US Patent 7161865 Semiconductor device

A high-density DDR-1/DDR-2 compatible SDRAM chip with a reduced output circuit area is provided. When the SDRAM is a DDR1 SDRAM, an output signal output from an output circuit (14) is output to an output terminal (17) as a main output signal. When the SDRAM is a DDR2 SDRAM, an output signal output from an output circuit (15) is output to the output terminal (17) as the main output signal and, at the same time, the output signal output from the output circuit (14) is output as a sub-output signal to perform operation for adjusting the slew rate or the amount of output current of the main output signal or for adjusting the impedance of the output terminal as viewed from an external point.