| 摘要 |
PURPOSE:To stably operate a sense amplifier so that it can be strong against a soft error, by providing a clamping circuit on a boosting circuit, and limiting the boosting potential. CONSTITUTION:On a boosting circuit, an MOS field effect transistor Q5 is provided. Q5 operates as a clamping circuit, and when a signal RX is boosted exceeding the sum of threshold voltage Vthm and supply voltage Vcc, Q5 is turned on so as to make the boosted voltage escape to Vcc, therefore, it becomes impossible to be boosted exceeding Vcc+Vthm. However, since the signal RX can be boosted up to a specified value, the bit line potential is varied, and larger read-out voltage than the case when it is not boosted can be obtained. After that, a sense amplifier operates to divide a bit line BL into a high potential side and a GND level side. In case when there is no recharging circuit, the high potential side drops from the Vcc level, therefore, when this value is denoted as VM, threshold voltage of Q5 is set so as to satisfy Vcc+Vthm-VM<Vthm. |
