| 摘要 |
A calibration circuit of on die termination device is provided to maintain the current flowing in an input/output node by controlling the resistance of calibration resistor unit according to power voltage change. A calibration circuit comprises a code generation unit(320) and a pull-up calibration resistor unit(330). A pull-up calibration resistor unit pull-up drives the calibration node in response to the pull-up calibration code, and if the power supply voltage is identical to the fixed voltage, the pull-up calibration resistor unit is calibrated in order to have the same resistance as the external resistance. If the power supply voltage is higher than the fixed voltage, pull-up calibration resistor unit is calibrated to have higher resistance than external resistance.
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