Tuners – Tuner unit directly responsive to voltage and/or current... – Reactance tuning
Patent
1976-05-28
1977-09-13
Gensler, Paul L.
Tuners
Tuner unit directly responsive to voltage and/or current...
Reactance tuning
325318, 333 32, H03J 318, H03J 324, H03H 738
Patent
active
040485986
ABSTRACT:
In the UHF tuning portion of a television receiver, a varactor tuned circuit is coupled to the gate electrode of a field effect transistor (FET) through an impedance transformation network comprising a series connected capacitor and shunt connected inductor. In order to increase the signal power transferred between the tuned circuit and the FET at the lower end of the UHF range, the values of the capacitor and inductor are selected so that the relatively low value of equivalent parallel impedance exhibited by the tuned circuit at the lower end of the UHF range is impedance transformed to a value approximately equal to the value of the impedance exhibited at the gate of the FET. A second impedance transformation network, similar to the first, is coupled between the drain of the FET and a second varactor tuned circuit to further increase the signal power transferred between the FET and the second tuned circuit at the lower end of the UHF band. The values of the capacitor and inductor comprising the impedance transformation networks are also selected so that the signal power gain of the UHF tuning portion at the upper end of the UHF range is not substantially degraded. Because of the impedance transformation networks, resonant points below the lowest frequency in the UHF band are established.
REFERENCES:
patent: 3570005 (1971-03-01), Prolss
patent: 3693096 (1972-09-01), Dosey et al.
Johnson, Multiband L Matching Network, QST, vol. 39, No. 12, Dec. 1955, pp. 45-47.
Emanuel Peter M.
Gensler Paul L.
RCA Corporation
Schaefer Kenneth R.
Whitacre Eugene M.
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