| 摘要 |
An impedance matching circuit and a semiconductor memory device including a comparison circuit are provided to obtain normal output without correcting the comparison circuit, by controlling differential amplification characteristics of the comparison circuit flexibly in correspondence to the variation of external environment. A mode register set(200) generates a test signal using a command and an address. A sink control signal output part(220) outputs a sink control signal corresponding to the test signal. A comparison part(240) outputs a comparison signal by comparing the level of a reference voltage with the level of an input voltage through pullup and pulldown driving, and controls the pulldown driving capability using the sync control signal. The mode register set generates a first test signal increasing pulldown driving capability of the comparison part and a second test signal reducing pulldown driving capability of the comparison part by coding the address.
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