| 摘要 |
PURPOSE:To compensate variation stably by altering the variation width of oscillation frequency due to power source variation and load current variation according to the oscillation frequency region by a variation compensating means. CONSTITUTION:Variation width by the variation signal of oscillation frequency at a time when switches SW1, SW3 are turned OFF and a switch SW2 is turned ON is represented by fD. Consequently, the variation width fF of oscillation frequency at a time when the switches SW1, SW3 are turned ON and the switch SW2 is turned OFF is made larger than that fD in the relationship of a resistor R0 and current mirror circuits 5, 6. A regulation in oscillation frequency fD can be controlled in dependent of an output regulation in fF by properly setting resistors R1, R2. That is, the change width of oscillation frequency to a variation signal is changed over by a frequency region by altering the resistance value of the resistor R0 according to the frequency region. Accordingly, variation can be compensated stably. |
