| 摘要 |
A high frequency signal selected via a pre-filter is inputted to first and second frequency conversion circuits together with a local oscillation signal. The first and second frequency conversion circuits each output a difference frequency component between both input signals. An output signal of the first frequency conversion circuit is inputted to an intermediate frequency filter while an output of the intermediate frequency filter is inputted to an amplifier. An output signal of the first frequency conversion circuit is inputted to an amplifier. The amplifier selects and amplifies any one of an intermediate frequency signal outputted from the intermediate frequency signal and an output signal of the second frequency conversion circuit, and thereafter, output it.
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