| 摘要 |
PROBLEM TO BE SOLVED: To provide an input/output circuit capable of supplying (outputting) correctly recognizable logical signals from supplied small amplitude signals even when a logical threshold level fluctuates. SOLUTION: This input/output circuit is constituted of a threshold detection means 15, an amplification part 14 for outputting the amplitude center level of the small amplitude signals, amplifying the small amplitude signals to a prescribed amplitude level, converting them into logical signals (rectangular waves) processible by a CMOS internal circuit 16 and supplying them through an output terminal out to the CMOS internal circuit 16, a constant current circuit 13 for changing the amplification factor of the inputted small amplitude signals and a feedback amplifier A2 for comparing the amplitude center level of the small amplitude signals and a voltage supplied from the threshold detection means 15 and performing feedback to the constant current circuit 13 so as to turn the amplitude center of signals amplified by the amplification part 14 to the voltage set by the threshold detection means 15.
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