| 摘要 |
<p>PURPOSE:To stabilize an access time by arranging a transistor(TR) to which an (m)th bit line is connected at its gate except on the (m)th bit line, connecting the drain to respective bit lines, and connecting the source to a 1st power source. CONSTITUTION:When a word line WL2 is selected and a memory cell 21 on the side of a photogransistor begins to be read, charges are supplied from a sense amplifier 61 to the wiring parasitic capacitance of a bit line BL1 and Mnps (n-channel transistor for by-passing) 41 - 43 which receive a gate input from the bit line BL1 turn on. Thus, the transistors Mnp41 - Mnp43 which receive the gate input from the selected bit line BL1 turn on and residual charges on all bit lines BL2 - BL4 except the bit line BL1 are discharged, so a rise in the source potential of a read memory cell is suppressed and the delay of the access time is prevented. Consequently, the access time of the read-only storage device is stabilized.</p> |
