Impedance calibration circuit and semiconductor apparatus including the same

A semiconductor apparatus comprising:

• a driving circuit configured to drive data and output a driving result outside the semiconductor apparatus by driving the data;
• a control circuit configured to internally generate a dummy impedance calibration command according to a voltage level of a power terminal;
• and
• an impedance calibration circuit configured to generate a plurality of impedance calibration signals by performing an impedance calibration operation using an internal reference resistor according to the dummy impedance calibration command and calibrate values of the plurality of impedance calibration signals by performing the impedance calibration operation using an external reference resistor when an external impedance calibration command is input.

A method comprising:

• determining whether a generated dummy impedance calibration command is an initial impedance calibration command received after power-up;
• performing an impedance calibration using a reference resistor internal to a semiconductor apparatus when the dummy impedance calibration command is the initial impedance calibration command received after power-up;
• and
• performing the impedance calibration using a reference resistor external to the semiconductor apparatus when the impedance calibration command is not the initial impedance calibration command.