| 摘要 |
The temperature of an oscillation circuit (47) is detected by a temperature detection circuit (13), a cubic term voltage generation circuit of a control voltage generation circuit (23) generates a cubic term voltage as a control voltage based on an output voltage of the temperature detection circuit (13), and a frequency adjustment circuit (45) changes an oscillation frequency of the oscillation circuit (47) by the control voltage. The cubic term voltage generation circuit includes a first MOS transistor (37) having a source connected to a first power line (25), a second MOS transistor (35) having a source connected to a second power line (26), and digital control voltage division circuits (31, 33) for generating a first and a second gate voltage, respectively based on the output voltage of the temperature detection circuit (13), in which the first and second gate voltages are applied to gates of the first and second MOS transistors (37, 35) respectively, and a connection point (44) where respective drains are commonly connected shall be an output terminal of the control voltage. |
