JPS5981927A - wideband tuner - Google Patents

wideband tuner

Info

Publication number
JPS5981927A
JPS5981927A JP57193006A JP19300682A JPS5981927A JP S5981927 A JPS5981927 A JP S5981927A JP 57193006 A JP57193006 A JP 57193006A JP 19300682 A JP19300682 A JP 19300682A JP S5981927 A JPS5981927 A JP S5981927A
Authority
JP
Japan
Prior art keywords
circuit
switching
filter
fill
signal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP57193006A
Other languages
Japanese (ja)
Inventor
Mitsuo Saito
斉藤　光男
Sadahiko Yamashita
山下　貞彦
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Panasonic Holdings Corp
Original Assignee
Matsushita Electric Industrial Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Matsushita Electric Industrial Co Ltd filed Critical Matsushita Electric Industrial Co Ltd
Priority to JP57193006A priority Critical patent/JPS5981927A/en
Publication of JPS5981927A publication Critical patent/JPS5981927A/en
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
    • H03J5/00—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner
    • H03J5/24—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner with a number of separate pretuned tuning circuits or separate tuning elements selectively brought into circuit, e.g. for waveband selection or for television channel selection
    • H03J5/242—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner with a number of separate pretuned tuning circuits or separate tuning elements selectively brought into circuit, e.g. for waveband selection or for television channel selection used exclusively for band selection
    • H03J5/244—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner with a number of separate pretuned tuning circuits or separate tuning elements selectively brought into circuit, e.g. for waveband selection or for television channel selection used exclusively for band selection using electronic means

Landscapes

  • Circuits Of Receivers In General (AREA)

Abstract

PURPOSE:To reduce filter circuits and to reduce parts in number by providing filter circuits which are divided corresponding to respective frequency bands in front of switching circuits for isolation and switching. CONSTITUTION:A trap filter circuit 22 is constituted in front of the switching circuits 2 and 3 to attenuate an unnecessary interference signal of 1/2 IF (intermediate frequency), IF, FM, etc., by >=25-35dB. The switching circuits 2 and 3 are those for separating and switching a desired frequency band, and a transmission system is switched associatively by control voltages from terminals 8 and 9. A low-pass filter is used for a VHF low-channel filter circuit 5 and a high-pass filter is used for a VHF high-channel filter 7.

Description

【発明の詳細な説明】 産業上の利用分野 本発明は０ＡＴＶを含むテレビンヨン信号を受信する広
帯域チューナに関するものである。DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a wideband tuner for receiving television signals including 0ATV.

従来例の構成とその問題点 第１図を用いて従来の広帯域受信チューナにっいて説明
する。図において、１はチューナの入力端子で、５０Ω
程度のコネクタ等が用いられている。２，３はフィルり
回路を分離２切換えるスイッチング回路で、端子８，９
からの制御電圧により伝送系統が連動でスイッチングさ
れるものである。４，６は％ＩＦ、ＩＦ、ＦＭ等の不要
の妨害信号を２５〜３５ｄＢ以上減衰させるフィルり回
路（以下トランプフィルり回路と記す）で、特にバンド
ストツプフィルり（ＢＳＦ）が用いられている。６は例
えばＶＨＦローチャンネルフィルり回路で、ローパヌフ
ィルり（ＬＰＦ）が一般的ニ用いられる。７は例えばＶ
ＨＦハイチャンネル。Conventional configuration and its problems A conventional wideband reception tuner will be explained using FIG. In the figure, 1 is the tuner input terminal, 50Ω
Connectors and the like are used. 2 and 3 are switching circuits that separate and switch the fill circuit, and terminals 8 and 9
The transmission system is switched in conjunction with the control voltage from the 4 and 6 are fill circuits (hereinafter referred to as trump fill circuits) that attenuate unnecessary interference signals such as %IF, IF, FM, etc. by 25 to 35 dB or more, and band stop filters (BSF) are particularly used. . Reference numeral 6 designates, for example, a VHF low channel fill circuit, in which a low pass filter (LPF) is generally used. For example, 7 is V
HF high channel.

Ｌｌｆ（Ｆチャンネルフィルり回路で、一般的ニハイパ
ヌフィルり（ＨＰＦ）が用いられる。このようにそれぞ
れの伝送系統での挿入損失は０．７　ｄＢ程度である。Llf (F-channel filter), which uses a general high-pass filter (HPF). In this way, the insertion loss in each transmission system is about 0.7 dB.

入力フィルり回路２１は前記のような構成になっている
。入力フィルり回路２１からの出力は、広帯域可変減衰
器１０で適正レベルに保たれる。１１はＡ（ｙＧ＠子で
ちる。広帯域可変減衰器１０からの信号は広帯域増幅器
１２を経て第１の混合器１３へ入力される。第１混合器
１３により広帯域増幅器１２からの信号と、緩衝増幅器
１４により増幅された電圧制御発振器１５からの信号と
を混合して第１中間周波数信号を得、この信号を帯域ろ
波器１６を介して第２混合器１７へ導く。帯域ｐ波器１
６を通過した第１中間周波数信号と固定発振器１８から
の信号とは第２混合器１７で混合され第２中間周波数と
して第２中間周波増幅器１９を経てＩＦ出力端子２０よ
り出力される。The input fill circuit 21 has the configuration described above. The output from the input filter circuit 21 is maintained at an appropriate level by the wideband variable attenuator 10. 11 is A(yG@child).The signal from the wideband variable attenuator 10 is input to the first mixer 13 via the wideband amplifier 12.The first mixer 13 combines the signal from the wideband amplifier 12 with the buffer. A first intermediate frequency signal is obtained by mixing the signal from the voltage controlled oscillator 15 amplified by the amplifier 14, and this signal is guided to the second mixer 17 via the bandpass filter 16. Bandwidth p-wave filter 1
6 and the signal from the fixed oscillator 18 are mixed by the second mixer 17 and output as a second intermediate frequency from the IF output terminal 20 via the second intermediate frequency amplifier 19.

以上のような従来の広帯域チューナは、入力フィルり回
路部２１において、４及び６に示されているごとく、％
ＩＦ、ＩＦ、ＦＭ等の不要の妨害信号を減衰させるトラ
ップフィルり回路が、ＶＨＦローチャンネル系統、Ｖｌ
（Ｆハイチャンネル及びＵＨＦチャンネル系統の２系統
に必要であり、部品点数が多くなり経済化が実現できな
いという欠点がある。更に、小形の入力フィルり回路が
実現出来ないという欠点がある。In the conventional wideband tuner as described above, as shown in 4 and 6 in the input fill circuit section 21, %
A trap fill circuit that attenuates unnecessary interference signals such as IF, IF, FM, etc. is used in the VHF low channel system, Vl
(It is necessary for two systems, the F high channel system and the UHF channel system, and has the disadvantage that the number of parts increases and economicalization cannot be realized. Furthermore, there is a disadvantage that a small input fill circuit cannot be realized.

発明の目的 小形、経済化を実現した広帯域チューナを提供すること
を目的とするものである。OBJECTS OF THE INVENTION It is an object of the invention to provide a broadband tuner that is compact and economical.

発明の構成 上記目的を達成するために本発明は、入力１言号を入力
フィルり回路部により処理し、その信号を少なくとも１
個の混合器を用いて中間周波数信号に変換する構成を有
し、前記入力フィルり回路部を並列構成の複数個のフィ
ルり回路と、前記フィルタ回路の前段及び後段に設けら
れ、周波数帯に対応して前記フィルり回路を分離、切換
える第１及び第２のスイッチング回路と、前記第１のス
イッチング回路の前段に設けられ、％ＩＦ、ＩＦ。Structure of the Invention In order to achieve the above object, the present invention processes one input word by an input fill circuit section, and processes the signal by at least one input word.
It has a configuration in which the input fill circuit section is configured to convert into an intermediate frequency signal using a mixer, and the input fill circuit section is provided with a plurality of fill circuits configured in parallel, and a plurality of fill circuits arranged in parallel, and a plurality of filter circuits provided before and after the filter circuit. first and second switching circuits that separate and switch the fill circuits correspondingly; and %IF, IF provided in a preceding stage of the first switching circuit.

ＦＭＩ−ランプ等の不要な妨害信号を除去する１−ラン
プフィルり回路とから少なくとも構成したもので、受信
感度を低下させることなく小形、経済化を実現したもの
である。It consists of at least one lamp filter circuit for removing unnecessary interfering signals from FMI lamps, etc., and is compact and economical without reducing reception sensitivity.

実施例の説明 第２図に本発明の実施例としての広帯域チューナの構成
を示す。従来例と同一機能を有する部位には同一符号を
付して詳細は省略する。１はチューナの入力端子で５０
Ω程度のコネクタまたは、ピン等が用いられている。２
２はスイッチング回路２，３の前段に１１４成されてい
る％ＩＦ（中間周波数）、ＩＦ、ＦＭ等の不要の妨害信
号を２６〜３６　ａ１５以」二減べさせるトラップフィ
ルり回路で、特にバンドストノフリイルり（ＢＳＦ）が
用いられている。２，３は所望の周波数信号帯を分離。DESCRIPTION OF EMBODIMENTS FIG. 2 shows the configuration of a broadband tuner as an embodiment of the present invention. The same reference numerals are given to parts having the same functions as those of the conventional example, and the details are omitted. 1 is the input terminal of the tuner and is 50
Connectors or pins of approximately Ω are used. 2
2 is a trap fill circuit that is constructed in front of the switching circuits 2 and 3 and reduces unnecessary interfering signals such as IF (intermediate frequency), IF, FM, etc. by 26 to 36 a15. Stonnofliil (BSF) is used. 2 and 3 separate the desired frequency signal band.

切換えるスイッチング回路で、端子８，９がらの制御電
圧によシ伝送系統が連動でスイッチングされるものであ
る。５は例えばＶ）ＩＦローチャンネルフィルり回路で
、ＬＰＦが用いられる。７は例えばＶＨＦハイチャンネ
ｉｖ、　Ｕ　ＨＦチャンネルフィルり回路で、ＨＰＦが
用いられている。This is a switching circuit in which the transmission system is switched in conjunction with the control voltages at terminals 8 and 9. 5 is, for example, a V) IF low channel fill circuit, in which an LPF is used. 7 is a VHF high channel iv, U HF channel fill circuit, for example, which uses an HPF.

以上のように人力フィルり回路２３が構成される。入力
フィルり回路２３後の信号の処理は次のようにして行わ
れる。１ｏは広帯域可変減衰器で、人力フィルり回路２
１からの信号を適ＩＦレベルにするために、ＡＧＣ端子
１１に適正電圧が外部がト供給されるものである。最大
挿入損失は１．２　ｄＢ程度である。１２は広帯域増幅
器で、広帯域可変減衰器１０からの信号を適正レベルに
増幅するもので、従来のこのチューナ構成において所望
の雑音指数（ＮＦ）を得るためには２０（ｉＢ程度の利
得が要求されている。この場合の広帯域増幅器１２のＮ
Ｆは２．５〜３．０　ｄＢ程度である。１３はダイオー
ドを用いた第１混合器で、広帯域増幅器１２からの信号
と電圧制御発振器１５から緩衝増幅器１４を経て得られ
た信号とを混合し、２．５Ｇｌ−ＩＺ帯以上の第１中間
周波数信号を取り出すもので、所望の１％混変調レベル
を確保できるように電圧制御発振器１５から適切な出力
レベルが供給されるものである。１６は第１中間周波数
帯を通過させ、不要信号を除去するだめの帯域Ｐ波器で
、帯域幅６　Ｍ　Ｈｚ　、挿入損失５．○ｄＢｄＢ程度
る。The manual fill circuit 23 is configured as described above. The signal after the input fill circuit 23 is processed as follows. 1o is a wideband variable attenuator, and the manual filter circuit 2
In order to bring the signal from 1 to the appropriate IF level, an appropriate voltage is externally supplied to the AGC terminal 11. The maximum insertion loss is about 1.2 dB. Reference numeral 12 denotes a wideband amplifier that amplifies the signal from the wideband variable attenuator 10 to an appropriate level. In this conventional tuner configuration, a gain of about 20 (iB) is required to obtain the desired noise figure (NF). N of the broadband amplifier 12 in this case
F is approximately 2.5 to 3.0 dB. 13 is a first mixer using a diode, which mixes the signal from the wideband amplifier 12 and the signal obtained from the voltage controlled oscillator 15 via the buffer amplifier 14, and mixes the signal from the wideband amplifier 12 and the signal obtained from the voltage controlled oscillator 15 via the buffer amplifier 14, and mixes the signal at a first intermediate frequency of 2.5 Gl-IZ band or higher. It extracts a signal, and an appropriate output level is supplied from the voltage controlled oscillator 15 so as to secure a desired 1% cross modulation level. Reference numeral 16 denotes a band P-wave device that passes the first intermediate frequency band and removes unnecessary signals, and has a bandwidth of 6 MHz and an insertion loss of 5. ○dB It is about dB.

１γはダイオードを用いた第２混合器で、帯域ｐ波器１
６かもの第１中間周波数信号と、固定発振器１８からの
信号とを混合し、第２中間周波数（標準中間周波数）信
号に変換するもので、変換損失６〜７６、Ｂ程度である
。所望の１％　ＣｒｏｓｓＭｏｄｕｌａｔｉｏｎ　（Ｇ
　Ｎ　）　レベルを確保できるように固定発振器１８か
ら適切な出力レベルが供給されるものである。１９は第
２中間周波増幅器（標準中間周波増幅器）で、２ｏはＩ
Ｆ出力端子である。1γ is the second mixer using a diode, and the band p-wave mixer 1
The six first intermediate frequency signals and the signal from the fixed oscillator 18 are mixed and converted into a second intermediate frequency (standard intermediate frequency) signal, and the conversion loss is about 6 to 76.B. Desired 1% CrossModulation (G
N) An appropriate output level is supplied from the fixed oscillator 18 to ensure the level. 19 is a second intermediate frequency amplifier (standard intermediate frequency amplifier), 2o is I
This is the F output terminal.

本実施例は特に入力フィルり回路を上記のような構成に
することにより、受信感度を低下させることなく広帯域
の受信が可能であり、また％ＩＦ。In this embodiment, in particular, by configuring the input filter circuit as described above, wideband reception is possible without reducing reception sensitivity, and %IF.

ＩＦ、ＦＭ等の不要妨害信号を減衰させるフィルり回路
を１個除去できるので、コイル、コンデンサ等の部品点
数を削減でき、コストダウン（低価格化）を実現出来る
利点がある。Since one filter circuit that attenuates unnecessary interference signals such as IF and FM can be removed, the number of parts such as coils and capacitors can be reduced, which has the advantage of reducing costs.

更に、」二記のフィルり回路を除去できるので、小形化
を可能とする人ツＪフィルタ回路２３を実現出来る利点
を有するものである。Furthermore, since the filter circuit 2 mentioned above can be removed, it has the advantage of realizing a compact filter circuit 23.

本実施例においては２系統のフィルり回路の分割につい
て説明しであるが、これに限定されるものではなく、妨
害信号等も考慮して多系統に分割。In this embodiment, the division of the fill circuit into two systems is explained, but the invention is not limited to this, and the division into multiple systems takes into account interference signals and the like.

切換えられるものである。また、それぞれの除法系統で
の挿入損失は０．７　（ＩＢ程度である。It can be switched. In addition, the insertion loss in each division system is 0.7 (about IB).

第３図に本実施例の入力フィルタ回路部の具体的回路構
成を示す。FIG. 3 shows a specific circuit configuration of the input filter circuit section of this embodiment.

第３図において、Ｃｏ、Ｌ＋は％ＩＦに対するＢＳＦ　
、　Ｃ２，Ｌ２はＦＭに対するＢＳＦ、Ｏｓ、Ｌ５はＩ
Ｆに対するＢＳＦで、これらがトラソフリイルり回路２
２を構成している。Ｄｉ、Ｄ２はスイッチングダイオー
ドで、Ｒ＋、　Ｒｓ、　１（５はバイアス抵抗、Ｃ４，
Ｏｓ、　Ｃ９ハＤ　Ｃバイアスカット用コンデンサで、
これらがスイッチング回路２を構成している。In Figure 3, Co, L+ are BSF relative to %IF
, C2, L2 is BSF for FM, Os, L5 is I
BSF for F, these are the trasofiril circuit 2
2. Di, D2 are switching diodes, R+, Rs, 1 (5 is bias resistance, C4,
Os, C9 C bias cut capacitor,
These constitute the switching circuit 2.

同様にＩＪ３．　Ｄ４はスイッチングダイオードで、Ｒ
２゜Ｒ４，Ｒ６はバイアス抵抗、Ｃａ、　Ｃ＋２．　Ｃ
１５はＤＣバイアスカット用コンデンサで、Ｃ１４，Ｃ
１５ハ７ベイパヌコンデンサで、これらがスイッチング
回路３を構成している。Ｌ４．　Ｃ６とＬ５．０７はそ
れぞれＬＰＦで、例えばＶＨＦローチャンネルフィルり
回路６を構成している。Ｌ６．　Ｌ７．　ＣｏｏはＨＰ
Ｆ。Similarly, IJ3. D4 is a switching diode, R
2゜R4, R6 are bias resistors, Ca, C+2. C
15 is a DC bias cut capacitor, C14, C
The switching circuit 3 is composed of 15 x 7 bay Panu capacitors. L4. C6 and L5.07 are each LPFs, and constitute, for example, a VHF low channel fill circuit 6. L6. L7. Coo is homepage
F.

Ｌ８，０＋１はＢＳＦで、Ｖ　ＨＦ　ハイｆ　ヤン’ネ
）Ｖ、ＵＨＦチャンネルフィルり回路γを構成している
。L8,0+1 is a BSF, which constitutes a UHF channel fill circuit γ.

８．９はスイッチング回路制御電圧供給端子である。8.9 is a switching circuit control voltage supply terminal.

発明の効果 以上のように本発明は少なくとも１個の混合器を有する
広帯域チューナにおいて、各周波数帯に対応して分割さ
れるフィルり回路を分離、切換えるスイッチング回路の
前段に、％ＩＦ、ＩＦ、ＦＭトラップ等の不要な妨害信
号を除去するフィルり回路を構成するようにしたもので
、％ＩＦ、ＩＦ、ＦＭ等の不要妨害信号を減衰させるフ
ィルり回路を１個除去できるので、コイル、コンデンサ
等の部品点数を削減でき低価格化を実現出来る特長を有
している。更に、フィルり回路を除去できるので小形化
を可能とする入力フィルり回路を実現できるという特長
を有するものである。Effects of the Invention As described above, the present invention provides a broadband tuner having at least one mixer, in which %IF, IF, It is designed to configure a fill circuit that removes unnecessary interference signals such as FM traps.Since it can remove one fill circuit that attenuates unnecessary interference signals such as %IF, IF, FM, etc., coils and capacitors can be removed. It has the advantage of being able to reduce the number of parts such as, and achieve lower prices. Furthermore, since the fill circuit can be removed, it is possible to realize an input fill circuit that can be made smaller.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は従来の広帯域チューナ構成を示すブロック図、
第２図は本発明の一実施例としての広帯域チューナＩｔ
ｌｊ成を示すグロック図、第３図は本発明の入力フィル
り回路の具体的回路構成を示す結線図である。 １・・・・・・入力端子、２，３・・・・・・スイッチ
ング回路、４．６．２２・・・・・・！ＡＩＦ、ＩＦ、
ＦＭ）ラップフィルり回路、５，７・・川・フィルりＦ
ｌ路、２１　、２３・・・・・・入力フィルり回路、ｓ
、９・旧・・スイッチング回路制御電圧供給端子、１０
・・・・・広帯域可変減衰器、１１・・・・・・ＡＣ，
Ｃ電圧供給端子、１２・・印・広帯域増幅器、１３・・
・・・・第１混合器、１４・・・・・・緩ｆ頗増幅器、
１５・・・・・・電圧制御発振器、１６・・・１・・帯
域ｒ波器、１７・・・・・・第２混合器、１８・・・・
・・固定発振器、１９・・・・・・中間周波増幅器、２
ｏ・・印・出力端子。FIG. 1 is a block diagram showing the configuration of a conventional wideband tuner.
FIG. 2 shows a wideband tuner It as an embodiment of the present invention.
FIG. 3 is a block diagram showing the lj configuration, and FIG. 3 is a wiring diagram showing a specific circuit configuration of the input fill circuit of the present invention. 1... Input terminal, 2, 3... Switching circuit, 4.6.22...! AIF, IF,
FM) Wrap fill circuit, 5, 7... River fill F
l path, 21, 23...input fill circuit, s
, 9. Old... Switching circuit control voltage supply terminal, 10
...Broadband variable attenuator, 11...AC,
C voltage supply terminal, 12... mark, broadband amplifier, 13...
...First mixer, 14... Slow-f amplifier,
15... Voltage controlled oscillator, 16... 1... Band r wave generator, 17... Second mixer, 18...
...Fixed oscillator, 19...Intermediate frequency amplifier, 2
o...mark/output terminal.

Claims (1)

【特許請求の範囲】[Claims] 人力信号を入力フィルり回路部によシ処理し、その信号
を少なくとも１個の混合器を用いて中間周波数信号に変
換する構成を有し、前記入力フィルタ回路部が、並列に
設けられた複数個のフィルり回路と、前記フィルり回路
の前段及び後段に設けられ、周波数帯に列応して前記フ
ィルり回路を分離、切換える第１及び第２のスイッチン
グ回路と、前記第１のスイッチング回路の前段に設けら
れた不要妨害信号を除去するｌ・ラソプフィルり回路と
を備えたことを特徴とする広帯域チューナ。It has a configuration in which a human input signal is processed by an input filter circuit section and the signal is converted into an intermediate frequency signal using at least one mixer, and the input filter circuit section includes a plurality of input filter circuit sections provided in parallel. a fill circuit, first and second switching circuits that are provided before and after the fill circuit and separate and switch the fill circuit according to the frequency band; and the first switching circuit. What is claimed is: 1. A wideband tuner comprising: an L-rasopfilter circuit for removing unnecessary interference signals, which is provided at the front stage of the tuner.
JP57193006A 1982-11-02 1982-11-02 wideband tuner Pending JPS5981927A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP57193006A JPS5981927A (en) 1982-11-02 1982-11-02 wideband tuner

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP57193006A JPS5981927A (en) 1982-11-02 1982-11-02 wideband tuner

Publications (1)

Publication Number Publication Date
JPS5981927A true JPS5981927A (en) 1984-05-11

Family

ID=16300631

Family Applications (1)

Application Number Title Priority Date Filing Date
JP57193006A Pending JPS5981927A (en) 1982-11-02 1982-11-02 wideband tuner

Country Status (1)

Country Link
JP (1) JPS5981927A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63158032U (en) * 1987-04-03 1988-10-17
US4835608A (en) * 1988-05-31 1989-05-30 Zenith Electronics Corporation Image trap filter circuit
EP1225697A3 (en) * 2001-01-12 2004-05-12 Nec Corporation Method and circuit for avoiding band interference wave in receiver

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63158032U (en) * 1987-04-03 1988-10-17
US4835608A (en) * 1988-05-31 1989-05-30 Zenith Electronics Corporation Image trap filter circuit
EP1225697A3 (en) * 2001-01-12 2004-05-12 Nec Corporation Method and circuit for avoiding band interference wave in receiver

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