Semiconductor memory device and memory module having various operation modes

Abstract

A semiconductor memory device includes a receiving circuit, a multiplexing circuit, a decoding circuit and a memory cell array. The receiving circuit receives a plurality of input command/address (CA) signals, and generates a plurality of CA signal groups based on the input CA signals and a clock signal. The multiplexing circuit operates in one of a first operation mode and a second operation mode based on a mode selection signal, outputs the plurality of CA signal groups as a plurality of selected CA signal groups in the first operation mode, and generates the plurality of selected CA signal groups by multiplexing the plurality of sub-CA signals included in the plurality of CA signal groups in the second operation mode. The decoding circuit generates a plurality of output CA signals based on the plurality of selected CA signal groups.