| 摘要 |
An impedance control circuit includes a reference voltage output circuit for outputting one of a plurality of reference voltages; a variable resistor; a comparator and a control circuit. The comparator includes a first input terminal supplied with a reference voltage from the reference voltage output circuit and a second input terminal connected to the variable resistor, and compares the voltages at the first and second input terminals. The control circuit controls the variable resistor and establishes a plurality of impedances corresponding to the reference voltages in response to the signal output from the comparator. It enables the single impedance control circuit to control the plurality of different impedances on the semiconductor integrated circuit.
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