JPH0325085B2 - - Google Patents
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- Publication number
- JPH0325085B2 JPH0325085B2 JP59270390A JP27039084A JPH0325085B2 JP H0325085 B2 JPH0325085 B2 JP H0325085B2 JP 59270390 A JP59270390 A JP 59270390A JP 27039084 A JP27039084 A JP 27039084A JP H0325085 B2 JPH0325085 B2 JP H0325085B2
- Authority
- JP
- Japan
- Prior art keywords
- output
- signal
- intermediate frequency
- amplifier
- external
- 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.)
- Expired - Lifetime
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- 239000003990 capacitor Substances 0.000 description 17
- 238000010586 diagram Methods 0.000 description 6
- 230000003321 amplification Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
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- Control Of Amplification And Gain Control (AREA)
Description
【発明の詳細な説明】
[発明の技術分野]
本発明は集積回路化に適したAM信号受信用の
受信回路に関する。DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a receiving circuit for receiving AM signals suitable for integration into an integrated circuit.
[発明の技術的背景]
現在AM/FM受信機の集積回路(以下ICとい
う。)の主流はAM/FM出力端子を共用としたも
のが一般的となつている。[Technical Background of the Invention] Currently, the mainstream of integrated circuits (hereinafter referred to as ICs) for AM/FM receivers is generally one in which the AM/FM output terminal is shared.
すなわち、第5図に示すように、IC1内には
FM変調信号を入力し、これをFM復調回路2に
より復調して出力端子3に導入している。また中
間周波信号を中間周波増幅器4で増幅し、さらに
AM復調回路5で復調し、その出力を外部端子6
に導出している。この外部端子6から外付けのコ
ンデンサC1とIC1内の抵抗R1から構成するロー
カツト回路7を介して出力端子8に導出し、この
出力端子8と上記FM復調回路2からの出力端子
3を可動接点9で択一的に切換えてAMあるいは
FM復調出力を外部出力端子OUT1を介して出力
している。 That is, as shown in Figure 5, inside IC1 there is
An FM modulated signal is input, demodulated by an FM demodulation circuit 2, and introduced to an output terminal 3. Further, the intermediate frequency signal is amplified by the intermediate frequency amplifier 4, and further
It is demodulated by AM demodulation circuit 5 and its output is sent to external terminal 6.
It has been derived. This external terminal 6 is led out to an output terminal 8 via a low-cut circuit 7 consisting of an external capacitor C 1 and a resistor R 1 in the IC 1, and this output terminal 8 and the output terminal 3 from the FM demodulation circuit 2 are connected to each other. AM or AM by selectively switching with movable contact 9
FM demodulation output is output via external output terminal OUT 1 .
また、AM復調信号が導出する外部端子6には
抵抗R2,R3コンデンサC2,C3による2段のロー
パスフイルタを外部端子10の介して中間周波増
幅器4にAGCをかけている。 A two-stage low-pass filter including resistors R 2 and R 3 and capacitors C 2 and C 3 is connected to the external terminal 6 from which the AM demodulated signal is derived, and AGC is applied to the intermediate frequency amplifier 4 via the external terminal 10 .
ここで上記AM復調後外部端子6にローカツト
回路7を介挿したのはFM放送が低域から高域ま
で広帯域で低減まで充分な増幅が必要であるのに
対し、AM放送では局間の制約で高域があまり伸
せず、このため低域をあまり増幅すると非常に開
きずらく、低域をカツトする必要があるからであ
る。 The reason for inserting the low-cut circuit 7 into the external terminal 6 after AM demodulation is that FM broadcasting requires sufficient amplification over a wide range from low to high frequencies, while AM broadcasting has restrictions between stations. This is because the high range cannot be extended very much, so if the low range is amplified too much, it will be very difficult to open up, and the low range will need to be cut.
ところで第6図に示すようにAM復調回路5の
出力信号を外部端子6に導出し、ローパス回路7
に入力する入力電圧をVinとし、コンデンサC1の
容量をC1、抵抗R1の抵抗値をR1としたとき外部
出力端子OUT1に発生する出力電圧VOUT1は
VOUT1=Vio(R1/R1+(1/jωC1))=Vio
(jωC1R1/1+jωC1R1)…(1)
式1で示すようになる。 By the way, as shown in FIG.
The output voltage V OUT1 generated at the external output terminal OUT 1 is V OUT1 = V io ( R 1 /R 1 + (1/jωC 1 )) = V io
(jωC 1 R 1 /1+jωC 1 R 1 )...(1) It becomes as shown in Formula 1.
[背景技術の問題点]
AM/FM復調信号の出力端子を切換えて共用
して使用したいときの従来の回路にあつてはAM
復調信号のみローカツトしたいときに外付部品が
増えてしまう問題がある。またAM用のローカツ
ト回路をIC内部に構成してもやはりICの外部端
子数とともに外付けも増えるものであつた。また
AGC信号を生成するローパスフイルタはAGC信
号のリツプルを少なくするための2段のローパス
フイルタとすることがあり、このことによつても
外付部品の増加となつていた。[Problems with the background technology] When the output terminal of the AM/FM demodulated signal is to be switched and shared for use, the conventional circuit is
There is a problem in that the number of external components increases when it is desired to low-cut only the demodulated signal. Furthermore, even if a low-cut circuit for AM is configured inside an IC, the number of external terminals of the IC and the number of external connections also increase. Also
The low-pass filter that generates the AGC signal is sometimes a two-stage low-pass filter to reduce ripples in the AGC signal, which also increases the number of external components.
[発明の目的]
本発明は上記した問題点を除去し、ICの外部
端子を減らすとともに外付部品数も減らした受信
回路を提供するものである。[Object of the Invention] The present invention eliminates the above-mentioned problems and provides a receiving circuit in which the number of external terminals of an IC and the number of external parts are reduced.
[発明の概要]
本発明の受信回路は、中間周波信号を増幅する
中間周波増幅器と、この中間周波増幅器を通じて
出力された振幅変調信号を復調する復調回路と、
この復調回路から出力された復調信号の高域成分
を除去する第1の高域成分除去手段と、前記復調
回路から出力された復調信号と前記第1の高域成
分除去手段から出力された信号との差成分を増幅
して出力する差動アンプと、前記第1の高域成分
除去手段より出力された信号の高域成分を除去す
る第2の高域成分除去手段と、この第2の高域成
分除去手段の出力信号を前記中間周波増幅器の利
得をコントロールする信号として該中間周波増幅
器に導入する接続手段とを具備することを特徴と
している。[Summary of the Invention] A receiving circuit of the present invention includes an intermediate frequency amplifier that amplifies an intermediate frequency signal, a demodulation circuit that demodulates an amplitude modulated signal outputted through the intermediate frequency amplifier,
a first high-frequency component removing means for removing a high-frequency component of the demodulated signal output from the demodulation circuit; and a demodulated signal output from the demodulation circuit and a signal output from the first high-frequency component removal means. a differential amplifier that amplifies and outputs a difference component between the signals; a second high-frequency component remover that removes the high-frequency component of the signal output from the first high-frequency component remover; It is characterized by comprising a connecting means for introducing the output signal of the high frequency component removing means into the intermediate frequency amplifier as a signal for controlling the gain of the intermediate frequency amplifier.
[発明の実施例]
以下本発明の一実施例につき図面を参照して詳
細に説明する。[Embodiment of the Invention] An embodiment of the present invention will be described in detail below with reference to the drawings.
第1図において、この実施例はAM復調回路5
から差動アンプ30を介して出力端子8に導出
し、可動端子9を介して外部出力端子OUT2から
出力している。また差動アンプ30のマイナス側
の入力端子とAM復調回路5間には抵抗R4を接続
し、この抵抗R4とマイナス側入力端子間から外
部端子31に接続するとともに抵抗R5を介して
外部端子32および中間周波増幅器4に接続して
いる。外部端子31と接地間にはコンデンサC4
が、外部端子32と接地間にはコンデンサC5を
それぞれ外付けしている。 In FIG. 1, this embodiment is an AM demodulation circuit 5.
It is led out to the output terminal 8 via the differential amplifier 30, and is outputted from the external output terminal OUT 2 via the movable terminal 9. Also, a resistor R4 is connected between the negative input terminal of the differential amplifier 30 and the AM demodulation circuit 5, and a connection is made between this resistor R4 and the negative input terminal to the external terminal 31 and via a resistor R5 . It is connected to the external terminal 32 and the intermediate frequency amplifier 4. A capacitor C4 is connected between external terminal 31 and ground.
However, a capacitor C5 is externally connected between the external terminal 32 and the ground.
また抵抗R4と差動アンプ30のマイナス端子
との接続点Aの信号は抵抗R4とコンデンサC4に
よるローパス特性を持ち、このA点での信号をさ
らに抵抗R5とコンデンサC5により平滑したもの
を中間周波増幅器4に印加し、この増幅器4の利
得をコントロールしている。 Furthermore, the signal at the connection point A between the resistor R 4 and the negative terminal of the differential amplifier 30 has a low-pass characteristic due to the resistor R 4 and the capacitor C 4 , and the signal at this point A is further smoothed by the resistor R 5 and the capacitor C 5 . is applied to the intermediate frequency amplifier 4, and the gain of this amplifier 4 is controlled.
ところで差動アンプ30は第2図に示すように
構成している。すなわち、AM復調回路5からの
出力を直接あるいは抵抗R4を介して差動アンプ
30に印加している。この差動アンプ30は主に
トランジスタQ1〜Q4、抵抗値の等しい抵抗R6,
R7それに電流源I1,I2から成り、電圧から電流に
変換するV−I変換部と、この変換部の電流出力
を電圧に変換するI−V変換部の機能を有してい
る。つまりトランジスタQ3のベース電位がトラ
ンジスタQ4のベースより高くなると、トランジ
スタQ3のエミツタからトランジスタQ4のエミツ
タ方向に抵抗R6を介して電流が流れる。このと
き抵抗R7にも同レベルの電流が流れる。これに
より抵抗R7に生じる電圧が出力端子OUT2に出力
電圧として現われる。なお、外付のコンデンサ
C4が抵抗R4とに基づいてローパスし、これによ
り出力端子OUT2の出力はローカツトしたものと
なる。また電源VBは出力端子OUT2の出力電圧を
設定するためのものである。 Incidentally, the differential amplifier 30 is constructed as shown in FIG. That is, the output from the AM demodulation circuit 5 is applied to the differential amplifier 30 directly or via the resistor R4 . This differential amplifier 30 mainly includes transistors Q 1 to Q 4 , resistors R 6 with equal resistance values,
It consists of R7 and current sources I1 and I2 , and has the functions of a VI converter that converts voltage to current, and an IV converter that converts the current output of this converter into voltage. In other words, when the base potential of transistor Q 3 becomes higher than the base potential of transistor Q 4 , current flows from the emitter of transistor Q 3 to the emitter of transistor Q 4 via resistor R 6 . At this time, the same level of current also flows through resistor R7 . As a result, the voltage generated across resistor R 7 appears at output terminal OUT 2 as an output voltage. Please note that the external capacitor
C4 is low-passed based on resistor R4 , so that the output of output terminal OUT2 is low-cut. Further, the power supply V B is used to set the output voltage of the output terminal OUT 2 .
ここで第1および第2図に示すAM復調回路5
の出力と出力端子OUT2間に接続した抵抗R4、差
動アンプ30それに外付のコンデンサC4からな
るローカツト回路を第3図に示すようにAM復調
回路5の出力電圧、換言すれば差動アンプ30の
入力電圧をVioとし、抵抗R4の抵抗値をR4、コン
デンサC4の容量をC4、差動アンプ30の利得1
としたときの出力端子OUT2に発生する出力電圧
VOUT2は次の式(2)で示す値となる。 Here, the AM demodulation circuit 5 shown in FIGS. 1 and 2
As shown in Figure 3, a low-cut circuit consisting of a resistor R 4 connected between the output of the AM demodulator 5 and the output terminal OUT 2 , a differential amplifier 30, and an external capacitor C 4 outputs the output voltage of the AM demodulator 5, in other words, the difference The input voltage of the differential amplifier 30 is Vio , the resistance value of the resistor R4 is R4 , the capacitance of the capacitor C4 is C4 , and the gain of the differential amplifier 30 is 1.
Output voltage generated at output terminal OUT 2 when
V OUT2 has the value shown by the following equation (2).
VOUT2=Vio−Vio((1/jωC4)/R4+(1/jωC
4))=Vio[1−
(1/jωC4R4+1)]=Vio(jωC4R4/1+j
ωC4R4)…(2)
ここで従来のローパス回路7の有する入出力電
の関係を示す式(1)と本発明の式(2)とは全く同一で
ある。このことから同じ周波数特性を有すること
が理解できる。換言すれば従来の第6図で示すロ
ーカツト特性と第3図で示す本発明のローカツト
特性も式(1)、(2)の伝達関数が等しいことから全く
同一である。 V OUT2 = V io −V io ((1/jωC 4 )/R 4 + (1/jωC
4 ))=V io [1- (1/jωC 4 R 4 +1)]=V io (jωC 4 R 4 /1+j
ωC 4 R 4 )...(2) Here, equation (1) showing the relationship between input and output power of the conventional low-pass circuit 7 and equation (2) of the present invention are completely the same. From this, it can be understood that they have the same frequency characteristics. In other words, the conventional low-cut characteristic shown in FIG. 6 and the low-cut characteristic of the present invention shown in FIG. 3 are exactly the same since the transfer functions of equations (1) and (2) are the same.
従つて、この実施例によれば、外部端子31,
32にコンデンサC4,C5のみの接続でAM復調回
路5の出力をローカツトできるとともに中間周波
増幅器4にAGCをかけることができる。 Therefore, according to this embodiment, the external terminals 31,
By connecting only capacitors C 4 and C 5 to 32, the output of the AM demodulation circuit 5 can be low-cut, and the intermediate frequency amplifier 4 can be subjected to AGC.
次に第4図を参照して本発明の他の実施例につ
き説明する。 Next, another embodiment of the present invention will be described with reference to FIG.
この実施例はAM復調回路5の出力を、電圧を
電流に変換するV−I変換器40のプラス入力
に、このV−I変換器40のマイナス入力外部端
子41に接続するとともにV−I変換器40の一
方の出力に接続している。V−I変換器40の他
方の出力は電流を電圧に変換するI−V変換器4
2から出力端子8、可動接点9介して外部出力端
子OUT3に接続し、ここから出力を導出してい
る。さらにV−I変換器40のマイナス入力は
AGCアツプ43を介して、中間周波増幅器4に
も接続し、AGCアツプ43のコントロール信号
を印加して中間周波増幅器4の利得をコントロー
ルしている。またAGCアツプ43の出力は外部
端子44にも接続している。ところで上記外部端
子41にはコンデンサC6を外部端子44にはコ
ンデンサC7をそれぞれ外付けしている。 In this embodiment, the output of the AM demodulation circuit 5 is connected to the positive input of a V-I converter 40 that converts voltage into current, and to the negative input external terminal 41 of this V-I converter 40, and the V-I converter is It is connected to one output of the device 40. The other output of the V-I converter 40 is an I-V converter 4 that converts current into voltage.
2 is connected to an external output terminal OUT 3 via an output terminal 8 and a movable contact 9, from which the output is derived. Furthermore, the negative input of the V-I converter 40 is
It is also connected to the intermediate frequency amplifier 4 via the AGC amplifier 43, and the gain of the intermediate frequency amplifier 4 is controlled by applying a control signal of the AGC amplifier 43. The output of the AGC up 43 is also connected to an external terminal 44. Incidentally, a capacitor C6 is externally connected to the external terminal 41, and a capacitor C7 is externally connected to the external terminal 44.
ところでこの実施例でのV−I変換器40は第
1図に示す抵抗R4と同じ働きをしている。カツ
トオフ周波数は[1/2π(1gm)C6]となる。但
し、gmはV−I変換器40の変換コンダクタン
ス、C6は外付のコンデンサC6の容量である。 By the way, the V-I converter 40 in this embodiment has the same function as the resistor R4 shown in FIG. The cutoff frequency is [1/2π(1gm)C 6 ]. However, gm is the conversion conductance of the VI converter 40, and C6 is the capacitance of the external capacitor C6 .
従つて、この実施例の場合でもコンデンサC6
に発生する電圧はハイカツトされた信号であるか
ら、これをAGC信号とすることができる。また
第1図の抵抗R5の代わりにAGCアンプ43が用
いられているが動作は全く同じである。 Therefore, even in this example, the capacitor C 6
Since the voltage generated at is a high-cut signal, this can be used as an AGC signal. Furthermore, an AGC amplifier 43 is used in place of the resistor R5 in FIG. 1, but the operation is exactly the same.
この実施例でも外部端子41,44にコンデン
サC6,C7のみの接続でAM復調回路5の出力をロ
ーカツトできるとともに中間周波増幅器4に
AGCをかけることができる。 In this embodiment as well, the output of the AM demodulation circuit 5 can be low-cut by connecting only the capacitors C 6 and C 7 to the external terminals 41 and 44, and the output of the intermediate frequency amplifier 4 can be low-cut.
AGC can be applied.
[発明の効果]
以上記載したように本発明によれば、AM/
FMの復調信号を1端子出力としながら、ICのピ
ン数並びに外付部品を少なくしてAM信用のみの
ローカツトができる。またAGCのコントロール
信号が2段のローパスフイルタを通過するように
構成していることからリツプルが少なく、かつ
AGCをかけたことによる歪も少くできる。[Effect of the invention] As described above, according to the present invention, AM/
While outputting the FM demodulated signal from one terminal, it is possible to reduce the number of IC pins and external components, making it possible to low-cut only for AM use. In addition, since the AGC control signal is configured to pass through a two-stage low-pass filter, ripples are small and
Distortion caused by applying AGC can also be reduced.
第1図は本発明の回路構成図、第2図は第1図
の主要部の回路図、第3図は同じく第1図の主要
部分を示す回路構成図、第4図は本発明の他の実
施例を示す回路構成図、第5図は従来の構成図、
第6図は第5図の主要部を示す回路構成図であ
る。
4……中間周波増幅器、5……AM復調回路、
30……差動アンプ、R4,R5……抵抗、C4,C5
……コンデンサ、40……V−I変換器、42…
…I−V変換器、43……AGCアンプ、C6,C7
……コンデンサ。
FIG. 1 is a circuit configuration diagram of the present invention, FIG. 2 is a circuit diagram of the main part of FIG. 1, FIG. 3 is a circuit diagram of the main part of FIG. A circuit configuration diagram showing an example of this, FIG. 5 is a conventional configuration diagram,
FIG. 6 is a circuit diagram showing the main parts of FIG. 5. 4...Intermediate frequency amplifier, 5...AM demodulation circuit,
30...Differential amplifier, R4 , R5 ...Resistor, C4 , C5
... Capacitor, 40 ... V-I converter, 42 ...
...IV converter, 43...AGC amplifier, C 6 , C 7
...Capacitor.
Claims (1)
この中間周波増幅器を通じて出力された振幅変調
信号を復調する復調回路と、この復調回路から出
力された復調信号の高域成分を除去する第1の高
域成分除去手段と、前記復調回路から出力された
復調信号と前記第1の高域成分除去手段から出力
された信号との差成分を増幅して出力する差動ア
ンプと、前記第1の高域成分除去手段より出力さ
れた信号の高域成分を除去する第2の高域成分除
去手段と、この第2の高域成分除去手段の出力信
号を前記中間周波増幅器の利得をコントロールす
る信号として該中間周波増幅器に導入する接続手
段とを具備することを特徴とする受信回路。1 an intermediate frequency amplifier that amplifies an intermediate frequency signal;
a demodulation circuit that demodulates the amplitude modulated signal outputted through the intermediate frequency amplifier; a first high-frequency component removal means that removes the high-frequency components of the demodulated signal outputted from the demodulation circuit; a differential amplifier that amplifies and outputs the difference component between the demodulated signal and the signal output from the first high frequency component removal means; a second high-frequency component removing means for removing the component; and a connecting means for introducing the output signal of the second high-frequency component removing means into the intermediate frequency amplifier as a signal for controlling the gain of the intermediate frequency amplifier. A receiving circuit characterized by:
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP27039084A JPS61147611A (en) | 1984-12-21 | 1984-12-21 | Agc circuit |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP27039084A JPS61147611A (en) | 1984-12-21 | 1984-12-21 | Agc circuit |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS61147611A JPS61147611A (en) | 1986-07-05 |
JPH0325085B2 true JPH0325085B2 (en) | 1991-04-05 |
Family
ID=17485591
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP27039084A Granted JPS61147611A (en) | 1984-12-21 | 1984-12-21 | Agc circuit |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS61147611A (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH01139617U (en) * | 1988-03-17 | 1989-09-25 | ||
JPH02162814A (en) * | 1988-12-15 | 1990-06-22 | Toshiba Corp | Agc circuit for am signal |
JP4876841B2 (en) * | 2005-12-28 | 2012-02-15 | 株式会社デンソー | Blower |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5178616A (en) * | 1974-12-28 | 1976-07-08 | Sony Corp | |
JPS56160118A (en) * | 1980-05-10 | 1981-12-09 | Sony Corp | Afc and agc circuit in common |
-
1984
- 1984-12-21 JP JP27039084A patent/JPS61147611A/en active Granted
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5178616A (en) * | 1974-12-28 | 1976-07-08 | Sony Corp | |
JPS56160118A (en) * | 1980-05-10 | 1981-12-09 | Sony Corp | Afc and agc circuit in common |
Also Published As
Publication number | Publication date |
---|---|
JPS61147611A (en) | 1986-07-05 |
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Legal Events
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EXPY | Cancellation because of completion of term |