| 摘要 |
PROBLEM TO BE SOLVED: To provide a single impedance control circuit for controlling a plurality of different impedance values on the same semiconductor integrated circuit. SOLUTION: The impedance control circuit includes: a reference voltage selection circuit (reference voltage switching device 4) for selecting a plurality of reference voltages (13-1, 13-2) and outputting the selected reference voltage; a variable resistor element (6); a comparator (5) having a first input to receive the reference voltage outputted from the reference voltage selection circuit (4) and a second input to which the variable resistor element is connected, and comparing the voltages at the first and second inputs; and a control circuit (3) for setting a plurality of impedance values (9-1, 9-2) corresponding to the plurality of reference voltages on the basis of a signal outputted from the comparator (5). COPYRIGHT: (C)2004,JPO
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