the like and generates the reference current iref 1 by applying a voltage vref from the stabilized power supply to the external internal resistance r 19 also the second reference current generator 5 has a stabilized band gap power supply similar to that of the first reference current generator 4 and generates the reference current iref 4 by applying the voltage vref from the stabilized band gap power supply to the internal resistance 18 which is expected to have the same value as the external resistance r 19 thus the reference current iref 1 and the reference current iref 4 can be represented by the following equations the generated reference current iref 1 is applied to the internal resistance 20 and the reference current iref 4 is applied to the internal resistance 21 the termination resistance controller 6 compares the voltage v 1 generated by the internal resistance 20 and the voltage v 2 generated by the internal resistance 21 the voltages v 1 and v 2 can be represented by the following equations the termination resistor generator 1 receives the control signal vcont outputted from the termination resistance controller 6 and drives the switch circuit since the switch circuit is turned on the basic resistor 13 and an adjustment resistor 12 are connected in parallel when the resistance of the adjustment resistor 12 is assumed to be a resistance r 12 and when the resistance of the basic resistor 13 is assumed to be a resistance r 13 its synthesized resistance.