JPS6214531A - Intermediate frequency pass filter of variable band width type - Google Patents
Intermediate frequency pass filter of variable band width typeInfo
- Publication number
- JPS6214531A JPS6214531A JP60153544A JP15354485A JPS6214531A JP S6214531 A JPS6214531 A JP S6214531A JP 60153544 A JP60153544 A JP 60153544A JP 15354485 A JP15354485 A JP 15354485A JP S6214531 A JPS6214531 A JP S6214531A
- Authority
- JP
- Japan
- Prior art keywords
- electric field
- circuit
- intermediate frequency
- changed
- amplifier
- 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.)
- Granted
Links
- 230000005684 electric field Effects 0.000 claims abstract description 16
- 230000003321 amplification Effects 0.000 claims abstract description 6
- 238000003199 nucleic acid amplification method Methods 0.000 claims abstract description 6
- 238000010586 diagram Methods 0.000 description 7
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 239000003990 capacitor Substances 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
Landscapes
- Tone Control, Compression And Expansion, Limiting Amplitude (AREA)
- Superheterodyne Receivers (AREA)
- Noise Elimination (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、受信電界に応じて帯域幅および増幅度を自動
的に可変するＡＭ受信機の中間周波帯域通過フィルタに
関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an intermediate frequency band-pass filter for an AM receiver that automatically varies its bandwidth and amplification depending on a received electric field.
スーパーヘテロゲイン型のＡＭ受信機ではＩＦ（中間周
波）帯域の幅を広くすると音質の向上が望めるが、反面
、弱電界での雑音や隣接妨害による雑音が増える欠点が
ある。この点を改善するために従来は、■スイッチでＩ
Ｆ帯域を広、狭に切換え、弱電界では狭帯域にする方法
や、■ＩＦの帯域幅は一定としたままＩＦ検波後のオー
ディオ帯域でＡＴＣ（オート・トーン・コントロール）
をかける方法がある。In a superhetero gain type AM receiver, sound quality can be expected to improve by widening the width of the IF (intermediate frequency) band, but on the other hand, it has the drawback of increasing noise in weak electric fields and noise due to adjacent interference. In order to improve this point, in the past, a switch was used to
How to switch the F band between wide and narrow, and make it narrow in weak electric fields, and ■ ATC (auto tone control) in the audio band after IF detection while keeping the IF bandwidth constant.
There is a way to apply it.
しかしながら、■の方法は手動操作でスイッチを切換え
るので車載用としては不便であり、また安全運転の妨げ
にもなる。一方、■の方法は自動化されたものであるが
、ＩＦ帯域は広くしてお（ので隣接局による抑圧（ＡＧ
Ｃ機能）が増え、またＡＴＣ用の回路もＣＲの一次フィ
ルタ程度の可変であるため効果が少ない欠点がある。さ
らに、ＡＭステレオを再生する場合は２チャンネル分の
回路が必要となる。加えて、これらの帯域可変回路とＩ
ＦのＡＧＣ回路は別に設ける必要があるので、受信機全
体の構成が複雑になることは避けられない。However, method (2) requires manual switching of the switch, which is inconvenient for use in a vehicle, and also impedes safe driving. On the other hand, method (■) is automated, but the IF band is widened (so that suppression by neighboring stations (AG
C function) increases, and the ATC circuit is as variable as a CR primary filter, so it has the drawback of being less effective. Furthermore, when reproducing AM stereo, circuits for two channels are required. In addition, these band variable circuits and I
Since the F AGC circuit must be provided separately, it is inevitable that the overall configuration of the receiver will become complicated.
本発明は、ＩＦ帯域の通過フィルタにおいてその帯域幅
を受信電界に応じて自動的に可変し、且つその増幅度も
同時に可変してＡＧＣ特性を持たせようとするものであ
る。The present invention aims to provide an IF band pass filter with AGC characteristics by automatically varying its bandwidth in accordance with the received electric field and simultaneously varying its amplification degree.
第１図は本発明の原理ブロック図で、＋ａ）は基本型、
（′ｂ）は改良型である。Ｑは共振回路で、ピークの利
得は１である。Ａは固定利得の増幅器である。Figure 1 is a block diagram of the principle of the present invention, +a) is the basic type,
('b) is an improved type. Q is a resonant circuit with a peak gain of 1. A is a fixed gain amplifier.
βは帰還回路で、制御電圧Ｖｃによって帰還率が制御さ
れる電圧制御増幅器（または減！Ｆ器）を用いる。以下
ではＱ、 Ａ、 βを選択度、利得、帰還率の各記号と
しても用いる。Ｎは引算器である。β is a feedback circuit, which uses a voltage controlled amplifier (or attenuator) whose feedback rate is controlled by a control voltage Vc. Below, Q, A, and β are also used as symbols for selectivity, gain, and feedback rate. N is a subtractor.
（ａｌの基本型の伝達関数は
となり、Ｑ＝９８．Ａ＝１０に設定した周波数特性は第
２図のようになる。同図の（ａ）〜（Ｃ）はβを０゜１
〜１の範囲で可変し、その代表的な３点を示したもので
ある。β＝０．１のときは帯域幅が最も狭いが、利得が
最も高い。これに対し、β＝１のときは帯域幅が最も広
いが、利得は最も低い。従って、制御電圧Ｖｃは受信電
界が高いときにβを１に近づけ、逆に低いときにβを０
．１に近づける特性を有すればよい。(The transfer function of the basic type of al is as follows, and the frequency characteristics set at Q=98.A=10 are as shown in Figure 2. In (a) to (C) of the same figure, β is set to 0°1
It can be varied within the range of 1 to 1, and three representative points are shown. When β=0.1, the bandwidth is the narrowest, but the gain is the highest. On the other hand, when β=1, the bandwidth is the widest, but the gain is the lowest. Therefore, the control voltage Vc brings β closer to 1 when the received electric field is high, and conversely brings β to 0 when the received electric field is low.
．． It suffices if it has a characteristic that brings it close to 1.
上述したβの可変範囲０．１〜１は、ＩＦのＡＧｃｌを
１０ｄＢ程度にする一般的な必要性を考慮して制限した
ものである。このようにすると帯域幅の変化量と利得の
変化量は一定の関係になるが、この関係を崩し、帯域幅
の可変範囲をより広くしたのが（ｂｌの改良型である。The above-mentioned variable range of β from 0.1 to 1 is limited in consideration of the general necessity of setting the IF AGcl to about 10 dB. If this is done, the amount of change in bandwidth and the amount of change in gain will have a fixed relationship, but the improved version of (bl) breaks this relationship and widens the variable range of bandwidth.
これはｆａｔの基本型の固定利得増幅器Ａと直列に、帰
還回路βと同じ特性の電圧制御増幅器（または減衰器）
β′を接続したものである。このフィルタの伝達関数は
となる。This is a voltage controlled amplifier (or attenuator) with the same characteristics as the feedback circuit β in series with the fat basic type fixed gain amplifier A.
β' is connected. The transfer function of this filter is:
上式は、β′による減衰量だけへの利得を高くでき、そ
の分食帰還が多くかかって帯域幅の可変範囲が拡大され
ることを示している。−例としてＡ＝１００に設定し、
β鳩β′を０．１〜１の範囲で可変した場合の周波数特
性を第３図に示す。同図（ｂｌはＡ＝１００． β＝
１であり、これを第２図（Ｃ）と比べると充分に広帯域
化されていることが判る。第３図（ａｌは第２図（ａｌ
と同じであり、帯域幅は最も狭い（利得は最大）。The above equation shows that the gain can be increased only for the amount of attenuation due to β', and the variable range of the bandwidth is expanded by increasing the amount of partial feedback. - As an example, set A=100,
FIG. 3 shows the frequency characteristics when β' is varied in the range of 0.1 to 1. The same figure (bl is A=100. β=
1, and when compared with FIG. 2(C), it can be seen that the band is sufficiently widened. Figure 3 (al is Figure 2 (al)
, with the narrowest bandwidth (maximum gain).
第４図は本発明の一実施例を示す回路図で、第１図（ｂ
）の改良型の例を示すものである。図中、トランジスタ
ＴＩ、Ｔ２と抵抗Ｒ１〜Ｒ３、それにコンデンサＣとイ
ンダクタンスＬの直列回路は共振回路Ｑを構成するが、
抵抗Ｒ１，Ｒ２の比Ｒ１／ Ｒ２を１００に設定してＡ
＝１００の増幅器の利得も兼用させている。尚、ＬＣの
共振点ｆａは４５０ＫＨｚであり、またＱ＝ωＬ／Ｒ２
である。FIG. 4 is a circuit diagram showing one embodiment of the present invention, and FIG.
) shows an example of an improved version of . In the figure, a series circuit of transistors TI and T2, resistors R1 to R3, capacitor C, and inductance L constitutes a resonant circuit Q.
Set the ratio R1/R2 of resistors R1 and R2 to 100 and
The gain of the amplifier of =100 is also used. In addition, the resonance point fa of LC is 450KHz, and Q=ωL/R2
It is.
帰還回路βはトランジスタＴ３〜Ｔ５と抵抗Ｒ１１〜Ｒ
１３からなる差動型の増幅器で、その利得は制御電圧Ｖ
ｃで変化する。Ｖｒｅｆは基準電圧、Ｖａ。Feedback circuit β includes transistors T3 to T5 and resistors R11 to R.
It is a differential type amplifier consisting of
It changes with c. Vref is a reference voltage, Va.
ｖｂはバイアス電圧である。この増幅器ではβを１〜０
．１の間で可変するために、
に設定しである。順方向の電圧制御増幅器β′も同じ構
成で、Ｔ ３ ’ 〜Ｔ ａ ’ はトランジスタ、Ｒ
１１’〜ＲＩ３′は抵抗である。vb is a bias voltage. In this amplifier, β is 1 to 0.
．． To vary between 1, set it to . The forward voltage control amplifier β' has the same configuration, T3' to Ta' are transistors, and R
11' to RI3' are resistors.
第５図は本発明を適用したＡＭ受信機の説明図で、１は
アンテナ、２は高周波（ＲＦ）回路及び周波数変換回路
、３は広帯域のＩＦ同調回路、４は本発明に係るＩＦ通
過フィルタ、５は検波器、６はそこから得られるシグナ
ルＶｓをＡＣＣ電圧ＶＡＧｃに変換してＲＦ回路２へ負
帰還するＡＧＣアンプ、７はその電圧Ｖ ＡＧＣを帯域
幅可変用の制御電圧Ｖｃに変換する電圧変換回路である
。この制御電圧ＶｃはＶ ５−ｖＡＧｃ −＋ｖ ｃと
変換されたものであるが、基本的には（ｄ）に示すよう
にアンテナ入力レベル（電界強度）と比例関係にある。FIG. 5 is an explanatory diagram of an AM receiver to which the present invention is applied, where 1 is an antenna, 2 is a radio frequency (RF) circuit and a frequency conversion circuit, 3 is a wideband IF tuning circuit, and 4 is an IF pass filter according to the present invention. , 5 is a detector, 6 is an AGC amplifier that converts the signal Vs obtained therefrom into an ACC voltage VAGc and provides negative feedback to the RF circuit 2, and 7 is a converter that converts the voltage VAGc into a control voltage Vc for varying the bandwidth. This is a voltage conversion circuit. This control voltage Vc is converted to V5-vAGc-+vc, and is basically in a proportional relationship with the antenna input level (field strength) as shown in (d).
（′ｂ）は帯域可変特性、（Ｃ１は利得可変特性であり
、いずれも実線はβのみ使用の基本型、破線はβ′を使
用した改良型の場合を示している。('b) is a band variable characteristic, (C1 is a gain variable characteristic, the solid line shows the basic type using only β, and the broken line shows the improved type using β'.
以上述べたように本発明によれば、ＡＭ受信機のＩＦ帯
域幅を電界強度に応じて連続的に可変できるので弱電界
時のＳ／Ｎを改善でき、しかも同時に増幅度も変化させ
てＡＧＣ機能を持たせたので、他にＩＦ帯のＡＧＣ回路
が不要になる利点がある。As described above, according to the present invention, since the IF bandwidth of the AM receiver can be continuously varied according to the electric field strength, the S/N ratio in a weak electric field can be improved, and at the same time, the amplification degree can also be changed. Since this function is provided, there is an advantage that no other IF band AGC circuit is required.
第１図は本発明の原理ブロック図、第２図および第３図
はその周波数特性図、第４図は本発明の一実施例を示す
回路図、第５図は本発明を通用したＡＭ受信機の説明図
である。
図中、Ｑは共振回路、Ａは固定利得増幅器、βは帰還回
路、β′は同特性の電圧可変増幅器（または減衰器）で
ある。
出 願 人 富士通テン株式会社
代理人弁理士 青 柳 稔
（改）基本型
■
（１））改良！
ｃ
、不全８１ｉ１ｆ＞原理７山・２り図
第１図
１１まFig. 1 is a principle block diagram of the present invention, Figs. 2 and 3 are frequency characteristic diagrams thereof, Fig. 4 is a circuit diagram showing an embodiment of the present invention, and Fig. 5 is an AM reception using the present invention. FIG. In the figure, Q is a resonant circuit, A is a fixed gain amplifier, β is a feedback circuit, and β' is a voltage variable amplifier (or attenuator) having the same characteristics. Applicant: Fujitsu Ten Ltd. Representative Patent Attorney Minoru Aoyagi (revised) Basic model ■ (1)) Improvement! c, Failure 81i1f>Principle 7 Mountains and 2 Diagrams Figure 1 11
Claims (1)
、その出力を増幅する固定利得の増幅器と、該増幅器の
出力を該共振回路の入力へ負帰還する帰還回路とを備え
、該帰還回路の帰還率を受信電界に応じて変化させるこ
とにより、中間周波に対する通過帯域幅を該受信電界に
比例して変化させ、同時に増幅度を該受信電界に反比例
して変化させるようにしてなることを特徴とする、ＡＭ
受信機の帯域幅可変型の中間周波通過フィルタ。A resonant circuit having a resonant point at a center frequency of an intermediate frequency band, a fixed gain amplifier that amplifies the output of the resonant circuit, and a feedback circuit that negatively feeds back the output of the amplifier to the input of the resonant circuit. By changing the feedback factor according to the received electric field, the passband width for the intermediate frequency is changed in proportion to the received electric field, and at the same time, the degree of amplification is changed in inverse proportion to the received electric field. A.M.
A variable bandwidth intermediate frequency pass filter for the receiver.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60153544A JPS6214531A (en) | 1985-07-12 | 1985-07-12 | Intermediate frequency pass filter of variable band width type |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60153544A JPS6214531A (en) | 1985-07-12 | 1985-07-12 | Intermediate frequency pass filter of variable band width type |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6214531A true JPS6214531A (en) | 1987-01-23 |
| JPH0320172B2 JPH0320172B2 (en) | 1991-03-18 |
Family
ID=15564832
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP60153544A Granted JPS6214531A (en) | 1985-07-12 | 1985-07-12 | Intermediate frequency pass filter of variable band width type |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6214531A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009069129A (en) * | 2007-09-18 | 2009-04-02 | Citizen Holdings Co Ltd | Radio correction clock |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5048814A (en) * | 1973-09-03 | 1975-05-01 |
-
1985
- 1985-07-12 JP JP60153544A patent/JPS6214531A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5048814A (en) * | 1973-09-03 | 1975-05-01 |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009069129A (en) * | 2007-09-18 | 2009-04-02 | Citizen Holdings Co Ltd | Radio correction clock |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0320172B2 (en) | 1991-03-18 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |