歪注入経路１５により構成される歪除去回路１６により構成される。主増幅器の増幅伝達経路１１には、可変減衰器２１、可変位相器２２と主増幅器２３の直列接続で構成される。線形信号伝達経路１２は、遅延線２４と位相反転回路２５の直列接続により構成される。主信号伝達経路１４は、遅延線２６により構成される。そして、歪注入経路１５は、可変減衰器２７、可変位相器２８と補助増幅器２９の直列接続により構成される。フィードフォワード増幅器の入力は、電力分配回路３１により、主増幅器の増幅伝達経路１１と線形信号伝達経路１２に分配される。また、歪検出回路１３と歪除去回路１６は、電力合成／分配器３２により縦続に構成される。フィードフォワード増幅器の出力は、主信号伝達経路１４と歪注入経路１５の各出力を合成する電力合成器３３より得られる。
【０００３】
フィードフォワード増幅器は、前段の歪検出回路１３で主増幅器２３より発生する歪成分を検出し、後段の歪除去回路１６で主増幅器２３より発生する歪成分の位相量と振幅量を調整して、主増幅器２３の出力信号に注入することで主増幅器２３より発生する非線形歪を除去する。一般にフィードフォワード増幅器の非線形歪改善量は、歪検出回路１３の可変減衰器２１と可変位相器２２、歪除去回路１６の可変減衰器２７と可変位相器２８と補助増幅器２９の調整により左右される。その調整等の精度は、特願昭６３−２３５７４「フィードフォワード増幅器の自動調整回路」に示されている。たとえば、３０ｄＢ以上の歪圧縮量を得るための位相及び振幅偏差は、それぞれ±２度以内及び±０．３ｄＢ以内であり、歪検出回路１３及び歪除去回路１６の伝送特性の平衡度及び調整の完全性について厳しい条件が要求されているといえる。
【０００４】
フィードフォワード増幅器で歪補償するのは、主増幅器２３の非線形歪である。従って、補助増幅器２９で発生する非線形歪は、回路構成上原理的にフィードフォワード増幅器により歪補償できない。また、上記二つの経路の平衡条件が厳しいため、従来のフィードフォワード増幅器の補助増幅器２９には、線形性が要求されている。一般に半導体増幅素子を用いた増幅回路の線形性を高めるには、いわゆるＡ級バイアスとする動作条件とし、増幅する信号のピーク電力よりも飽和出力を十分に大きくしていた。
【０００５】
【発明が解決しようとする課題】
近年無線装置の小型化・経済化・低消費電力化などが求められている。フィードフォワード増幅器を用いる無線装置においても同様である。フィードフォワード増幅器の低消費電力化を達成するために、主増幅器及び補助増幅器の高効率化が必須である。これにより、増幅器の放熱板などを小型化でき、結果として無線装置の小型化を達成できる。
【０００６】
主増幅器の高効率化は、Ｂ級バイアス条件のプッシュプル回路等により可能である。主増幅器で生じる非線形歪は、従来のフィードフォワード増幅器により補償できる。これに対して、フィードフォワード増幅器の歪注入経路１５に挿入される補助増幅器２９の電力効率を高めることは、一般に補助増幅器の半導体増幅素子をいわゆるＢ級、Ｃ級などバイアス条件で動作させる必要がある。これらのバイアス条件により生じる非線形歪は、上記で述べたようにフィードフォワード増幅で原理的に補償できない。従って、補助増幅器２９の高効率化は、フィードフォワード増幅器の歪補償能力を低下させる問題があった。
【０００７】
たとえば、文献（野島俊雄、楢橋祥一、「移動通信用超低歪多周波共通増幅器」、電子情報通信学会無線通信システム研究会技術報告、ＲＣＳ９０−４、１９９０）によると、主増幅器の飽和出力を１００Ｗ、補助増幅器の飽和出力を主増幅器飽和出力の１／８、１．５ＧＨｚ帯、主増幅器と補助増幅器の半導体増幅素子にＧａＡｓのＭＥＳＦＥＴの場合において、主増幅器のＭＥＳＦＥＴのドレイン電圧１２Ｖ、ドレイン電流２０Ａ、補助増幅器のＭＥＳＦＥＴのドレイン電圧１２Ｖ、ドレイン電流５Ａとし、いずれもＡ級バイアスの条件でフィードフォワード増幅器への供給電力は１５３Ｗ程度になり、ドレイン効率を求めると、約５％以下になる。主増幅器にＢ級プッシュプルなどの高効率増幅回路、補助増幅器にＡ級増幅回路を用いても高々約１０％以下のドレイン効率しか得られない。
【０００８】
歪検出回路及び歪除去回路は、等振幅、等遅延、逆位相になるようにそれぞれのループの可変減衰器と可変位相器を制御する必要がある。一般にフィードフォワード増幅器の非線形歪改善量は、これら可変減衰器と可変位相器の調整によるループの平衡性に左右される。その調整等の精度は、特願昭６３−２３５７４「フィードフォワード増幅器の自動調整回路」に示されている。たとえば、３０ｄＢ以上の歪圧縮量を得るための位相及び振幅偏差は、それぞれ±２度以内及び±０．３ｄＢ以内であり、歪検出回路及び歪除去回路の伝送特性の平衡度及び調整の完全性について厳しい条件が要求されていることがいえる。実際には、歪検出回路及び歪除去回路とのそれぞれの回路の平衡性を完全に保持することは容易でない。また、仮に初期設定が完全であっても、周囲温度、電源等の変動により増幅器の特性が変化するため、時間的に安定して良好な平衡性を維持することはきわめて困難である。
【０００９】
このフィードフォワード増幅器の歪検出回路及び歪除去回路の完全な平衡性を高精度に保持する方法として、パイロット信号を用いた自動調整方法が知られている。たとえば、特願昭６３−２３５７４があり、これらを実用化した装置として、野島俊雄、楢橋祥一、「移動通信用超低歪多周波共通増幅器……自己調整形フィードフォワード増幅器（ＳＡＦＦ−Ａ）…」、電子情報通信学会、無線通信システム研究会、ＲＣＳ９０−４，１９９０が知られている。
【００１０】
これらの自動調整方法は、いずれも従来の主増幅器の発生した非線形歪成分を除去するフィードフォワード増幅器に適用されている。これまで、歪注入経路をフィードフォワード構成化した高効率増幅可能なフィードフォワード増幅器に適用可能なパイロット信号を用いた自動調整方法はなかった。
この発明の解決するべき課題は、従来のフィードフォワード増幅器と同等以上の歪補償能力を持ち、かつ高効率増幅可能なフィードフォワード増幅器の各ループの自動調整を可能とするフィードフォワード増幅器を提供することにある。
【００１１】
【課題を解決するための手段】
この発明によれば歪注入経路をフィードフォワード増幅器構成とする。具体的には補助増幅器を主増幅器と見なして、補助増幅器（第一補助増幅器）に対する第一補助増幅器用歪検出回路と第一補助増幅器用歪除去回路とを用いて歪注入経路が構成され、補助増幅器（第一補助増幅器）で発生する非線形歪を、歪注入経路のこのフィードフォワード構成により補償する。また補助増幅器（第一補助増幅器）をＡ級バイアス以外のＢ級、Ｃ級、Ｅ級、Ｆ級等による高効率動作を可能にする。
【００１２】
更に以下に述べるように各請求項において各ループの平衡が自動的にとれる構成としている。
（１）請求項１の発明によれば、第一補助増幅器用歪検出回路の遅延線路と位相反転回路にて構成されていた経路を可変減衰器と可変位相器にて構成し、主増幅器に注入されるパイロット信号を第一補助増幅器用歪除去経路にて検出し、その検出レベルを最小にするように制御器にて該可変減衰器と該可変位相器を制御する。歪検出回路と第一補助増幅器用歪除去回路のループの平衡性を達成し、歪除去回路のループの平衡性を、第一補助増幅器の入力側の可変減衰器と可変位相器を主増幅器に注入されたパイロット信号をフィードフォワード増幅器出力にて検出し、その検出レベルを最小にするように制御器にて制御する。あらたに挿入した可変減衰器と可変位相器は、このとき制御した減衰量と位相量により連動して設定値を調整する。これにより、歪除去回路と第一補助増幅器用歪検出回路の平衡性を同時に達成できる。
【００１３】
（２）請求項２の発明によれば、第一補助増幅器用歪検出回路の遅延線路と位相反転回路にて構成されていた経路を可変減衰器と可変位相器にて構成し、歪注入経路の入力端に注入されるパイロット信号を第一補助増幅器用歪除去経路にて検出し、その検出レベルを最小にするように制御器にて該可変減衰器と該可変位相器を制御する。歪検出回路と第一補助増幅器用歪除去回路のループの平衡性を達成し、歪除去回路のループの平衡性を第一補助増幅器の入力側の可変減衰器と可変位相器を主増幅器に注入されたパイロット信号をフィードフォワード増幅器出力にて検出し、その検出レベルを最小にするように制御器にて制御する。あらたに挿入した可変減衰器と可変位相器は、このとき制御した減衰量と位相量により連動して設定値を調整する。これにより、歪除去回路と第一補助増幅器用歪検出回路の平衡性を同時に達成できる。
【００１４】
（３）請求項３の発明によれば、第二可変位相器と第二可変減衰器を第一補助増幅器用歪検出回路の入力の電力分配器の前に挿入する。第一補助増幅器用歪検出回路の第一補助増幅器用信号伝達経路に遅延線路を用い、第一補助増幅器用線形信号伝達経路に第四可変位相器と第四可変減衰器と位相反転回路を用いて第一補助増幅器用歪検出回路を構成する。請求項１の発明において第二制御器と第四制御器の協調動作を必要としていたが、請求項３の発明ではこの協調動作を必要としない。フィードフォワード増幅器の４つのループの平衡を独立に達成できる。
【００１５】
（４）請求項４の発明によれば、第二可変位相器と第二可変減衰器を第一補助増幅器用歪検出回路の入力の電力分配器の前に挿入する。第一補助増幅器用歪検出回路の第一補助増幅器用信号伝達経路に遅延線路を用い、第一補助増幅器用線形信号伝達経路に第四可変位相器と第四可変減衰器と位相反転回路を用いて第一補助増幅器用歪検出回路を構成する。請求項２の発明において第二制御器と第四制御器の協調動作を必要としていたが、請求項４の発明ではこの協調動作を必要としない。フィードフォワード増幅器の４つのループの平衡を独立に達成できる。
作用
この発明は、歪注入経路をフィードフォワード構成化により、補助増幅器を高効率化することができ、その高効率化に伴い発生した歪成分を除去することができる。またこの歪注入経路のフィードフォワード構成化により存在する４つのループの平衡性をそれぞれパイロット信号を用いて、そのレベルを最小にするように各ループの可変減衰器と可変位相器を制御することで、主増幅器の発生する歪成分の補償と第一補助増幅器の発生する歪成分の補償を可能にし、第一補助増幅器の半導体増幅素子にＡ級バイアス条件以外の高効率増幅の動作条件を適用できる。
【００１６】
【発明の実施の形態】
図１にこの発明の請求項１の実施例を示す。図１は、３つのパイロット信号と４つの制御手段を用いる。この発明のフィードフォワード増幅器は、増幅器入力側に第一パイロット信号発生器４１と、第一パイロット信号を増幅器入力に注入する方向性結合器４２と、増幅器入力信号を二経路に分配する電力分配器３１と、分配された信号を入力する、第一可変減衰器２１と第一可変位相器２２と主増幅器２３により構成される経路１１と、遅延線路２４と位相反転回路２５により構成される経路１２と、主増幅器２３の段間に注入する第二パイロット信号発生器４３と、これら二つの経路１１，１２を電力合成し、二経路に分配する電力合成／分配器３２と、この電力合成／分配器３２により分配された信号を入力する遅延線路２６と、分配された信号を入力し第一パイロット信号を抽出する方向性結合器４４と、抽出された第一パイロット信号を検出する第一パイロット信号検出器４５と、その検出されたレベルを入力し、そのレベルを最小にするように第一可変減衰器２１と第一可変位相器２２を制御する第一制御器４６と、第一パイロット信号を抽出した方向性結合器４４の出力を入力し、二経路に分配する電力分配器４７と、分配された信号を入力する、第二可変減衰器２７と第二可変位相器２８と第一補助増幅器２９により構成される経路４８と、分配された信号を入力する第四可変減衰器４９と第四可変位相器５１と位相反転回路５２にて構成される経路５３と、第一補助増幅器２９の段間に第三パイロット信号を注入する手段と第三パイロット信号発生器５４と、これら二つの経路４８，５３を電力合成し、二経路に分配する電力合成／分配器５５と、分配された信号を入力する遅延線路５６よりなる経路６０と、分配された信号を入力し第二パイロット信号を抽出する方向性結合器５７と、抽出された第二パイロット信号のレベルを検出する第二パイロット信号検出器５８と、その検出されたレベルを最小にするように第四可変減衰器４９と第四可変位相器５１を制御する第四制御器５９と、方向性結合器５７の出力を入力する、第三可変減衰器６１と第三可変位相器６２と第二補助増幅器６３により構成される経路６４と、これら二つの経路６０，６４の出力を合成する電力合成器６５と、その電力合成器６５の出力を入力し第三パイロット信号を抽出する方向性結合器６６と、抽出された第三パイロット信号を入力し、そのレベルを検出する第三パイロット信号検出器６７と、その検出されたレベルを最小になるように第三可変減衰器６１と第三可変位相器６２を制御する第三制御器６８と、上記遅延線路２６による経路１４の出力と第三パイロット信号を抽出する方向性結合器６６の出力を電力合成する電力合成器３３と、電力合成された信号を入力し第二パイロット信号を抽出する方向性結合器６９と、抽出された第二パイロット信号のレベルを検出する第二パイロット信号検出器７１と、その検出されたレベルが最小になるように第二可変減衰器２７と第二可変位相器２８を制御する第二制御器７２により構成される。
【００１７】
第二可変減衰器２７、第二可変位相器２８、第一補助増幅器２９よりなる経路４８と、第四可変減衰器４９、第四可変位相器５１、位相反転回路５２よりなる経路５３とにより第一補助増幅器用歪検出回路７３が構成され、この第一補助増幅器用歪検出回路７３により第一補助増幅器２９で発生する歪成分を検出する。遅延線路５６の経路６０と第三可変減衰器６１、第三可変位相器６２、第二補助増幅器６３よりなる経路６４とより第一補助増幅器用歪除去回路７４が構成され、第一補助増幅器用歪検出回路７３にて検出した歪成分を逆位相、等振幅、等遅延で第一補助増幅器２９の出力に注入して、第一補助増幅器２９で発生する歪成分を除去する。
【００１８】
このように歪注入経路１５のフィードフォワード構成化により、第一補助増幅器２９にＡ級バイアス以外の動作条件で第一補助増幅器２９の半導体増幅素子を高効率に動作させ、この高効率化に基づき補助増幅器２９から新たに生じた歪成分を、補助増幅器用歪検出回路７３で検出し、この検出した歪成分で補助増幅器用歪除去回路７４において、第一補助増幅器２９の増幅出力中の第一補助増幅器２９で生じた歪成分を除去する。よって、第一補助増幅器２９の高効率増幅を可能にできる。
【００１９】
このように、歪除去回路１６の遅延線路２６による経路１４と、第二可変減衰器２７と第二可変位相器２８と第一補助増幅器２９と遅延線路５６にて構成される経路によるループと、第一補助増幅器用歪検出回路７３のループを独立に達成するために、第一補助増幅器用歪検出回路７３に第四可変減衰器４９と第四可変位相器５１を新たに設ける。
【００２０】
この発明によるフィードフォワード増幅器は、３つのパイロット信号を用いて、歪検出回路１３、第一補助増幅器用歪検出回路７３、第一補助増幅器用歪除去回路７４、歪除去回路１６の各平衡を達成する。このとき、これまで述べてきたように、第一補助増幅器用歪検出回路７３のループの平衡性は、第二パイロット信号を用いて第四可変減衰器４９と第四可変位相器５１により達成する。歪除去回路１６のループの平衡性は、第一補助増幅器用歪検出回路７３のループの平衡性を達成後、第二パイロット信号を用いて第二可変減衰器２７と第二可変位相器２８を用いて達成する。このとき、第一補助増幅器２９の経路４８上の第二可変減衰器２７と第二可変位相器２８の設定値を、第一補助増幅器用歪検出回路７３のループの平衡性達成後に変更するため、第四可変減衰器４９と第四可変位相器５１の設定値をそれぞれ第二可変減衰器２７と第二可変位相器２８の設定値に連動して修正する。この一連の設定値の連動・修正過程により、歪除去回路１６と第一補助増幅器用歪検出回路７３のそれぞれのループの平衡性を達成する。
【００２１】
図２にこの発明の請求項２の実施例を示す。図２は、４つのパイロット信号と４つの制御手段を用いる。図２において図１と対応する部分は同一番号を付けてある。この実施例では第一パイロット信号を抽出した方向性結合器４４の出力が方向性結合器８１に入力され、第四パイロット信号発生器８２よりの第四パイロット信号が方向性結合器８１に注入され、方向性結合器８１の出力は電力分配器４７に入力される。方向性結合器５７の出力から第四パイロット信号検出器８３で第四パイロット信号が抽出され、その第四パイロット信号のレベルが検出される。第四制御器５９はこの検出された第四パイロット信号のレベルを最小にするように第四可変減衰器４９と第四可変位相器５１を制御する。その他の構成は図１の場合と同様である。
【００２２】
このように、歪除去回路１６の遅延線路２６による経路１４と、第二可変減衰器２７と第二可変位相器２８と第一補助増幅器２９と遅延線路５６にて構成される経路によるループと、第一補助増幅器用歪検出回路７３のループを独立に達成するために、第一補助増幅器用歪検出回路７３に第四可変減衰器４９と第四可変位相器５１と、第一補助増幅器用歪検出回路７３の入力側に第四パイロット信号発生器８２と注入手段である方向性結合器８１を新たに設ける。
【００２３】
この実施例によるフィードフォワード増幅器は、４つのパイロット信号を用いて、歪検出回路１３、第一補助増幅器用歪検出回路７３、第一補助増幅器用歪除去回路７４、歪除去回路１６の各平衡を達成する。このとき、これまで述べてきたように、第一補助増幅器用歪検出回路７３のループの平衡性は、第四パイロット信号を用いて第四可変減衰器４９と第四可変位相器５１により達成する。歪除去回路１６のループの平衡性は、第一補助増幅器用歪検出回路７３のループの平衡性を達成後、第二パイロット信号を用いて第二可変減衰器２７と第二可変位相器２８を用いて達成する。このとき、第一補助増幅器２９の経路上の第二可変減衰器２７と第二可変位相器２８の設定値を第一補助増幅器用歪検出回路７３のループの平衡性達成後に変更するため、第四可変減衰器４９と第四可変位相器５１の設定値を第二可変減衰器２７と第二可変位相器２８の設定値に連動して修正する。この一連の設定値の連動・修正過程により、歪除去回路１６と第一補助増幅器用歪検出回路７３のそれぞれのループの平衡性を達成する。
【００２４】
図３にこの発明の請求項３の実施例を示し、図１と対応する部分に同一番号を付けてある。この図３は、３つのパイロット信号と４つの制御手段を用いる。この実施例のフィードフォワード増幅器では、第一パイロット信号抽出した方向性結合器４４の出力は電力分配器４７ではなく、第二可変減衰器２７と第二可変位相器２８の直列回路に入力され、この直列回路の出力が電力分配器４７に入力され、電力分配器４７で、分配された一方の信号は遅延線路８５と第一補助増幅器２９により構成される経路に、分配された他方の信号は第四可変減衰器４９と第四可変位相器５１と位相反転回路５２にて構成される経路にそれぞれ入力される。これら二つの経路の出力は電力合成／分配器５５に供給される。その他は図１と同様である。
【００２５】
このように、歪除去回路１６の遅延線路２６による経路と、第二可変減衰器２７と第二可変位相器２８と遅延線路８５と第一補助増幅器２９と遅延線路５６にて構成される経路によるループと、第一補助増幅器用歪検出回路７３のループを独立に達成するために、第一補助増幅器用歪検出回路７３の入力に第二可変位相器２７と第二可変減衰器２８を設け、第一補助増幅器用歪検出回路７３に第四可変減衰器４９と第四可変位相器５１を設ける。
【００２６】
この実施例によるフィードフォワード増幅器は、３つのパイロット信号を用いて、歪検出回路１３、第一補助増幅器用歪検出回路７３、第一補助増幅器用歪除去回路７４、歪除去回路１６の各平衡を達成する。このとき、第一補助増幅器用歪検出回路７３のループの平衡性は、第二パイロット信号を用いて第四可変減衰器４９と第四可変位相器５１により達成する。歪除去回路１６のループの平衡性は、第二パイロット信号を用いて第二可変減衰器２７と第二可変位相器２８を用いて達成する。ループの調整手段である可変位相器と可変減衰器をいずれも共有していないため、第一補助増幅器用歪検出回路７３のループの平衡と歪除去回路１６のループの平衡は独立に達成できる。このようにして、歪除去回路１６と第一補助増幅器用歪検出回路７３のそれぞれのループの平衡は、歪除去回路１６のループの調整手段を第一補助増幅器用歪検出回路７３の前に設け、第一補助増幅器用歪検出回路７３のループの調整手段を第一補助増幅器用歪検出回路７３に設けることでそれぞれ独立に達成できる。
【００２７】
図４にこの発明の請求項４の実施例を示し、図３と対応する部分に同一番号を付けてある。図４では、４つのパイロット信号と４つの制御手段を用いる。この実施例では第二可変位相器２８と電力分配器４７との間に方向性結合器８１が挿入され、この方向性結合器８１に、第四パイロット信号発生器８２からの第四パイロット信号が注入される。方向性結合器５７の出力から第四パイロット信号検出器８３で第四パイロット信号が検出され、そのレベルが検出され、その検出されたレベルを最小にするように第四可変減衰器４９と第四可変位相器５１を第四制御器５９で制御する。その他は図３と同様である。
【００２８】
このように、歪除去回路１６の遅延線路２６による経路と、第二可変減衰器２７と第二可変位相器２８と遅延線路８５と第一補助増幅器２９と遅延線路５６にて構成される経路によるループと、第一補助増幅器用歪検出回路７３のループを独立に達成するために、第一補助増幅器用歪検出回路７３の入力に第二可変位相器２７と第二可変減衰器２８を設け、第一補助増幅器用歪検出回路７３に第四可変減衰器４９と第四可変位相器５１とを設け、第一補助増幅器用歪検出回路７３の入力側に第四パイロット信号発生器８２と注入手段である方向性結合器８１を新たに設ける。
【００２９】
この実施例によるフィードフォワード増幅器は、４つのパイロット信号を用いて、歪検出回路１３、第一補助増幅器用歪検出回路７３、第一補助増幅器用歪除去回路７４、歪除去回路１６の各平衡を達成する。このとき、第一補助増幅器用歪検出回路７３のループの平衡性は、第四パイロット信号を用いて第四可変減衰器４９と第四可変位相器５１により達成する。歪除去回路１６のループの平衡性は、第二パイロット信号を用いて第二可変減衰器２７と第二可変位相器２８を用いて達成する。ループの調整手段である可変位相器と可変減衰器をいずれも共有していないため、第一補助増幅器用歪検出回路７３のループの平衡と歪除去回路１６のループの平衡は独立に達成できる。このようにして、歪除去回路１６と第一補助増幅器用歪検出回路７３のそれぞれのループの平衡は、歪除去用ループの調整手段を第一補助増幅器用歪検出回路７３の前に設け、第一補助増幅器用歪検出回路７３のループの調整手段を第一補助増幅器用歪検出回路７３に設けることでそれぞれ独立に達成できる。
上記各実施例における第一から第四制御器は、各パイロット信号から検出されたレベルを最小にする点において、制御アルゴリズムを共通できるため、各可変減衰器と各可変位相器の制御を時分割で行う単一の制御器で実現してもよい。これにより、制御器を共通化でき、制御器の消費電力を削減できる。制御アルゴリズムについては、従来から実用化されている摂動法、最小自乗推定等の適応アルゴリズムを適用できる。一般にフィードフォワード増幅器のループの平衡性は、電源電圧の変動、装置温度の変化などにより変動する。その変動の時間率は、比較的遅い。このため、最適値に収束するのに時間のかかる制御アルゴリズムであっても、この発明の二重ループを持つフィードフォワード増幅器の制御に十分対応できる。
【００３０】
各パイロット信号については、それぞれ異なる周波数に設定された無変調波、または異なる変調波による同一周波数の搬送波を変調したものに設定され、あるいはそれぞれ異なる拡散符号による同一搬送波の拡散変調のいずれかでもよい。無変調波を用いるパイロット信号を検出するパイロット信号検出器は、狭帯域のレベル検出器により構成される。たとえば、帯域通過フィルタで制限し、そのフィルタ出力をしダイオード等のレベル検出器で検波する構成とされる。変調波を用いるパイロット信号を検出するパイロット信号検出器は、パイロット信号の帯域をベースバンド帯に周波数変換する周波数変換器と、周波数変換されたベースバンド信号を復調する復調器にて構成される。無変調波によるパイロット信号に比べて、変調波によるパイロット信号はパイロット信号を復調するため、各種の干渉、雑音などに対する等化処理、誤り訂正処理などを適用できる。このため、より少ないパイロット信号電力で各ループの平衡を達成できる。拡散符号を用いるパイロット信号を検出するパイロット信号検出器は、パイロット信号の帯域をベースバンド帯に周波数変換する周波数変換器と、周波数変換されたベースバンド信号を逆拡散処理する逆拡散器と、その信号を復調する復調器にて構成される。このようにして、この発明のフィードフォワード増幅器の自動調整装置は、各種パイロット信号に適用できる。
【００３１】
【発明の効果】
この発明により、次の効果がある。
（１）高効率増幅可能な二重ループを持つフィードフォワード増幅器の自動調整装置の提供。
（２）安定した歪補償能力を提供できること。
（３）（１）と（２）より、フィードフォワード増幅器の低消費電力化を達成し、小型な装置、経済性のある装置の提供。
【図面の簡単な説明】
【図１】請求項１の実施例を示すブロック図。
【図２】請求項２の実施例を示すブロック図。
【図３】請求項３の実施例を示すブロック図。
【図４】請求項４の実施例を示すブロック図。
【図５】従来のフィードフォワード増幅器を示すブロック図。
【符号の説明】
１３歪検出回路５１第四可変位相器
１６歪除去回路５２位相反転回路
２１第一可変減衰器６１第三可変減衰器
２２第一可変位相器６２第三可変位相器
２７第二可変減衰器６３第二補助増幅器
２８第二可変位相器７３第一補助増幅器用歪検出回路
２９第一補助増幅器７４第一補助増幅器用歪除去回路
４９第四可変減衰器８２第四パイロット信号発生器[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a feedforward amplifier which is a linear amplifier mainly used in a high frequency band, and more particularly, to a power efficiency-improved one.
[0002]
[Prior art]
FIG. 5 shows the configuration of the feedforward amplifier. The feedforward amplifier includes a distortion detection circuit 13 including an amplification transmission path 11 and a linear signal transmission path 12 of the main amplifier, and a distortion removal circuit 16 including a main signal transmission path 14 and a distortion injection path 15. . The amplification transmission path 11 of the main amplifier is composed of a variable attenuator 21, a variable phase shifter 22 and a main amplifier 23 connected in series. The linear signal transmission path 12 is configured by connecting a delay line 24 and a phase inverting circuit 25 in series. The main signal transmission path 14 is configured by a delay line 26. The strain injection path 15 is constituted by a series connection of a variable attenuator 27, a variable phase shifter 28, and an auxiliary amplifier 29. The input of the feedforward amplifier is distributed by the power distribution circuit 31 to the amplification transmission path 11 and the linear signal transmission path 12 of the main amplifier. Further, the distortion detection circuit 13 and the distortion removal circuit 16 are cascaded by a power combiner / distributor 32. The output of the feedforward amplifier is obtained from a power combiner 33 that combines the outputs of the main signal transmission path 14 and the distortion injection path 15.
[0003]
The feedforward amplifier detects the distortion component generated from the main amplifier 23 by the distortion detection circuit 13 in the previous stage, and adjusts the phase amount and amplitude amount of the distortion component generated from the main amplifier 23 in the distortion removal circuit 16 in the subsequent stage. By injecting the output signal of the main amplifier 23, nonlinear distortion generated from the main amplifier 23 is removed. In general, the amount of nonlinear distortion improvement of the feedforward amplifier depends on the adjustment of the variable attenuator 21 and variable phase shifter 22 of the distortion detection circuit 13 and the variable attenuator 27, variable phase shifter 28 and auxiliary amplifier 29 of the distortion removal circuit 16. . The accuracy of the adjustment is shown in Japanese Patent Application No. 63-23574 “Automatic Adjustment Circuit of Feedforward Amplifier”. For example, the phase and amplitude deviation for obtaining a distortion compression amount of 30 dB or more are within ± 2 degrees and ± 0.3 dB, respectively, and the balance and adjustment of the transmission characteristics of the distortion detection circuit 13 and the distortion removal circuit 16 are adjusted. It can be said that strict conditions are required for completeness.
[0004]
It is the non-linear distortion of the main amplifier 23 that compensates for distortion by the feedforward amplifier. Therefore, the nonlinear distortion generated in the auxiliary amplifier 29 cannot be compensated for by the feedforward amplifier in principle in terms of the circuit configuration. Further, since the balance condition between the two paths is severe, the auxiliary amplifier 29 of the conventional feedforward amplifier is required to have linearity. In general, in order to improve the linearity of an amplifier circuit using a semiconductor amplifier, the so-called class A bias is used as an operating condition, and the saturation output is sufficiently larger than the peak power of the signal to be amplified.
[0005]
[Problems to be solved by the invention]
In recent years, miniaturization, economy, and low power consumption of wireless devices have been demanded. The same applies to a radio apparatus using a feedforward amplifier. In order to achieve low power consumption of the feedforward amplifier, it is essential to increase the efficiency of the main amplifier and the auxiliary amplifier. As a result, it is possible to reduce the size of the heat dissipation plate of the amplifier, and as a result, it is possible to reduce the size of the wireless device.
[0006]
The efficiency of the main amplifier can be increased by a push-pull circuit under a class B bias condition. Nonlinear distortion occurring in the main amplifier can be compensated by a conventional feedforward amplifier. On the other hand, to increase the power efficiency of the auxiliary amplifier 29 inserted in the distortion injection path 15 of the feedforward amplifier, it is generally necessary to operate the semiconductor amplifier element of the auxiliary amplifier under a bias condition such as a so-called class B or class C. is there. Nonlinear distortion caused by these bias conditions cannot be compensated in principle by feedforward amplification as described above. Therefore, increasing the efficiency of the auxiliary amplifier 29 has a problem of reducing the distortion compensation capability of the feedforward amplifier.
[0007]
For example, according to the literature (Toshio Nojima, Shoichi Takahashi, “Ultra Low Distortion Multi-Frequency Common Amplifier for Mobile Communications”, IEICE Technical Report on Radio Communication Systems, RCS90-4, 1990), the saturation output of the main amplifier 100 W, the saturation output of the auxiliary amplifier is 1/8 of the saturation output of the main amplifier, 1.5 GHz band, and in the case of a GaAs MESFET as the semiconductor amplification element of the main amplifier and the auxiliary amplifier, the drain voltage of the main amplifier MESFET is 12 V, the drain The current is 20A, the drain voltage of the auxiliary amplifier MESFET is 12V, and the drain current is 5A. In all cases, the power supplied to the feedforward amplifier is about 153 W under the condition of class A bias, and the drain efficiency is about 5% or less. . Even when a high-efficiency amplifier circuit such as a class B push-pull is used as the main amplifier and a class A amplifier circuit is used as the auxiliary amplifier, only a drain efficiency of about 10% or less can be obtained.
[0008]
The distortion detection circuit and the distortion removal circuit need to control the variable attenuator and variable phase shifter of each loop so as to have equal amplitude, equal delay, and opposite phase. In general, the amount of improvement in nonlinear distortion of a feedforward amplifier depends on the balance of the loop by adjusting these variable attenuators and variable phase shifters. The accuracy of the adjustment is shown in Japanese Patent Application No. 63-23574 “Automatic Adjustment Circuit of Feedforward Amplifier”. For example, the phase and amplitude deviation for obtaining a distortion compression amount of 30 dB or more are within ± 2 degrees and ± 0.3 dB, respectively, and the balance of transmission characteristics of the distortion detection circuit and distortion removal circuit and the completeness of adjustment. It can be said that strict conditions are required. Actually, it is not easy to completely maintain the balance of each of the distortion detection circuit and the distortion removal circuit. Even if the initial setting is complete, the characteristics of the amplifier change due to fluctuations in the ambient temperature, power supply, etc., and it is extremely difficult to maintain good balance with time stability.
[0009]
An automatic adjustment method using a pilot signal is known as a method for maintaining the complete balance of the distortion detection circuit and distortion removal circuit of the feedforward amplifier with high accuracy. For example, Japanese Patent Application No. 63-23574 is available. Toshio Nojima, Shoichi Takahashi, “Ultra-low distortion multi-frequency common amplifier for mobile communication …… Self-adjusting feedforward amplifier (SAFF-A)” ... ", The Institute of Electronics, Information and Communication Engineers, Radio Communication Systems Research Group, RCS90-4, 1990 is known.
[0010]
Any of these automatic adjustment methods is applied to a feedforward amplifier that removes a nonlinear distortion component generated by a conventional main amplifier. Until now, there has been no automatic adjustment method using a pilot signal applicable to a feedforward amplifier capable of high-efficiency amplification with a feedforward configuration of the strain injection path.
The problem to be solved by the present invention is to provide a feedforward amplifier having a distortion compensation capability equal to or higher than that of a conventional feedforward amplifier and capable of automatically adjusting each loop of the feedforward amplifier capable of high efficiency amplification. It is in.
[0011]
[Means for Solving the Problems]
According to the present invention, the strain injection path has a feedforward amplifier configuration. Specifically, assuming that the auxiliary amplifier is a main amplifier, a distortion injection path is configured using a first auxiliary amplifier distortion detecting circuit and a first auxiliary amplifier distortion removing circuit for the auxiliary amplifier (first auxiliary amplifier), Non-linear distortion generated in the auxiliary amplifier (first auxiliary amplifier) is compensated by this feedforward configuration of the strain injection path. In addition, the auxiliary amplifier (first auxiliary amplifier) can be operated with high efficiency by Class B, Class C, Class E, Class F, etc. other than Class A bias.
[0012]
Further, as will be described below, each loop is automatically balanced in each claim.
(1) According to the invention of claim 1, the path constituted by the delay line and the phase inverting circuit of the distortion detection circuit for the first auxiliary amplifier is constituted by the variable attenuator and the variable phase shifter. The injected pilot signal is detected by the first auxiliary amplifier distortion elimination path, and the controller controls the variable attenuator and the variable phase shifter so as to minimize the detection level. The balance of the distortion detection circuit and the distortion elimination circuit for the first auxiliary amplifier is balanced, and the distortion of the distortion elimination circuit loop is changed to the main amplifier using the variable attenuator and variable phase shifter on the input side of the first auxiliary amplifier. The injected pilot signal is detected at the feedforward amplifier output and controlled by the controller so as to minimize the detection level. The newly inserted variable attenuator and variable phase adjuster adjust the set value in conjunction with the controlled attenuation and phase. Thereby, the balance of the distortion removing circuit and the first auxiliary amplifier distortion detecting circuit can be achieved at the same time.
[0013]
(2) According to the invention of claim 2, the path constituted by the delay line and the phase inversion circuit of the distortion detection circuit for the first auxiliary amplifier is constituted by the variable attenuator and the variable phase shifter, and the distortion injection path A pilot signal injected into the input terminal of the first auxiliary amplifier is detected by a distortion removal path for the first auxiliary amplifier, and the controller controls the variable attenuator and the variable phase shifter so as to minimize the detection level. Achieving loop balance of the distortion detection circuit and the distortion removal circuit for the first auxiliary amplifier, and injecting the balance of the distortion removal circuit loop into the main amplifier with the variable attenuator and variable phase shifter on the input side of the first auxiliary amplifier The pilot signal thus detected is detected by the feedforward amplifier output and controlled by the controller so as to minimize the detection level. The newly inserted variable attenuator and variable phase adjuster adjust the set value in conjunction with the controlled attenuation and phase. Thereby, the balance of the distortion removing circuit and the first auxiliary amplifier distortion detecting circuit can be achieved at the same time.
[0014]
(3) According to the invention of claim 3, the second variable phase shifter and the second variable attenuator are inserted before the power divider at the input of the first auxiliary amplifier distortion detection circuit. A delay line is used for the first auxiliary amplifier signal transmission path of the first auxiliary amplifier distortion detection circuit, and a fourth variable phase shifter, a fourth variable attenuator, and a phase inverting circuit are used for the first auxiliary amplifier linear signal transmission path. The first auxiliary amplifier distortion detection circuit is configured. In the invention of claim 1, the cooperative operation of the second controller and the fourth controller is required, but in the invention of claim 3, this cooperative operation is not required. The balance of the four loops of the feedforward amplifier can be achieved independently.
[0015]
(4) According to the invention of claim 4, the second variable phase shifter and the second variable attenuator are inserted in front of the power divider at the input of the first auxiliary amplifier distortion detection circuit. A delay line is used for the first auxiliary amplifier signal transmission path of the first auxiliary amplifier distortion detection circuit, and a fourth variable phase shifter, a fourth variable attenuator, and a phase inverting circuit are used for the first auxiliary amplifier linear signal transmission path. The first auxiliary amplifier distortion detection circuit is configured. In the invention of claim 2, the cooperative operation of the second controller and the fourth controller is required. However, in the invention of claim 4, this cooperative operation is not required. The balance of the four loops of the feedforward amplifier can be achieved independently.
Action
According to the present invention, it is possible to increase the efficiency of the auxiliary amplifier by configuring the strain injection path with a feedforward configuration, and it is possible to remove the distortion component generated with the increased efficiency. In addition, by controlling the variable attenuator and variable phase shifter of each loop so as to minimize the level of the balance of the four existing loops by using the feed-forward configuration of the distortion injection path, respectively, using a pilot signal. Enables compensation of distortion components generated by the main amplifier and distortion components generated by the first auxiliary amplifier, and can apply operating conditions of high-efficiency amplification other than class A bias conditions to the semiconductor amplifying element of the first auxiliary amplifier. .
[0016]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an embodiment of claim 1 of the present invention. FIG. 1 uses three pilot signals and four control means. The feedforward amplifier according to the present invention includes a first pilot signal generator 41 on the amplifier input side, a directional coupler 42 for injecting the first pilot signal into the amplifier input, and a power distributor for distributing the amplifier input signal in two paths. 31, a path 11 configured by the first variable attenuator 21, the first variable phase shifter 22, and the main amplifier 23, and a path 12 configured by the delay line 24 and the phase inverting circuit 25. A second pilot signal generator 43 that is injected between the stages of the main amplifier 23, a power combiner / distributor 32 that combines these two paths 11 and 12 and distributes them to the two paths, and this power combiner / distributor A delay line 26 for inputting the signal distributed by the detector 32, a directional coupler 44 for inputting the distributed signal and extracting the first pilot signal, and the extracted first pilot signal A first pilot signal detector 45 to detect, and a first controller 46 that inputs the detected level and controls the first variable attenuator 21 and the first variable phase shifter 22 to minimize the level. The output of the directional coupler 44 from which the first pilot signal has been extracted is input, the power distributor 47 that distributes the signals in two paths, the second variable attenuator 27 and the second variable phase shifter that receive the distributed signals 28 and the first auxiliary amplifier 29, a path 53 composed of a fourth variable attenuator 49, a fourth variable phase shifter 51 and a phase inverting circuit 52 for inputting the distributed signal; A means for injecting a third pilot signal between the stages of one auxiliary amplifier 29, a third pilot signal generator 54, and a power combiner / distributor 55 for combining these two paths 48 and 53 and distributing them to the two paths; , The distributed signal A path 60 comprising a delay line 56 to be applied, a directional coupler 57 for inputting the distributed signal and extracting the second pilot signal, and a second pilot signal detector for detecting the level of the extracted second pilot signal 58, a fourth controller 59 for controlling the fourth variable attenuator 49 and the fourth variable phase shifter 51 so as to minimize the detected level, and an output of the directional coupler 57 are input. A path 64 composed of a variable attenuator 61, a third variable phase shifter 62, and a second auxiliary amplifier 63, a power combiner 65 that combines the outputs of these two paths 60 and 64, and an output of the power combiner 65 And a third pilot signal detector 67 for inputting the extracted third pilot signal and detecting its level, and for detecting the detected level to a minimum. A third controller 68 for controlling the third variable attenuator 61 and the third variable phase shifter 62 so that the output of the path 14 and the third pilot signal by the delay line 26 are extracted. A power combiner 33 that combines the output power, a directional coupler 69 that receives the power combined signal and extracts the second pilot signal, and a second pilot signal detection that detects the level of the extracted second pilot signal And a second controller 72 for controlling the second variable attenuator 27 and the second variable phase shifter 28 so that the detected level is minimized.
[0017]
A path 48 including the second variable attenuator 27, the second variable phase shifter 28, and the first auxiliary amplifier 29 and a path 53 including the fourth variable attenuator 49, the fourth variable phase shifter 51, and the phase inverting circuit 52 One auxiliary amplifier distortion detection circuit 73 is configured, and the first auxiliary amplifier distortion detection circuit 73 detects a distortion component generated in the first auxiliary amplifier 29. A first auxiliary amplifier distortion removing circuit 74 is configured by the path 60 of the delay line 56 and the path 64 including the third variable attenuator 61, the third variable phase shifter 62, and the second auxiliary amplifier 63. The distortion component detected by the distortion detection circuit 73 is injected into the output of the first auxiliary amplifier 29 with reverse phase, equal amplitude, and equal delay, and the distortion component generated in the first auxiliary amplifier 29 is removed.
[0018]
As described above, the feed-forward configuration of the strain injection path 15 allows the first auxiliary amplifier 29 to operate the semiconductor amplification element of the first auxiliary amplifier 29 with high efficiency under operating conditions other than the class A bias. A distortion component newly generated from the auxiliary amplifier 29 is detected by the distortion detection circuit 73 for auxiliary amplifier, and the first distortion in the amplified output of the first auxiliary amplifier 29 is detected by the distortion removal circuit 74 for auxiliary amplifier using the detected distortion component. The distortion component generated in the auxiliary amplifier 29 is removed. Therefore, high efficiency amplification of the first auxiliary amplifier 29 can be achieved.
[0019]
Thus, the path 14 by the delay line 26 of the distortion elimination circuit 16, the loop by the path constituted by the second variable attenuator 27, the second variable phase shifter 28, the first auxiliary amplifier 29, and the delay line 56, In order to achieve the loop of the first auxiliary amplifier distortion detection circuit 73 independently, a fourth variable attenuator 49 and a fourth variable phase shifter 51 are newly provided in the first auxiliary amplifier distortion detection circuit 73.
[0020]
The feedforward amplifier according to the present invention achieves each balance of the distortion detection circuit 13, the first auxiliary amplifier distortion detection circuit 73, the first auxiliary amplifier distortion elimination circuit 74, and the distortion elimination circuit 16 using three pilot signals. To do. At this time, as described above, the loop balance of the first auxiliary amplifier distortion detection circuit 73 is achieved by the fourth variable attenuator 49 and the fourth variable phase shifter 51 using the second pilot signal. . As for the balance of the loop of the distortion removal circuit 16, after the balance of the loop of the distortion detection circuit 73 for the first auxiliary amplifier is achieved, the second variable attenuator 27 and the second variable phase shifter 28 are connected using the second pilot signal. Use to achieve. At this time, the setting values of the second variable attenuator 27 and the second variable phase shifter 28 on the path 48 of the first auxiliary amplifier 29 are changed after the balance of the loop of the first auxiliary amplifier distortion detection circuit 73 is achieved. The set values of the fourth variable attenuator 49 and the fourth variable phase shifter 51 are corrected in conjunction with the set values of the second variable attenuator 27 and the second variable phase shifter 28, respectively. By this series of setting value interlocking and correction processes, the balance of the respective loops of the distortion removing circuit 16 and the first auxiliary amplifier distortion detecting circuit 73 is achieved.
[0021]
FIG. 2 shows an embodiment of claim 2 of the present invention. FIG. 2 uses four pilot signals and four control means. In FIG. 2, parts corresponding to those in FIG. In this embodiment, the output of the directional coupler 44 from which the first pilot signal has been extracted is input to the directional coupler 81, and the fourth pilot signal from the fourth pilot signal generator 82 is injected into the directional coupler 81. The output of the directional coupler 81 is input to the power distributor 47. The fourth pilot signal is extracted from the output of the directional coupler 57 by the fourth pilot signal detector 83, and the level of the fourth pilot signal is detected. The fourth controller 59 controls the fourth variable attenuator 49 and the fourth variable phase shifter 51 so as to minimize the level of the detected fourth pilot signal. Other configurations are the same as those in FIG.
[0022]
Thus, the path 14 by the delay line 26 of the distortion elimination circuit 16, the loop by the path constituted by the second variable attenuator 27, the second variable phase shifter 28, the first auxiliary amplifier 29, and the delay line 56, In order to independently achieve a loop of the first auxiliary amplifier distortion detection circuit 73, the first auxiliary amplifier distortion detection circuit 73 includes a fourth variable attenuator 49, a fourth variable phase shifter 51, and a first auxiliary amplifier distortion. A fourth pilot signal generator 82 and a directional coupler 81 as injection means are newly provided on the input side of the detection circuit 73.
[0023]
The feedforward amplifier according to this embodiment uses the four pilot signals to balance each of the distortion detection circuit 13, the first auxiliary amplifier distortion detection circuit 73, the first auxiliary amplifier distortion removal circuit 74, and the distortion removal circuit 16. Achieve. At this time, as described above, the loop balance of the first auxiliary amplifier distortion detection circuit 73 is achieved by the fourth variable attenuator 49 and the fourth variable phase shifter 51 using the fourth pilot signal. . As for the balance of the loop of the distortion removal circuit 16, after the balance of the loop of the distortion detection circuit 73 for the first auxiliary amplifier is achieved, the second variable attenuator 27 and the second variable phase shifter 28 are connected using the second pilot signal. Use to achieve. At this time, the setting values of the second variable attenuator 27 and the second variable phase shifter 28 on the path of the first auxiliary amplifier 29 are changed after the balance of the loop of the first auxiliary amplifier distortion detection circuit 73 is achieved. The set values of the four variable attenuators 49 and the fourth variable phase shifter 51 are corrected in conjunction with the set values of the second variable attenuator 27 and the second variable phase shifter 28. By this series of setting value interlocking and correction processes, the balance of the respective loops of the distortion removing circuit 16 and the first auxiliary amplifier distortion detecting circuit 73 is achieved.
[0024]
FIG. 3 shows an embodiment of claim 3 of the present invention, and the same reference numerals are given to the portions corresponding to those in FIG. FIG. 3 uses three pilot signals and four control means. In the feedforward amplifier of this embodiment, the output of the directional coupler 44 extracted from the first pilot signal is input to the series circuit of the second variable attenuator 27 and the second variable phase shifter 28 instead of the power distributor 47, The output of this series circuit is input to the power distributor 47, where one of the distributed signals is routed to a path constituted by the delay line 85 and the first auxiliary amplifier 29, and the other distributed signal is The signals are input to paths constituted by the fourth variable attenuator 49, the fourth variable phase shifter 51, and the phase inversion circuit 52, respectively. The outputs of these two paths are supplied to the power combiner / distributor 55. Others are the same as in FIG.
[0025]
As described above, the path by the delay line 26 of the distortion removing circuit 16 and the path constituted by the second variable attenuator 27, the second variable phase shifter 28, the delay line 85, the first auxiliary amplifier 29, and the delay line 56 are used. In order to independently achieve the loop and the loop of the first auxiliary amplifier distortion detection circuit 73, the second variable phase shifter 27 and the second variable attenuator 28 are provided at the input of the first auxiliary amplifier distortion detection circuit 73, A fourth variable attenuator 49 and a fourth variable phase shifter 51 are provided in the first auxiliary amplifier distortion detection circuit 73.
[0026]
The feedforward amplifier according to this embodiment uses the three pilot signals to balance each of the distortion detection circuit 13, the first auxiliary amplifier distortion detection circuit 73, the first auxiliary amplifier distortion removal circuit 74, and the distortion removal circuit 16. Achieve. At this time, the balance of the loop of the first auxiliary amplifier distortion detection circuit 73 is achieved by the fourth variable attenuator 49 and the fourth variable phase shifter 51 using the second pilot signal. The balance of the loop of the distortion removal circuit 16 is achieved by using the second variable attenuator 27 and the second variable phase shifter 28 using the second pilot signal. Since neither the variable phase shifter nor the variable attenuator as the loop adjusting means is shared, the balance of the loop of the first auxiliary amplifier distortion detection circuit 73 and the balance of the loop of the distortion removal circuit 16 can be achieved independently. In this way, the balance of the respective loops of the distortion removal circuit 16 and the first auxiliary amplifier distortion detection circuit 73 is provided in such a manner that the loop adjustment means of the distortion removal circuit 16 is provided in front of the first auxiliary amplifier distortion detection circuit 73. By providing the first auxiliary amplifier distortion detection circuit 73 with the loop adjustment means of the first auxiliary amplifier distortion detection circuit 73, each can be achieved independently.
[0027]
FIG. 4 shows an embodiment of claim 4 of the present invention, in which parts corresponding to those in FIG. In FIG. 4, four pilot signals and four control means are used. In this embodiment, a directional coupler 81 is inserted between the second variable phase shifter 28 and the power divider 47, and the fourth pilot signal from the fourth pilot signal generator 82 is inserted into the directional coupler 81. Injected. A fourth pilot signal is detected by the fourth pilot signal detector 83 from the output of the directional coupler 57, its level is detected, and the fourth variable attenuator 49 and the fourth variable so as to minimize the detected level. The variable phase shifter 51 is controlled by the fourth controller 59. Others are the same as FIG.
[0028]
As described above, the path by the delay line 26 of the distortion removing circuit 16 and the path constituted by the second variable attenuator 27, the second variable phase shifter 28, the delay line 85, the first auxiliary amplifier 29, and the delay line 56 are used. In order to independently achieve the loop and the loop of the first auxiliary amplifier distortion detection circuit 73, the second variable phase shifter 27 and the second variable attenuator 28 are provided at the input of the first auxiliary amplifier distortion detection circuit 73, A fourth variable attenuator 49 and a fourth variable phase shifter 51 are provided in the distortion detection circuit 73 for the first auxiliary amplifier, and a fourth pilot signal generator 82 and injection means are provided on the input side of the distortion detection circuit 73 for the first auxiliary amplifier. A directional coupler 81 is newly provided.
[0029]
The feedforward amplifier according to this embodiment uses the four pilot signals to balance each of the distortion detection circuit 13, the first auxiliary amplifier distortion detection circuit 73, the first auxiliary amplifier distortion removal circuit 74, and the distortion removal circuit 16. Achieve. At this time, the balance of the loop of the first auxiliary amplifier distortion detection circuit 73 is achieved by the fourth variable attenuator 49 and the fourth variable phase shifter 51 using the fourth pilot signal. The balance of the loop of the distortion removing circuit 16 is achieved by using the second variable attenuator 27 and the second variable phase shifter 28 using the second pilot signal. Since neither the variable phase shifter nor the variable attenuator as the loop adjusting means is shared, the balance of the loop of the first auxiliary amplifier distortion detection circuit 73 and the balance of the loop of the distortion removal circuit 16 can be achieved independently. In this way, the respective balances of the distortion removal circuit 16 and the first auxiliary amplifier distortion detection circuit 73 are balanced by providing a distortion removal loop adjusting means in front of the first auxiliary amplifier distortion detection circuit 73. This can be achieved independently by providing the first auxiliary amplifier distortion detection circuit 73 with loop adjustment means for the one auxiliary amplifier distortion detection circuit 73.
Since the first to fourth controllers in the above embodiments can share a control algorithm in terms of minimizing the level detected from each pilot signal, the control of each variable attenuator and each variable phase shifter is time-shared. It may be realized by a single controller performed in (1). Thereby, a controller can be made common and the power consumption of a controller can be reduced. As the control algorithm, adaptive algorithms such as a perturbation method and a least square estimation that have been put into practical use can be applied. In general, the balance of the loop of the feedforward amplifier varies due to variations in power supply voltage, changes in device temperature, and the like. The time rate of variation is relatively slow. Therefore, even a control algorithm that takes time to converge to an optimum value can sufficiently cope with the control of a feedforward amplifier having a double loop according to the present invention.
[0030]
Each pilot signal may be set to either a non-modulated wave set to a different frequency, a modulated signal of a carrier wave of the same frequency using a different modulated wave, or a spread modulation of the same carrier using a different spreading code. . A pilot signal detector that detects a pilot signal using an unmodulated wave is constituted by a narrow band level detector. For example, the filter is limited by a band-pass filter, and the filter output is detected by a level detector such as a diode. A pilot signal detector that detects a pilot signal that uses a modulated wave includes a frequency converter that converts the frequency of the pilot signal band to a baseband band, and a demodulator that demodulates the frequency-converted baseband signal. Compared to a pilot signal based on a non-modulated wave, a pilot signal based on a modulated wave demodulates the pilot signal, so that equalization processing, error correction processing, and the like for various types of interference and noise can be applied. For this reason, the balance of each loop can be achieved with less pilot signal power. A pilot signal detector that detects a pilot signal using a spreading code includes a frequency converter that converts a frequency of a pilot signal band to a baseband band, a despreader that despreads the frequency-converted baseband signal, and It consists of a demodulator that demodulates the signal. In this way, the feedforward amplifier automatic adjustment apparatus of the present invention can be applied to various pilot signals.
[0031]
【The invention's effect】
The present invention has the following effects.
(1) Provision of an automatic adjustment device for a feedforward amplifier having a double loop capable of high efficiency amplification.
(2) A stable distortion compensation capability can be provided.
(3) From (1) and (2), the power consumption of the feedforward amplifier can be reduced, and a small device and an economical device can be provided.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of claim 1;
FIG. 2 is a block diagram showing an embodiment of claim 2;
FIG. 3 is a block diagram showing an embodiment of claim 3;
FIG. 4 is a block diagram showing an embodiment of claim 4;
FIG. 5 is a block diagram showing a conventional feedforward amplifier.
[Explanation of symbols]
13 Distortion detection circuit 51 Fourth variable phase shifter
16 Distortion removal circuit 52 Phase inversion circuit
21 First variable attenuator 61 Third variable attenuator
22 First variable phase shifter 62 Third variable phase shifter
27 Second variable attenuator 63 Second auxiliary amplifier
28 Second variable phase shifter 73 Distortion detection circuit for first auxiliary amplifier
29 1st auxiliary amplifier 74 Distortion removal circuit for 1st auxiliary amplifier
49 4th variable attenuator 82 4th pilot signal generator

Claims

A distortion detection circuit for detecting the nonlinear distortion of the main amplifier;
A distortion removal circuit that amplifies the detected distortion component using the first auxiliary amplifier and then cancels the distortion component by injecting it again into the output of the main amplifier;
A distortion detection circuit for a first auxiliary amplifier that detects nonlinear distortion of the first auxiliary amplifier of the distortion removal circuit;
The distortion component detected by the distortion detection circuit for the first auxiliary amplifier is amplified by the second auxiliary amplifier and injected again into the output of the first auxiliary amplifier to cancel the distortion component of the first auxiliary amplifier. A distortion removal circuit for the first auxiliary amplifier that is reinjected into the output of the main amplifier;
Means inserted into the input path of the feedforward amplifier and injecting a first pilot signal;
A first electrical variable attenuation means and a first electrical variable phase means inserted in the input path of the main amplifier of the distortion detection circuit;
First pilot signal detection means inserted in the input path of the first auxiliary amplifier distortion detection circuit;
A first controller for inputting the output signal of the first pilot signal detecting means and controlling the first electric variable attenuator and the first electric variable phase shifter;
Means inserted between the stages of the main amplifier of the distortion detection circuit and injecting a second pilot signal;
A second electrical variable attenuation means and a second electrical variable phase means inserted in the input path of the first auxiliary amplifier of the first auxiliary amplifier distortion detection circuit;
A first second pilot signal detecting means inserted in the output path of the distortion removing circuit;
A second controller that inputs the output of the first second pilot signal detection means and controls the second electrical variable attenuator and the second electrical variable phase shifter;
Means inserted between the stages of the first auxiliary amplifier and injecting a third pilot signal;
A third electrically variable attenuating means and a third electrically variable phase means inserted in the input path of the second auxiliary amplifier of the distortion removing circuit for the first auxiliary amplifier;
A third pilot signal detecting means inserted into the output path of the first auxiliary amplifier distortion removing circuit;
A third controller for inputting the output of the third pilot signal detection means and controlling the third electrical variable attenuation means and the third electrical variable phase means;
A fourth electrical variable attenuation means and a fourth electrical variable phase means inserted in the linear signal transmission path of the first auxiliary amplifier distortion detection circuit;
A second second pilot signal detecting means inserted in the input path of the second auxiliary amplifier of the first auxiliary amplifier distortion removing circuit;
A fourth controller for inputting the output of the second second pilot signal detection means and controlling the fourth electrical variable attenuation means and the fourth electrical variable phase means;
The first electrical variable attenuation means and the first electrical variable phase means are controlled stepwise by the first controller so as to minimize the first pilot signal detection level detected by the first pilot signal detection means. And
In order to minimize the second pilot signal detection level detected by the second second pilot detection means, the fourth electrical variable attenuation means and the fourth electrical variable phase means are stepped by the fourth controller. Control to
The third electrical variable attenuation means and the third electrical variable phase means are controlled stepwise by the third controller so as to minimize the third pilot signal detection level detected by the third pilot signal detection means. The second electrical variable attenuation means and the second electrical variable phase means are connected to the second controller so as to minimize the second pilot signal detection level detected by the first second pilot signal detection means. And the control amount of each of the second electrical variable attenuation means and the second electrical variable phase means controlled by the second controller is controlled by the fourth controller by the fourth controller. Control means for controlling interlocking with respect to the static variable damping means and the fourth electrical variable phase means,
A feedforward amplifier having a double loop characterized by comprising:

A distortion detection circuit for detecting the nonlinear distortion of the main amplifier;
A distortion removal circuit that amplifies the detected distortion component using the first auxiliary amplifier and then cancels the distortion component by injecting it again into the output of the main amplifier;
A distortion detection circuit for a first auxiliary amplifier that detects nonlinear distortion of the first auxiliary amplifier of the distortion removal circuit;
The distortion component detected by the distortion detection circuit for the first auxiliary amplifier is amplified by the second auxiliary amplifier and injected again into the output of the first auxiliary amplifier to cancel the distortion component of the first auxiliary amplifier. A distortion removal circuit for the first auxiliary amplifier that is reinjected into the output of the main amplifier;
Means inserted into the input path of the feedforward amplifier and injecting a first pilot signal;
A first electrical variable attenuation means and a first electrical variable phase means inserted in the input path of the main amplifier of the distortion detection circuit;
First pilot signal detection means inserted in the input path of the first auxiliary amplifier distortion detection circuit;
A first controller for inputting the output signal of the first pilot signal detecting means and controlling the first electric variable attenuator and the first electric variable phase shifter;
Means inserted between the stages of the main amplifier of the distortion detection circuit and injecting a second pilot signal;
A second electrical variable attenuation means and a second electrical variable phase means inserted in the input path of the first auxiliary amplifier of the first auxiliary amplifier distortion detection circuit;
Second pilot signal detecting means inserted in the output path of the distortion removing circuit;
A second controller that inputs the output of the second pilot signal detection means and controls the second electrical variable attenuator and the second electrical variable phase shifter;
Means inserted between the stages of the first auxiliary amplifier and injecting a third pilot signal;
A third electrically variable attenuating means and a third electrically variable phase means inserted in the input path of the second auxiliary amplifier of the distortion removing circuit for the first auxiliary amplifier;
Means inserted into the input path of the first auxiliary amplifier distortion detection circuit and injecting a fourth pilot signal;
A fourth electrical variable attenuation means and a fourth electrical variable phase means inserted in the linear signal transmission path of the first auxiliary amplifier distortion detection circuit;
A third pilot signal detecting means inserted into the output path of the first auxiliary amplifier distortion removing circuit;
A third controller for inputting the output of the third pilot signal detection means and controlling the third electrical variable attenuation means and the third electrical variable phase means;
A fourth pilot signal detecting means inserted in the input path of the second auxiliary amplifier of the first auxiliary amplifier distortion removing circuit;
A fourth controller for inputting the output of the fourth pilot signal detection means and controlling the fourth electrical variable attenuation means and the fourth electrical variable phase means;
The first electrical variable attenuation means and the first electrical variable phase means are controlled stepwise by the first controller so as to minimize the first pilot signal detection level detected by the first pilot signal detection means. And
The second electrical variable attenuation means and the second electrical variable phase means are controlled stepwise by the second controller so as to minimize the second pilot signal detection level detected by the second pilot detection means. ,
The third electrical variable attenuation means and the third electrical variable phase means are controlled stepwise by the third controller so as to minimize the third pilot signal detection level detected by the third pilot signal detection means. The fourth electrical variable attenuating means and the fourth electrical variable phase means are stepped by the fourth controller so as to minimize the fourth pilot signal detection level detected by the fourth pilot signal detecting means. And the control amount of each of the second electrical variable attenuation means and the second electrical variable phase means controlled by the second controller is controlled by the fourth controller. Control means for controlling interlocking with respect to the means and the fourth electrical variable phase means,
A feedforward amplifier having a double loop characterized by comprising:

A distortion detection circuit for detecting the nonlinear distortion of the main amplifier;
A distortion removal circuit that amplifies the detected distortion component using the first auxiliary amplifier and then cancels the distortion component by injecting it again into the output of the main amplifier;
A distortion detection circuit for a first auxiliary amplifier that detects nonlinear distortion of the first auxiliary amplifier of the distortion removal circuit;
The distortion component detected by the distortion detection circuit for the first auxiliary amplifier is amplified by the second auxiliary amplifier and injected again into the output of the first auxiliary amplifier to cancel the distortion component of the first auxiliary amplifier. A distortion removal circuit for the first auxiliary amplifier that is reinjected into the output of the main amplifier;
Means inserted into the input path of the feedforward amplifier and injecting a first pilot signal;
A first electrical variable attenuation means and a first electrical variable phase means inserted in the input path of the main amplifier of the distortion detection circuit;
First pilot signal detection means inserted in the input path of the first auxiliary amplifier distortion detection circuit;
A first controller for inputting the output signal of the first pilot signal detecting means and controlling the first electric variable attenuator and the first electric variable phase shifter;
Means inserted between the stages of the main amplifier of the distortion detection circuit and injecting a second pilot signal;
A second electrically variable attenuating means and a second electrically variable phase means inserted before the power divider at the input of the distortion detecting circuit for the first auxiliary amplifier;
A first second pilot signal detecting means inserted in the output path of the distortion removing circuit;
A second controller that inputs the output of the first second pilot signal detection means and controls the second electrical variable attenuator and the second electrical variable phase shifter;
Means inserted between the stages of the first auxiliary amplifier and injecting a third pilot signal;
A third electrically variable attenuating means and a third electrically variable phase means inserted in the input path of the second auxiliary amplifier of the distortion removing circuit for the first auxiliary amplifier;
A third pilot signal detecting means inserted into the output path of the first auxiliary amplifier distortion removing circuit;
A third controller for inputting the output of the third pilot signal detection means and controlling the third electrical variable attenuation means and the third electrical variable phase means;
A fourth electrical variable attenuation means and a fourth electrical variable phase means inserted in the linear signal transmission path of the first auxiliary amplifier distortion detection circuit;
A second second pilot signal detecting means inserted in the input path of the second auxiliary amplifier of the first auxiliary amplifier distortion removing circuit;
A fourth controller for inputting the output of the second second pilot signal detection means and controlling the fourth electrical variable attenuation means and the fourth electrical variable phase means;
The first electrical variable attenuation means and the first electrical variable phase means are controlled stepwise by the first controller so as to minimize the first pilot signal detection level detected by the first pilot signal detection means. And
In order to minimize the second pilot signal detection level detected by the second second pilot detection means, the fourth electrical variable attenuation means and the fourth electrical variable phase means are stepped by the fourth controller. Control to
The third electrical variable attenuation means and the third electrical variable phase means are controlled stepwise by the third controller so as to minimize the third pilot signal detection level detected by the third pilot signal detection means. And the second electric variable attenuation means and the second electric variable phase means are controlled by the second control so as to minimize the second pilot signal detection level detected by the first second pilot signal detection means. Control means for controlling in stages with a vessel;
A feedforward amplifier having a double loop characterized by comprising:

A distortion detection circuit for detecting the nonlinear distortion of the main amplifier;
A distortion removal circuit that amplifies the detected distortion component using the first auxiliary amplifier and then cancels the distortion component by injecting it again into the output of the main amplifier;
A distortion detection circuit for a first auxiliary amplifier that detects nonlinear distortion of the first auxiliary amplifier of the distortion removal circuit;
The distortion component detected by the distortion detection circuit for the first auxiliary amplifier is amplified by the second auxiliary amplifier and injected again into the output of the first auxiliary amplifier to cancel the distortion component of the first auxiliary amplifier. A distortion removal circuit for the first auxiliary amplifier that is reinjected into the output of the main amplifier;
Means inserted into the input path of the feedforward amplifier and injecting a first pilot signal;
A first electrical variable attenuation means and a first electrical variable phase means inserted in the input path of the main amplifier of the distortion detection circuit;
First pilot signal detection means inserted in the input path of the first auxiliary amplifier distortion detection circuit;
A first controller for inputting the output signal of the first pilot signal detecting means and controlling the first electric variable attenuator and the first electric variable phase shifter;
A second electrical variable attenuation means and a second electrical variable phase means inserted in front of the power divider at the input of the distortion detection circuit for the first auxiliary amplifier;
Means inserted between the stages of the main amplifier of the distortion detection circuit and injecting a second pilot signal;
Second pilot signal detecting means inserted in the output path of the distortion removing circuit;
A second controller that inputs the output of the second pilot signal detection means and controls the second electrical variable attenuator and the second electrical variable phase shifter;
Means inserted between the stages of the first auxiliary amplifier and injecting a third pilot signal;
A third electrically variable attenuating means and a third electrically variable phase means inserted in the input path of the second auxiliary amplifier of the distortion removing circuit for the first auxiliary amplifier;
Means inserted into the input path of the first auxiliary amplifier distortion detection circuit and injecting a fourth pilot signal;
A fourth electrical variable attenuation means and a fourth electrical variable phase means inserted in the linear signal transmission path of the first auxiliary amplifier distortion detection circuit;
A third pilot signal detecting means inserted into the output path of the first auxiliary amplifier distortion removing circuit;
A third controller for inputting the output of the third pilot signal detection means and controlling the third electrical variable attenuation means and the third electrical variable phase means;
A fourth pilot signal detecting means inserted in the input path of the second auxiliary amplifier of the first auxiliary amplifier distortion removing circuit;
A fourth controller for inputting the output of the fourth pilot signal detection means and controlling the fourth electrical variable attenuation means and the fourth electrical variable phase means;
The first electrical variable attenuation means and the first electrical variable phase means are controlled stepwise by the first controller so as to minimize the first pilot signal detection level detected by the first pilot signal detection means. And
The second electrical variable attenuation means and the second electrical variable phase means are controlled stepwise by the second controller so as to minimize the second pilot signal detection level detected by the second pilot detection means. ,
The third electrical variable attenuation means and the third electrical variable phase means are controlled stepwise by the third controller so as to minimize the third pilot signal detection level detected by the third pilot signal detection means. And the fourth electrical variable attenuation means and the fourth electrical variable phase means are staged by the fourth controller so as to minimize the fourth pilot signal detection level detected by the fourth pilot signal detection means. Control means for controlling automatically,
A feedforward amplifier having a double loop characterized by comprising: