Patent ID: 8013630

Claim:
A ternary value input circuit for converting and outputting three states of an input terminal into a combination of states of two output terminals, comprising: a pull-up switching device for controlling connection and non-connection of said input terminal and a first power supply; a pull-down switching device for controlling connection and non-connection of said input terminal and a second power supply; and a pull signal generator circuit for generating a pull-up control signal for on and off control of said pull-up switching device and a pull-down control signal for on and off control of said pull-down switching device; wherein said pull-up switching device and said pull-down switching device are operated exclusively on and off in time division to hold and output the state of said input terminal during each operating state from said two output terminals; and wherein the pull signal generator circuit comprises: a first NOT gate having an input terminal and an output terminal; a buffer having an input terminal and an output terminal; an OR gate having a first and second input terminals and an output terminal; an AND gate having a first and second input terminals and an output terminal; and a second NOT gate having an input terminal and an output terminal; wherein the output terminal of the first NOT gate is connected to the input terminal of the buffer, the first input terminal of the OR gate, and the first input terminal of the AND gate; the output terminal of the buffer is connected to the second input terminal of the OR gate and the second input terminal of the AND gate; and the output terminal of the OR gate is connected to the output terminal of the NOT gate.