| 摘要 |
<p>PROBLEM TO BE SOLVED: To achieve decrease of power consumption by shortening the cycles of a ring oscillator during the period before reaching a step-up voltage and letting the ring oscillator operate fast, and controlling so as to lengthen the ring oscillator cycle after the voltage has been stepped up. SOLUTION: This semiconductor memory device is comprised of a ring oscillator 1 which generates a step-up potential and operates by shortening the cycles during the period before reaching the step-up voltage and lengthening the cycles after the potential has been stepped up, and a step-up circuit 2 which steps up a word line of a memory cell 3 based on the step-up potential outputted from the ring oscillator 1. The ring oscillator 1 reduces an AC current flowing through the ring oscillator 1 itself by stepping up a word line potential of a memory cell 3 plural times before the potential reaches a potential level VBB necessary for writing the memory cell, and stepping up the word line potential with a high speed by quickening the cycles of the ring oscillator output ROC during the plural step-up times, and lengthens the cycles of the ring oscillator after the potential has reached the step-up level BB.</p> |
