Patent ID: 7049847

Claim:
A semiconductor device comprising: a tristate buffer circuit comprising, on an output stage, a first transistor for pull-up driving and a second transistor for pull-down driving, in which, when a control signal is of a value indicating an enable state, an output is set to a high level or to a low level, depending on a data signal, and in which, when the control signal is of a value indicating a disable state, said first and second transistors are both turned off to set the output in a high impedance state; a control circuit for performing control to speed up the transition from an on-state to an off-state of said first transistor when said control signal is switched from said enable state to said disable states; a logic circuit for receiving said data signal and said control signal as inputs and outputting a first signal for controlling the on/off state of said first transistor; and a transmission gate comprising a third transistor, said third transistor being turned on when said control signal is of a value indicating the enable state and receiving said first signal output from said logic circuit to transfer said first signal to a control terminal of said first transistor, said third transistor being turned off when said control signal is of the value indicating the disable state, wherein; said control circuit comprises a circuit for receiving said control signal and delaying the timing of changing over the state of said third transistor of said transmission gate from an on-state to an off-state at the time of switching the state of said control signal from the enable state to the disable state; and during the time said third transistor is on, when the state of said control signal is switched from the enable state to the disable state, said transmission gate transfers the level of said first signal output from said logic circuit for turning off said first transistor to a control terminal of said first transistor to speed up the transition from the on-state to the off-state of said first transistor.