| 摘要 |
In a preferred embodiment of the present invention, a bidirectional buffer connects a first device, such as a CMOS chip having a first voltage, such as VCC, to a second device having a second voltage, such as VDD, through a terminal pad. The buffer includes a bootstrap capacitor to assist in driving up the terminal pad. In particular, the buffer comprises an output and an input portion. The output portion includes a first driver for driving the terminal pad up to VDD and a second driver for driving the terminal pad down to VSS. The first driver includes a pull-up PMOS transistor and a pull-up NMOS transistor connected in series and the second driver includes a pull-down NMOS transistor. Further, preferably one pair of push-pull bootstrap control transistors are connected in parallel to the gate of the pull-up NMOS transistor for quickly driving up the first driver to a voltage level based on the bootstrap capacitor having a predetermined capacitance. The input portion includes an invertor and a protection resistor for protecting the invertor from static charges.
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