| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem, in a crystal oscillation circuit in which a feedback resistor having a high resistance is connected between an input and an output of an amplifier that, since a DC bias is set to 1/2 the power supply voltage, the power supply voltage needs a threshold voltage of at least some two times that of an MOSFFT constituting the amplifier, causing limitation in lowering the power voltage, and further, when increasing an amplification ratio by increasing the power supply voltage at starting of oscillation, the power supply voltage fluctuates when making the power supply voltage drop at the time of constant oscillation, this fluctuation causes drawbacks, such as oscillation stoppage or unstable oscillations. SOLUTION: A DC bias of an amplifier 20 is biased by a constant current by a reference current source 51, without depending on a power supply voltage, thereby lowering the power supply voltage of a oscillation circuit. Further, since the oscillation circuit operates in the expotential function region of a MOSFFT, only the bias current of the amplifier is increased at starting of the oscillations. Thus, changes in the power supply voltage can be prevented, and oscillation with low power and stability can be obtained.
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