| 摘要 |
PURPOSE:To set a continuous output voltage and to obtain a stable output voltage by using at least two resistance means to divide the voltage between an output terminal and a reference potential and using this divided voltage to control a pull-down means for the output voltage. CONSTITUTION:The impedance of resistance R2 and R3 are set at levels much higher than the impedance set in the conduction mode of an FET-T3. Thus the potential VB1 is defined at a point B1 as VB1=VA-VTHT3, where VA and VTHT3 show the voltage and the threshold voltage at a point A respectively. While the potential VC is shown at a point C as VC=VB1.{R2/(R2+R3)}. Here VC=VTHT2+alpha is also satisfied, where alpha and VTHT2 show the value showing the conduction degree of FET-T2 and the threshold voltage respectively. Under such conditions, VA=VTHT3+[1+{(R2/R3)}.(VTHT2+alpha)] is satisfied. Therefore the output voltage VA depends on R2/R3, and the resistance value can be changed by the geometric form of an element. Thus it is possible to change continuously the set level of the voltage VA without complicating the manufactur ing process.
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