| CPC G11C 11/4099 (2013.01) [G11C 5/04 (2013.01); G11C 5/063 (2013.01)] | 13 Claims |

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1. 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 or a reference voltage 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 is diode-connected, wherein the reference current or the reference voltage is generated on a first memory die of the plurality of memory dies and shared with the other memory dies of the plurality of memory dies;
supplying a plurality of first currents corresponding to the reference current or the reference voltage to pull-up drivers of the plurality of memory dies, respectively;
performing ZQ calibration of pull-up drivers of the plurality of memory dies, respectively, wherein ZQ calibration of a pull-up driver of the first memory die is performed simultaneously with ZQ calibration of pull-up drivers of the other memory dies; and
performing ZQ calibration of pull-down drivers of the plurality of memory dies respectively, wherein ZQ calibration of a pull-down driver is performed based on an output impedance of a corresponding ZQ calibrated pull-up driver in the same memory die.
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