Patent ID: 7388410
Filing Date: 2008-06-17
Classification: H03K

Abstract:
1. An input circuit, comprising: an input signal transmission circuit configured to output a first transmission signal at a first output node in response to an input signal at an input node; and a Schmitt trigger inverter having an input connected to the first output node and an output connected to a second output node and configured to output a second transmission signal at the second output node in response to the input signal and the first transmission signal; wherein the input signal transmission circuit comprises: a voltage drop element having a first terminal connected to the input node and having a second terminal and being configured to provide a voltage drop between the first terminal thereof and the second terminal thereof; a first MOS transistor having a first current terminal connected to the second terminal of the voltage drop element and a gate to which a first supply voltage is applied; a second MOS transistor having a first current terminal connected to a second current terminal of the first MOS transistor at a common node and a gate to which a second supply voltage is applied; a third MOS transistor having a first current terminal connected to a second current terminal of the second MOS transistor, a second current terminal connected to a ground voltage and a gate to which the second transmission signal is applied; and a switch having an input connected directly to the input node and an output connected to the first output node and configured to transmit the input signal to the first output node in response to a voltage at a common terminal of the first and second MOS transistors and a third supply voltage that is different from the first supply voltage.