Ground loop injection VHF tuner
OwnerHoward S. Teller, Jr.inventor
Life of this patent
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Abstract
A VHF tuner circuit comprising an oscillator for generating a harmonic which is close to the RF frequency, including resonant circuit means for providing a low impedance path for coupling the desired harmonic current to the mixer and for providing a high impedance path for all the other harmonics, thereby suppressing the reception of spurious signals.
Claims6
An improved circuit for providing a predetermined harmonic injection current derived from an oscillator frequency signal to an RF frequency mixer and for suppressing all other harmonics, wherein said mixer receives said predetermined harmonic and an RF signal as outputs of a tuned circuit including an inductance and capacitance, said improved circuit comprising an oscillator providing a harmonic-rich signal current including a predetermined harmonic for injecting into said mixer, which predetermined harmonic is relatively close in frequency to the input RF frequency, and a first capacitor and a portion of the inductance of said tuned circuit connected as a series circuit coupled to said oscillator and having a low series impedance for the predetermined harmonic injection current and a high series impedance to other harmonics.
Dependencies are inferred from the claim text.