| 摘要 |
PURPOSE:To facilitate the decision of reading and to miniaturize a chip size by setting the potential of a word line during a read action to a low voltage corresponding to a comparatively highly-set threshold voltage of a memory element with the aid of the write action. CONSTITUTION:A voltage clamp circuit is constructed with switch MOSFETs Q18 and Q19 whose one ends are connected to word lines W1 and W2 and Zener Diodes ZD1 and ZD2 whose ends are connected to the word lines W1 and W2. A read signal we is made at a high level, the MOSFETs Q18 and Q19 are made in an on state, and the Zener diodes ZD1 and Zd2 are connected to the word lines W1 and W2. Accordingly, when an address decoder XDCR transmits a signal to one word line at a selection level of about 5V, the Zener diode ZD causes a transistor to be clamped at a low voltage such as about 3.5V, that is, a threshold voltage. The FAMOS transistor having a high threshold voltage in such a way can flow only a fine current, thereby facilitating decision. |
