| 摘要 |
PURPOSE: A data output buffer circuit is provided which controls the threshold voltages of transistors according to input/output data to improve data output characteristic and blocks noise when a negative level data is input to perform a stable operation. CONSTITUTION: A data output buffer circuit is constructed in such a manner that an output signal of an inverter(IN11) to which an input signal(V1) is applied is supplied to the gate of a pull-up transistor(N1) and the drain of a clamp transistor(N3) whose gate is grounded, an output signal of an inverter(IN12) to which an input signal(V2) is applied is supplied to the gate of a pull-down transistor(N2), the sources of the pull-up transistor and the clamp transistor and the drain of the pull-down transistor are connected in common to generate an output signal(DQ) at the connection node, to thereby output data by pull-up and pull-down operations according to the input signals. The circuit further has a threshold voltage controller. The threshold voltage controller decreases the threshold voltages of the pull-up and pull-down transistors but increases the threshold voltage of the clamp transistor is increased when data is output using a read signal(RD) as an input signal. In addition, the threshold voltage controller increases the threshold voltages of the pull-up and pull-down transistors but decreases the threshold voltage of the clamp transistor is increased when data is input.
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