| 摘要 |
PROBLEM TO BE SOLVED: To provide a termination resistance adjusting circuit which holds a termination resistance constant even if input differential signals vary in common voltage, and has a simple circuit constitution. SOLUTION: The termination resistance adjusting circuit includes a first termination resistance circuit whose resistance value is adjustable, a second termination resistance circuit which is connected in parallel to the first termination resistance circuit and whose resistance value is adjustable, an adjusting resistance circuit for adjusting the resistance values of the first and second termination resistance circuits, a first amplifying circuit which inputs a first voltage determined by the adjusting resistance circuit and a second voltage determined by an externally connected reference resistance, operates so that both the voltages become equal to each other, and also outputs a resistance adjustment signal to the first and second termination resistance circuits, a first terminal to which the first termination resistance circuit is connected, a second terminal to which the second termination resistance circuit is connected, and a second amplifying circuit which receives a voltage based upon the common voltage of the differential signal supplied to the first and second terminals and the first or second voltage, and operates so that both the voltage become equal to each other. COPYRIGHT: (C)2011,JPO&INPIT
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