JP3784664B2

JP3784664B2 - Variable attenuator

Info

Publication number: JP3784664B2
Application number: JP2001160699A
Authority: JP
Inventors: 通明笠原; 護重檜枝; 賢一宮口; 英司谷口; 義忠伊山
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2001-05-29
Filing date: 2001-05-29
Publication date: 2006-06-14
Anticipated expiration: 2021-05-29
Also published as: JP2002353765A

Description

【０００１】
【発明の属する技術分野】
この発明は可変減衰器に関し、特に、マイクロ波帯及びミリ波帯において信号の振幅を電気的に変化させるための可変減衰器に関するものである。
【０００２】
【従来の技術】
可変減衰器は、レーダーや通信装置などの送受信器において、必要とする送信電力や受信電力を得るための、高周波信号の振幅制御用に広く用いられている。一方、複数のアンテナ素子の各々に接続されている送受信器と移相器を用い、高周波信号の位相を制御することでアンテナの指向方向を変えるフェーズドアレイアンテナにおいては、移相量の誤差はアンテナの指向方向の誤差要因となるため、送受信器の構成品の一部である可変減衰器においても、減衰量を可変した場合の通過位相量の変動を極力少なくする必要がある。
【０００３】
図８は、例えば特開平８−１６２８８６号公報に示された従来の可変減衰器の構成を示したものである。図において、１０１ａ及び１０１ｂは高周波信号入出力端子、１０２は可変減衰器、１０３は位相調整器、１０４は制御信号入力端子、１０５はＡ／Ｄ変換器、１０６はマイクロプロセッサユニット、１０７はＲＯＭ、１０８ａ及び１０８ｂはＤ／Ａ変換器である。
【０００４】
次に動作について説明する。高周波信号入出力端子１０１ａに入力された高周波信号は、可変減衰器１０２を経て位相調整器１０３に入力され、位相補償を与えられた後、高周波信号入出力端子１０１ｂから出力される。ここで、減衰量を制御するために制御信号入力端子１０４から入力される制御信号は、Ａ／Ｄ変換器１０５でデジタルデータに変換され、この変換されたデジタルデータはさらにマイクロプロセッサユニット１０６により可変減衰器２及び位相調整器１０３を制御するための２種のデジタル信号にさらに変換される。この変換は、ＲＯＭ１０７に記録された電圧―減衰特性及び電圧―位相特性の変換テーブルを用いて行われる。このようにして変換された２種のデジタル信号は、Ｄ／Ａ変換器１０８ａ及び１０８ｂにより、アナログ信号としての直流電圧に再変換され、それぞれ可変減衰器１０２及び位相調整器１０３に印加される。このとき可変減衰器１０２により生じる高周波信号の通過位相量の変動を、予めＲＯＭ１０７に記憶させておき、その通過位相量の変動を相殺させるような位相変化を、位相調整器１０３で行うことにより、減衰時の通過位相量の変動が少ない可変減衰器を得る。
【０００５】
【発明が解決しようとする課題】
従来の可変減衰器は、可変減衰器の通過位相量の変動を補正するために位相調整器が必要であるため、回路が大型化し、高価になってしまうという問題点があった。
【０００６】
この発明は、かかる問題点を解決するためになされたものであり、減衰時の通過位相量の変動が少ない、小型で安価な可変減衰器を得ることを目的とする。
【０００７】
【課題を解決するための手段】
この発明は、制御電圧により抵抗値が変化する可変抵抗手段を有し、この可変抵抗手段に制御電圧を印加するようにした可変減衰器であって、前記可変抵抗手段の制御電圧と前記可変減衰器の通過減衰特性及び通過位相特性との関係を示すデータを記録したＲＯＭと、前記ＲＯＭに記録された前記データを基に、所望の通過減衰量が得られ、かつ、通過位相量の変動が最小となる制御電圧印加条件を求める計算回路と、前記制御電圧印加条件に基づき、前記可変抵抗手段に制御電圧を印加するＤ／Ａ変換回路とを備え、前記ＲＯＭが、前記データに加え、さらに、前記可変抵抗手段の制御電圧と前記可変減衰器の反射特性との関係を示すデータを記録しており、前記計算回路が、前記ＲＯＭに記録された前記データを基に、所望の通過減衰量および反射量が得られ、かつ、通過位相量の変動が最小となる制御電圧印加条件を求めることを特徴とする可変減衰器である。
【０００８】
また、前記ＲＯＭが、各々の使用温度毎の、前記可変抵抗素子の制御電圧と前記可変減衰器の通過減衰特性、反射特性及び通過位相特性との関係を示すデータを記録しており、前記計算回路が、使用する温度情報を入力とし、前記ＲＯＭに記録された前記データを基に、入力された使用温度において所望の通過減衰量および反射量が得られ、かつ、通過位相量の変動が最小となる制御電圧印加条件を求める。
【０００９】
また、この発明は、制御電圧により抵抗値が変化する可変抵抗手段を有し、この可変抵抗手段に制御電圧を印加するようにした可変減衰器であって、前記可変抵抗手段の制御電圧と前記可変減衰器の通過減衰特性及び通過位相特性との関係を示すデータを記録したＲＯＭと、前記ＲＯＭに記録された前記データを基に、所望の通過減衰量が得られ、かつ、通過位相量の変動が最小となる制御電圧印加条件を求める計算回路と、前記制御電圧印加条件に基づき、前記可変抵抗手段に制御電圧を印加するＤ／Ａ変換回路とを備え、前記ＲＯＭが、各々の使用温度毎の、前記可変抵抗素子の制御電圧と前記可変減衰器の通過減衰特性、反射特性及び通過位相特性との関係を示すデータを記録しており、前記計算回路が、使用する温度情報を入力とし、前記ＲＯＭに記録された前記データを基に、入力された使用温度において所望の通過減衰量および反射量が得られ、かつ、通過位相量の変動が最小となる制御電圧印加条件を求めることを特徴とする可変減衰器である。
【００１０】
【発明の実施の形態】
実施の形態１．
図１はこの発明の実施の形態１による可変減衰器の構成を示す図である。図１において、１ａ及び１ｂは、高周波信号の入出力が行われる高周波信号入出力端子、２ａ及び２ｂは、制御電圧により抵抗値が変化する可変抵抗素子としての働きをする第１のＦＥＴ、３は同じく可変抵抗素子としての働きをする第２のＦＥＴ、４は第１のＦＥＴ２ａ，２ｂおよび第２のＦＥＴ３から構成される減衰回路、５は、後述するＲＯＭデータを基に、外部から設定された所望の通過減衰特性を満足しし、かつ、通過位相量の変動が最小となる制御電圧印加条件を求める計算回路、６は、第１及び第２のＦＥＴ２，３の制御電圧と可変減衰器４の通過減衰特性、通過位相特性の各々の関係を変換テーブルとして記録したＲＯＭ、７ａ及び７ｂは、計算回路５により得られた制御電圧印加条件に基づいて、第１及び第２のＦＥＴ２，３に制御電圧を印加するＤ／Ａ変換器である。
【００１１】
図２は、図１に示した可変減衰器内に設けられている減衰回路４の等価回路を示す図である。図２において、８ａ及び８ｂは図１中の第１のＦＥＴ２ａ及び２ｂの等価回路にあたる第１の可変抵抗、９は図１中の第２のＦＥＴ３の等価回路にあたる第２の可変抵抗である。
【００１２】
次に動作について説明する。第１のＦＥＴ２および第２のＦＥＴ３は、ゲート電極に印加する電圧を制御することで、ドレイン電極とソース電極間の抵抗値が変化し、可変抵抗素子と見なせるので、図１の減衰回路４は、図２に示すπ型減衰回路として動作する。高周波信号入出力端子１ａから入力された高周波信号は、第1のＦＥＴ２および第２のＦＥＴ３から構成される減衰回路４で所定の減衰を受けた後、高周波信号入出力端子１ｂから出力される。
【００１３】
次に、減衰回路４における減衰量設定方法について述べる。第１のＦＥＴ２ａ，２ｂ（のゲート電極）に印加される制御電圧をＶｇ１とし、第２のＦＥＴ３（のゲート電極）に印加される制御電圧をＶｇ２とすると、ＲＯＭ６には、制御電圧Ｖｇ１、Ｖｇ２をパラメータとした、予め取得された通過減衰特性および通過位相特性のデータが記録されている。図３に、制御電圧Ｖｇ１をｘ軸、Ｖｇ２をｙ軸にとった、通過減衰量の分布図の一例を示す。また、図４に、制御電圧Ｖｇ１をｘ軸、Ｖｇ２をｙ軸にとった、通過位相量の分布図の一例を示す。
【００１４】
計算回路５では、これらＲＯＭ６に記録された図３および図４のデータを用いて、外部から設定される所望の通過減衰量が得られ、かつ、通過位相量の変動が最小となる制御電圧条件を計算する。例えば、所望の通過減衰量が５〜２０ｄＢの範囲とした場合、通過位相量の変動が最小となるように、制御電圧印加線Ａを、図３および図４のように設定する。上記のように決定され、計算回路５から出力された制御電圧データは、Ｄ／Ａ変換器７ａ及び７ｂにて、第１のＦＥＴ２および第２のＦＥＴ３に印加される。このような減衰量設定を行うことで、図５に示す通過減衰量対通過位相量の特性が得られる。
【００１５】
以上のように、この実施の形態１における可変減衰器によれば、ＲＯＭ６に記録された、通過減衰量および通過位相量の分布データを用いて、計算回路５により、所望の通過減衰量が得られ、かつ、通過位相量の変動が最小となる制御電圧条件を計算し、この制御電圧条件を用いて減衰回路４を動作させるようにしたので、位相変動補償用の位相調整器が不要となり、通過位相変動量が小さく、かつ、小型で安価な可変減衰器を得ることができる。
【００１６】
実施の形態２．
上述の実施の形態１では、ＲＯＭ６に記録されたデータは、減衰回路４の制御電圧Ｖｇ１、Ｖｇ２をパラメータとした通過減衰特性及び通過位相特性であったが、本実施の形態においては、これらに加え、減衰回路４の制御電圧Ｖｇ１、Ｖｇ２をパラメータとした反射特性をＲＯＭ６に記録するようにしたものである。図６に制御電圧Ｖｇ１をｘ軸、Ｖｇ２をｙ軸にとった、反射量の分布図の一例を示す。反射特性は、回路に入力する高周波信号と回路から反射されて戻ってくる高周波信号との比を表すもので、入力する高周波信号と反射される高周波信号とが重畳されるため、反射量が大きいほど、入力した高周波信号の位相の変動が増大する。なお、本実施の形態における可変減衰器の構成は、図１及び図２に示すものと基本的に同じであるため、以下の説明においては、図１及び図２を参照するものとする。
【００１７】
本実施の形態の減衰回路４における減衰量設定方法について述べる。ＲＯＭ６には、減衰回路４の制御電圧Ｖｇ１、Ｖｇ２をパラメータとした、予め取得された通過減衰特性、通過位相特性、反射特性のデータが記録されている。計算回路５では、ＲＯＭ６に記録された図３、図４、図６のデータを用い、外部から設定される所望の通過減衰量および反射量が得られ、かつ、通過位相量の変動が最小となる制御電圧条件を計算する。例えば、所望の通過減衰量が５〜２０ｄＢの範囲で、反射量が−１０ｄＢ以下とした場合、通過位相量の変動が最小となるように、制御電圧印加線Ｂを、図３、図４、図６のように設定する。上記のように決定され、計算回路５から出力された制御電圧データは、Ｄ／Ａ変換器７にて第１のＦＥＴ２および第２のＦＥＴ３に印加される。
【００１８】
以上のように、この実施の形態２における可変減衰器によれば、ＲＯＭ６に記録された、通過減衰量、反射量、通過位相量の分布データを用いて、所望の通過減衰量および反射量が得られ、かつ、通過位相量の変動が最小となる制御電圧条件を計算し、この制御電圧条件を用いて減衰回路４を動作させるようにしたので、位相変動補償用の位相調整器が不要となり、また、高周波信号の振幅変動と位相変動の要因となる反射量を小さく抑えられるので、実施の形態１に比べ、更に通過位相変動量が小さく、かつ、小型で安価な可変減衰器が得られる。
【００１９】
実施の形態３．
図７はこの発明の実施の形態３による可変減衰器の構成を示す図である。図１と同一または相当する構成については、同一の符号を付している。本実施の形態においては、計算回路５に、さらに、使用する温度情報を外部から入力するようにし、また、ＲＯＭ６に、第１及び第２のＦＥＴ２，３の制御電圧と可変減衰器４の通過減衰特性、反射特性、通過位相特性の各々の使用温度毎の関係を変換テーブルとして記録している点が、上述の実施の形態１と異なる。
【００２０】
実施の形態３では、ＲＯＭ６に記録するデータを、使用する温度毎に取得した、減衰回路４の制御電圧Ｖｇ１、Ｖｇ２をパラメータとした通過減衰特性、通過位相特性、反射特性のデータとし、計算回路５に、外部から使用する温度情報（以下、温度条件とする。）を入力するようにしたものである。
【００２１】
次に、実施の形態３の減衰回路４における減衰量設定方法について述べる。ＲＯＭ６には、使用する温度毎に予め取得した、減衰回路４の制御電圧Ｖｇ１、Ｖｇ２をパラメータとした通過減衰特性、通過位相特性、反射特性のデータが記録されている。計算回路５では、これらＲＯＭ６に記録されたデータと外部から入力する温度条件を用い、使用温度において、外部から設定される所望の通過減衰量および反射量が得られ、かつ、通過位相量の変動が最小となる制御電圧条件を計算する。計算回路５から出力された制御電圧データはＤ／Ａ変換器７にて第１のＦＥＴ２および第２のＦＥＴ３に印加される。
【００２２】
以上のように、この実施の形態３によれば、使用する温度条件における、可変減衰器４への制御電圧条件が設定できるため、更に、通過位相変動量を小さくすることができる。
【００２３】
上記実施の形態１〜３では、減衰回路４としてＦＥＴを使用したπ型減衰回路を用いた例について記しているが、ＦＥＴの代わりにダイオードなどの他の可変抵抗素子を用いてもよく、また、π型減衰回路の代わりにＴ型減衰回路やはしご型減衰回路などの、制御電圧を印加する可変抵抗素子を用いた減衰回路を用いても同様の効果が得られる。
【００２４】
また、上記実施の形態１〜３では、減衰回路４の制御電圧が２つの場合の例について記しているが、１つないし３つ以上の制御電圧を用いる減衰回路の場合でも、同様の減衰量設定方法を適用することが可能である。
【００２５】
【発明の効果】
この発明は、制御電圧により抵抗値が変化する可変抵抗手段を有し、この可変抵抗手段に制御電圧を印加するようにした可変減衰器であって、前記可変抵抗手段の制御電圧と前記可変減衰器の通過減衰特性及び通過位相特性との関係を示すデータを記録したＲＯＭと、前記ＲＯＭに記録された前記データを基に、所望の通過減衰量が得られ、かつ、通過位相量の変動が最小となる制御電圧印加条件を求める計算回路と、前記制御電圧印加条件に基づき、前記可変抵抗手段に制御電圧を印加するＤ／Ａ変換回路とを備えた可変減衰器であるので、位相変動補償用の位相調整器が不要で、可変減衰器の通過位相変動量が小さく、かつ、小型で安価に構成できるという効果が得られる。
【００２６】
また、前記ＲＯＭが、前記データに加え、さらに、前記可変抵抗手段の制御電圧と前記可変減衰器の反射特性との関係を示すデータを記録しており、前記計算回路が、前記ＲＯＭに記録された前記データを基に、所望の通過減衰量および反射量が得られ、かつ、通過位相量の変動が最小となる制御電圧印加条件を求めるようにしたので、位相変動補償用の位相調整器が不要で、可変減衰器の通過位相変動量が更に小さく、かつ、小型で安価に構成できるという効果が得られる。
【００２７】
また、この発明は、制御電圧により抵抗値が変化する可変抵抗手段を有し、この可変抵抗手段に制御電圧を印加するようにした可変減衰器であって、前記可変抵抗手段の制御電圧と前記可変減衰器の通過減衰特性及び通過位相特性との関係を示すデータを記録したＲＯＭと、前記ＲＯＭに記録された前記データを基に、所望の通過減衰量が得られ、かつ、通過位相量の変動が最小となる制御電圧印加条件を求める計算回路と、前記制御電圧印加条件に基づき、前記可変抵抗手段に制御電圧を印加するＤ／Ａ変換回路とを備え、前記ＲＯＭが、各々の使用温度毎の、前記可変抵抗素子の制御電圧と前記可変減衰器の通過減衰特性、反射特性及び通過位相特性との関係を示すデータを記録しており、前記計算回路が、使用する温度情報を入力とし、前記ＲＯＭに記録された前記データを基に、入力された使用温度において所望の通過減衰量および反射量が得られ、かつ、通過位相量の変動が最小となる制御電圧印加条件を求めることを特徴とする可変減衰器であるので、位相変動補償用の位相調整器が不要で、可変減衰器の通過位相変動量が小さく、かつ、小型で安価に構成できるという効果が得られる。また、前記ＲＯＭが、各々の使用温度毎の、前記可変抵抗素子の制御電圧と前記可変減衰器の通過減衰特性、反射特性及び通過位相特性との関係を示すデータを記録しており、前記計算回路が、使用する温度情報を入力とし、前記ＲＯＭに記録された前記データを基に、入力された使用温度において所望の通過減衰量および反射量が得られ、かつ、通過位相量の変動が最小となる制御電圧印加条件を求めるようにしたので、使用する温度条件毎における、可変減衰器への制御電圧条件が設定できるため、可変減衰器の通過位相変動量が更に小さく、かつ、小型で安価に構成できるという効果が得られる。
【図面の簡単な説明】
【図１】この発明の実施の形態１による可変減衰器の構成を示す構成図である。
【図２】図１に示した可変減衰器における減衰回路の等価回路を示す回路図である。
【図３】図１及び図２に示した減衰回路の制御電圧対通過減衰量の分布の一例を示す説明図である。
【図４】図１及び図２に示した減衰回路の制御電圧対通過位相量の分布の一例を示す説明図である。
【図５】この発明の実施の形態１による可変減衰器の通過減衰量対通過位相量の特性を示す説明図である。
【図６】この発明の実施の形態２による可変減衰器における減衰回路の制御電圧対反射量の分布の一例を示す説明図である。
【図７】この発明の実施の形態３による可変減衰器の構成を示す図である。
【図８】従来の可変減衰器の構成を示す構成図である。
【符号の説明】
１，１ａ，１ｂ高周波信号入出力端子、２，２ａ，２ｂ第１のＦＥＴ、３第２のＦＥＴ、４減衰回路、５計算回路、６ＲＯＭ、７，７ａ，７ｂＤ／Ａ変換器、８第１の可変抵抗、９第２の可変抵抗、１０１ａ，１０１ｂ高周波信号入出力端子、１０２可変減衰器、１０３位相調整器、１０４制御信号入力端子、１０５Ａ／Ｄ変換器、１０６マイクロプロセッサユニット、１０７ＲＯＭ、１０８ａ，１０８ｂＤ／Ａ変換器。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a variable attenuator, and more particularly to a variable attenuator for electrically changing the amplitude of a signal in a microwave band and a millimeter wave band.
[0002]
[Prior art]
A variable attenuator is widely used for amplitude control of a high-frequency signal to obtain necessary transmission power and reception power in a transceiver such as a radar or a communication device. On the other hand, in a phased array antenna that uses a transceiver and a phase shifter connected to each of a plurality of antenna elements and changes the direction of the antenna by controlling the phase of the high-frequency signal, the error in the amount of phase shift is Therefore, even in a variable attenuator that is a part of the component of the transceiver, it is necessary to minimize the variation of the passing phase amount when the attenuation amount is varied.
[0003]
FIG. 8 shows a configuration of a conventional variable attenuator disclosed in, for example, Japanese Patent Application Laid-Open No. 8-162886. In the figure, 101a and 101b are high-frequency signal input / output terminals, 102 is a variable attenuator, 103 is a phase adjuster, 104 is a control signal input terminal, 105 is an A / D converter, 106 is a microprocessor unit, 107 is ROM, Reference numerals 108a and 108b denote D / A converters.
[0004]
Next, the operation will be described. The high-frequency signal input to the high-frequency signal input / output terminal 101a is input to the phase adjuster 103 via the variable attenuator 102, and after being subjected to phase compensation, is output from the high-frequency signal input / output terminal 101b. Here, the control signal input from the control signal input terminal 104 for controlling the attenuation is converted into digital data by the A / D converter 105, and the converted digital data is further changed by the microprocessor unit 106. It is further converted into two kinds of digital signals for controlling the attenuator 2 and the phase adjuster 103. This conversion is performed using a voltage-attenuation characteristic and voltage-phase characteristic conversion table recorded in the ROM 107. The two types of digital signals thus converted are reconverted into DC voltages as analog signals by the D / A converters 108a and 108b and applied to the variable attenuator 102 and the phase adjuster 103, respectively. At this time, the fluctuation of the passing phase amount of the high-frequency signal generated by the variable attenuator 102 is stored in the ROM 107 in advance, and the phase adjuster 103 performs a phase change that cancels the fluctuation of the passing phase amount. A variable attenuator with little variation in the amount of passing phase during attenuation is obtained.
[0005]
[Problems to be solved by the invention]
Since the conventional variable attenuator requires a phase adjuster to correct the variation in the passing phase amount of the variable attenuator, there is a problem that the circuit becomes large and expensive.
[0006]
The present invention has been made to solve such a problem, and an object of the present invention is to obtain a small and inexpensive variable attenuator in which the variation of the passing phase amount at the time of attenuation is small.
[0007]
[Means for Solving the Problems]
The present invention is a variable attenuator having variable resistance means whose resistance value changes according to a control voltage, and applying the control voltage to the variable resistance means, the control voltage of the variable resistance means and the variable attenuation Based on the ROM that records data indicating the relationship between the pass attenuation characteristic and the pass phase characteristic of the detector, and the data recorded in the ROM, a desired pass attenuation amount can be obtained, and fluctuations in the pass phase amount can be obtained. A calculation circuit for obtaining a minimum control voltage application condition; and a D / A conversion circuit for applying a control voltage to the variable resistance means based on the control voltage application condition , wherein the ROM further includes the data, , Data indicating the relationship between the control voltage of the variable resistance means and the reflection characteristic of the variable attenuator is recorded, and the calculation circuit calculates a desired passing attenuation amount based on the data recorded in the ROM. Preliminary reflection amount can be obtained, and a variable attenuator and obtains the control voltage applying conditions change the passing phase amount is minimized.
[0008]
The ROM records data indicating the relationship between the control voltage of the variable resistance element and the pass attenuation characteristic, reflection characteristic, and pass phase characteristic of the variable attenuator for each operating temperature, and the calculation The circuit receives the temperature information to be used as input, and based on the data recorded in the ROM, a desired passing attenuation and reflection amount can be obtained at the inputted operating temperature, and the fluctuation of the passing phase amount is minimized. A control voltage application condition is obtained.
[0009]
Further, the present invention is a variable attenuator having variable resistance means whose resistance value is changed by a control voltage, and applying the control voltage to the variable resistance means, wherein the control voltage of the variable resistance means and the control voltage Based on the ROM in which data indicating the relationship between the pass attenuation characteristic and the pass phase characteristic of the variable attenuator is recorded, and the data recorded in the ROM, a desired pass attenuation amount is obtained, and the pass phase amount A calculation circuit that obtains a control voltage application condition that minimizes fluctuations, and a D / A conversion circuit that applies a control voltage to the variable resistance means based on the control voltage application condition; Data indicating the relationship between the control voltage of the variable resistance element and the pass attenuation characteristic, reflection characteristic, and pass phase characteristic of the variable attenuator is recorded, and the calculation circuit receives temperature information to be used as input. Based on the data recorded on the ROM, desired pass attenuation and reflection amount can be obtained in the input operating temperature, and characterized by obtaining the control voltage applying conditions change the passing phase amount is minimized Is a variable attenuator .
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
1 is a diagram showing a configuration of a variable attenuator according to Embodiment 1 of the present invention. In FIG. 1, reference numerals 1a and 1b denote high-frequency signal input / output terminals for inputting and outputting high-frequency signals, and reference numerals 2a and 2b denote first FETs that function as variable resistance elements whose resistance values change according to control voltages. The second FET, which also functions as a variable resistance element, 4 is an attenuation circuit composed of the first FETs 2a and 2b and the second FET 3, and 5 is set from the outside based on ROM data described later. A calculation circuit for obtaining a control voltage application condition that satisfies the desired pass attenuation characteristics and minimizes the fluctuation of the pass phase amount; and 6, a control voltage and a variable attenuator for the first and second FETs 2 and 3 The ROMs 7a and 7b, in which the relations between the pass attenuation characteristics and the pass phase characteristics of 4 are recorded as conversion tables, are based on the control voltage application conditions obtained by the calculation circuit 5, and the first and second FETs 2 3 is a D / A converter for applying a control voltage to the.
[0011]
FIG. 2 is a diagram showing an equivalent circuit of the attenuation circuit 4 provided in the variable attenuator shown in FIG. 2, 8a and 8b are first variable resistors corresponding to the equivalent circuit of the first FETs 2a and 2b in FIG. 1, and 9 is a second variable resistor corresponding to the equivalent circuit of the second FET 3 in FIG.
[0012]
Next, the operation will be described. Since the first FET 2 and the second FET 3 can be regarded as variable resistance elements by controlling the voltage applied to the gate electrode, the resistance value between the drain electrode and the source electrode is changed, the attenuation circuit 4 in FIG. 2 operates as a π-type attenuation circuit shown in FIG. The high-frequency signal input from the high-frequency signal input / output terminal 1a is output from the high-frequency signal input / output terminal 1b after being subjected to predetermined attenuation by the attenuation circuit 4 including the first FET 2 and the second FET 3.
[0013]
Next, an attenuation amount setting method in the attenuation circuit 4 will be described. If the control voltage applied to the first FET 2a, 2b (the gate electrode) is Vg1, and the control voltage applied to the second FET 3 (the gate electrode) is Vg2, the ROM 6 has the control voltages Vg1, Vg2. The data of the pass attenuation characteristic and the pass phase characteristic acquired in advance with the above as parameters are recorded. FIG. 3 shows an example of a distribution diagram of the passing attenuation amount in which the control voltage Vg1 is taken on the x axis and Vg2 is taken on the y axis. FIG. 4 shows an example of a distribution diagram of the passing phase amount in which the control voltage Vg1 is on the x-axis and Vg2 is on the y-axis.
[0014]
The calculation circuit 5 uses the data of FIG. 3 and FIG. 4 recorded in the ROM 6 to obtain a desired passing attenuation amount set from the outside and control voltage conditions that minimize the variation of the passing phase amount. Calculate For example, when the desired pass attenuation is in the range of 5 to 20 dB, the control voltage application line A is set as shown in FIGS. 3 and 4 so that the fluctuation of the pass phase amount is minimized. The control voltage data determined as described above and output from the calculation circuit 5 is applied to the first FET 2 and the second FET 3 by the D / A converters 7a and 7b. By performing such attenuation setting, the characteristics of the passing attenuation amount versus the passing phase amount shown in FIG. 5 can be obtained.
[0015]
As described above, according to the variable attenuator in the first embodiment, a desired pass attenuation amount is obtained by the calculation circuit 5 using the distribution data of the pass attenuation amount and the pass phase amount recorded in the ROM 6. Since the control voltage condition that minimizes the variation in the passing phase amount is calculated and the attenuation circuit 4 is operated using this control voltage condition, the phase adjuster for compensating the phase fluctuation becomes unnecessary. A small and inexpensive variable attenuator can be obtained with a small amount of variation in the passing phase.
[0016]
Embodiment 2. FIG.
In the first embodiment described above, the data recorded in the ROM 6 is the pass attenuation characteristic and the pass phase characteristic using the control voltages Vg1 and Vg2 of the attenuation circuit 4 as parameters. In the present embodiment, these data are In addition, reflection characteristics using the control voltages Vg1 and Vg2 of the attenuation circuit 4 as parameters are recorded in the ROM 6. FIG. 6 shows an example of a reflection amount distribution diagram in which the control voltage Vg1 is on the x-axis and Vg2 is on the y-axis. The reflection characteristic represents the ratio between the high-frequency signal input to the circuit and the high-frequency signal reflected back from the circuit, and the input high-frequency signal and the reflected high-frequency signal are superimposed, so that the reflection amount is large. As a result, the fluctuation of the phase of the input high-frequency signal increases. The configuration of the variable attenuator in the present embodiment is basically the same as that shown in FIGS. 1 and 2, and therefore, in the following description, reference is made to FIGS. 1 and 2.
[0017]
An attenuation amount setting method in the attenuation circuit 4 of the present embodiment will be described. The ROM 6 stores data of pass attenuation characteristics, pass phase characteristics, and reflection characteristics acquired in advance using the control voltages Vg1 and Vg2 of the attenuation circuit 4 as parameters. The calculation circuit 5 uses the data of FIGS. 3, 4, and 6 recorded in the ROM 6 to obtain a desired passing attenuation amount and reflection amount set from the outside, and the variation in the passing phase amount is minimized. Calculate the control voltage condition. For example, when the desired pass attenuation amount is in the range of 5 to 20 dB and the reflection amount is −10 dB or less, the control voltage application line B is set as shown in FIGS. Settings are made as shown in FIG. The control voltage data determined as described above and output from the calculation circuit 5 is applied to the first FET 2 and the second FET 3 by the D / A converter 7.
[0018]
As described above, according to the variable attenuator in the second embodiment, the desired pass attenuation amount and reflection amount can be obtained using the distribution data of the pass attenuation amount, the reflection amount, and the pass phase amount recorded in the ROM 6. Since the control voltage condition that can be obtained and the variation in the passing phase amount is minimized is calculated and the attenuation circuit 4 is operated using this control voltage condition, the phase adjuster for compensating the phase fluctuation becomes unnecessary. In addition, since the amount of reflection that causes the amplitude fluctuation and phase fluctuation of the high-frequency signal can be reduced, a variable attenuator having a smaller amount of passage phase fluctuation and smaller and less expensive than that of the first embodiment can be obtained. .
[0019]
Embodiment 3 FIG.
FIG. 7 is a diagram showing a configuration of a variable attenuator according to Embodiment 3 of the present invention. The same or corresponding components as those in FIG. 1 are denoted by the same reference numerals. In the present embodiment, temperature information to be used is further input to the calculation circuit 5 from the outside, and the control voltage of the first and second FETs 2 and 3 and the passage of the variable attenuator 4 are input to the ROM 6. The difference from Embodiment 1 described above is that the relationship between the attenuation characteristic, reflection characteristic, and passing phase characteristic for each operating temperature is recorded as a conversion table.
[0020]
In the third embodiment, data to be recorded in the ROM 6 is obtained as data of pass attenuation characteristics, pass phase characteristics, and reflection characteristics using the control voltages Vg1 and Vg2 of the attenuator circuit 4 obtained as parameters for each temperature to be used. In FIG. 5, temperature information (hereinafter referred to as temperature conditions) to be used from outside is input.
[0021]
Next, an attenuation amount setting method in the attenuation circuit 4 of the third embodiment will be described. The ROM 6 stores data of pass attenuation characteristics, pass phase characteristics, and reflection characteristics, which are acquired in advance for each temperature to be used, using the control voltages Vg1, Vg2 of the attenuation circuit 4 as parameters. The calculation circuit 5 uses the data recorded in the ROM 6 and the temperature condition inputted from the outside, and obtains the desired passing attenuation amount and reflection amount set from the outside at the operating temperature, and changes in the passing phase amount. Calculate the control voltage condition that minimizes. The control voltage data output from the calculation circuit 5 is applied to the first FET 2 and the second FET 3 by the D / A converter 7.
[0022]
As described above, according to the third embodiment, since the control voltage condition to the variable attenuator 4 can be set under the temperature condition to be used, the passing phase fluctuation amount can be further reduced.
[0023]
In the first to third embodiments, an example using a π-type attenuation circuit using an FET as the attenuation circuit 4 is described, but other variable resistance elements such as a diode may be used instead of the FET, The same effect can be obtained by using an attenuation circuit using a variable resistance element that applies a control voltage, such as a T-type attenuation circuit or a ladder-type attenuation circuit, instead of the π-type attenuation circuit.
[0024]
In the first to third embodiments, an example in which the control voltage of the attenuation circuit 4 is two is described. However, the same attenuation amount is applied to an attenuation circuit using one to three or more control voltages. It is possible to apply a setting method.
[0025]
【The invention's effect】
The present invention is a variable attenuator having variable resistance means whose resistance value changes according to a control voltage, and applying the control voltage to the variable resistance means, the control voltage of the variable resistance means and the variable attenuation Based on the ROM that records data indicating the relationship between the pass attenuation characteristic and the pass phase characteristic of the detector, and the data recorded in the ROM, a desired pass attenuation amount can be obtained, and fluctuations in the pass phase amount can be obtained. Since it is a variable attenuator comprising a calculation circuit for obtaining a minimum control voltage application condition and a D / A conversion circuit for applying a control voltage to the variable resistance means based on the control voltage application condition, phase fluctuation compensation Therefore, there is no need for a phase adjuster, and there is an effect that the amount of variation in the passing phase of the variable attenuator is small, and that the configuration can be made small and inexpensive.
[0026]
In addition to the data, the ROM further records data indicating the relationship between the control voltage of the variable resistance means and the reflection characteristics of the variable attenuator, and the calculation circuit is recorded in the ROM. Further, based on the above data, the control voltage application condition for obtaining the desired passing attenuation amount and reflection amount and minimizing the variation of the passing phase amount is obtained. This is unnecessary, and the effect that the amount of variation in the passing phase of the variable attenuator is further small, and the configuration can be reduced in size and at low cost.
[0027]
Further, the present invention is a variable attenuator having variable resistance means whose resistance value is changed by a control voltage, and applying the control voltage to the variable resistance means, wherein the control voltage of the variable resistance means and the control voltage Based on the ROM in which data indicating the relationship between the pass attenuation characteristic and the pass phase characteristic of the variable attenuator is recorded, and the data recorded in the ROM, a desired pass attenuation amount is obtained, and the pass phase amount A calculation circuit that obtains a control voltage application condition that minimizes fluctuations, and a D / A conversion circuit that applies a control voltage to the variable resistance means based on the control voltage application condition; Data indicating the relationship between the control voltage of the variable resistance element and the pass attenuation characteristic, reflection characteristic, and pass phase characteristic of the variable attenuator is recorded, and the calculation circuit receives temperature information to be used as input. Based on the data recorded in the ROM, a control voltage application condition is obtained in which a desired passing attenuation amount and reflection amount can be obtained at the input use temperature and the variation of the passing phase amount is minimized. Thus, there is no need for a phase adjuster for compensating for phase fluctuations, the amount of passing phase fluctuation of the variable attenuator is small, and there is an effect that the configuration can be made small and inexpensive. The ROM records data indicating the relationship between the control voltage of the variable resistance element and the pass attenuation characteristic, reflection characteristic, and pass phase characteristic of the variable attenuator for each operating temperature, and the calculation The circuit receives the temperature information to be used as input, and based on the data recorded in the ROM, a desired passing attenuation and reflection amount can be obtained at the inputted operating temperature, and the fluctuation of the passing phase amount is minimized. Since the control voltage application condition for the variable attenuator can be set for each temperature condition to be used, the amount of variation in the passing phase of the variable attenuator is further reduced, and it is small and inexpensive. The effect that it can be comprised is acquired.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a configuration of a variable attenuator according to a first embodiment of the present invention.
2 is a circuit diagram showing an equivalent circuit of an attenuation circuit in the variable attenuator shown in FIG. 1. FIG.
3 is an explanatory diagram illustrating an example of a distribution of control voltage versus passing attenuation amount of the attenuation circuit illustrated in FIGS. 1 and 2; FIG.
4 is an explanatory diagram illustrating an example of a distribution of control voltage versus passing phase amount of the attenuation circuit illustrated in FIGS. 1 and 2; FIG.
FIG. 5 is an explanatory diagram showing characteristics of a passing attenuation amount versus a passing phase amount of the variable attenuator according to the first embodiment of the present invention.
FIG. 6 is an explanatory diagram showing an example of a distribution of control voltage versus reflection amount of an attenuation circuit in a variable attenuator according to Embodiment 2 of the present invention;
FIG. 7 is a diagram showing a configuration of a variable attenuator according to a third embodiment of the present invention.
FIG. 8 is a configuration diagram showing a configuration of a conventional variable attenuator.
[Explanation of symbols]
1, 1a, 1b High-frequency signal input / output terminals, 2, 2a, 2b 1st FET, 3rd FET, 4 attenuation circuit, 5 calculation circuit, 6 ROM, 7, 7a, 7b D / A converter, 8 1st variable resistance, 9 2nd variable resistance, 101a, 101b high frequency signal input / output terminal, 102 variable attenuator, 103 phase adjuster, 104 control signal input terminal, 105 A / D converter, 106 microprocessor unit, 107 ROM, 108a, 108b D / A converter.

Claims

A variable attenuator having variable resistance means whose resistance value changes according to the control voltage, and applying the control voltage to the variable resistance means,
ROM recording data indicating the relationship between the control voltage of the variable resistance means and the pass attenuation characteristic and pass phase characteristic of the variable attenuator;
Based on the data recorded in the ROM, a calculation circuit for obtaining a control voltage application condition for obtaining a desired passing attenuation amount and minimizing a variation in the passing phase amount;
A D / A conversion circuit for applying a control voltage to the variable resistance means based on the control voltage application condition ,
In addition to the data, the ROM further records data indicating the relationship between the control voltage of the variable resistance means and the reflection characteristics of the variable attenuator,
The calculation circuit obtains a control voltage application condition for obtaining a desired pass attenuation amount and reflection amount based on the data recorded in the ROM and minimizing a change in the pass phase amount. Variable attenuator.

The ROM records data indicating the relationship between the control voltage of the variable resistance element and the pass attenuation characteristic, the reflection characteristic, and the pass phase characteristic of the variable attenuator for each operating temperature,
The calculation circuit receives temperature information to be used as an input, and based on the data recorded in the ROM, a desired passing attenuation amount and reflection amount can be obtained at the inputted operating temperature, and the fluctuation of the passing phase amount is obtained. 2. The variable attenuator according to claim 1, wherein a control voltage application condition that minimizes the voltage is obtained.

A variable attenuator having variable resistance means whose resistance value changes according to the control voltage, and applying the control voltage to the variable resistance means,
ROM recording data indicating the relationship between the control voltage of the variable resistance means and the pass attenuation characteristic and pass phase characteristic of the variable attenuator;
Based on the data recorded in the ROM, a calculation circuit for obtaining a control voltage application condition for obtaining a desired passing attenuation amount and minimizing a variation in the passing phase amount;
A D / A converter circuit for applying a control voltage to the variable resistance means based on the control voltage application condition;
With
The ROM records data indicating the relationship between the control voltage of the variable resistance element and the pass attenuation characteristic, the reflection characteristic, and the pass phase characteristic of the variable attenuator for each operating temperature,
The calculation circuit receives temperature information to be used as an input, and based on the data recorded in the ROM, a desired passing attenuation amount and reflection amount can be obtained at the inputted operating temperature, and the fluctuation of the passing phase amount is obtained. There variable attenuator it and obtains the control voltage applying conditions is minimized.