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AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsHiroshi Onishi, Sadahiko Yamashita
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In a double superheterodyne tuner for receiving TV channel signals, a frequency in a range defined between 2520 and 2700 MHz is selected as the first intermediate frequency, while the first intermediate frequency is obtained by subtracting a desired channel frequency from a first local oscillator frequency. The tuner comprises first and second mixing circuits respectively used for effecting frequency conversion, where each of these mixing circuits has parallel coupled lines so that each mixing circuit operates as a balance-to-unbalance transformer. The second mixing circuit further comprises a short-circuit line placed between the parallel coupled lines. The tuner also comprises a band pass filter having a band width less than 5 MHz, which selectively transmits the first intermediate frequency signal from the first mixing circuit.
A VHF-UHF all-band tuner of the double superheterodyne type including a first mixing circuit for converting an incoming signal frequency into a first intermediate frequency by mixing said incoming signal with a first local oscillator signal whose frequency is variable, a filter circuit for selectively receiving said first intermediate frequency signal, and a second mixing circuit responsive to the output signal of said filter circuit and to a second local oscillator signal whose frequency is fixed, for converting said first intermediate frequency into a second intermediate frequency;
A VHF-UHF all-band tuner comprising:
A VHF-UHF all-band tuner comprising:
A microwave mixing circuit comprising:
Dependencies are inferred from the claim text.