US Patent 9373378 Semiconductor device for driving sub word lines

The semiconductor device incorporates a selected sub word line driver and a first voltage switching circuit. The selected sub word line driver has an input node connected to a selected main word line, an output node connected to a selected sub word line, a reference node supplied with a common reference voltage, and a power node. The first voltage switching circuit selectively supplies a first power voltage, a second power voltage, or the common reference voltage to the power node of the selected sub word line driver. In an active mode, the first voltage switching circuit supplies the first power voltage to pull the selected sub word line to a logic high level. In a precharge mode, the first voltage switching circuit supplies the common reference voltage and then supplies the second power voltage, thereby pulling the selected sub word line to a logic low level. A voltage level of the second power supply node is lower than a voltage level of the first power voltage and higher than the common reference voltage.