| 摘要 |
PURPOSE:To obtain a highly stable oscillation frequency immune to temperature fluctuation by generating an internal voltage of a switching element from a circuit obtained by a product between a proportional constant and a thermal voltage and setting a current for frequency setting by a voltage being the subtraction of the interval voltage from a foward voltage drop of a diode at the lower side of a multivibrator. CONSTITUTION:The thermal voltage VT is obtained as a voltage difference between bases of two transistors (TR)Q11, Q12 of an mVT generating circuit 10, and the proportional constant (m) is obtained by applying natural logarithm to a current ratio I1/I2. The current ratio is set by the resistance ratio of resistors R11, R12. The value of the mVT is subtracted from the forward voltage drop of a diode D3 at the lowr side of the multivibrator by using a differential amplifier 20 to cancel the temperature coefficient of clamp diodes D1, D2 and the diode D3, then the oscillated frequency with high temperature stability is obtained.
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