| 摘要 |
PURPOSE:To derease the number of elements and at the same time reduce the power consumption, by deciding the constant voltage output by the difference between two levels of threshold boltage plus the voltage dividing ratio caused by the resistance. CONSTITUTION:The levels of threshold voltage are different between a P-MOSFET 51 and a P-MOSFET52 that constitute a voltage comparator, and the output voltage of an output driving n-MOSFET55 which is controlled by the output of the above- mentioned comparator is directly applied to the gates. Otherwise, the voltage divided by resistances 56 and 57 is applied to those gates. FETs 53 and 54 constitute a current Miller circuit and thus work so as to ensure a coincidence between the currents I1 and I2. The output voltage Vout becomes equal to (Vtph-Vtpl)/(1-r), where (r) is the voltage dividing ratio and Vtph and Vtpl (Vtph>Vtpl) are the threshold voltage of the FETs 51 and 52, respectively. |
