Semiconductor memory device having bit lines widely spaced without sacrifice of narrow pitch of source/drain lines of memory cells

摘要

When a data bit is read out from a semiconductor read only memory device, a current-mirror type sense amplifier is electrically connected through a bit line, a first selector, a selected memory cell and a second selector to a discharging line so as to check a potential drop on the bit line, and each of the first and second selectors selectively connects the bit line or the discharging line to eight columns of memory cells by increasing the component switching transistors thereof so as to space the bit line from the discharging line, thereby increasing a margin for a bit line contact.