Apparatus and method for zq calibration of data transmission driving circuit in memory chip package of multi-memory die structure

A method for ZQ calibration for a data transmission driving circuit of each memory die in a memory chip package in which a plurality of memory dies are stacked, the method comprising:

• generating a reference current through a reference resistor connected between a power terminal supplying a power voltage of the data transmission driving circuit and a ground terminal and a first transistor that are diode-connected;
• supplying a plurality of first currents corresponding to the reference currents to a pull-up driver of the plurality of memory dies, respectively;
• performing ZQ calibration of a pull-up driver of a corresponding memory die by comparing a first voltage formed by each first current with a reference voltage formed by the reference current in each of the plurality of memory dies;
• and
• performing ZQ calibration of a pull-down driver of the corresponding memory die based on an output impedance of the ZQ calibrated pull-up driver in each of the plurality of memory dies.