| 摘要 |
PURPOSE:To obtain a stable output voltage against variation in element characteristics by utilizing a voltage sum of threshold voltages of a couple of a P- channel MOSFET and an N-channel MOSFET whose gates and drains are used in common so as to form a unit reference voltage. CONSTITUTION:Since a couple of P-channel MOSFET and an N-channel MOSFET are used, a sum voltage of threshold voltages Tthp and Vthn is obtained between both sources, after the MOSFETs are brough into on-state. Thus, a current does not flow before a power supply voltage Vcc is 2(Vthp+Vthn), and the current does not flow at a voltage below the said voltage. The variation of the threshold voltages Vthp and Vthn of the P-channel MOSFET and the N- channel MOSFET due to fluctuation of the density of a well region and ion implantation amount produced in the process of CMOS integrated circuits appears so as to be cancelled to each other. Thus, the sum of the voltages (Vthp+Vthn) of both threshold voltages is made nearly constant against process variation. |
