JPH088692A - Electronic tuning circuit for am receiver - Google Patents
Electronic tuning circuit for am receiverInfo
- Publication number
- JPH088692A JPH088692A JP15815294A JP15815294A JPH088692A JP H088692 A JPH088692 A JP H088692A JP 15815294 A JP15815294 A JP 15815294A JP 15815294 A JP15815294 A JP 15815294A JP H088692 A JPH088692 A JP H088692A
- Authority
- JP
- Japan
- Prior art keywords
- antenna
- coil
- tuning circuit
- variable capacitance
- opposite
- 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
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、カーラジオ等に適した
ＡＭ受信機の電子同調回路に関し、アンテナと高周波増
幅回路間に構成される。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic tuning circuit for an AM receiver suitable for a car radio or the like, which is arranged between an antenna and a high frequency amplifier circuit.
【０００２】[0002]
【従来の技術】カーラジオ等でＡＭ放送を受信する場
合、アンテナから受信機まで同軸ケーブルを引き回す必
要があるため、受信機側から見込んだアンテナの容量は
60〜80pF程度になる。この容量は、可変容量ダイオード
を用いて電子同調回路を構成する場合、同調回路の容量
に等価的に並列に接続されるために容量可変比を圧縮す
る。すなわち、可変容量ダイオードの容量の可変範囲に
その容量が加わることになるので、可変範囲が狭くな
る。2. Description of the Related Art When receiving an AM broadcast on a car radio or the like, it is necessary to route a coaxial cable from the antenna to the receiver.
It will be about 60 to 80 pF. This capacitance compresses the capacitance variable ratio because it is equivalently connected in parallel to the capacitance of the tuning circuit when the electronic tuning circuit is configured using the variable capacitance diode. That is, since the capacitance is added to the variable range of the capacitance of the variable capacitance diode, the variable range is narrowed.
【０００３】従って、ＡＭ放送の周波数帯域である530
〜1710KHz の同調に必要な容量可変比を得ることが難し
くなる。また、電界強度の強い入力信号による過入力に
対して可変容量ダイオードの非直線歪みが発生したり、
可変容量ダイオードに加わる電圧が変動することにより
容量値が不安定になる。このために、アンテナに入力さ
れる全帯域の信号が選択されずに高周波増幅回路に加え
られるので、増幅回路が強い妨害信号によって飽和し易
いと言う問題があった。Therefore, the frequency band of AM broadcasting is 530.
It becomes difficult to obtain the capacitance variable ratio necessary for tuning ~ 1710KHz. In addition, non-linear distortion of the varactor diode occurs due to excessive input due to an input signal with a strong electric field strength,
The capacitance value becomes unstable because the voltage applied to the variable capacitance diode fluctuates. For this reason, the signals of the entire band input to the antenna are not selected and added to the high frequency amplifier circuit, so that there is a problem that the amplifier circuit is easily saturated by a strong interference signal.
【０００４】[0004]
【発明が解決しようとする課題】本発明の課題は、ＡＭ
放送の周波数帯域の全帯域で同調可能な容量可変比を得
ることのできるＡＭ受信機の電子同調回路を提供するこ
とにある。また、可変容量ダイオードの非直線歪みを少
なくし、妨害信号の影響の少ないＡＭ受信機の電子同調
回路を提供することにある。さらに、これによって強い
妨害信号の選択除去を可能にし、高周波増幅回路を飽和
しにくくすることにある。Problem to be Solved by the Invention
An object of the present invention is to provide an electronic tuning circuit for an AM receiver capable of obtaining a variable capacity ratio that can be tuned over the entire frequency band of broadcasting. Another object of the present invention is to provide an electronic tuning circuit for an AM receiver in which the nonlinear distortion of the variable capacitance diode is reduced and the influence of interfering signals is small. Further, this makes it possible to selectively remove a strong interfering signal and make it difficult for the high frequency amplifier circuit to saturate.
【０００５】[0005]
【課題を解決するための手段】本発明のＡＭ受信機の電
子同調回路は、アンテナに直列接続するコイル、コイル
のアンテナ側の端と共通電位点間に接続する二つの可変
容量ダイオード、コイルのアンテナ側と反対側の端と共
通電位点間に接続するコンデンサからなり、該可変容量
ダイオードは互いに逆極性になるようにして並列接続さ
れていることを特徴とする。An electronic tuning circuit of an AM receiver according to the present invention comprises a coil connected in series with an antenna, two variable capacitance diodes connected between an end of the coil on the antenna side and a common potential point, and a coil. It is characterized in that it comprises a capacitor connected between the end on the side opposite to the antenna side and the common potential point, and the variable capacitance diodes are connected in parallel so as to have opposite polarities.
【０００６】[0006]
【実施例】以下、本発明のＡＭ受信機の電子同調回路の
実施例を示す回路図である図１を参照しながら説明す
る。図１において、アンテナ２と受信機の入力端子３は
同軸ケーブル５で接続されている。電子同調回路は点線
で囲み示してあるように、アンテナ２に直列接続される
コイルＬ１、コイルＬ１のアンテナ側の端とアース間に
接続する特性のほぼ同じ二つの可変容量ダイオードＤ
１、Ｄ２、コイルＬ１のアンテナ側とは反対側の端とア
ース間に接続するコンデンサＣ１から構成される。1 is a circuit diagram showing an embodiment of an electronic tuning circuit of an AM receiver according to the present invention. In FIG. 1, the antenna 2 and the input terminal 3 of the receiver are connected by a coaxial cable 5. As indicated by the dotted line, the electronic tuning circuit includes a coil L1 connected in series with the antenna 2 and two variable capacitance diodes D having substantially the same characteristics connected between the antenna-side end of the coil L1 and the ground.
1, D2, and a capacitor C1 connected between the end of the coil L1 opposite to the antenna side and the ground.
【０００７】可変容量ダイオードＤ１は、アノードがコ
イルＬ１のアンテナ側の端に接続され、カソードが直流
成分を遮断するためのコンデンサＣ２を経てアースされ
る。可変容量ダイオードＤ２は、アノードがアースさ
れ、カソードが直流成分を遮断するためのコンデンサＣ
３を経てコイルＬ１のアンテナ側の端に接続される。従
って、可変容量ダイオードＤ１、Ｄ２は、互いに極性を
逆にして並列接続さている。The variable capacitance diode D1 has an anode connected to the end of the coil L1 on the antenna side, and a cathode grounded via a capacitor C2 for blocking a DC component. The variable-capacitance diode D2 has a capacitor C for grounding the anode and blocking the DC component at the cathode.
3 and is connected to the end of the coil L1 on the antenna side. Therefore, the variable capacitance diodes D1 and D2 are connected in parallel with their polarities reversed.
【０００８】可変容量ダイオードＤ１、Ｄ２のカソード
には、端子１から抵抗Ｒ２、Ｒ３を介して同調電圧が加
えられる。コンデンサＣ１は、同調周波数によって同調
回路の出力インピーダンスが変化することを防ぐために
容量値を大きくしてある。また、コイルＬ１のアンテナ
側と反対側は高周波増幅回路４の入力側に接続されてい
る。A tuning voltage is applied from the terminal 1 to the cathodes of the variable capacitance diodes D1 and D2 through the resistors R2 and R3. The capacitor C1 has a large capacitance value in order to prevent the output impedance of the tuning circuit from changing depending on the tuning frequency. The side of the coil L1 opposite to the antenna side is connected to the input side of the high frequency amplifier circuit 4.
【０００９】このように構成された同調回路は、容量素
子がコイルＬ１の両側に接続されており、両側の容量素
子同志は直列接続されている。また、アンテナ側の容量
素子である可変容量ダイオードＤ１、Ｄ２は互いに並列
接続されている。さらに、可変容量ダイオードＤ１、Ｄ
２には、夫々コンデンサＣ２、Ｃ３が直列接続されてい
る。従って、コイルＬ１に接続する容量値としては、コ
ンデンサＣ１の大きな容量値、コンデンサＣ２、Ｃ３の
容量値を無視できるので、可変容量ダイオードＤ１、Ｄ
２の容量値だけである。In the tuning circuit thus constructed, the capacitive element is connected to both sides of the coil L1, and the capacitive elements on both sides are connected in series. The variable capacitance diodes D1 and D2, which are the capacitance elements on the antenna side, are connected in parallel with each other. Furthermore, variable capacitance diodes D1 and D
Capacitors C2 and C3 are connected in series to 2, respectively. Therefore, as the capacitance value connected to the coil L1, the large capacitance value of the capacitor C1 and the capacitance values of the capacitors C2 and C3 can be ignored, so that the variable capacitance diodes D1 and D
There is only a capacity value of 2.
【００１０】可変容量ダイオードＤ１、Ｄ２は、前記し
たように並列接続されているので、その容量値としては
一つの場合の２倍の容量値になる。入力端子３とアース
間に等価的に接続されるアンテナ２の容量値は、可変容
量ダイオードＤ１、Ｄ２の容量値に加算されるが、可変
容量ダイオードＤ１、Ｄ２の容量値が大きいので、その
影響は小さい。受信する周波数帯域に必要な同調回路の
可変容量比は、周知のように最大周波数と最小周波数の
比の二乗であり、前記した周波数帯域では１１倍程度が
必要である。Since the variable capacitance diodes D1 and D2 are connected in parallel as described above, the capacitance value thereof is twice the capacitance value of one case. The capacitance value of the antenna 2 equivalently connected between the input terminal 3 and the ground is added to the capacitance values of the variable capacitance diodes D1 and D2, but the capacitance values of the variable capacitance diodes D1 and D2 are large. Is small. As is well known, the variable capacitance ratio of the tuning circuit required for the frequency band to be received is the square of the ratio of the maximum frequency to the minimum frequency, and about 11 times is required in the above-mentioned frequency band.
【００１１】容量の可変範囲が、700PF から12PF程度の
可変容量ダイオードは容易に得られるから、アンテナ2
の60〜80pF程度の容量値が加算されても１１倍程度の可
変容量比を容易に得ることができる。また、二つの可変
容量ダイオードは前記のように逆極性となるように接続
されているので、同調回路に誘起される交流信号電圧が
可変容量ダイオードの両端では互いに逆極性となるよう
に接続されていることになる。そして、過入力に対して
二つの可変容量ダイオードは極性が逆相となるように動
作するので、可変容量ダイオードの非直線歪みも相殺さ
れることになる。Since a variable capacitance diode having a variable capacitance range of 700PF to 12PF is easily obtained, the antenna 2
Even if a capacitance value of about 60 to 80 pF is added, a variable capacitance ratio of about 11 times can be easily obtained. Further, since the two varactor diodes are connected so as to have opposite polarities as described above, the AC signal voltages induced in the tuning circuit are connected so as to have opposite polarities at both ends of the varactor diode. Will be there. Since the two varactor diodes operate so that their polarities are opposite to each other with respect to the excessive input, the non-linear distortion of the varactor diode is also canceled.
【００１２】さらに、可変容量ダイオードは極度の過入
力に対しては順方向電流が流れるので、クランプ回路と
して動作する。なお、入力端子３に接続されるコイルＬ
１は、アンテナ２がＦＭ放送の受信用に兼用される場合
に、ＡＭ受信機にＦＭ波の混入を防ぐために設けられ、
可変コンデンサＣ４はアンテナ２の容量のばらつきを考
慮して、その容量を設定値にするために設けられてい
る。抵抗Ｒ１は、同調回路の出力インピーダンスを調整
するために設けられている。これらは、実際の回路にお
いて適宜設けられるものであり、本発明とは直接関係な
い。Further, the varactor diode operates as a clamp circuit because a forward current flows in case of excessive over-input. The coil L connected to the input terminal 3
1 is provided in order to prevent FM waves from being mixed in the AM receiver when the antenna 2 is also used for receiving FM broadcasting,
The variable capacitor C4 is provided to set the capacitance to a set value in consideration of the variation in the capacitance of the antenna 2. The resistor R1 is provided to adjust the output impedance of the tuning circuit. These are appropriately provided in an actual circuit and are not directly related to the present invention.
【００１３】[0013]
【発明の効果】以上述べたように本発明のＡＭ受信機の
電子同調回路は、アンテナに直列接続するコイルの両側
に容量素子を接続し、アンテナ側には互いに逆極性にな
るようにして並列接続された可変容量ダイオードを接続
してある。そして、アンテナの容量を含めて同調がとら
れる。アンテナの容量には、ケーブルの容量も含まれ
る。従って、ＡＭ放送の周波数帯域をおおう十分な容量
可変比を得ることができる。As described above, in the electronic tuning circuit of the AM receiver of the present invention, the capacitive elements are connected to both sides of the coil connected in series to the antenna, and the antenna sides are connected in parallel so that the polarities are opposite to each other. The connected variable capacitance diode is connected. Then, tuning is performed including the capacity of the antenna. The capacity of the antenna includes the capacity of the cable. Therefore, it is possible to obtain a sufficient capacity variable ratio that covers the frequency band of AM broadcasting.
【００１４】また、過入力に対する可変容量ダイオード
の非直線性の影響を除去できるので、歪みや妨害波の影
響の少ない同調回路が得られる。これによって、同調回
路によって妨害波が選択除去されるために、高周波増幅
回路が飽和しにくくなる。さらに、アンテナの容量を含
めて同調がとられることにより、受信機の近接周波数分
離度が向上し、感度が向上する。Further, since the influence of the non-linearity of the variable capacitance diode on the over-input can be eliminated, a tuning circuit with less influence of distortion and interfering waves can be obtained. As a result, since the interference wave is selectively removed by the tuning circuit, the high frequency amplifier circuit is less likely to be saturated. Further, the tuning including the capacitance of the antenna improves the close frequency separation of the receiver and improves the sensitivity.
【図１】本発明のＡＭ受信機の電子同調回路の実施例を
示す回路図である。FIG. 1 is a circuit diagram showing an embodiment of an electronic tuning circuit of an AM receiver of the present invention.
Ｌ１ コイル Ｄ１、Ｄ２：可変容量ダイオード L1 coil D1, D2: variable capacitance diode
───────────────────────────────────────────────────── フロントページの続き (72)発明者 横山 元 埼玉県鶴ケ島市大字五味ケ谷18番地 東光 株式会社埼玉事業所内 (72)発明者 高田 昇 埼玉県鶴ケ島市大字五味ケ谷18番地 東光 株式会社埼玉事業所内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Gen Yokoyama, 18 Gomigaya, Tsurugashima City, Saitama Prefecture, Saitama Works (72) Noboru Takada 18 Gomigaya, Tsurugashima City, Saitama Prefecture, Toko Co., Ltd. Saitama Office
Claims (4)
のアンテナ側の端と共通電位点間に接続する二つの可変
容量ダイオード、コイルのアンテナ側と反対側の端と共
通電位点間に接続するコンデンサからなり、該可変容量
ダイオードは互いに逆極性になるようにして並列接続さ
れていることを特徴とするＡＭ受信機の電子同調回路。1. A coil connected in series to an antenna, two variable capacitance diodes connected between an end of the coil on the antenna side and a common potential point, and a capacitor connected between an end of the coil on the side opposite to the antenna side and a common potential point. And an electronic tuning circuit for an AM receiver, wherein the variable capacitance diodes are connected in parallel so as to have opposite polarities.
のアンテナ側の端と共通電位点間に接続する二つの可変
容量ダイオード、コイルのアンテナ側と反対側の端と共
通電位点間に接続するコンデンサからなり、コイルのア
ンテナ側と反対側の端は高周波増幅回路の入力側に接続
し、可変容量ダイオードは互いに逆極性になるようにし
て並列接続されていることを特徴とするＡＭ受信機の電
子同調回路。2. A coil connected in series to an antenna, two variable capacitance diodes connected between an end of the coil on the antenna side and a common potential point, and a capacitor connected between an end of the coil on the side opposite to the antenna side and a common potential point. The end of the coil opposite to the antenna side is connected to the input side of the high frequency amplifier circuit, and the variable capacitance diodes are connected in parallel so that their polarities are opposite to each other. Tuning circuit.
続するコイル、コイルのアンテナ側の端と共通電位点間
に接続する二つの可変容量ダイオード、コイルのアンテ
ナ側と反対側の端と共通電位点間に接続するコンデンサ
からなり、コイルのアンテナ側と反対側の端は高周波増
幅回路の入力側に接続し、可変容量ダイオードは互いに
逆極性になるようにして並列接続されていることを特徴
とするＡＭ受信機の電子同調回路。3. A coil connected in series to an antenna via a coaxial cable, two variable capacitance diodes connected between an end of the coil on the antenna side and a common potential point, and an end of the coil on the side opposite to the antenna side and a common potential point. It is composed of a capacitor connected in between, the end of the coil opposite to the antenna side is connected to the input side of the high frequency amplifier circuit, and the variable capacitance diodes are connected in parallel so that their polarities are opposite to each other. Electronic tuning circuit for AM receiver.
性である請求項１、請求項２、請求項３のいずれかのＡ
Ｍ受信機の電子同調回路。4. The A of any one of claims 1, 2 and 3, wherein the two variable capacitance diodes have substantially the same characteristics.
Electronic tuning circuit of M receiver.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15815294A JPH088692A (en) | 1994-06-17 | 1994-06-17 | Electronic tuning circuit for am receiver |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15815294A JPH088692A (en) | 1994-06-17 | 1994-06-17 | Electronic tuning circuit for am receiver |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH088692A true JPH088692A (en) | 1996-01-12 |
Family
ID=15665405
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP15815294A Pending JPH088692A (en) | 1994-06-17 | 1994-06-17 | Electronic tuning circuit for am receiver |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH088692A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002368546A (en) * | 2001-06-06 | 2002-12-20 | Nec Corp | Distortion pre-compensator and linear amplifier using the same |
-
1994
- 1994-06-17 JP JP15815294A patent/JPH088692A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002368546A (en) * | 2001-06-06 | 2002-12-20 | Nec Corp | Distortion pre-compensator and linear amplifier using the same |
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