| 摘要 |
<p>PURPOSE:To increase the operational tolerance of a memory cell to operate it with a low voltage by reducing the threshold voltage of a switching transistor TR relatively lower than that of a drive TR. CONSTITUTION:Constitution elements are equal to conventional those. N-channel enhancement TRs Tr1 to Tr4 have the same threshold voltage in the conventional device. When the threshold voltage of switching TRs Tr3 and Tr4 is set to a value lower than conventional, the high level for memory cell write is higher than conventional, and the width of a static noise margin SNM is extended to increase the operational tolerance. Or when the threshold voltage of drive TRs Tr1 and Tr2 is raised to relatively reduce the threshold voltage of TRs Tr3 and Tr4, an input voltage is raised, and as the result, the width of the SNM is extended in the same manner as reduction of the threshold of TRs Tr3 and Tr4 to increase the operational tolerance of the memory cell.</p> |
