US Patent 7145820 Semiconductor memory device for reducing chip area

Disclosed is a semiconductor memory device capable of reducing chip area by precharging all banks simultaneously. The semiconductor memory device includes: a command decoder for generating an auto refresh signal in response to an external command; an active information signal generator for generating an active information signal in response to a bank grouping signal when the auto refresh signal is activated; a tRAS controller for generating a tRAS control signal for each bank in response to an activated bank active detection signal, wherein the tRAS control signal maintains an active state during a row active time; a precharge information signal generator for generating a precharge information signal in response to the tRAS control signal of a last activated bank; and a bank control signal generator for generating a bank active signal in response to the active information signal and generates a bank precharge signal in response to the precharge information signal, respectively.