Hitachi, Ltd.

Hitachi Vlsi Engineering Corp.

Hitachi Ulsi Engineering Corp.

Hitachi, Vlsi Eng. Corp.

Satoshi Shinagawa

Yoichi Sato

Masao Mizukami

Yukio Nakano

Takahiko Kozaki

Yoshio Iioka

Masayuki Miyasaka

Masami Hasegawa

Yasushi Shimono

Takatoshi Tamura

Write column selection MOSFETs of memory cells MC are coupled with, for example, the earth potential of the circuit. Write column selection signals supplied to these MOSFETs are formed selectively according to the column selection address signal and the write data. Thereby the write column selection MOSFETs of the memory cells MC function as a substantial write means. That is, the write column selection signal lines are used as the data lines at the same time.

Multiplexed multi-write port semiconductor memory

A rate conversion circuit area (8) is provided between a spread gate area (4) which operates in synchronization with a clock signal CLK and a RAM core (7) (macro cell) operating in synchronization with a clock signal (ck) whose frequency is higher than that of the clock signal (CLK). With this arrangement, the single port core is made accessible as a dual port RAM by forming the clock signal (ck) whose frequency is multiplied an optional number of times that of the clock signal (CLK), receiving access data equivalent to a plurality of operating cycles in parallel from the spread gate area during a predetermined unit operating access cycle period in the spread gate area, and serially supplying these to the RAM core 7 during the plurality of operating cycle periods in synchronization with the clock signal (ck).

Semiconductor integrated circuit

A memory array of a static RAM or the like is divided in a word line extending direction to constitute a plurality of sub memory arrays SM0 to SM7, and array selecting signals for selecting the sub memory arrays and sub word line selecting signals for selecting sub word lines are combined to form word line selecting signals selectively. Main word lines M0000 to M0003 for transmitting those word line signals are arranged in parallel with the sub word lines SW000 to SW255. Sub word line drive circuits SWD000 to SWD255 are also coupled to the individual sub word lines for bringing the corresponding sub word lines selectively into selected states by combining at least 2 bits of the word line selecting signals.

Semiconductor storage device

A multi-port memory device has a memory cell array including one or more memory blocks each of which has a plurality of memory cells arranged in rows and columns, and a plurality of dummy cells, with one dummy cell being provided for each row of memory cells in each of the memory blocks so that the dummy cells are connected with associated ones of the word lines extending in the row direction. The dummy cells are further connected with dummy cell bit lines extending in the column direction. Sense amplifiers are connected to receive outputs of those memory cells in the memory cell array which are selected in a memory cell selection operation and outputs of those dummy cells among the plurality of dummy cells which are selected in the memory cell selection operation for amplifying differences between the selected memory cell outputs and the selected dummy cell outputs. Precharging and shielding arrangements are also provided for improved operation.

Multi-port memory device having precharged bit lines

A semiconductor memory device is provided which includes a plurality of word line drivers and logic decoding circuitry coupled to the inputs of the word line drivers. In large memory arrays, the word line driver circuits can place large capacitive loads on the output of the logic decoding circuit because the word line driver transistors must be relatively large. This large load on the logic decoding circuitry adversely effects the operating speed of the memory. Accordingly, to reduce this load, a switching arrangement is provided between the output of the logic decoding circuitry and the word line drivers. This switching arrangement can be controlled to respectively connect the output of the logic decoding circuit to the word line drivers based on control output signals of a pre-decoder. Reset MOSFETs can also be provided to prevent the inputs of the word line drivers from floating.

Growing community of inventors

Akishima, Japan

Satoshi Shinagawa