Oki Electric Industry Co., Ltd.

Yoshihiro Murashima

Yoshimasa Sekino

Takayuki Tanaka

Junichi Suyama

Takeru Yonaga

Yasuhiro Tokunaga

Joji Ueno

A dynamic random access memory of the complementary MOS transistor type has memory cells connected between complementary bit lines on one side of a pair of transfer gates and a sense amplifier connected to nodes on the other side of the transfer gates, so that the sense amplifier can be connected to the bit lines and memory cells through the pair of transfer gates. A sense amplifier equalizing circuit and a bit line equalizing circuit are provided on opposite sides of the transfer gates so that the potentials on the bit lines can be equalized independently of equalization of the potentials on the nodes. Accordingly, there is no delay in the equalization due to the transfer gates connecting the nodes to the bit lines. According to another aspect of the invention, the transfer gates each include a pair of MOSFET transistors connected to each other in parallel, wherein one transistor of each pair of MOSFET transistors is an n-channel MOSFET transistor and the other transistor of each pair of MOSFET transistors is a p-channel MOSFET transistor. By, for example, connecting the gate of the NMOS transistor of each transfer to the power source and connecting the gate of each PMOS transistor to the ground, it is possible to prevent erroneous operation of the DRAM from a drop in the gate potential.

Dynamic random access memory with bit line equalizing means

A semiconductor memory device provided that first data is read out from a first memory cell within a first readout period; and second data is read out from the second memory cell within a second readout period; wherein an amplifier circuit receiving the first and second data, outputting first data signals having first electric potential level corresponding to the first and second data and outputting second data signal having second electric potential level; control circuit, in response to an external control signal, generating a first control signal in each of the first and second readout periods, the first control signal indicating first logic level during an enabling period of time within each of the first and second readout periods, otherwise the first control signal indicating second logic level; a first latch circuit latching the first data signals in the respective first and second readout periods and outputting a first latched data signal at the time of the first control signal indicating the first logic level; a second latch circuit latching the second data signals in the respective first and second readout periods and outputting a second latched data signal at the time of the first control signal indicating the first logic level; and a reset circuit placing the first and second latch circuit in an initial status after the first control signal is transferred from the first logic level to the second logic level in the first readout period and before the first control signal is transferred from the second logic level to the first logic level in the second readout period.

Semiconductor memory device

In a semiconductor memory device having memory cells (21.sub.i, 21.sub.i+1) disposed at intersections of bit lines (BL, BL) and word lines (WL.sub.i, WL.sub.i+1) and operating on an internal power source voltage (V.sub.D) which is lower than an external power source voltage for the memory device, sense amplifiers (41) are activated by a voltage on a drive common node (NS), and a comparator (110) is activated by the control signal (PAS) and compares the voltage on the common node (PS) with the internal power source voltage (V.sub.D). The comparator has an output which is in a first state when the common node (PS) voltage is not higher than the reference voltage (V.sub.R) and which is in a second state when the common node (PS) voltage exceeds the reference voltage (V.sub.R). A latch circuit (120) is turned from a first state to a second state when the control signal (PAS) is turned active, thereby to activate the comparator (110) and a power source supply circuit (130, 132) which then supplies a drive voltage to the common node (PS). The latch circuit is turned from the first state to the second state when the output of the comparator (110) is turned to the second state. The latch circuit deactivates the comparator (110) when it is turned to the first state.

In a dynamic random access memory comprising first and second memory cell arrays, and a plurality of word lines, each split into two sections extending through the first and the second memory cell arrays, respectively, word line drive circuits are divided into three blocks. The first block is disposed between the inner sides of the memory cell arrays and connected to the inner ends of the alternate word line sections. The second and the third blocks are disposed adjacent to the outer sides of the memory cell arrays and are connected to the outer ends of the intervening word line sections. Because the word line drive circuits for the respective word lines are disposed on both sides of each memory cell array, alternately, the area for the word line drive circuit for each word line can extend twice the pitch of the word lines. Thus, the pitch of the word lines can be reduced, or the size of the word line drive transistors can be increased, enabling a higher degree of integration.

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Tokyo, Japan

Yoshihiro Murashima