JPS6175680A

JPS6175680A - Antenna mixer

Info

Publication number: JPS6175680A
Application number: JP19656184A
Authority: JP
Inventors: Shinichi Fujimura; 藤村　信一; Tsutomu Kawase; 川瀬　務
Original assignee: Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Holdings Corp
Priority date: 1984-09-21
Filing date: 1984-09-21
Publication date: 1986-04-18

Abstract

PURPOSE:To obtain a good damping characteristic of the interference signal with simple circuit composition by connecting a coil in parallel to the transistor for amplifying a TV signal and the switching diode which turns on-off and setting a responance frequency of the parallel resonance circuit formed by a reverse capacity of the diode and inductance of the coil to the interference frequency. CONSTITUTION:A parallel coil L1 is inserted to the switching diode D1, when D1 is off, a parallel resonance is composed by the reverse capacity of D1 and the coil L1 and the resonance frequency is set to the interference frequency. Within + or -32MHz of the set value, the damping characteristic of min 20dB can be obtained. Matching with 20dB in the non-action condition of a transistor Q2, a resonance characteristic 40dB or above can be obtained and the necessary resonance frequency min 40dB is satisified by only one step of the transistor Q2. A resistance R1 is the one for the bias from a B circuit of the switching diode D1 and to stably operate the switching diode D1. A capacitor C1 is for a direct cut.

Description

【発明の詳細な説明】（産業上の利用分野）本発明は、アンテナミキサに関する。[Detailed description of the invention] (Industrial application field) The present invention relates to an antenna mixer.

（従来例の構成とその問題点）第２図は、従来のアンテナミキサ回路を示す図であるが
、説明を簡単にするため、信号伝送回路とバイアス回路
のみとする。(Structure of Conventional Example and Its Problems) FIG. 2 is a diagram showing a conventional antenna mixer circuit, but to simplify the explanation, only a signal transmission circuit and a bias circuit are shown.

ＲＦ−ＩＮより入力された外部信号（ＴＶ信号）は、ト
ランジスタロ工で増幅され、分配トランスＴ□で一方は
ＶＴＲ−０ＵＴ　（ＶＴＲの録画用人力信号としてＶＴ
Ｒのデモシュレータ入力）に、他方は、トランジスタＱ
２・Ｑ、を介しコンバータ信号（ＶＴＲ再生信号）と整
合トランスＴ２で合成されＲＦ−ＯＵＴに出力される。The external signal (TV signal) input from RF-IN is amplified by a transistor transformer, and one side is amplified by a distribution transformer T□.
(demosulator input of R), the other is a transistor Q
2.Q, the signal is combined with the converter signal (VTR reproduction signal) by the matching transformer T2, and output to RF-OUT.

この回路には、トランジスタロ工を動作させる８回路と
トランジスタＱ２・Ｑ３をｏｎ−ｏｆｆする８５回路を
有している。This circuit has 8 circuits for operating the transistors and 85 circuits for turning on and off the transistors Q2 and Q3.

Ｂ５回路は、ＴＶ−ＭＯＤＥ　（ＴＶ受信）時とＶＴＲ
−ＭＯＤＥ　（ＶＴＲ再生）時を切換え、それぞれ１２
Ｖ・Ｏｖに設定する。The B5 circuit is used for TV-MODE (TV reception) and VTR.
-Switch the MODE (VTR playback) time, each with 12
Set to V・Ov.

Ｂ、＝１２Ｖ時、ＴＶ−ＭＯＤＥ”Ｃ−スイッチングダ
イオードＤ工・Ｄ２はｏｎ　となり、トランジスタＱ２
・Ｑ、が動作状態となりＲＦ−ＩＮよりの信号がロスな
くＲＦ−ＯＵＴに伝送される。When B, = 12V, TV-MODE"C-switching diode D/D2 is on, and transistor Q2
-Q becomes operational and the signal from RF-IN is transmitted to RF-OUT without loss.

Ｂｓ＝ｏｖ時、ＶＴＲ−ＭＯＤＥ’？’スイッチングダ
イオードＤ工・Ｄ２はｏｆｆとなり、トランジスタＱ２
・Ｑ、は不動作状態となり、ＲＦ−ＩＮよりの信号が減
衰され、ＲＦコンバータ１の再生信号に外部信号による
妨害を与えないようになっている。When Bs=ov, VTR-MODE'? 'Switching diode D/D2 is turned off, and transistor Q2
Q is in an inactive state, and the signal from RF-IN is attenuated so that the reproduced signal of the RF converter 1 is not interfered with by external signals.

ところで、特殊地区においては、ＲＦコンバータ１の再
生信号（５９１，２５±３２ＭＨｚ）付近に外部妨害信
号を有し、再生信号にビート等の妨害を与えないよう前
記の回路を有している。すなわちトランジスタＱ２・Ｑ
□の不動作状態でミニマム（ｗｉｎ）４０ｄＢの減衰特
性を満たす回路構成になっている。By the way, in special areas, there is an external interference signal near the reproduced signal (591, 25±32 MHz) of the RF converter 1, and the above-mentioned circuit is provided to prevent interference such as beats from being caused to the reproduced signal. In other words, transistor Q2・Q
The circuit configuration satisfies a minimum (win) 40 dB attenuation characteristic in the non-operating state of □.

しかしながら、従来のものは、妨害信号の減衰特性ｍ１
ｎ４０ｄＢを得る為に、複雑な回路構成を必要としてい
た。However, in the conventional method, the attenuation characteristic m1 of the interference signal is
In order to obtain n40dB, a complicated circuit configuration was required.

（発明の目的）本発明は、斯かる事情に鑑みてなされたもので、簡単な
回路構成で、妨害信号の良好な減衰特性が得られるアン
テナミキサを提供しようとするものである。(Objective of the Invention) The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an antenna mixer that has a simple circuit configuration and can obtain good attenuation characteristics for interfering signals.

（発明の構成）本発明は、ＶＴＲ用アンテナミキサ回路において、ＴＶ
信号増幅用トランジスタをｏｎ−ｏｆｆするスイッチン
グダイオードに並列にコイルを接続し、前記ダイオード
の逆容量と前記コイルのインダクタンスで形成される並
列共振回路の共振周波数を妨害周波数に設定し、必要な
減衰特性を達成するものである。(Structure of the Invention) The present invention provides an antenna mixer circuit for a VTR.
A coil is connected in parallel to a switching diode that turns the signal amplification transistor on and off, and the resonant frequency of the parallel resonant circuit formed by the inverse capacitance of the diode and the inductance of the coil is set to the disturbance frequency, and the necessary attenuation characteristics are set. The goal is to achieve the following.

（実施例の説明）第１図は本発明によるアンテナミキサ回路の一実施例を
示す図で、第２図と同一符号は同一内容を示している。(Description of Embodiment) FIG. 1 is a diagram showing an embodiment of an antenna mixer circuit according to the present invention, and the same reference numerals as in FIG. 2 indicate the same contents.

第２図の説明においてスイッチングダイオードＤ□は、
トランジスタＱ２のバイアスをｏｎ−ｏｆｆする動作で
あったが１本実施例においては、このスイッチングダイ
オードＤ、に並列にコイルＬ工を挿入し、Ｄ工のｏｆｆ
時、Ｄｌの逆容量とコイルＬ□で並列共振回路を構成し
、その共振周波数を妨害周波数に設定する。設定値の±
３２ＭＨｚ内でｍ１ｎ２０ｄＢの減衰特性を得る事がで
きる。トランジスタＱ２の不動作状態で２０ｄＢと合せ
て、減衰特性４０ｄＢ以上になり、第２図における、ト
ランジス５０２段の回路を省略しても、必要な減衰特性
ｍ１ｎ４０ｄＢを満足する。In the explanation of FIG. 2, the switching diode D□ is
The operation was to turn on and off the bias of the transistor Q2, but in this embodiment, a coil L is inserted in parallel with this switching diode D, and the bias of the transistor Q2 is turned off.
At this time, the inverse capacitance of Dl and the coil L□ constitute a parallel resonant circuit, and the resonant frequency is set as the disturbance frequency. ± of setting value
Attenuation characteristics of m1n20dB can be obtained within 32MHz. Combined with 20 dB in the non-operating state of the transistor Q2, the attenuation characteristic becomes 40 dB or more, and even if the circuit of 502 stages of transistors in FIG. 2 is omitted, the required attenuation characteristic m1n of 40 dB is satisfied.

抵抗Ｒ工は、スイッチングダイオードＤ工の８回路より
のバイアス用抵抗であり、スイッチングダイオードＤ１
を安定動作させるためである。コンデンサＣ工は直流カ
ット用である。The resistor R is a bias resistor for the 8 circuits of switching diodes D, and the switching diode D1
This is to ensure stable operation. Capacitor C type is for DC cut.

（発明の効果）以上のように本発明によれば回路素子を大幅に削減し、
簡単な回路構成で従来と同等以上の妨害排除能力を有す
ることができ、工業的価値は非常に高いものである。(Effects of the Invention) As described above, according to the present invention, the number of circuit elements can be significantly reduced.
With a simple circuit configuration, it is possible to have an interference rejection ability equal to or higher than that of the conventional one, and the industrial value is extremely high.

[Brief explanation of drawings]

第１図は本発明によるアンテナミキサ回路の一実施例を
示す図、第２図は従来のアンテナミキサ回路を示す図で
ある。１　・・・ＲＦコンバータ、　Ｑ工、Ｑ２・・・　トラ
ンジスタ、　Ｔよ、Ｔ２・・・　トランス、　Ｄ工・・
・スイッチングダイオード、　Ｌｌ・・・コイル。Ｃ０・・・コンデンサ。FIG. 1 is a diagram showing an embodiment of an antenna mixer circuit according to the present invention, and FIG. 2 is a diagram showing a conventional antenna mixer circuit. 1...RF converter, Q engineering, Q2... transistor, T, T2... transformer, D engineering...
・Switching diode, Ll...coil. C0... Capacitor.

Claims

[Claims]

In an antenna mixer circuit for a VTR, a coil is connected in parallel to an on/off diode of a transistor for TV signal amplification, and the resonant frequency of a parallel resonant circuit formed by the inverse capacitance of the diode and the inductance of the coil is set to the interference frequency. Antenna mixer characterized by: