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Dual mode tuning arrangement

A dual-mode, series-connected device technology, used in discrete pre-tuning circuits for discontinuous tuning, television, electrical characteristic frequency control, etc. The effect of reducing parasitic oscillations

Inactive Publication Date: 2008-11-05
卡莱汉系乐有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Increasing the value of the damping resistor can increase the attenuation of parasitic oscillations, however this solution tends to result in more noise and lower performance of the oscillator
Another problem is that there is a practical upper limit to the value of the damping resistor due to the fact that this resistance also acts as a DC path to ground for the mode switching diode

Method used

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  • Dual mode tuning arrangement
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  • Dual mode tuning arrangement

Examples

Experimental program
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Effect test

Embodiment Construction

[0012] figure 1 The tuning device consists of two inductors L 1 and L 2 constitutes the first series arrangement together with the varactor diode C v and pad capacitor C p1 constitute the second series device. The two series devices are at junction J 1 and J 2 interconnected to form a parallel device. Place the small capacitor C 3 with the varactor diode C v in parallel. Connect the junction J of the two series devices 1 through the coupling capacitor C 1 and positive feedback capacitor C 2 Connect to amplifier A. The amplifier A and the two capacitors C 1 and C 2 constitutes the active part of the device or a current source S that feeds the junction J 1 Provides alternating current. will tune the voltage V t through resistor R 3 applied to the varactor C v and pad capacitor C p1 of junctions. The tuning voltage may eg originate from a frequency synthesizer, which together with the amplifier A is located in a monolithic integrated circuit.

[0013] The mo...

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PUM

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Abstract

In a local oscillator for a tuning arrangement for both TV and FM signals there is substantial risk of parasitic oscillation. A special provision is disclosed for effectively reducing this risk. The special provision is a connection of a damping resistor (R 1 a) for suppressing parsitic oscillations between ground and a junction (J 2 ) of a parallel LC resonator of the local oscillator.

Description

technical field [0001] The invention relates to a dual mode tuning device for tuning to a VHF television signal and for tuning to an FM radio signal, said device having a local oscillator circuit comprising a first and a second inductance A second series arrangement of a series arrangement, a varactor diode and a first pad capacitor, said first and second series arrangement being interconnected at first and second junctions to form a parallel arrangement, the active oscillator element connected at between the first junction of said parallel arrangement and ground, said dual mode tuning arrangement further comprising a third series arrangement of a mode switching diode and a second padding capacitor in parallel with one of said first and second inductors , means for providing a tuning voltage to a junction of the varactor diode and the first pad capacitor and means for providing a mode switching voltage to a junction of the mode switching diode and the second pad capacitor. Th...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H03B5/12H04N5/60H03B1/00H03J7/08H04B1/16H04B1/18H04B1/26
CPCH03B5/1243H03B5/1268H03B1/00H03B2201/025H03B5/1206H03B5/12H03J5/24
Inventor 杨振龙林贵荣
Owner 卡莱汉系乐有限公司