Mitsubishi Denki Kabushiki Kaisha

Zenya Kawaguchi

Takeshi Hamamoto

Motoko Hara

Complementary signals on a pair of first signal lines are transferred onto a pair of second signal lines in synchronization with a clock signal by a buffer circuit. The buffer circuit includes an equalize circuit to equalize a pair of internal nodes to a prescribed potential, a transfer gate circuit activated, when the equalize circuit completes equalization, to couple the pair of first signal lines and the pair of internal nodes, an amplifier circuit to differentially amplify the signals on the internal nodes when the transfer gate completes the transfer operation, an output transfer circuit to transmit the signals on the pair of internal nodes onto the pair of second signal lines in synchronization with the clock signal, and a control circuit to control the operation of the equalize circuit, the transfer gate circuit and the amplifier circuit. After the pair of internal nodes is equalized to the prescribed potential, the signals from the pair of first signal lines are received and amplified. Even if the signals are small amplitude signals, therefore, they can be correctly amplified and transferred in synchronization with the clock signal without destroying the signal amplitude.

Buffer circuit capable of correctly transferring small amplitude signal in synchronization with high speed clock signal

A command decoder receives an externally supplied command independently of an internal clock signal, decodes the command, generates a column access mode instruction signal, and activates a column address activation signal when the internal clock signal rises. An internal column address signal generating circuit generates an internal column address signal from an externally supplied address signal according to the column address activation signal. Accordingly, the internal column address is generated at an advanced timing to enable a following column selecting operation to be started at a faster timing. A synchronous semiconductor memory device capable of performing the column selecting operation at a high speed is thus provided.

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Hyogo, Japan

Zenya Kawaguchi