| 摘要 |
An input buffer is provided that converts a TTL logic signal to a CMOS logic signal and controls an CMOS output level while eliminating static current consumption even when an external bias voltage is changed. The input buffer improves a low-to-high input signal switching speed. Further, the input buffer can be used for low current and high-speed operation. The input buffer includes an inverter unit having pull-up and pull-down transistors with commonly coupled drains coupled between a power supply voltage and a ground voltage. The input buffer further can include a transistor control unit that receives an output signal of the input buffer to completely turn off the pull-up transistor when the TTL input signal is a high level and rapidly turn on the transistor when the TTL input signal is a low level. The transistor control unit can include a first transistor having a gate and a source for respectively receiving the TTL input signal and the ground voltage, a second transistor having a gate for receiving an output signal from a drain of the first transistor and an output signal from the input buffer and a source for receiving a power supply voltage. A third transistor has a drain commonly coupled to the drain of the second transistor and the gate of the pull-up transistor, a gate that receives an internal power supply voltage, which is lower than an external bias voltage, and a source that receives the input signal.
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