| 摘要 |
PURPOSE: An output buffer of low noise is provided to have improved noise characteristic by differently controlling pull-up/pull-down transistors according to the level of a drive voltage. CONSTITUTION: In case of inputting logic low as an input signal(SAI), a pull-up drive control signal generator(200) outputs a pull-up drive control signal(pch1) of high level through an indefinite logical sum gate(NR1). And, a pull-down drive control signal generator(300) outputs a pull-down drive control signal(nch1) of high level through an indefinite logical product gate(ND1). Thus, an NMOS transistor(MN2) is turned on for outputting an output signal(DOUT_A1) of low level. Herein, the voltage of the pull-down drive control signal is maintained for a certain voltage regardless of a supply voltage. Therefore, an instantaneous current applied to the NMOS transistor is reduced for repressing the generation of noise.
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