| 摘要 |
PURPOSE:To convert a drive current capacitance of an output buffer by control signals by a method wherein a pair of transistors are provided, which are controlled by a buffer switching control signal so as to turn a second CMOS transistor active or not, and a first and a second drive currents are outputted together. CONSTITUTION:An input signal IN is connected with gates of transistor 5, 6, 9, 12, and 13, a buffer switching control signal A outputted from a register 1 is connected with a transistor 10 gate and moreover a transistor 7 gate through the intermediary of an inverter 3. A buffer switching control signal B outputted from the register 1 is connected with a transistor 14 gate and moreover a transistor 11 gate through the intermediary of an inverter 2. Junctures of transistors 5 and 6, transistors 8 and 9, and transistor 12 and 13 are connected with an output terminal 4. The transistors 7-14 are turned on or off by setting data to the control signals A and B, whereby the drive currents of the output buffer are switched.
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