| 摘要 |
A calibration circuit on die termination apparatus which regularly maintains the current amount of an input-output node regardless of the change of the power supply voltage is provided to reduce or increase resistance of a pull-up calibration resistance according to the change of the power supply voltage. A code generation area(320) produces a pull-up calibration code in response to the voltage of a calibration node and reference voltage. The external resistance is connected to the calibration node. A pull-up calibration resistive portion(330) pull-up drives the calibration node in response to the pull-up calibration code. If the power supply voltage is identical with the fixed voltage, the external resistance the pull-up calibration resistive portion is the calibration in order to have the same resistance. If the power supply voltage is higher than the fixed voltage, resistive portion is the calibration in order to have the resistance higher than the external resistance the pull-up calibration. If the power supply voltage is lower than that of the fixed voltage, the pull-up calibration resistive portion is the calibration in order to have the resistance lower than the external resistance.
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