| 摘要 |
<p>PURPOSE:To apply exactly a reset even if a variation of a power supply voltage is generated slowly, by setting each characteristic so that a transistor characteris tic of an RAM cell and a transistor characteristic for inverting it forcibly cross each other at a detected voltage point. CONSTITUTION:A source of a transistor 2 is not connected directly to VSS, but connected through a constant-voltage element 7. This constant-voltage ele ment 7 always generates a constant voltage VB, and always supplies a voltage of VSS+VB to the source of the transistor 2. The source of the N channel transistor 2 always becomes a form to which a bias is applied by VB, therefore, an operation characteristic on a circuit becomes a curve C' which is shifted to the right by VB. The circuit is operated so that if VGS corresponding to the power supply voltage is larger than a voltage V3 (detected voltage) of an intersection point of a curve jA and the curve C', a reset signal becomes 'H', and if said voltage is smaller, the reset signal becomes 'L'. In this way, an extremely stable operation can be executed, comparing with the case a character istic which does not have such an intersection point as the curve A and a curve C is utilized.</p> |
