Semiconductor memory device having the operating voltage of the memory cell controlled

摘要

An SRAM circuit operates at a reduced operation margin, especially at a low operating voltage by increasing or optimizing the operation margin of the SRAM circuit. The threshold voltage of the produced transistor in the SRAM circuit is detected to compare the operating voltage of a memory cell with the operating voltage of a peripheral circuit in order to adjust it to the optimum value, and the substrate bias voltage is further controlled.