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UHF tuning circuit utilizing a varactor diode

  • US 4,048,598 A
  • Filed: 05/28/1976
  • Issued: 09/13/1977
  • Est. Priority Date: 05/28/1976
  • Status: Expired due to Term
First Claim
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1. In a UHF tuner, the apparatus comprising:

  • a tuned circuit including a varactor diode;

    a field effect transistor having a plurality of electrodes including a gate electrode;

    an impedance transformation means coupled between said tuned circuit and said gate electrode of said field effect transistor, said impedance transformation means including capacitance means coupled in series between said tuned circuit and said gate electrode and inductance means coupled in shunt with said gate electrode, said capacitance means and said inductance means being selected to provide a resonant frequency below the lowest channel frequency in the UHF range so that the impedance coupled to said gate electrode is approximately matched with the impedance of said field effect transistor at said gate electrode at the low end of the UHF range and the power gain of said apparatus at the low end of said UHF range is approximately equal to the power gain of said apparatus at the high end of said UHF range.

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