| 摘要 |
PURPOSE:To attain inexpensive temperature compensation with simple constitution by providing a diode to a midpoint of a bridge circuit where two thermisters are provided diagonally and applying an output voltage of the bridge circuit to a varactor diode connected to a crystal oscillator element. CONSTITUTION:When room temperature rises, the resistance of the thermisters 11,12 is decreased, a diode 14 is conductive and the resistor 10 and the thermister 12 are connected in parallel. The capacitance of a variable capacitor 5 is reduced to compensate the change in the natural oscillation frequency of the crystal oscillator 2. When the room temperature decreases, the resistance of the thermisters 11, 12 is increased, the diode 14 is nonconductive and only the resistor 10 and the thermister 11 are connected to the variable capacitor 5 via the resistor 15. In this case, since the voltage at the connecting point between the resistor 10 and the thermister 11 is increased, the change in the natural frequency is compensated.
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