| 摘要 |
PURPOSE: An electronic tuner is provided to reduce the degradation of its electrical characteristics caused by the rise of temperature despite of its simple circuit configuration. CONSTITUTION: The double conversion type electronic turner(1) has an IF signal amplifier circuit(5) that includes a field effect transistor(T51). The circuit(5) amplifies the first intermediate frequency signal(IF1) with prescribed gain and inputs the resultant signal to a down converter(7) via a BPF(6). A temperature compensating part(11) consists of a series circuit including an NTC thermistor(TH1) that is placed between both amplifier circuit(5, 6) and a coupling capacitor(C61) of the BRP(6). When the temperature changes, the degree of coupling of both circuits(5, 6) changes and the gain variation caused by the temperature change is compensated. At the same time, the characteristics of a capacitor(C62) constituting a parallel resonance circuit are also changed by the temperature change and accordingly the matching loss is reduced.
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