| 摘要 |
PROBLEM TO BE SOLVED: To reduce an effect due to the temperature characteristics of a ceramic filter in an intermediate frequency circuit in a superheterodyne receiver. SOLUTION: At the output end of a mixer circuit 13, an intermediate frequency transformer 41 to which a primary coil is connected, and a capacitor C41 for resonance connected to the primary coil of the intermediate frequency transformer 41 are provided. A ceramic filter 42 connected to a secondary coil of the intermediate frequency transformer 41, and an amplifier 43 for amplifying the output signal of the ceramic filter 42 are provided. The center frequency of the total group delay characteristics of the intermediate frequency transformer 41 and the ceramic filter 42 at a normal temperature is set to an intermediate frequency. The temperature characteristics of the capacitor C41 are set so that the temperature change in the intermediate frequency in the group delay characteristics of the ceramic filter 42 is canceled by the temperature characteristics of the capacitor C41.
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