JPS5648709A - Local oscillating circuit of fm receiver - Google Patents
Local oscillating circuit of fm receiverInfo
- Publication number
- JPS5648709A JPS5648709A JP12379879A JP12379879A JPS5648709A JP S5648709 A JPS5648709 A JP S5648709A JP 12379879 A JP12379879 A JP 12379879A JP 12379879 A JP12379879 A JP 12379879A JP S5648709 A JPS5648709 A JP S5648709A
- Authority
- JP
- Japan
- Prior art keywords
- varicap
- voltage
- control
- capacitor
- coil
- 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
Classifications
-
- 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
Landscapes
- Noise Elimination (AREA)
Abstract
PURPOSE:To improves S/N by preventing the capacitor of a varicap from varying with an AC component of a hum, etc., superposed upon a control DC voltage, by applying the AC component to both terminals of the varicap in phase. CONSTITUTION:Resistance R3, grounded while connected in series to varicap D, has its value set sufficiently large and sufficiently small for the impednace of varicap D and control DC voltage V is all applied to varicap D. Further, capacitor C3 and coil L2 both have low impedance values. Thus, control DC voltage V is applied to varicap D via resistance R2 and coil L2 to vary the capacity. Since capacitor C3 and coil L2 provide low impedance and resistance R3 high impedance, an AC component of a hum superposed upon this voltage is applied across varicap D in phase, and consequently a difference in potential across varicap D disappears, so that varicap D will vary in capacity only with control DC voltage V.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP12379879A JPS5648709A (en) | 1979-09-28 | 1979-09-28 | Local oscillating circuit of fm receiver |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP12379879A JPS5648709A (en) | 1979-09-28 | 1979-09-28 | Local oscillating circuit of fm receiver |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS5648709A true JPS5648709A (en) | 1981-05-02 |
JPS6243573B2 JPS6243573B2 (en) | 1987-09-16 |
Family
ID=14869567
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP12379879A Granted JPS5648709A (en) | 1979-09-28 | 1979-09-28 | Local oscillating circuit of fm receiver |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS5648709A (en) |
-
1979
- 1979-09-28 JP JP12379879A patent/JPS5648709A/en active Granted
Also Published As
Publication number | Publication date |
---|---|
JPS6243573B2 (en) | 1987-09-16 |
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