CN1164795A - 电视调谐器输入电路 - Google Patents

电视调谐器输入电路 Download PDF

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Publication number
CN1164795A
CN1164795A CN97104102A CN97104102A CN1164795A CN 1164795 A CN1164795 A CN 1164795A CN 97104102 A CN97104102 A CN 97104102A CN 97104102 A CN97104102 A CN 97104102A CN 1164795 A CN1164795 A CN 1164795A
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frequency
inductance
mirror image
variable capacitance
input circuit
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CN97104102A
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国岛努
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Alps Alpine Co Ltd
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Alps Electric Co Ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
    • H04N5/50—Tuning indicators; Automatic tuning control
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/06—Receivers
    • H04B1/16—Circuits
    • H04B1/26—Circuits for superheterodyne receivers
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/01—Frequency selective two-port networks
    • H03H7/12—Bandpass or bandstop filters with adjustable bandwidth and fixed centre frequency
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/01—Frequency selective two-port networks
    • H03H7/17—Structural details of sub-circuits of frequency selective networks
    • H03H7/1708—Comprising bridging elements, i.e. elements in a series path without own reference to ground and spanning branching nodes of another series path
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/01—Frequency selective two-port networks
    • H03H7/17—Structural details of sub-circuits of frequency selective networks
    • H03H7/1741—Comprising typical LC combinations, irrespective of presence and location of additional resistors
    • H03H7/175—Series LC in series path
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/01—Frequency selective two-port networks
    • H03H7/17—Structural details of sub-circuits of frequency selective networks
    • H03H7/1741—Comprising typical LC combinations, irrespective of presence and location of additional resistors
    • H03H7/1758—Series LC in shunt or branch path
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
    • H03J3/00—Continuous tuning
    • H03J3/02—Details
    • H03J3/16—Tuning without displacement of reactive element, e.g. by varying permeability
    • H03J3/18—Tuning without displacement of reactive element, e.g. by varying permeability by discharge tube or semiconductor device simulating variable reactance
    • H03J3/185—Tuning without displacement of reactive element, e.g. by varying permeability by discharge tube or semiconductor device simulating variable reactance with varactors, i.e. voltage variable reactive diodes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/06—Receivers
    • H04B1/16—Circuits
    • H04B1/18—Input circuits, e.g. for coupling to an antenna or a transmission line

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Multimedia (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
  • Channel Selection Circuits, Automatic Tuning Circuits (AREA)
  • Noise Elimination (AREA)

Abstract

电视调谐器输入电路包括镜像截获电路，该镜像截获电路由含有镜像截获电容和第二变容二极管的串联电路与含有调谐电感和第一变容二极管的串联电路相互并联而构成。调谐公共电压施加于第一和第二变容二极管以改变其电容量，从而改变谐振频率和镜像截获频率。

Description

电视调谐器输入电路
本发明涉及电视调谐器输入电路，其中包括用以消除镜像频率的镜像截获电路，该镜像频率作为目标谐振频率的干扰波。
一般地，根据电视调谐器等装置，通过将所需接收频率与比其高某个中频的本振频率相混频，可以得到该中频。当输入的接收频率(镜像频率)比本振频率高某个中频时，将产生图像干扰。
图3给出了常规电视调谐器的基本输入电路1。利用VHF波段选择滤波器(IF滤波器)3从天线2接收的信号中提取VHF波段(40至470MHz)并通过耦合电容C1和输入电路1将其施加于高频放大器4。在输入电路1中，电感L1和L2的端头与耦合电容C1相接，而电感L1的另一个端头通过电容C2接地。电感L2的另一个端头经由变容二极管VD1接地，同时通过变容二极管VD2与高频放大器4相接。电感L2与变容二极管VD2相连后，其两端与电容C3相并联连接。
VHF波段(40至470MHz)中，最低频率与最高频率的比率很大。因此，根据所需谐振频率处于高频道波段或处于低频道波段，通过控制电感L1和L2的电感量，使其在接收高频时小而接收低频时大，就可以在整个波段内实现调谐。
另外，通过控制变容二极管VD1和VD2的电容量，使其在接收高频时小而接收低频时大，则可以在所需频率上实现阻抗匹配。如图4所示，将电容C3与电感L2和变容二极管VD2的串联电路相并联，就构成了镜像截获电路，该电路用以截获作为所需谐振频率干扰波的镜像频率。
然而，根据常规输入电路1，电容C3与电感L2和变容二极管VD2的串联电路相并联以便构成镜像截获电路。但是，这种布局使得电容C3的电容量非常难以控制，从而会产生不利的图像干扰。换句话说，有以下两点：
1)通过增加电容C3的电容量可以扩展镜像截获频率的可变范围，但该可变范围不能扩展至高频。因为在接收高频时电感L1和L2调谐而具有小电感量，电容C3与具有小电感量的电感L2并联相接，而目标镜像截获频率比接收谐振频率高两个中频。因此，在这些条件下，为了与目标镜像截获频率相调谐，必须减小电容C3的电容量。
2)然而，减小电容C3的电容量将使镜像截获频率的可变范围变窄，这使得难于将镜像截获频率调谐于目标镜像频率。
因此，本发明的目的在于提供一种电视调谐器输入电路，其中可扩展镜像截获频率的可变范围，且该镜像截获频率可方便地调谐于目标镜像频率。
根据本发明，上述目的通过提供一种电视调谐器输入电路而实现，其中包含镜像截获电容和第二变容二极管的串联电路与包含调谐电感和第一变容二极管的串联电路相并联，且调谐公共电压施加于第一和第二变容二极管以改变它们的电容量，从而使谐振频率和镜像截获频率发生变化。
根据该电视调谐器输入电路，甚至当镜像截获电容的电容量相对增加时，该电容与变容二极管的组合电容量可在接收高频时得到减小。因此，镜像截获频率的可变范围得到扩展，且该镜像截获频率可方便地调谐于目标镜像频率。
如上所述，根据本发明，通过将附加变容二极管与镜像截获电容相连，可以按照接收频率改变该变容二极管的电容量。因此，甚至当该电容的电容量相对增加时，该电容与变容二极管的组合电容量可在接收高频时得到减小，从而可扩展镜像截获频率的可变范围，且该镜像截获频率可调谐于目标镜像频率。
以下将参考附图说明本发明的一种方案。
图1的电路图描述了根据本发明一种方案的电视调谐器输入电路；
图2描述了图1所示的镜像截获电路；
图3的电路图描述了常规电视调谐器输入电路的基本模式；
图4的电路图描述了图3中所示的镜像截获电路。
其中与常规实例相同的元件以同样的参考数字进行标注。
如图1所示，利用VHF波段选择滤波器3提取天线2所接收信号中的VHF波段(40至470MHz)，并通过输入电路1a和耦合电容5将其施加于高频放大电路4。在输入电路1a的输入端23与输出端24之间接有电感6、7、8、电容9、电感10和变容二极管28，同时在该输入端与输出端之间还接有镜像截获电容11和变容二极管29。
电感6和7的连接点同时通过二极管13和电感16与电阻20、22和电容21的端头相连。电阻22的另一端与VHF低波段选择端27相接。电阻20和电容21的另一端接地。电感7和8的连接点同时与电感12的一端相连，电感12的另一端通过电容18接地并通过电阻31与VHF高波段选择端26相接。
另外，电感8和电容9的连接点同时通过二极管14与二极管13和电感16的接点相连。经由调谐电压源端25提供的反向电压通过电阻19施加于变容二极管15和28，并通过电阻30施加于变容二极管29。
此时，电压选择性地施加于VHF低波段选择端27和VHF高波段选择端26。换句话说，当接收VHF低波段信号时，电压选择性地施加于VHF低波段选择端27，从而二极管13和14关断。当接收VHF高波段信号时，电压选择性地施加于VHF高波段选择端26，从而二极管13和14接通。
图2的等效电路图描述了从图1所示输入电路1a中抽出的镜像截获电路。在图2中，图1所示的电容9被短路，因为它具有大电容量且用于防止直流流通。另外，VD1表示组合可变电容，它由变容二极管29与电容11串联组合而成，而L为组合电感，其电感量可以由二极管13和14所改变。
当二极管13和14关断时，组合电感L由电感6、7、8和10串联而组成。当二极管13和14接通时，组合电感L由电感7与8短路及电感6与10并联而构成。换句话说，当接收VHF低波段信号时镜像截获电路的电感量变大，而当接收VHF高波段信号时该电感量变小。
另外，组合可变电容VD1的电容量通过改变施加于调谐电压源端25的反向电压以及变容二极管15和18的电容量而改变。当接收高频道信号时组合可变电容VD1的电容量变小，而当接收低频道信号时该电容量变大。
因此，当接收VHF波段信号时，可通过波段开关使组合电感L的电感量改变两种状态。同样，组合可变电容VD1的电容量在相同的波段内也可通过频道选择而进行改变，从而，镜像截获频率可根据接收频道的变化而改变。
因而，镜像截获频率可在最低频率与最高频率之间的范围内根据谐振频率而同时改变。这样，镜像截获频率的可变范围得到扩展，且该镜像截获频率可方便地调谐于目标镜像频率。

Claims (1)

1.电视调谐器输入电路，其中包含镜像截获电容和第二变容二极管的串联电路与包含调谐电感和第一变容二极管的串联电路相互并联，且调谐公共电压施加于该第一和第二变容二极管以改变其电容量，从而改变谐振频率和镜像截获频率。
CN97104102A 1996-04-17 1997-04-17 电视调谐器输入电路 Pending CN1164795A (zh)

Applications Claiming Priority (2)

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JP095487/96 1996-04-17
JP8095487A JPH09284157A (ja) 1996-04-17 1996-04-17 テレビジョンチューナの入力回路

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JP (1) JPH09284157A (zh)
KR (1) KR100243838B1 (zh)
CN (1) CN1164795A (zh)
DE (1) DE19715956C2 (zh)
GB (1) GB2312345A (zh)
MX (1) MX9702782A (zh)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1320773C (zh) * 2002-10-31 2007-06-06 松下电器产业株式会社 高频接收装置
CN1320750C (zh) * 2002-02-01 2007-06-06 皇家飞利浦电子股份有限公司 电视调谐器及其中所用的印制电路板
CN100353663C (zh) * 2003-02-27 2007-12-05 阿尔卑斯电气株式会社 电视调谐器的输入电路
CN101179677B (zh) * 2006-11-08 2011-12-14 奇景光电股份有限公司 电视调谐器与其制造方法

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3592160B2 (ja) 1999-11-25 2004-11-24 アルプス電気株式会社 チューナの複同調回路
JP3097064U (ja) * 2003-04-09 2004-01-15 アルプス電気株式会社 入力同調回路
DE10330449B3 (de) * 2003-07-05 2005-02-24 Daimlerchrysler Ag Nockenwellenversteller
EP1889360A1 (en) 2005-06-09 2008-02-20 TELEFONAKTIEBOLAGET LM ERICSSON (publ) A tunable circuit arrangement and a method for providing such an arrangement

Family Cites Families (5)

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Publication number Priority date Publication date Assignee Title
JPS6352510A (ja) * 1986-08-22 1988-03-05 Toshiba Corp 電子同調チユ−ナ
US4835608A (en) * 1988-05-31 1989-05-30 Zenith Electronics Corporation Image trap filter circuit
JPH0352323A (ja) * 1989-07-19 1991-03-06 Matsushita Electric Ind Co Ltd 電子チューナ
US5054117A (en) * 1989-08-01 1991-10-01 Zenith Electronics Corporation Tunable UHF filter for switchable VHF/UHF receiver
JP3053150B2 (ja) * 1993-02-26 2000-06-19 アルプス電気株式会社 Ｔｖチューナの入力同調回路

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1320750C (zh) * 2002-02-01 2007-06-06 皇家飞利浦电子股份有限公司 电视调谐器及其中所用的印制电路板
CN1320773C (zh) * 2002-10-31 2007-06-06 松下电器产业株式会社 高频接收装置
CN100353663C (zh) * 2003-02-27 2007-12-05 阿尔卑斯电气株式会社 电视调谐器的输入电路
CN101179677B (zh) * 2006-11-08 2011-12-14 奇景光电股份有限公司 电视调谐器与其制造方法

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GB9707390D0 (en) 1997-05-28
MX9702782A (es) 1998-04-30
KR100243838B1 (ko) 2000-02-01
DE19715956C2 (de) 2003-08-14
KR970073038A (ko) 1997-11-07
GB2312345A (en) 1997-10-22
JPH09284157A (ja) 1997-10-31
DE19715956A1 (de) 1997-11-06

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