发明授权
US06933984B2 Television tuner which maintains UHF band tuning circuit bandwidth constant in low to high band range 失效
电视调谐器,保持UHF频段调谐电路带宽在低到高频带范围内恒定

Television tuner which maintains UHF band tuning circuit bandwidth constant in low to high band range
摘要:
A tuning circuit's bandwidth is maintained almost constant throughout a UHF low to high band range so as to prevent interference by a neighboring channel, particularly in receiving high band television signals, and also to improve NF in receiving low band television signals, eliminating a difference in NF between channels. To realize this, a UHF tuner comprises: a UHF tuning circuit which has a varactor diode first and second inductance elements serially interconnected and connected in parallel with the varactor diode, where the varactor diode 11a varies a tuning frequency within a prescribed frequency range in the UHF band; and impedance means which is serially inserted between an input terminal and the junction of the two inductance elements, where the impedance by the impedance means increases as a frequency increases within the prescribed frequency range in the UHF band.
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