JPS60109303A - Fm demodulation circuit - Google Patents
Fm demodulation circuitInfo
- Publication number
- JPS60109303A JPS60109303A JP21620983A JP21620983A JPS60109303A JP S60109303 A JPS60109303 A JP S60109303A JP 21620983 A JP21620983 A JP 21620983A JP 21620983 A JP21620983 A JP 21620983A JP S60109303 A JPS60109303 A JP S60109303A
- Authority
- JP
- Japan
- Prior art keywords
- demodulation
- circuit
- constant current
- loop
- frequency
- 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
Links
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
- H03D3/00—Demodulation of angle-, frequency- or phase- modulated oscillations
- H03D3/02—Demodulation of angle-, frequency- or phase- modulated oscillations by detecting phase difference between two signals obtained from input signal
- H03D3/24—Modifications of demodulators to reject or remove amplitude variations by means of locked-in oscillator circuits
- H03D3/241—Modifications of demodulators to reject or remove amplitude variations by means of locked-in oscillator circuits the oscillator being part of a phase locked loop
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
- H03D2200/00—Indexing scheme relating to details of demodulation or transference of modulation from one carrier to another covered by H03D
- H03D2200/0001—Circuit elements of demodulators
- H03D2200/0025—Gain control circuits
- H03D2200/0027—Gain control circuits including arrangements for assuring the same gain in two paths
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
- H03D2200/00—Indexing scheme relating to details of demodulation or transference of modulation from one carrier to another covered by H03D
- H03D2200/0041—Functional aspects of demodulators
- H03D2200/0047—Offset of DC voltage or frequency
Abstract
Description
【発明の詳細な説明】
〔−発明の利用分野〕
本発明は、ＦＭ変調信号を復調するＦＭ復調回路の構成
に関するものである。DETAILED DESCRIPTION OF THE INVENTION [-Field of Application of the Invention] The present invention relates to the configuration of an FM demodulation circuit that demodulates an FM modulated signal.
静止衛星を使ったテレビの放送では、ＦＭ変調されたテ
レビ信号が用いられる。この放送を受信する受信機では
、衛星からの微弱な電波からテレビ信号を復調するため
、弱電界特性に優れるＰＬＬ（フェイズロックドループ
）ＦＭ復調回路がよく使われる。第１図に一般的なＰＬ
Ｌ−ＦＭ復調回路の構成を示す。入力端子ｌから入力さ
れたＦＭ信号は、位相検波器２、増幅器３、ループフィ
ルタ４さ電圧制御発振器５の閉ループから成るＰＬＬ−
ＦＭ復調回路で復調され、電圧制御発振器５０入力線路
を分岐して出力端６から復調されたテレビ信号を取り出
す。Television broadcasts using geostationary satellites use FM-modulated television signals. In receivers that receive this broadcasting, PLL (phase-locked loop) FM demodulation circuits, which have excellent weak electric field characteristics, are often used to demodulate television signals from weak radio waves from satellites. Figure 1 shows a typical PL
The configuration of an L-FM demodulation circuit is shown. The FM signal input from the input terminal 1 is processed by a PLL circuit consisting of a closed loop of a phase detector 2, an amplifier 3, a loop filter 4, and a voltage controlled oscillator 5.
The TV signal is demodulated by the FM demodulation circuit, and the input line of the voltage controlled oscillator 50 is branched to take out the demodulated television signal from the output terminal 6.
このＦＭ復調回路は、位相検波器２で発生する入力信号
と電圧制御発振器５の差の周波数のビート成分を、増幅
器３で増幅し、ループフィルタ４で位相と利得とを調整
し、電圧制御発振器５の発振周波数制御端子へ印加する
ことにより、上記ビート成分の周波数を０とする閉ルー
プの働きにより、電圧制御発振器５の発振周波数制御端
子には入力ＦＭ信号の原信号であるテレビ信号が発生し
、上記閉ループはＦＭ復調回路となる。したがって、こ
のＦＭ復調回路の復調帯域は閉ループ内の増幅器３とル
ープフィルり４で形成される利得および位相特性で決定
され、この復調帯域を必要最小の帯域に設定できるため
、弱電界時の復調特性が優れている。This FM demodulation circuit amplifies the beat component of the frequency of the difference between the input signal generated by the phase detector 2 and the voltage controlled oscillator 5 with the amplifier 3, adjusts the phase and gain with the loop filter 4, and By applying voltage to the oscillation frequency control terminal of the voltage controlled oscillator 5, a television signal, which is the original signal of the input FM signal, is generated at the oscillation frequency control terminal of the voltage controlled oscillator 5 due to a closed loop function that sets the frequency of the beat component to 0. , the above closed loop becomes an FM demodulation circuit. Therefore, the demodulation band of this FM demodulation circuit is determined by the gain and phase characteristics formed by the amplifier 3 and loop fill 4 in the closed loop, and since this demodulation band can be set to the minimum required band, demodulation during weak electric field is possible. Excellent characteristics.
衛星放送におけるＦＭ信号の一例として、映像信号の同
期信号の先端から白信号レベルまでを１７ＭＨｚ の周
波数変化のＦＭ信号の場合、上記ＰＬＬ・ＦＭ復調回路
の閉ループでは、１７ＭＨｚの１の８．５ ＭＨｚまで
ループ利得は１以上、位相変化９０’以下にすると、位
相検波器２の±８．５ＭＨｚのビート成分まで閉ループ
の制御がかかり復調帯域は１７ＭＨｚが得られる。第２
図に、この復調帯域特性を示す。ＰＬＬ＠ＦＭ復調回路
の入力信号の周波数を変化させた時の、復調出力端子の
電圧特性で、中心周波数ｆＯに対し、入力周波数が−８
，５ＭＨｚまではビート成分が表われ、−８，５ＭＨｚ
以下になると閉ループの制御が働き、−８，５ＭＨｚか
ら＋８．５ ＭＨｚまで電圧制御発振器の印加電圧と発
振周波数の特性７に沿って、ｆＯと入力周波数の周波数
差に比例した直流電圧が発信し、＋８．５Ｍｆｌ！以上
では、またビート成分の出力となる。このように、ＰＬ
Ｌ＠ＦＭ復調回路では、ループ内の増幅回路とループフ
ィルタにより、復調帯域を必要最小限に狭く設定できる
特長をもつが、このように映像周波数変移か１７ＭＨｚ
と大きい場合ループの利得帯域は８．５ＭＨｚ以上が必
要であり、映像信号帯域４．５ＭＨｚに比べ約２倍の広
帯域回路が必要であると同時にｔループ内の雑音も８．
５ＭＨｚと帯域か広いため、入力信号のＣ／Ｈに対する
復調信号のＳ／Ｎが大キく劣化するスレツシュホールド
レベルカ映像周波数変移が小さい場合に比べ悪くなる欠
点をもっていた。As an example of an FM signal in satellite broadcasting, in the case of an FM signal with a frequency change of 17 MHz from the tip of the synchronization signal of the video signal to the white signal level, the closed loop of the PLL/FM demodulation circuit described above changes the frequency by 8.5 MHz of 1 of 17 MHz. When the loop gain is set to 1 or more and the phase change is set to 90' or less, closed loop control is applied to the beat component of ±8.5 MHz of the phase detector 2, and a demodulation band of 17 MHz is obtained. Second
The figure shows this demodulation band characteristic. The voltage characteristics of the demodulation output terminal when the frequency of the input signal of the PLL@FM demodulation circuit is changed.The input frequency is -8 with respect to the center frequency fO.
, a beat component appears up to 5MHz, and -8.5MHz
When the frequency is below, closed-loop control is activated, and a DC voltage proportional to the frequency difference between fO and the input frequency is transmitted from -8.5 MHz to +8.5 MHz in accordance with the characteristics 7 of the applied voltage and oscillation frequency of the voltage controlled oscillator. ,+8.5Mfl! In the above case, the beat component is output again. In this way, P.L.
The L@FM demodulation circuit has the advantage of being able to set the demodulation band as narrow as necessary using the amplification circuit and loop filter in the loop.
If this is large, the gain band of the loop needs to be 8.5 MHz or more, which requires a wideband circuit that is about twice as wide as the video signal band of 4.5 MHz, and at the same time, the noise in the t-loop is 8.5 MHz or more.
Since the band is as wide as 5 MHz, the threshold level, which causes a large deterioration in the S/N of the demodulated signal with respect to the C/H of the input signal, is worse than when the video frequency shift is small.
本発明の目的は、上記したＰＬＬ−ＦＭ復調回路の欠点
を解消し、簡単な回路構成で、ループ内の利得帯域を狭
＜シ、映像周波数変移の大きさに関係なく良好なスレッ
シュホールドレベルが得られるＦＭ復調回路を提供する
にある。An object of the present invention is to eliminate the drawbacks of the PLL-FM demodulation circuit described above, to narrow the gain band in the loop with a simple circuit configuration, and to maintain a good threshold level regardless of the magnitude of the video frequency shift. The object of the present invention is to provide an FM demodulation circuit obtained by the present invention.
本発明では、復調回路の復調帯域の中心周波数を復調信
号に応じて移動する構成を用Ｇ）ることにより、復調ル
ープ内の帯域特性を狭くし、簡単な構成で、スレッシュ
ホールドレベルの向上を図る。In the present invention, by using a configuration in which the center frequency of the demodulation band of the demodulation circuit is moved according to the demodulation signal, the band characteristics in the demodulation loop are narrowed, and the threshold level can be improved with a simple configuration. Plan.
以下、本発明を図に示す実施例に従って詳細に説明する
。第３図と第４図は本発明の詳細な説明する図である。Hereinafter, the present invention will be explained in detail according to embodiments shown in the drawings. FIGS. 3 and 4 are diagrams explaining the present invention in detail.
第３図は、トランジスタＱ４とＱ５のミラー回路から成
る定電流源をもつトランジスタＱ１とＱ２の差動増幅器
で、前記ＰＬＬＦＭ後調回路復調幅器の一部にこの差動
増幅器を使用し、トランジスタＱ１とＱ２のベース８ａ
。Figure 3 shows a differential amplifier consisting of transistors Q1 and Q2 having a constant current source consisting of a mirror circuit of transistors Q4 and Q5. Base 8a of Q1 and Q2
.
８ｂを平衡信号入力とし、トランジスタＱ１のコレクタ
からトランジスタＱ３を介して信号を出力しこの出力端
子９をループフィルタへ接続する。8b is a balanced signal input, a signal is output from the collector of transistor Q1 via transistor Q3, and this output terminal 9 is connected to a loop filter.
ここで、定電流源の電流を可変抵抗１０で変えると、第
４図に示すように、中心周波数ｆ１の復調特性１１が、
電圧制御発振器の印加電圧ｌこ対する発振周波数特性７
に沿って、中心周波数ｆ２の復調特性１２へ変化し、こ
の時、ループ利得および位相は変わらないため、復調特
性１１（！：１２の復調帯域は同じである。Here, when the current of the constant current source is changed by the variable resistor 10, the demodulation characteristic 11 of the center frequency f1 becomes as shown in FIG.
Oscillation frequency characteristics versus applied voltage l of voltage controlled oscillator 7
The demodulation characteristic 11 (!:12) changes to the demodulation characteristic 12 with the center frequency f2, and at this time, the loop gain and phase remain unchanged, so the demodulation band of the demodulation characteristic 11 (!:12) is the same.
第５図に本発明の一実施例を示す。ＰＬＬ・ＦＭ復調回
路の増幅器３′の後段に定電流源１３をもつ差動増幅器
１４を配置し、差動増幅器１４の出力を分岐して、一方
をループフィルタ４へ接続し、他方を増幅器１５と電圧
変換回路１６を介して定電流源１３へ接続し、差動増幅
器１４の出力の復調信号を用いて、定電流源１３の電流
を変化させ、律ひＮ ％７域の中心周波数を移動させる
。FIG. 5 shows an embodiment of the present invention. A differential amplifier 14 having a constant current source 13 is arranged after the amplifier 3' of the PLL/FM demodulation circuit, and the output of the differential amplifier 14 is branched, one side is connected to the loop filter 4, and the other side is connected to the amplifier 15. is connected to the constant current source 13 via the voltage conversion circuit 16, and the demodulated signal of the output of the differential amplifier 14 is used to change the current of the constant current source 13, moving the center frequency in the N%7 range. let
第６図に、本発明ＦＭ復調回路の復調帯域移ｉ４！Ｉを
行なう増幅器部の回路の実施例を示す。前記差動増幅器
のＰＬＬ閉ループ出力を分岐してＰＮＰ トランジスタ
Ｑ６で取り出し、このトランジスタ６のコレクタをトラ
ンジスタＱｓのコレクタへ、またトランジスタ６のエミ
ッタを抵抗１７を介して正極電源へ接続することにより
、入力ＦＭ信号の周波数が高くなると、トランジスタＱ
１のコレクタ電圧が高くなり、トランジスタＱ６を流れ
る電流が減少してトランジスタＱ４のベース電圧は低く
なり、トランジスタＱ４を流れる電流が減少して、ＦＭ
復調帯域を高い周波数側へ移動する。この時、ＰＬＬの
閉ループの利得と位相は影響を受けないため復調帯域は
変化しない。この復調帯域を移動させる感度はトランジ
スタＱ６のエミッタ抵抗１７０大きさで決まり、この抵
抗１７を小さくすると移動１ｈが大きくなるが本構成で
は、ＦＭ入力信号の中心周波数で差動増幅器の直流バラ
ンスをとるため抵抗１７を小さくできない。そこで、第
７図に示すように、抵抗１７の電源側にトランジスタＱ
７から成る定電圧源を構成することにより、抵抗１７を
小さくして、復調帯域の移動を大きくできる。今、この
抵抗１７を、トランジスタＱ１とＱ２のコレクタ電圧が
常に等しくなるように辿ぶと、入力ＦＭ’＋Ｗ号が常に
復調帯域の中心にあるように復調帯域が移動する。この
動作を第８図に示す。入力ＦＭ信号の中心周波数ｆＯが
入力された時、差動増幅器の直流バランスがとれている
ため、周波数ｆｏ’ｅ中心とするａの復調帯域をもち、
入力信号がΔｆ変移したＨか１差動増幅器のトランジス
タＱ１の出力電圧が上昇するが、定電流源の電流が減少
してトランジスタＱ２のコレクタ電圧かトランジスタＱ
１のコレクタ電圧と等しくなるため、この電圧で差動増
幅器のバランスがとれ周波数ＣｆＯ＋Δｆ）を中心とす
るｂの復調帯域となり、入力信号が周波数−Δｆ変移し
た時ｌこは同様に周波数（ｆｏ−Δｆ）蛋・中心とする
Ｃの復調帯域となる。したがって、映像周波数質移り大
きいＦＭ信号も本発明を用いると復調でき、ＰＬＬ閉ル
ープの周波泌・特性も、映像信号の崇高周波数４．５
ＭＨｚまで狭くでき、これによって閉ループ内の雑音帯
域幅も小さくなってスレッシュボールドレベルが良くな
る。さらに、ヘテロダイン受信機のり論部として本発明
のＦＭ復調＠ｆ＃ｆそ用いるとヘテロダイン受信機の局
部発振周波数の変動によってＦΔ１榎調口調回路入力心
周波数が変っても常に復調帯域の中心で復調するため復
調伺号の劣化はない。FIG. 6 shows the demodulation band shift i4! of the FM demodulation circuit of the present invention. An embodiment of a circuit of an amplifier section that performs I will be shown. The PLL closed loop output of the differential amplifier is branched and taken out by a PNP transistor Q6, and the collector of this transistor 6 is connected to the collector of a transistor Qs, and the emitter of the transistor 6 is connected to the positive power supply via a resistor 17. When the frequency of the FM signal increases, the transistor Q
The collector voltage of transistor Q1 increases, the current flowing through transistor Q6 decreases, the base voltage of transistor Q4 decreases, the current flowing through transistor Q4 decreases, and FM
Move the demodulation band to higher frequencies. At this time, the gain and phase of the closed loop of the PLL are not affected, so the demodulation band does not change. The sensitivity of shifting this demodulation band is determined by the size of the emitter resistor 170 of the transistor Q6, and the smaller the resistor 17, the larger the shift 1h, but in this configuration, the DC balance of the differential amplifier is maintained at the center frequency of the FM input signal. Therefore, the resistance 17 cannot be made small. Therefore, as shown in FIG. 7, a transistor Q is connected to the power supply side of the resistor 17.
By configuring a constant voltage source consisting of 7, the resistance 17 can be made small and the movement of the demodulation band can be increased. Now, if this resistor 17 is traced so that the collector voltages of transistors Q1 and Q2 are always equal, the demodulation band moves so that the input FM'+W signal is always at the center of the demodulation band. This operation is shown in FIG. When the center frequency fO of the input FM signal is input, since the differential amplifier is DC balanced, it has a demodulation band a centered on the frequency fo'e,
The output voltage of the transistor Q1 of the H-1 differential amplifier increases when the input signal shifts by Δf, but the current of the constant current source decreases and the collector voltage of the transistor Q2 or the transistor Q increases.
Since this voltage is equal to the collector voltage of 1, the differential amplifier is balanced with this voltage, resulting in a demodulation band of b centered at the frequency CfO + Δf), and when the input signal shifts in frequency -Δf, the frequency l is also equal to the frequency (fo- Δf) This is the demodulation band centered on C. Therefore, FM signals with large video frequency quality fluctuations can be demodulated using the present invention, and the frequency loss and characteristics of the PLL closed loop can also be adjusted to 4.5 at the sublime frequency of the video signal.
MHz, which also reduces the noise bandwidth in the closed loop and improves the threshold level. Furthermore, if the FM demodulation@f#f of the present invention is used as the logic part of a heterodyne receiver, even if the input heart frequency of the FΔ1 tuning circuit changes due to fluctuations in the local oscillation frequency of the heterodyne receiver, the demodulation will always be at the center of the demodulation band. Therefore, there is no deterioration of the demodulated signal.
また、雑音等による複画帯域移動の誤動作を防ぐには、
第９図に示すように、増幅器１５の後段に振幅制限回路
１８を設けることにより復調帯域の移動幅を制限するの
が良い。さらに、第１０図に一例を示すように、復調信
号の低周波振幅が大きい場合には、増幅器１５から定電
流源１３の系の中に低域通過フィルタ１９ソ配置して復
調信号の低周波数成分だけで復調帯域の移動を行なうこ
ともできる。この第１０図の例は第９図の構成で示した
が、これは第５図の構成においても同じである。In addition, to prevent malfunction of multiple image band movement due to noise etc.
As shown in FIG. 9, it is preferable to provide an amplitude limiting circuit 18 after the amplifier 15 to limit the movement width of the demodulation band. Furthermore, as shown in an example in FIG. 10, when the low frequency amplitude of the demodulated signal is large, a low pass filter 19 is placed in the system from the amplifier 15 to the constant current source 13 to reduce the frequency of the demodulated signal. It is also possible to shift the demodulation band using only the components. Although the example shown in FIG. 10 is shown in the configuration shown in FIG. 9, the configuration shown in FIG. 5 is also the same.
以上、本発明を第５図の差動増幅器の出力を分岐して復
調信号を用いる構成で説明したが、この構成に限るもの
ではなく、差動増幅器の定電流源を駆動する復調信号は
、差動増幅器の出力電圧が上昇した時に定電流源の電流
を減少させる極性であれば良く、第１１図に示すように
ＰＬＬ−ＦＭ復調回路出力の信号でも、差動増幅器の前
段の増幅回路から分岐した信号でも良いことは明らかで
ある。Although the present invention has been described above using a configuration in which the output of the differential amplifier shown in FIG. 5 is branched and a demodulated signal is used, the present invention is not limited to this configuration. Any polarity is sufficient as long as it reduces the current of the constant current source when the output voltage of the differential amplifier increases, and as shown in Figure 11, even the signal output from the PLL-FM demodulation circuit can be transmitted from the amplifier circuit in the previous stage of the differential amplifier. It is clear that a branched signal may also be used.
また、差動増幅器はループフィルタの前段に配置したが
、これに限るものではなく、閉ループ内の増幅器の途中
あるいは初段に配置しても良いことは明らかである。Moreover, although the differential amplifier is placed before the loop filter, it is obvious that the present invention is not limited to this, and may be placed in the middle of the amplifier in the closed loop or at the first stage.
本発明は、ＰＬＬ＠ＦＭ′４１調回路の閉ループ調料路
と位相を変化させずに、復調帯域の中心周波数を復調信
号に応じて移動するため、簡単な構成で、ＰＬＬ−ＦＭ
復調回路の閉ループを広帯域にする必要はなく、映像周
波数変移の大きいＦＭ信号を復調でき、入力ＦＭ信号の
中心周波数のズレに対しても良好な復′ｆＡをし、スレ
ッシュホールドレベルを大幅に改善する効果をもつ。The present invention moves the center frequency of the demodulation band according to the demodulation signal without changing the closed-loop tuning path and phase of the PLL@FM'41 modulation circuit.
There is no need to make the closed loop of the demodulation circuit broadband, it is possible to demodulate FM signals with large video frequency shifts, and it performs good demodulation even when the center frequency of the input FM signal shifts, greatly improving the threshold level. It has the effect of
第１図は、従来のＰＬＬ ＠ＦＭ復調回路の構成図、第
２図は、従来のＰＬＬ＠ＦＭ復調回路の特性図、第３図
と第４図は、本発明の詳細な説明する回路図と特性図、
第５図は本発明の実施例を示す構成図、第６図と第７図
は本発明ζこ使用する回路側図、第８図は、本発明の詳
細な説明する特性図、第９図、第１０図、第１１図は、
本発明の変形を示す構成図である。
１・・・ＦＭ信号人力 ２・・・位相検波器３．３’、
１５・・・増幅器 ４・・・ループフィルり５・・・電
圧制御発振器 ６・・・復調出力１３・・・定電流源
１４・・・差動増幅器１６・・・電圧変換回路 １８・
・・振幅制限回路１９・・・低域通過フィルタ
オ ｌＩ！ｌ
り
第２図
第３図
才４図
オｆ図
オ６図
オフ図
第２１凹
オｑ肥
第１１図FIG. 1 is a block diagram of a conventional PLL@FM demodulation circuit, FIG. 2 is a characteristic diagram of a conventional PLL@FM demodulation circuit, and FIGS. 3 and 4 are circuit diagrams explaining the present invention in detail. and characteristic diagram,
FIG. 5 is a configuration diagram showing an embodiment of the present invention, FIGS. 6 and 7 are side diagrams of a circuit using the present invention, FIG. 8 is a characteristic diagram explaining the present invention in detail, and FIG. 9 , Figures 10 and 11 are
It is a block diagram which shows the modification of this invention. 1... FM signal human power 2... Phase detector 3.3',
15...Amplifier 4...Loop fill 5...Voltage controlled oscillator 6...Demodulation output 13...Constant current source
14... Differential amplifier 16... Voltage conversion circuit 18.
...Amplitude limiting circuit 19...Low pass filter lI! l Figure 2 Figure 3 Figure 4 Off Figure O Figure 6 Off Figure 21 Recessed Figure 11
Claims (1)
制御発振器で閉ループを形成するフェイズロックドルー
プ方式のＦＭ復調回路において、ＦＭ復調スロープの周
波数をＦＭ復調した信号で変化させる構成を特徴とする
ＦＭ復調回路。 （２、特許請求の範囲第１項において、増幅器の一部に
定電流回路をもつ定電流駆動の差動増幅回路を形成し、
この定電流回路の電流を、ＦＭ復調した信号で変化させ
る構成を特徴とするＦＭ復調回路。 （３） 特許請求の範囲第２項ζこおいて、定電流回路
の電流を変化させるＦＭ復調した信号を、前記フェイズ
ロックドループの閉ループ内から分岐して取り出した構
成を特徴とするＦＭ復調回路。 （４）特許請求の範囲第３項において、閉ループ内の分
岐から定電流回路までの系に増幅回路を配置した構成を
特徴とするＦＭ復調回路。 （５）特許請求の範囲第４項において、閉ループ内の分
岐から定電流回路までの系の増幅回路の後段に振幅制限
回路を配置した構成を特徴とするＦＭ復調回路。 （６）特許請求の範囲第４項才たは第５項において、閉
ループ内の分岐から定電流回路までの系に低域通過フィ
ルタを配置した構成を特徴とするＦＭ復調回路。 （７）特許請求の範囲第３項において、定電流回路の電
流を変化させるＦＭ復調した信号を、前記差動増幅回路
のフェイズロックドループの閉ループを形成している出
力を分岐して取り出した構成を特徴とするＦＭ復調回路
。[Claims] (Re) In a phase-locked loop FM demodulation circuit in which a phase detector, an amplifier, a loop filter, and a voltage controlled oscillator form a closed loop, the frequency of the FM demodulation slope is changed by the FM demodulated signal. A characterized FM demodulation circuit. (2. In claim 1, a constant current drive differential amplifier circuit having a constant current circuit as a part of the amplifier is formed,
An FM demodulation circuit characterized by a configuration in which the current of this constant current circuit is changed by an FM demodulated signal. (3) An FM demodulation circuit according to claim 2 ζ, characterized in that the FM demodulated signal for changing the current of the constant current circuit is branched and extracted from the closed loop of the phase-locked loop. . (4) The FM demodulation circuit according to claim 3, characterized in that an amplifier circuit is arranged in the system from the branch in the closed loop to the constant current circuit. (5) The FM demodulation circuit according to claim 4, characterized in that an amplitude limiting circuit is disposed at a subsequent stage of the amplifier circuit in the system from the branch in the closed loop to the constant current circuit. (6) The FM demodulation circuit according to claim 4 or 5, characterized in that a low-pass filter is arranged in the system from the branch in the closed loop to the constant current circuit. (7) In claim 3, the configuration is such that the FM demodulated signal that changes the current of the constant current circuit is extracted by branching the output forming the closed loop of the phase-locked loop of the differential amplifier circuit. An FM demodulation circuit featuring:
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21620983A JPS60109303A (en) | 1983-11-18 | 1983-11-18 | Fm demodulation circuit |
| CA000467751A CA1227547A (en) | 1983-11-18 | 1984-11-14 | Fm demodulator |
| US06/671,876 US4602217A (en) | 1983-11-18 | 1984-11-15 | FM demodulator capable of shifting demodulation-band center frequency |
| EP84113807A EP0143400A3 (en) | 1983-11-18 | 1984-11-15 | Fm demodulator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21620983A JPS60109303A (en) | 1983-11-18 | 1983-11-18 | Fm demodulation circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS60109303A true JPS60109303A (en) | 1985-06-14 |
Family
ID=16684981
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP21620983A Pending JPS60109303A (en) | 1983-11-18 | 1983-11-18 | Fm demodulation circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60109303A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61173596A (en) * | 1985-01-28 | 1986-08-05 | Sony Corp | Pll demodulating circuit |
| JPH02266707A (en) * | 1989-04-07 | 1990-10-31 | Alps Electric Co Ltd | Fm video signal detection circuit |
-
1983
- 1983-11-18 JP JP21620983A patent/JPS60109303A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61173596A (en) * | 1985-01-28 | 1986-08-05 | Sony Corp | Pll demodulating circuit |
| JPH0681314B2 (en) * | 1985-01-28 | 1994-10-12 | ソニー株式会社 | PLL demodulation circuit |
| JPH02266707A (en) * | 1989-04-07 | 1990-10-31 | Alps Electric Co Ltd | Fm video signal detection circuit |
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