| 摘要 |
PURPOSE: An output buffer circuit of a semiconductor memory device is provided to reduce a ground noise by separating a pull-down transistor from a ground and simultaneously driving the pull-down transistor sequentially. CONSTITUTION: The circuit is composed of a number of output buffers(OB1-OB16), and each output buffer which includes a number of buffer groups(GR1-GR4) with a pull-up transistor and a pull-down transistor connected between a power supply voltage and a ground, a plurality of NMOS transistors(NME11-NME14) which are connected between a ground voltage and a source of the pull-down transistor so that the pull-down transistor of the output buffer of each buffer group is separated from the ground voltage, and drive the output buffer groups sequentially by connecting the pull-down transistor with the ground voltage by a control signal applied to a gate; and a control signal generation part(20) comprising a number of control signal generation units(21-24) generating a number of control signals to each gate, so that the plurality of NMOS transistors drive the buffer groups sequentially by receiving an output enable signal from the external.
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