Patent ID: 7251149

Claim:
A semiconductor memory device comprising: a write signal line to transmit write data; a write buffer coupled to the write signal line to output the write data; a write column selection switch being possible to transmit said write data on said write signal line to a bit line; a write column selection line supplying an operation control signal to said write column selection switch; a sense amplifier column comprising a plurality of sense amplifier circuits to amplify read data which are read to said bit line from a memory cell; a read signal line to transmit read data, said read signal line being different from said write signal line; a main amplifier coupled only to the read signal line to amplify the read data on the read signal line; a read column selection switch to selectively transmit the read data of said bit line to said read signal line; a read column selection line supplying an operation control signal to said read column selection switch; and a control circuit to control operations of said write column selection switch and read column selection switch in different timings, wherein said write signal line and said read signal line are allocated crossing said sense amplifier column and said write column selection line and said read column selection line are allocated in parallel to said sense amplifier column, the write data is transferred from the write buffer to said bit line via the write signal line, and the read data is transferred from said bit line to said main amplifier via the read signal line, and a period of activating the read column selection switch is shorter than a period of activating the write column selection switch.