摘要:
A semiconductor memory device capable of accelerating address access and shortening cycle time is provided. A first address decoder (2) and first refresh address decoder (5) respectively decode an external address (Xn) supplied from outside the semiconductor memory device and a refresh address (RXn) used for refreshing within the semiconductor memory device. A multiplexer (8) selects the external address side decode signal (XnDm) or the refresh address side decode signal (XnRm) and outputs the signal as a decode signal (XnMm) based on an external address transmission signal (EXTR) and refresh address transmission signal (RFTR) so that a refresh operation and a read/write operation is performed continuously within one memory cycle. A word driver (10) then decodes decode signals (XnMm, XpMq) selected with multiplexer (8) and so forth, and activates a word line (WLmq).
摘要:
A one-shot signal generation circuit is provided which makes it easy to adjust pulse width and to deal with variation of skew of an ATD signal, and can reduce chip area. A timing determination section (100) is reset by an edge of a first detected signal among a plurality of address transition detection signals (ATD signals) which have arrived within the skew period of an address signal, measures a first predetermined time by taking an edge of a second detected signal as start instant, and outputs a signal DST which reflects the result of this measurement. A timing determination section (110) measures a second predetermined time by taking an edge of the first detected signal as start instant, and outputs a signal PG which reflects the result of this measurement. An LC generation circuit (14) outputs a one-shot signal (LC) whose start instant is determined by the signal PG and whose end instant is determined by the signal DST.
摘要:
The present invention provides a semiconductor memory device capable of checking operation in the worst case in address combinations, and its manufacturing method. Specific data for test are written into a memory cell array 30. Then, a test signal TE1 is set “1” to set a device in a test mode. Refresh addresses for test are then stored in a data store circuit 51. A first address for test is applied to an address terminal 21, whereby a normal read or write operation is accomplished based on the first address for test. A second address for test is applied to the address terminal 21, whereby a refresh operation is accomplished based on the address for test, and subsequently another normal read or write operation is accomplished based on the second address for test. Data of the memory cell array 30 are checked to decide the presence or absence of any abnormality.
摘要:
The present invention provides a non-synchronous semiconductor memory device configured as a pseudo-SRAM and capable of relaxing the limitation to address skew and improving the read rate. A data latch circuit 110 holds data having been read out of memory cells in a memory cell array 106 designated by a tow address included in an address ADD in a read mode. Upon transitions of column addresses A0, A1 included in the address, a multiplexer 111 sequentially and non-synchronously feeds out the data held in the data latch circuit 110 based on the column addresses A0, A1.
摘要:
A semiconductor memory device is provided which effectively reduces a consumption of current of a system of circuits associated with refresh operations. A control signal circuit 2 controls n-channel transistors 3C, 4B to be in an OFF-state based on an internal chip select signal SCI in an interval time period between the refresh operations, wherein the n-channel transistors 3C, 4B are connected between the system of circuits associated with refresh operations (an internal voltage-down circuit 3 and a boost circuit 4) and the ground, so as to break down a leak path of the system of circuits associated with refresh operations for reducing the leakage of current. At a timing of starting the refresh operation by triggering a timer, the internal chip select signal SCI is transitioned to a high level for supplying a ground voltage to the internal voltage-down circuit 3 and the boost circuit 4.
摘要:
A semiconductor memory device is provided, which is capable of effectively reducing a current comsumption caused by a self-refresh operation in a stand-by mode.In the refresh operation in the stand-by mode, under the control by a refresh control circuit 8B, firstly, a suppression is made for current driving abilities of sense amplifiers 70A˜70D provided for amplifying data signals appearing on bit lines, and secondly, an expansion is made of a pulse width of a row enable signal RE, which defines a period of time for selecting word lines WL, and thirdly, parallel activations of plural word lines are made based on the row enable signal RE with the expanded pulse width, thereby reducing the frequency of operations of the circuit system associated with the refresh operations, resulting in a suppression of the current consumption.
摘要:
A semiconductor memory device is provided for preventing a late-write from disturbing a refresh operation and also for reducing a current consumption in a write cycle with execution of the late-write. Upon a transition of an address ADD, an address transition detector circuit detects this address transition. Upon receipt of a result of detection by the address transition detector circuit, a state control circuit judges an operation to be executed, from an output enable signal /OE and a write enable signal /WE, and then outputs any of a read statement RS, a write statement WS, and a refresh statement FS. According to a clock signal ACLK, input signals such as addresses are taken for executions of operations based on the statements.
摘要:
Refresh of memory cells is performed periodically by a refresh timer, and collision between memory access and memory refresh is avoided. When memory access occurs, an F/F 163 is set by a one shot pulse from an OS circuit 161, a memory access request is inputted to a memory accessing pulse generator circuit 171 through a NOR gate 167, and a latch control signal LC and an enable signal REN are outputted. When a refresh request from the refresh timer is inputted to an AND gate 168 during the memory access, the output of the NOR gate 167 is at the “L” level, and the refresh request is blocked by the AND gate 168. Thereafter, at the time when the latch control signal LC is turned into the “L” level, F/Fs 163, 164 and 165 are reset, the output of the NOR gate 167 is turned into the “H” level, the refresh request is inputted to a refreshing pulse generator circuit 170, and a refresh enable signal RERF is outputted.
摘要翻译:通过刷新定时器周期性地执行存储器单元的刷新,并避免存储器访问和存储器刷新之间的冲突。 当存储器访问发生时,通过来自OS电路161的单触发脉冲设置F / F 163,通过NOR门167将存储器访问请求输入到存储器访问脉冲发生器电路171,以及锁存控制信号LC和 输出使能信号REN。 当在存储器访问期间来自刷新定时器的刷新请求被输入到与门168时,或非门167的输出处于“L”电平,刷新请求由与门168阻止。此后, 当锁存控制信号LC变为“L”电平时,F / F 163,164和165被复位,或非门167的输出变成“H”电平,刷新请求被输入到 输出刷新脉冲发生器电路170和刷新使能信号RERF。
摘要:
Refresh of memory cells is performed periodically by a refresh timer, and collision between memory access and memory refresh is avoided. When memory access occurs, an F/F 163 is set by a one shot pulse from an OS circuit 161, a memory access request is inputted to a memory accessing pulse generator circuit 171 through a NOR gate 167, and a latch control signal LC and an enable signal REN are outputted. When a refresh request from the refresh timer is inputted to an AND gate 168 during the memory access, the output of the NOR gate 167 is at the “L” level, and the refresh request is blocked by the AND gate 168. Thereafter, at the time when the latch control signal LC is turned into the “L” level, F/Fs 163, 164 and 165 are reset, the output of the NOR gate 167 is turned into the “H” level, the refresh request is inputted to a refreshing pulse generator circuit 170, and a refresh enable signal RERF is outputted.
摘要翻译:通过刷新定时器周期性地执行存储器单元的刷新,并避免存储器访问和存储器刷新之间的冲突。 当存储器访问发生时,通过来自OS电路161的单触发脉冲设置F / F 163,通过NOR门167将存储器访问请求输入到存储器访问脉冲发生器电路171,以及锁存控制信号LC和 输出使能信号REN。 当在存储器访问期间来自刷新定时器的刷新请求被输入到与门168时,或非门167的输出处于“L”电平,刷新请求由与门168阻止。 此后,当锁存控制信号LC变为“L”电平时,F / F 163,164和165被复位,或非门167的输出变为“H”电平,刷新请求 被输入到刷新脉冲发生器电路170,并且输出刷新使能信号RERF。
摘要:
A semiconductor memory device is provided which operates according to the specification of an SRAM, and which is capable of making the memory cycle shorter than heretofore, without normal access being delayed by the influence of refresh. An ATD circuit (4) receives change of an address (“Address”), and generates a one shot pulse in an address transition detect signal (ATD) after an address skew period has elapsed. In the case of a write request, a write enable signal (/WE) is dropped within the address skew period. First, writing or reading is performed from the rising edge of the one shot pulse, and, in the case of writing, late writing is performed using the address and the data which were presented at the time of the directly preceding write request. Next, refresh is performed during the period from the falling edge of the one shot pulse until the address skew period of the subsequent memory cycle is completed. And, for late writing at the time of the next write request, the address and the data are taken into register circuits (3, 12) upon the rising edge of the write enable signal (/WE).