Patent attributes
Disclosed is a module where semiconductor memory devices each having a DLL (Delay Lock Loop) are stacked or a multi-chip module (MCM) having the semiconductor memory devices, a dedicated pad for sharing a clock signal between one of the semiconductor memory devices and other semiconductor memory device is included. The clock signal is delay adjusted by the DLL. The DLL in the one semiconductor memory device is operated, while the DLL in the other semiconductor memory device is not operated. A flying lock clock signal synchronized with an external differential clock signal and generated from a clock signal delay adjusted by the DLL is output from the dedicated pad of the one semiconductor memory device. The other semiconductor memory device receives the flying lock clock signal from the dedicated pad.
