| 摘要 |
PURPOSE:To prevent a frequency alteration caused by a temperature by inserting a capacitor having a negative temperature coefficient between an oscillation coil and a variable capacity diode. CONSTITUTION:The capacitor 7 for compensating temperature is connected between the (b) terminal of the variable capacity diode 9 and the oscillation coil 5 and also a resistor 8 is connected between the (b) terminal and an earth. Generally speaking, the variable capacity diode 9 has a positive temperature coefficient, which is large when a bias voltage is small. Therefore, the frequency alteration by the temperature becomes large when the electrostatic capacity of the variable capacity diode 9 is large. In this case, the capacitor 7 for compensating temperature has the negative temperature coefficient and the effect of the capacitor 7 for compensating temperature is large by means of the electrostatic capacity ratio when the electrostatic capacity of the variable capacity diode 9 is large, then the effect of the capacitor 7 for compensating temperature becomes small when the electrostatic capacity of the variable capacity diode 9 is small, so that the frequency alteration by the temperature can be prevented keeping a good balance.
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