| 摘要 |
<p>PURPOSE:To prevent an oscillation frequency from varying owing to variation in power voltage, by controlling the supply voltage of a bias supplying circuit connected to the input side of the positive feedback path of an operational amplifier so that it is equal to the saturation voltage of the operational amplifier. CONSTITUTION:To the negative feedback path of an operational amplifier 1, a time constant circuit consisting of a capacitor C and a resistance R4 is connected to the input side of the opsitive feedback path, a bias obtained by dividing a power voltage VCC through resistances R1 and R2 is applied while an output VO is fed back via a resistance R3. Then, a voltage control element 2 is connected between the resistances R1 and R2, and power source VCC, and consequently the power voltage is so controlled that the supply voltage of a bias supply circuit will be equal to the saturation output voltage VO of the operational amplifier 1. Namely, the power voltage VCC is lowered by a voltage DELTAV nearly equal to the difference between the saturation output voltage VO and power voltage VCC, and the voltage drop is used as the supply voltage of the bias supply circuit.</p> |
