| 摘要 |
PURPOSE:To reduce mutual interference disturbance by constituting the titled tuner of an active element ensuring isolation between the input and output, selecting the 1st and 2nd local oscillation signals from the output, and inputting the signal to the 3rd mixing circuit. CONSTITUTION:The 1st and 2nd local oscillation signals are obtained respectively from the output of the 1st mixing circuit 3 and the 2nd mixing circuit 7 to connect the 3rd mixing circuit 22 to the 1st local oscillating signal 4 and the 2nd local oscillating signal 8 via the 1st mixing circuit 3 and the 2nd mixing circuit 7. The active element such as a transistor (TR) is used for the 1st mixing circuit 3 and the 2nd mixing circuit 7 to use the mixing circuit having a large isolation (having large loss in the reverse transmission from the output to the input) between the input and output. Thus, the effect of the 3rd mixing circuit on the 1st and 2nd local oscillation signals is reduced, the 1st and 2nd local oscillation signals leaked to the 1st and 2nd mixing circuit via the 3rd mixing circuit is suppressed to reduce mutual interference disturbance.
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