Refresh circuit having variable restore time according to operating mode of semiconductor memory device and refresh method of the same

摘要

A refresh circuit having a variable restore time according to an operating mode of a semiconductor memory device and a refresh method of the same is provided. The refresh circuit includes a refresh pulse generating unit for receiving a clock signal to generate first and second refresh signals, a standby refresh signal generating unit for receiving the second refresh signal and a chip select signal to generate a standby refresh signal, the chip select signal representing an active state and a standby state of the semiconductor memory device, and a word-line pulse generating unit for receiving the first refresh signal and the standby refresh signal to generate a word-line driving signal. A pulse width of the word-line driving signal generated at the standby state is longer than that generated at the active state resulting in a sufficient refresh time at each memory cell.