| 摘要 |
PROBLEM TO BE SOLVED: To provide an electronic tuning circuit in which third intermodulation distortion is suppressed. SOLUTION: A coil L1 and a first capacitor C1 constitute a parallel circuit, and the capacitor C1 is connected in parallel with a series circuit of a second capacitor C2 and a variable capacitance diode D1. The variable range of a control voltage VT and variable range of the capacitance of the variable capacitance diode D1 are specified and the capacitance of the capacitor C2 is determined in a range of 2-4 times the maximum capacitance of the variable capacitance diode D1 within the variable range thereof. The capacitance of the capacitor C1 and inductance of the coil L1 are determined based on the variable range of resultant capacitance of a series circuit of the capacitor C2 and the variable capacitance diode D1 and the frequency of a signal to be received by a tuning circuit.
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