WO2006013632A1 - 半導体メモリ - Google Patents
半導体メモリ Download PDFInfo
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- WO2006013632A1 WO2006013632A1 PCT/JP2004/011267 JP2004011267W WO2006013632A1 WO 2006013632 A1 WO2006013632 A1 WO 2006013632A1 JP 2004011267 W JP2004011267 W JP 2004011267W WO 2006013632 A1 WO2006013632 A1 WO 2006013632A1
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- signal
- word line
- address
- word
- refresh
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Classifications
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
- G11C11/21—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements
- G11C11/34—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements using semiconductor devices
- G11C11/40—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements using semiconductor devices using transistors
- G11C11/401—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements using semiconductor devices using transistors forming cells needing refreshing or charge regeneration, i.e. dynamic cells
- G11C11/406—Management or control of the refreshing or charge-regeneration cycles
- G11C11/40618—Refresh operations over multiple banks or interleaving
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
- G11C11/21—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements
- G11C11/34—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements using semiconductor devices
- G11C11/40—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements using semiconductor devices using transistors
- G11C11/401—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements using semiconductor devices using transistors forming cells needing refreshing or charge regeneration, i.e. dynamic cells
- G11C11/406—Management or control of the refreshing or charge-regeneration cycles
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
- G11C11/21—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements
- G11C11/34—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements using semiconductor devices
- G11C11/40—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements using semiconductor devices using transistors
- G11C11/401—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements using semiconductor devices using transistors forming cells needing refreshing or charge regeneration, i.e. dynamic cells
- G11C11/4063—Auxiliary circuits, e.g. for addressing, decoding, driving, writing, sensing or timing
- G11C11/407—Auxiliary circuits, e.g. for addressing, decoding, driving, writing, sensing or timing for memory cells of the field-effect type
- G11C11/408—Address circuits
- G11C11/4087—Address decoders, e.g. bit - or word line decoders; Multiple line decoders
Definitions
- the present invention relates to a semiconductor memory that automatically executes refresh of memory cells.
- a memory block and a word line are allocated to the lower bits and upper bits of a refresh address generated in the DRAM, respectively, and the address pre-decode signal reset frequency is set during the self-refresh mode.
- a technique for reducing power consumption by lowering is disclosed (for example, Patent Document 1).
- a semiconductor memory called pseudo-SRAM has been developed.
- Pseudo SRAM has DRAM memory cells (dynamic memory cells) and operates as SRAM by automatically executing the refresh operation of the memory cells internally.
- the dynamic memory cell used for pseudo SRAM has a small area. Therefore, it is possible to develop a large capacity pseudo SRAM with low bit cost.
- Patent Document 1 Japanese Patent Laid-Open No. 9-161477
- the refresh operation Since the refresh address is sequentially incremented or decremented, the address of the memory cell to be accessed (refreshed) next is known. On the other hand, since pseudo SRAM accepts access requests even during the standby period, the address of the memory cell accessed next does not have enough power until an external address is received. Therefore, the technology described in the above document that operates under conditions where no access request is generated cannot be applied to pseudo SRAM.
- An object of the present invention is to reduce the power consumption of a semiconductor memory that automatically executes refresh. In particular, it is to reduce power consumption by minimizing an increase in circuits. Means for solving the problem
- the memory block includes a plurality of memory cells and a plurality of word lines connected to the memory cells.
- a plurality of word line groups are constituted by a predetermined number of word lines.
- the refresh request generation circuit generates a refresh request for refreshing the memory cells at a predetermined cycle.
- the refresh address generation circuit sequentially generates refresh addresses indicating word lines connected to the memory cells to be refreshed in response to the refresh request. That is, the semiconductor memory automatically executes a refresh operation.
- the first word decoder is formed corresponding to each word line group.
- the first word decoder selects a word line selection signal line in order to select one of the word lines in the word line group according to the refresh address or the external address.
- the second word decoder is formed corresponding to each word line.
- the second word decoder selects one of the word lines in the word line group according to the refresh address or the external address in response to the selection of the word line selection signal line.
- the word control circuit holds the selected state of the word line selection signal line selected for each memory block corresponding to the refresh address after the refresh operation.
- the word control circuit deselects only the word line selection signal line of the memory block selected by the external address corresponding to the access request in response to the access request.
- At least one least significant bit of the refresh address generated by the refresh address generation circuit is assigned to select a memory block. Therefore, the memory block to be refreshed is switched for each refresh request, and the refresh operation for the word line selected by the refresh address is executed.
- the word line selection signal line is not deselected until it is switched to the next refresh address or an access request is received. Therefore, the frequency of deselecting and selecting the word line selection signal line can be reduced. As a result, the charge / discharge current of the word line selection signal line can be reduced, and the current consumption of the semiconductor memory can be reduced.
- the word control circuit has a reset prohibition control circuit and a block reset control circuit.
- the reset disable control circuit activates the reset disable signal in response to the refresh request (reset disabled state), and deactivates the reset disable signal in response to the access request (reset enabled state).
- the block reset control circuit is formed for each memory block and generates a block reset signal for deselecting a word line selection signal line selected in a memory block selected by an external address corresponding to an access request.
- the reset prohibition control circuit generates a reset prohibition signal common to the memory blocks, and the block reset circuit generates a block reset signal for each memory block selected according to the address. Therefore, the word line selection signal line selected in the memory block accessed by the access request can be easily deactivated with a simple circuit.
- a word line selection signal line is continuously selected for refresh.
- the first word decoder deselects this word line selection signal line.
- the word line selection signal line is selected in response to the first word decoder block reset signal selected by the external address. Since the word line selection signal lines for refresh and access are not selected at the same time, it is possible to prevent multiple word lines from being selected. As a result, malfunction of the semiconductor memory can be prevented.
- the word line group selected for the refresh operation is deselected in response to the access request, it is not necessary to specify the selected word line group.
- a circuit to be deselected can be simplified.
- the semiconductor memory has a burst access function for continuously executing a read operation or a write operation in response to one access request. Yes.
- the active key mask circuit formed in the reset prohibition control circuit masks the active key of the reset prohibition signal during burst access.
- burst access where access operations are continuously executed after the refresh operation, it is possible to prevent the word control circuit from operating wastefully by prohibiting the activation of the reset inhibit signal during burst access. Can be prevented. Therefore, the power consumption of the word control circuit can be reduced.
- the refresh operation is executed by sequentially switching the memory blocks in accordance with the refresh address, and then executed by sequentially switching the selected address of the word line. Executed by sequentially switching word line groups.
- the reset prohibition control circuit deactivates the reset prohibition signal during the period in which the memory block refresh operation completes immediately before the word line group is switched.
- the word line selection signal lines selected in each memory block are sequentially switched.
- the word line selection signal line can be deselected for each refresh operation during this period.
- the selected word line selection signal line is switched to the next word line selection signal line by continuing the refresh operation, the selected word line selection signal line is deselected in advance. Switching control is simpler than when two word line selection signal lines are not selected and selected at the same time.
- the reset prohibition control circuit includes an entry generation circuit and a flip-flop.
- the entry generation circuit generates an entry signal in synchronization with the timing signal indicating the start of the refresh operation while the access request is not received.
- the flip-flop activates the reset prohibition signal in synchronization with the entry signal, and deactivates the reset prohibition signal in synchronization with the access request.
- Access requests and refresh requests are generated asynchronously. For this reason, when the entry signal is generated in synchronization with the refresh request, the entry signal and the access request may be input to the flip-flop input almost simultaneously.
- the flip-flop can be prevented from malfunctioning, and the reset prohibition signal can be reliably activated or deactivated.
- the reset prohibition control circuit deactivates the reset prohibition signal to deselect the word line selection signal line when the semiconductor memory is powered on. For this reason, it is possible to prevent multiple word lines from being selected immediately after power-on, and to prevent the semiconductor memory from malfunctioning.
- the reset prohibition control circuit is , An entry generation circuit and a flip-flop.
- the entry generation circuit generates an entry signal responding to the refresh request using a plurality of timing signals. Since some of the timing signals are generated asynchronously with each other, the pulse width (valid period) of the entry signal may become narrower if the timing is shifted.
- the flip-flop is composed of a transistor having a predetermined threshold voltage. The flip-flop activates the reset prohibition signal in synchronization with the entry signal, and deactivates the reset prohibition signal in synchronization with the access request.
- the reset prohibition signal is activated from the entry signal, and at least one of the threshold voltages (absolute values) of the transistors existing in the signal path fed back to the input is the threshold voltage (absolute value) of the other transistors. Value). Therefore, the flip-flop can determine its own state at high speed even when the pulse width of the entry signal is narrow. Therefore, the flip-flop can be prevented from becoming unstable, and malfunction of the semiconductor memory can be prevented.
- the semiconductor memory has a plurality of memory banks that are selected according to the bank address and operate independently of each other.
- Each memory bank has a plurality of memory blocks, a plurality of word line groups, and a plurality of first and second word decoders.
- the reset prohibition control circuit transmits an inactive signal of a reset prohibition signal responding to the access request only to the memory bank selected according to the bank address. Therefore, the word line selection signal line can be unselected independently for each memory bank. In memory banks that are not involved in access requests, unnecessary deselection of word line selection signal lines can be prevented, thus reducing power consumption.
- the address latch control circuit is formed in each memory block, and generates an address latch signal in response to selection of the memory block by a refresh address or an external address.
- the address latch circuit is formed corresponding to each address signal line for selecting the first word decoder, latches the refresh address or the external address in synchronization with the corresponding address latch signal, and the latched address is the first word. Output to the decoder. Whether the first word decoder selects or deselects the word line selection signal line depends on the address latched in the address latch circuit. In other words, the word line selection signal line selection Z non-selection state is the address It is held as long as the latch state of the latch circuit does not change.
- the word line selection signal line selected for refreshing V and V is deselected, and at the same time, the word line selection signal line for access is selected. Is selected.
- a simple circuit can maintain the selected state of the word line selection signal line after the refresh operation and switch the word line selection signal line selected in response to the access request for each memory block. Since the circuit configuration is simplified, the operation verification time during circuit design can be shortened. Non-selection of two word line selection signal lines Z selection can be switched at the same time, so access required power Time required to start an access operation can be shortened. That is, the access time can be shortened.
- the first test control circuit outputs a first test signal common to the address latch control circuit during the test mode.
- Each address latch control circuit generates an address latch signal in synchronization with the output of the first test signal. Therefore, the address latch circuit of each memory block can be operated simultaneously during the test mode, and for example, a multiple selection test of word lines can be performed.
- the second test control circuit outputs a second test signal common to the first word decoder during the test mode.
- Each first-side decoder selects a word line selection signal line in synchronization with the output of the first test signal. For this reason, all the word line selection signal lines can be simultaneously selected during the test mode, and the test time of the burn-in test, for example, can be shortened.
- each address latch circuit has a level shifter that converts a high level voltage of the latched address into a boosted voltage.
- the first word decoder receives the boosted voltage as a high level power supply and sets the high level voltage of the word line selection signal line to the boosted voltage.
- the semiconductor memory has a plurality of memory banks that are selected according to the bank address and operate independently of each other.
- Each memory bank includes a plurality of memory blocks, a plurality of word line groups, a plurality of first and first It has a 2-word decoder. Only the address latch circuit of the memory bank selected according to the bank address latches the external address corresponding to the access request, and the word line selection signal line can be selected independently for each memory bank. Since it is possible to prevent unnecessary deselection of the word line selection signal line in the memory bank regardless of the access request, power consumption can be reduced.
- the program circuit is formed corresponding to each memory block, and the defective address is programmed in advance.
- the program circuit outputs a redundant hit signal when the refresh address or the external address matches the defective address.
- a redundant word line is formed in each memory block and is selected in response to a redundant hit signal.
- the first word decoder deselects the selected word line selection signal line in synchronization with the output of the redundant hit signal. For this reason, even in a semiconductor memory having a redundant word line, the selection state of the word line selection signal line selected by the refresh operation can be held, and the corresponding word line selection signal line can be deselected when accessing the redundant word line. .
- the word line selection signal line and the word line are a main word line and a sub word line, respectively.
- the first word decoder is the main word decoder.
- the second word decoder is a sub-word decoder that is distributed in each memory block. Since the main word line needs to be connected to the distributed sub word decoder, its wiring length is long. For this reason, a large charge / discharge current is generated by selecting the main word line Z and not selecting it.
- the charge / discharge current of the main word line can be reduced and the current consumption of the semiconductor memory can be reduced.
- At least one most significant bit of the refresh address generated by the refresh address generation circuit is allocated for selecting a word line group. Bits other than the! /, Bits assigned to the refresh address! /, The memory block and the word line group are assigned to select the first line. By assigning a word line group to the top of the refresh address, the refresh operation is executed repeatedly. The switching frequency of the line selection signal line can be minimized and the current consumption of the semiconductor memory can be reduced.
- the word line selection signal line and the word line are a sub word selection signal line and a sub word line, respectively.
- the first word decoder is a subword selection decoder.
- the second word decoder is a sub-word decoder that is distributed in each memory block. Since the sub-word selection signal line needs to be connected to the distributed sub-word decoder, the wiring length is long. For this reason, a large charge / discharge current is generated by the selection Z deselection of the sub word selection signal line. By reducing the frequency of non-selection and selection of the sub word selection signal line according to the present invention, the charge / discharge current of the sub word selection signal line can be reduced and the current consumption of the semiconductor memory can be reduced.
- At least one most significant bit of the refresh address generated by the refresh address generation circuit is assigned to select a word line! /. Bits other than the bits assigned to select the memory block and the first line at the refresh address are assigned to select the word line group! /.
- the semiconductor memory has a plurality of memory banks that are selected according to the bank address and operate independently of each other.
- Each memory bank has a plurality of memory blocks, a plurality of word line groups, and a plurality of first and second word decoders.
- the word control circuit deselects only the memory bank selected according to the bank address, in response to the access request, the word line selection signal line that has been selected for refresh. For this reason, as described above, the word line selection signal line can be selected Z unselected independently for each memory bank. In a memory bank that is not involved in access requests, unnecessary deselection of the word line selection signal line can be prevented, thus reducing power consumption.
- the invention's effect By applying the present invention to a semiconductor memory that automatically executes refresh of memory cells, the power consumption of the semiconductor memory can be reduced.
- FIG. 1 is a block diagram showing a first embodiment of a semiconductor memory of the present invention.
- FIG. 2 is a circuit diagram showing details of the reset control circuit shown in FIG. 1.
- FIG. 3 is a block diagram showing details of the fuse circuit shown in FIG. 1.
- FIG. 4 is a circuit diagram showing a main part of the memory core shown in FIG. 1.
- FIG. 5 is a block diagram showing details of each word decoder shown in FIG. 4.
- FIG. 6 is a circuit diagram showing details of the main word decoder and redundant main word decoder shown in FIG. 5.
- FIG. 6 is a circuit diagram showing details of the main word decoder and redundant main word decoder shown in FIG. 5.
- FIG. 7 is a timing chart showing operations of the main word decoder and the redundant main word decoder when a read operation or a write operation is executed in the first embodiment.
- FIG. 8 is a timing diagram showing another example of the operations of the main word decoder and the redundant main word decoder when the read operation or the write operation is performed in the first embodiment.
- FIG. 9 is a timing chart showing operations of the arbiter Z operation control circuit, reset control circuit, and reset signal generation circuit in the first embodiment.
- FIG. 10 is a timing diagram showing operations of the arbiter Z operation control circuit, the reset control circuit, and the reset signal generation circuit in the first embodiment.
- FIG. 11 is a timing chart showing the operation of the memory core in the first embodiment.
- FIG. 12 is a circuit diagram showing a main part of a second embodiment of the semiconductor memory of the present invention.
- FIG. 13 is a circuit diagram showing the main part of a third embodiment of the semiconductor memory of the present invention.
- FIG. 14 is a block diagram showing a fourth embodiment of a semiconductor memory of the present invention.
- FIG. 15 is a block diagram showing details of the word decoder shown in FIG.
- 16 is a circuit diagram showing details of the address latch control circuit and the address latch circuit shown in FIG.
- FIG. 17 is a circuit diagram showing details of a main word decoder and a redundant main word decoder. is there.
- FIG. 18 is a timing diagram showing operations of the main word decoder and the redundant main word decoder when the read operation or the write operation is executed in the fourth embodiment.
- FIG. 19 is a timing diagram showing another example of the operations of the main word decoder and the redundant main word decoder when the read operation or the write operation is performed in the fourth embodiment.
- FIG. 20 is a timing chart showing the operation of the memory core in the fourth embodiment.
- FIG. 23 is a block diagram showing a sixth embodiment of a semiconductor memory of the present invention.
- FIG. 24 is a block diagram showing details of the bank shown in FIG. 23.
- FIG. 25 is a timing chart showing an operation of the pseudo SRAM according to the sixth embodiment.
- FIG. 26 is a block diagram showing a seventh embodiment of the semiconductor memory of the present invention.
- FIG. 27 is a block diagram showing details of the bank shown in FIG. 26.
- FIG. 29 is a block diagram showing an eighth embodiment of the semiconductor memory of the present invention.
- FIG. 30 is a circuit diagram showing a main part of the memory core shown in FIG. 29.
- FIG. 31 is a block diagram showing details of each word decoder shown in FIG. 30.
- FIG. 32 is a circuit diagram showing details of the sub-word selection decoder shown in FIG. 31.
- ⁇ 33 A timing diagram showing the operation of the subword selection decoder when the read operation or write operation is executed in the eighth embodiment.
- FIG. 34 is a timing chart showing operations of the arbiter Z operation control circuit, the reset control circuit, and the reset signal generation circuit in the eighth embodiment.
- FIG. 35 is a block diagram showing a ninth embodiment of a semiconductor memory according to the present invention.
- FIG. 36 is a block diagram showing details of the word decoder shown in FIG. 35.
- FIG. 37 is a circuit diagram showing details of an address latch control circuit and an address latch circuit shown in FIG. 36.
- FIG. 38 is a circuit diagram showing details of the sub-word selection decoder shown in FIG. 36.
- FIG. 39 is a timing chart showing an operation of the subword selection decoder when the read operation or the write operation is executed in the ninth embodiment.
- FIG. 40 is a timing chart showing the operation of the memory core in the ninth embodiment.
- FIG. 41 is a block diagram showing another example of pseudo SRAM to which the present invention is applied.
- FIG. 42 is a block diagram showing another example of pseudo SRAM to which the present invention is applied.
- Double circles in the figure indicate external terminals.
- the signal lines indicated by bold lines in the figure are composed of a plurality of lines. Some of the blocks to which the thick lines are connected are composed of multiple circuits. Use the same symbol as the terminal name for the signal supplied via the external terminal. In addition, the same symbol as the signal name is used for the signal line through which the signal is transmitted.
- a signal with "Z” at the end indicates positive logic. Signals with "z” at the beginning and signals with "X” at the end indicate negative logic.
- FIG. 1 shows a first embodiment of the semiconductor memory of the present invention.
- This semiconductor memory is formed as pseudo SRAM on a silicon substrate using a CMOS process.
- the pseudo SRAM is used, for example, as a work memory mounted on a mobile device such as a mobile phone.
- the pseudo SRAM has a burst access function that continuously executes read or write operations in response to a single access request.
- the pseudo SRAM includes an external command input circuit 10, a refresh request generation circuit 12, a refresh address generation circuit 14, an arbiter Z operation control circuit 16, a reset control circuit 18 (reset inhibition control circuit), and a reset signal generation circuit 20 ( Reset prohibition control circuit), external address input circuit 22, external data input / output circuit 24, internal row address generation circuit 26, predecoder 28 for selecting a later-described row block RBLK (memory block), and a later sub-node line Predecoder 29 for selecting SWL (word line), predecoder 30 for selecting main word line MW LX described later, predecoder 32 for column address CAD, fuse circuit 34 (program circuit) and memory It has a core CORE.
- the reset control circuit 18, the reset signal generation circuit 20, and the block reset control circuit RSTC shown in FIG. 4 are the main word line MWL selected for each row block RBLK corresponding to the refresh address. Operates as a word control circuit that holds the selected state of X (Fig. 4) after the refresh operation and deselects only the main word line MWLX of the row block RBLK selected by the external address EAL supplied in response to the access request To do.
- a pseudo SRAM having a burst access function operates in synchronization with an external clock received at a clock terminal. In this embodiment, description of an external clock is omitted.
- the external command input circuit 10 has an input buffer and receives a command signal CMD (for example, a chip enable signal ZCE1, a write enable signal Z WE, and an output enable signal ZOE) supplied to the command terminal CMD. To do.
- the external command input circuit 10 has a command decoder function. According to the received command signal CMD, the read control signal RDPZ for executing the read operation and the write control signal WRPZ for executing the write operation. Etc. are output.
- the chip enable signal ZCE1 indicating the access request is supplied to the internal circuit as the internal chip enable signal CEX via the input buffer.
- the refresh request generation circuit 12 has a refresh timer (not shown) that generates a refresh request SRTZ for refreshing the memory cell MC at a predetermined cycle. For example, the refresh request SRTZ is generated every few seconds.
- the refresh address generation circuit 14 counts in synchronization with the refresh request SRTZ and generates an internal address (hereinafter also referred to as a refresh address) IALO-12Z composed of 13 bits. Of the refresh address IALO—12Z, the lower 4 bits IALO—3Z are used to select the row block RBLK0—15, and the next 2 bits are used to select the sub word line SWL. The 7 bits are used to select the main word line MWLX.
- the refresh address IALO — 12Z identifies the subword line SWL connected to the memory cell MC to be refreshed. Since the low-block RBLK is assigned to the low-order bits of the refresh address IALO—12Z, the refresh operation is executed with a different row block RBLK for each refresh request. By assigning the lower and upper bits of the refresh address IAL to the row block RBLK and the main word line MWLX, respectively, the frequency with which the main word line MWLX is deselected during the pseudo SRAM standby period is reduced as described later. be able to.
- the refresh address generation circuit 14 includes four The refresh counter signal SRTXZ is held high while the refresh address (bits IAL4-5Z are both high) for selecting the last subword line SWL3 of subword lines SWLO-3.
- the arbiter Z operation control circuit 16 has an arbiter function that determines the priority order of an access request (read command and write command) to which external power of the pseudo SRAM is supplied and a refresh request generated inside the pseudo SRAM. is doing. In addition, the arbiter Z operation control circuit 16 causes the memory core CORE to perform a read operation or a write operation in response to an access request, and in order to cause the memory core CORE to perform a refresh operation in response to a refresh request. It has the function of an operation control circuit that outputs control signals and timing signals to the circuit.
- the arbiter Z operation control circuit 16 outputs a command latch signal (pulse signal) CMDLP Z in synchronization with reception of an access request (RDPZ, WRPZ), and executes an access operation (read operation, write operation).
- RASZ and RASDZ are output.
- the basic timing signal RASDZ is a signal obtained by delaying the basic timing signal RASZ. For example, the selection period of the word line WL is set by the basic timing signal RASZ.
- the reset control circuit 18 activates the reset inhibition signal NORSTZ in synchronization with the start of the refresh operation, and deactivates the reset inhibition signal NORSTZ in synchronization with reception of the access request. However, during the burst access operation described later and during the selection period of the sub word line SWL3 (the high level period of the refresh counter signal SRTXZ), the reset inhibit signal NORSTZ is activated and the reset inhibit signal NORSTZ is deactivated. Hold the heel state.
- the reset signal generation circuit 20 outputs the basic timing signal RASZ as the reset signal RSTX while the reset prohibition signal NORSTZ is inactive (low level period).
- the external address input circuit 22 has an input buffer, receives the external address AD supplied to the address terminal AD, and receives the received signal as an external address EAL0-12Z (row address) and a column address CAD. Output as.
- the external data input / output circuit 24 has an input buffer and an output buffer.
- the external data input / output circuit 24 Moricore CORE force Read data transferred via the common data bus CDB is output to the external data terminal DQ. During the write operation, the external data input / output circuit 24 receives the write data via the external data terminal DQ and transfers the received data to the memory core CORE via the common data bus CDB.
- the internal row address generation circuit 26 outputs the external address EAL0 — 12Z as the row address RA0 — 12Z when executing the access operation, and the internal address IALO — 12Z as the row address RAO — when executing the refresh operation. Output as 12Z. That is, the internal address generation circuit 26 functions as a selector that switches between the external address EAL and the internal address IAL. The internal row address generation circuit 26 has a function of latching the row address RAO-12Z.
- the predecoder 28 predecodes the 4-bit row address RAO-3Z to select one of the row blocks RBLK0-15 (Fig. 4) and outputs eight predecode signals X01Z ⁇ 0: 3>, X23Z ⁇ 0: 3> (row block address) is generated. Note that 0: n> at the end of the signal name indicates that the signal power is composed of 1 bit.
- Predecode signals X01Z and X23Z are signals obtained by decoding row addresses RA0-1Z and RA2-3Z, respectively.
- Predecoder 30 predecodes 7-bit row address RA6-12Z to select one of main word lines MWLX0—127 (Fig.
- predecode signals X67Z, X89Z, and X101112Z are signals obtained by decoding the row addresses RA6-7Z, RA8-9Z, and RA10-12Z, respectively.
- the predecoder 32 predecodes the column address CAD in order to select the column switch connected to the bit lines BL and ZBL for each data terminal DQ, and outputs the generated predecode signal to the column decoder CDEC.
- the fuse circuit 34 outputs a redundant hit signal RHITX or the like when the value of the row address RA6-12Z matches the programmed address value.
- the fuse circuit 34 is a control circuit for replacing the defective main word line MWLX (the MWLX corresponding to the defective memory cell) with the redundant main word line R MWLX. In this embodiment, one main word line MWLX can be relieved for each row block RBLK.
- the memory core CORE has a memory array ARY, a word decoder WDEC, a column decoder CDEC, a sense amplifier SA, a precharge circuit PRE, a sense buffer SB, and a write amplifier WA.
- the memory array ARY includes a plurality of volatile memory cells MC (dynamic memory cells) arranged in a matrix, a plurality of word lines WL (hereinafter also referred to as sub word lines SWL) connected to the memory cells MC, and a plurality of It has a bit line pair BL and ZBL.
- Memory cell MC has a capacitor for holding data as electric charge, and a transfer transistor arranged between the capacitor and bit line BL (or ZBL). The gate of the transfer transistor is connected to the word line WL.
- the word decoder WDEC has a main word decoder MWD (first word decoder) and a sub word decoder SWD (second word decoder) as shown in FIG.
- the main word line MWLX selected by the main word decoder MWD is deselected in synchronization with the activation signal of the reset signal RSTX.
- the main word line MWLX selected for the refresh operation in each row block RBLK is selected for another main word line MWLX until an access request is received or by a subsequent refresh operation. Do not be deselected until ...
- the column decoder CDEC outputs a column line signal for turning on a column switch (not shown) for connecting the bit lines BL, / BL and the local data bus lines LDB, / LDB, respectively, according to the column address CAD.
- the sense amplifier SA is activated during the activation of the sense amplifier activation signal output from the arbiter Z operation control circuit 16, and differentially amplifies the data signal read on the bit lines BL and ZBL.
- the precharge circuit PRE is activated during the activation of the precharge control signal output from the arbiter Z operation control circuit 16, and supplies a precharge voltage to the bit lines BL and ZBL.
- the sense buffer unit SB amplifies the signal amount of the read data on the local data bus lines LDB and ZLDB during the read operation, and outputs it to the common data bus CDB.
- the write amplifier section WA outputs write data to the local data bus lines LDB and ZLDB according to the write data on the common data bus CDB during the write operation.
- FIG. 2 shows details of the reset control circuit 18 shown in FIG. Reset control circuit 18 Is an entry generation circuit 36 that generates an entry pulse signal ENTPX that responds to a refresh request using a plurality of timing signals WLSPX, CEX, REFZ, and WLCHCTLZ, an exit generation circuit 38 that generates an exit pulse signal EXITPX, and a pair of NANDs
- An RS flip-flop 40 composed of a gate, a filter circuit 42, and a reset prohibition generation circuit 44 that generates a reset prohibition signal NORST Z are provided.
- the activation of entry pulse signal ENTPX is prohibited during burst access operation by burst flag signal WLCHCTLZ. Therefore, the entry generation circuit 36 operates as an active mask circuit that masks the activation of the reset inhibition signal NORSTZ during the burst access operation.
- the exit generation circuit 38 temporarily activates the exit pulse signal EXITPX in synchronization with the activation of the command latch signal CMDLPZ or the initialization signal CLRX.
- the initialization signal CLRX is activated to a low level when the pseudo SRAM is powered on.
- the exit pulse signal EXITPX is activated, the reset disable signal NORSTZ is deactivated, and the main word line MWLX, which will be described later, is deselected. By deselecting all the main word lines MWLX at power-on, it is possible to prevent multiple word lines from being selected immediately after power-on, and to prevent malfunction of the pseudo SRAM.
- the flip-flop 40 sets the output nodes ND1 and ND2 to a high level and a low level in synchronization with the activation of the entry pulse signal ENTPX, and outputs the output node ND1 in synchronization with the activation of the exit pulse signal EXITP X. Reset ND2 to low level and high level, respectively.
- pseudo SRAM refresh requests and access requests are generated asynchronously.
- the filter circuit 42 has an inverter that inverts the node ND1 and transmits it to the node ND3, and a NOR gate that outputs negative AND logic of the nodes ND2 and ND3.
- the entry pulse signal ENTPX when the entry pulse signal ENTPX is generated, the low level of the node ND2 is transmitted to the reset prohibition generation circuit 44 as the prereset prohibition signal PNORSTZ until the flip-flop 40 is set. Is prohibited. Therefore, even when the pulse width is short due to noise or the like, the entry pulse signal ENTPX is generated, and the state of the flip-flop 40 becomes unstable, the reset control circuit 18 is prevented from malfunctioning.
- the pre-reset inhibit signal PNORSTZ can be deactivated quickly.
- the main word line MWLX selected for the refresh operation can be quickly switched in response to the access request, and the access time can be shortened.
- the reset prohibition generation circuit 44 activates the reset prohibition signal NORSTZ in synchronization with the prereset prohibition signal PNORSTZ while the refresh counter signal SRTXZ is at a low level.
- the reset prohibition generation circuit 44 fixes the reset prohibition signal NORSTZ at a low level while the refresh counter signal SRTXZ is at a high level.
- the refresh counter signal SRTX Z is activated during the period when both of the internal addresses IAL4-5Z for selecting the sub word lines output from the refresh address generation circuit 14 are high. That is, the reset disable signal NORSTZ is applied to the pre-reset disable signal PNORSTZ during the period when the last sub word line SWL3 among the four sub word lines SWL0-3 corresponding to each main word line is selected for the refresh operation. Independent and deactivated to a low level.
- FIG. 3 shows details of the fuse circuit 34 shown in FIG.
- the fuse circuit 34 has fuse units FUS for programming the addresses of the redundant main word lines RMWLX of the row blocks RBLK0-15.
- Each fuse section FUS detects the redundant selection signal RWSZ (RWSOZ-RWS 15Z!) And redundant hit signal RHITX (RHITOX—R HIT15X) when the input address RA0-12Z matches the programmed address. Activating!
- FIG. 4 shows a main part of the memory core CORE shown in FIG. Memory core CORE It has 16 row blocks RBLKO-15 selected according to the block address X01Z ⁇ 0: 3> and X23Z ⁇ 0: 3>.
- the word decoder WDEC has a block reset control circuit RSTC, a main word decoder MWD (first word decoder), and a sub word decoder SWD (second word decoder).
- the block reset control circuit RSTC is formed for each row block RBLKO-15.
- the main word decoder MWD is formed for each main word line MWLX.
- the sub word decoder SWD is formed for each sub word line SWL.
- the block reset control circuit RSTC is not shown for operating the block reset signal SRSTX and the memory core CORE according to the reset signal RSTX and the row block address X 01Z 0: 3>, X23Z ⁇ 0: 3>.
- the main word decoder MWD is selected for each row block RBLKO-15 according to the main word address X67Z ⁇ 0: 3>, X89Z ⁇ 0: 3>, X101112Z ⁇ 0: 7>.
- the selected main word decoder MWD selects the main word line MW LX while the block reset signal SRSTX is inactive.
- the main word decoder MWD that selects the main word line MWLX deselects the main word line MWLX (word line selection signal line) in synchronization with the selection of the block reset signal SRSTX.
- each main word line MWLX is connected to four subword decoders SWD.
- the four sub word decoders SWD corresponding to the sub word line SWLO-3 are selected by the selected main word line MWLX, and the sub word decoder SWD is further selected by the sub word address RA 4 5Z. Is selected, and the subword line SWL is selected by the selected subword decoder SWD.
- a word line group is formed by sub word lines SWLO-3 corresponding to the main word lines MWLX. That is, the main word decoder MWD is formed for each word line group.
- the sub word decoder SWD is distributed in the row block RBLK. Since the main word line MWLX is connected to all the corresponding sub word decoders SWD, its wiring length is long. Therefore, a large charge / discharge current flows each time the main word line MWLX is selected and Z is not selected. In this embodiment, as described later, the main word line MWLX is selected Z By reducing the frequency of selection, the charge / discharge current is reduced and the power consumption is reduced.
- the sub word decoder group SWD sandwiched between the memory cell arrays ALY is commonly used for the memory cell arrays ALY on both sides. For this reason, in the sub-word decoder group SWD arranged in the horizontal direction in the figure, either the odd-numbered sub-word decoder group SWD or the even-numbered sub-word decoder group SWD operates to execute the access operation or the refresh operation.
- FIG. 5 shows details of each word decoder WDEC shown in FIG.
- the block reset control circuit RSTC generates the row block selection signal RBLKSELZ according to the row block address X01Z 0: 3>, X23Z ⁇ 0: 3>, and the timing according to the row block selection signal R BLKSELZ.
- Timing signal generation circuit TSC that generates signals MUX, EQL, LE, and WLENZ, and a NAND gate that outputs reset signal RSTX as block reset signal SRSTX during the activation of row block selection signal RBLKSELZ Yes.
- the block reset signal SRSTX is activated for each row block RBLK in synchronization with the reset signal RSTX generated in response to the inactivation of the reset inhibit signal NO RSTZ.
- the main word line MWLX selected in the corresponding row block RBLK is deselected by the deactivation of the block reset signal SRSTX.
- the timing signal MUX is used to turn on and off the switch that connects the bit lines BL and ZBL to the sense amplifier SA.
- the timing signal EQL is used to equalize the voltages on the bit lines BL and / BL and set them to the precharge voltage.
- the timing signal LE is used to activate the sense amplifier SA.
- the timing signal WLENZ is used to generate the selection timing of the sub word line SWL.
- the pseudo SRAM has a redundant main word decoder RMWD connected to the redundant main word line RMWLX for each row block RBLKO-15.
- the redundant main word line RMWLX is selected in synchronization with the activation signal of the redundant selection signal RWSOZ (the number of the signal name indicates the number of the row block RBLK).
- the redundant hit signal RHITX is activated and the main word decoder MWD is not selected.
- the redundant main word line RMWLX is connected to the main row of the corresponding row block RBLK. Used to relieve the lead wire MWLX. Further, even when a memory cell MC connected to one sub word line SWL has a defect, the defect is relieved by the main word line MWLX unit (sub word line SWLO-3 unit).
- FIG. 6 shows details of the main word decoder MWD and the redundant main word decoder RMWD.
- main word addresses X67Z, X89Z, and X101112Z respectively indicate main word addresses X67Z ⁇ 0: 3>, X89Z ⁇ 0: 3>, and X101112Z ⁇ 0: 7>.
- the common circuit COM is a circuit common to the main word decoders MWD and RMWD.
- the common circuit COM has a level converter LEVC1 for the main word decoder MWD, a pulse unit PLS for generating a pulsed predecode signal RX67Z, and a level converter LEVC2 for the redundant main word decoder RMWD.
- the level converter LEVC1 generates the block reset signal PRSTX by converting the high level of the block reset signal SRSTX from the internal power supply voltage VII to the boost voltage VPP while the redundant hit signal RHITX (RHITOX—RHIT15X) is inactive.
- the boost voltage VPP is generated by a boost voltage generation circuit formed in a pseudo SRAM.
- the NOR part PLS converts the predecode signal X67Z into the predecode signal RX67Z synchronized with the timing signal WLENZ that determines the selection period of the sub word line SWL during the inactive state of the redundant hit signal RHITX.
- the level converter LEVC2 generates a redundant block reset signal RPRSTX by converting the high level of the block reset signal SRSTX from the internal power supply voltage VII to the boost voltage VPP.
- the main word decoder MWD includes a pMOS transistor that receives the block reset signal PRSTX at the gate, an nMOS transistor that receives the predecode signals RX67Z, X89Z, and X101112Z at the gate, and a latch connected to the drain of the pMOS transistor. Yes.
- the pMOS transistor and the nMOS transistor are connected in series between the boost power supply line VPP and the ground line VSS.
- the output of the latch is connected to the main node line MWLX via an inverter.
- the redundant main word decoder RMWD is the same circuit as the main word decoder MWD.
- the pMOS transistor of the redundant main word decoder RMWD receives the redundant block reset signal RPRSTX at the gate! Redundant main word decoder RMWD nMOS transistor
- the registers receive the redundancy selection signal RWSZ, the internal power supply voltage VII, and the redundancy block reset signal RPRSTX at their gates, respectively.
- FIG. 7 shows operations of the main word decoder MWD and the redundant main word decoder RMWD when a read operation or a write operation is executed.
- the redundant hit signal RHITX that does not cause a failure in the main word line MWLX or the memory cell MC is not activated is shown.
- the arbiter Z operation control circuit 16 activates the access signal ACTPZ in response to an access command (read command or write command) (FIG. 7 (a)).
- the main word addresses X67Z, X89Z, and X101112Z (predecode signals) are activated in synchronization with the activation of the access signal ACTPZ (Fig. 7 (b)), and the reset signal RSTX is activated (Fig. 7 (c)).
- the row block selection signal RBLKSELZ of the input block RBLK selected by the row block addresses X01Z and X23Z predecode signal
- FIG. 7 (d) the row block selection signal RBLKSELZ of the input block RBLK selected by the row block addresses X01Z and X23Z
- the block reset signal SRSTX is activated in synchronization with the activation of the input block selection signal RBLKSELZ (Fig. 7 (e)), and the pMOS transistor of the main word decoder MWD is turned on and selected to execute the refresh operation.
- the main word line MWLX that continues is deselected (Fig. 7 (f)). That is, the main word line MWLX is not selected only in the row block RBLK that executes the read operation or the write operation (access operation).
- the basic timing signal RASZ is activated for the access operation, and the reset signal RSTX and the block reset signal SRSTX are sequentially deactivated (FIG. 7 (g)).
- the main word decoder MWD selected for the access operation activates the predecode signal RX67Z in synchronization with the activation signal of the timing signal WLENZ and the deactivation signal of the block reset signal SRSTX (FIG. 7). (h)).
- the predecode signal RX67Z is not activated until the block reset signal SRSTX is deactivated.
- the main node line MWLX corresponding to the access request is selected and the access operation is executed (FIG. 7 (i)).
- Access signal ACTPZ The activation time for the main word line MWLX is Tl.
- the timing signal WLENZ is deactivated (Fig. 7 (j)), and the predecode signal RX67Z is deactivated (Fig. 7 (k)).
- the predecode signal RX67Z is deactivated, the selected state of the main word line MWLX is held by the latch circuit.
- the reset signal RSTX and the block reset signal SRSTX are activated in synchronization with the deactivation of the basic timing signal RASZ (Fig. 7 (1)).
- the pMOS transistor of the decoder unit DEC is turned on in synchronization with the activation signal of the block reset signal SRSTX, and is selected for the access operation, and the main word line MWLX is deactivated (Fig. 7 (m)) .
- FIG. 8 shows another example of the operation of the main word decoder MWD and the redundant main word decoder RMWD when a read operation or a write operation is executed.
- the main word line MWLX or the memory cell MC has a defect, and the redundant hit signal RHITX is activated. Detailed description of the same operation as in FIG. 7 is omitted.
- the reset signal RSTX and the block reset signal SRSTX are activated (FIG. 8 (a)), and the main word line MWLX that is continuously selected for executing the refresh operation is not selected. (Fig. 8 (b)).
- the fuse circuit 34 receives the row address RA6-12Z and activates the redundant hit signal RHITX (FIG. 8 (c)).
- the activation of the redundant hit signal RHITX prohibits the activation of the predecode signal RX67Z and also activates the block reset signal P RSTX, so that the main word decoder MWD holds the unselected state of the main word line MWLX. To do.
- the redundancy word decoder RMWD selects the redundancy main word line RMWLX (FIG. 8 (d)). . That is, the main word line is replaced and the defect is relieved.
- the time required to select the redundant main word line RMWLX for the active signal of the access signal ACTPZ is T1 as in FIG. Thereafter, the access operation is completed, and the redundant main word line RMWLX is not selected as in FIG. It is.
- FIG. 9 and FIG. 10 show operations of the arbiter Z operation control circuit 16, the reset control circuit 18, and the reset signal generation circuit 20 in the first embodiment.
- the waveform at the right end of Fig. 9 is connected to the waveform at the left end of Fig. 10.
- the refresh operation that is automatically executed in the pseudo SRAM is executed by updating the row block RBLK number for each refresh request, then updating the sub word line SWL number, and finally performing the main operation.
- the word line MWLX number is updated and executed.
- the update order is determined by the allocation of internal addresses IAL0-12Z generated by the refresh address generation circuit 14.
- the pseudo SRAM receives a write request and a burst write request sequentially between the second and third refresh requests SRTZ.
- the standby state continues without receiving an access request.
- the sub word line SWL connected to the memory cell MC is activated in synchronization with the high level period of the basic timing signal RASZ.
- burst access operation burst write operation or burst read operation
- write operation or read operation continues even after chip enable signal ZCE1 is deactivated in response to one write request or read request. And executed.
- the entry pulse signal ENT PX is generated in synchronization with the start of the first refresh operation (FIG. 9 (a)), and the reset inhibition signal NORSTZ is activated (FIG. 9 (b)). ). While the reset disable signal NORSTZ is active, the pseudo SRAM enters the reset disable mode.
- the reset signal RSTX is generated by the OR logic of the reset disable signal NORSTZ and the basic timing signal RASZ (Fig. 9 (c)). While the reset signal RSTX is inactive (high level), deselection of the main word line MWLX is prohibited.
- the exit pulse signal EXITPX is generated and the reset inhibit signal NORSTZ is deactivated (Fig. 9 (e)).
- the reset prohibit mode is then released.
- the reset signal RSTX is activated in synchronism with the earlier of the reset disable signal NORSTZ inactive or the basic timing signal RASZ inactive associated with the refresh operation. (Fig. 9 (f)).
- the main word line MWLX is continuously selected for the refresh operation, and the write operation is executed. Main word line MWLX is selected.
- the other row blocks RBLK continue to select the main word line MWLX for the refresh operation.
- a burst write request is supplied and the command latch signal CMDLPZ is activated (FIG. 9 (g)).
- the third refresh request is generated immediately after the burst write request (Fig. 9 (h)).
- the refresh operation corresponding to this refresh request is executed during the burst write operation.
- the reset control circuit 18 receives a burst flag signal WLCHCTLZ having a wider V and active period than the active period of the basic timing signal RASZ for the refresh operation (FIG. 9 (i)). Therefore, the reset disable signal NORSTZ is not activated even when the refresh operation is executed (Fig. 9 (j)).
- the reset signal RSTX is activated in synchronization with the deactivation of the basic timing signal RASZ during the deactivation of the reset inhibit signal NORSTZ (Fig. 9 (k)).
- the third refresh operation is executed immediately after the first burst write (FIG. 9 (1)).
- the reset disable signal NORSTZ is activated in synchronization with the start of the fourth refresh operation (Fig. 9 (m)). Since no access request is generated thereafter, the reset inhibition signal NORST Z holds the activated state. Therefore, the main word line MWLX selected for the refresh operation is not deselected unless the main word addresses X67Z, X89Z, and X101112Z are updated.
- the 33rd to 48th refresh operations are performed on the last sub-word line SWL3 (subword decoder SWD3).
- bits IAL4-5Z of the internal address are held at a high level, and the refresh address generation circuit 14 holds the refresh counter signal SRTXZ at a high level (FIG. 10 (a)).
- the reset disable signal NORSTZ is deactivated by the low-level refresh counter signal S RTXZ (Fig. 10 (b)). Therefore, the main word line MWLX selected in each row block RBLK is refreshed.
- the basic timing signal for the operation is deselected sequentially in synchronization with the inactive state of RASZ.
- the refresh operation for the sub word line SWLO of another main word line MWLX is executed.
- the adjacent main word line MWLX can be quickly selected in the subsequent refresh operation.
- FIG. 11 shows the operation of the memory core CORE in the first embodiment.
- the memory core CORE has four row blocks RBLK0-3 and two sub word lines SWL0-1.
- the number attached to the refresh signal REFPZ indicates the number of the row block RBLK in which the refresh operation REF is executed.
- the refresh operation REF is the number of the row block RBLK for each refresh request. It is executed by incrementing by one. In this example, immediately after the third refresh operation REF, the access operation ACT of the row block RBLK2 that is executing the refresh operation REF is executed. In addition, after the sixth refresh operation REF, the access operation ACT of the row block RBLK3 different from the row block RBLK1 that executed the refresh operation REF is executed.
- the non-selection of the main word line MWLX is performed only in the row block R BLK in which the access request is generated.
- the selected main word line MWLX holds the selected state. Since the plurality of main word lines MWLX are not simultaneously deselected, the peak current due to charging / discharging of the main word line MWLX can be dispersed. Therefore, the voltage drop can be reduced as compared with the case where a plurality of main word lines MWLX are not simultaneously selected. In other words, the power supply wiring can be narrowed, and the pseudo SRAM chip size can be reduced. In addition, electoric port migration in the power supply wiring is less likely to occur, improving reliability.
- the main word line MWLX is not selected in synchronization with the completion of the refresh operation REF.
- the main word line MWLX is not selected by executing the access operation ACT (the seventh and eighth REFs)
- the main word line MWLX is selected only for the period of the refresh operation REF. Since the main word line MWLX is not selected after the refresh operation for each row block RBLK, the peak current due to charging / discharging of the main word line MWLX can be dispersed.
- the main word line MWLX has a long wiring length because it is connected to the sub word decoder SWD distributed in the memory core CORE. For this reason, the charge / discharge current generated when Z is not selected for main word line MW LX is large.
- the charge / discharge current of the main word line MWLX can be reduced, and the current consumption of the pseudo SRAM can be reduced. Further, since the main word line MWLX is selected and deselected for each row block RBLK, the peak current due to charging / discharging of the main word line MWLX can be dispersed.
- the reset control circuit 18 and the reset signal generation circuit 20 generate the reset signal RSTX common to the row block RBLK, and the block reset control circuit RSTC formed for each row block RBLK generates the block reset signal SRSTX As a result, the main word line MWLX selected in the row block RBLK accessed by the access request is changed. Can be easily deselected with a simple circuit.
- main word line MWLX for access is selected after the main word line MWLX for refresh is not selected, multiple selection of the word line SWL can be prevented. As a result, the malfunction of the pseudo SRAM can be prevented. Further, since it is not necessary to designate the main word line MWLX to be deselected, a circuit for deselecting the main word line MWLX can be simplified. By generating the entry pulse signal ENTPX in synchronization with the start of the refresh operation, the flip-flop 40 can be prevented from malfunctioning, and the reset inhibition signal NORSTZ can be reliably activated or deactivated.
- the main word line MWLX which no longer needs to be selected, can be deselected in synchronization with the completion of the refresh operation of the sub word line SWL3. Therefore, when the main word line MWLX is switched by updating the refresh address, it is possible to prevent the two main word lines MWLX from being simultaneously deselected and selected, and the switching control of the main word line MWLX can be simplified.
- the word line SWL is multiple-selected by deactivating the reset inhibit signal NORSTZ in response to the initialization signal CLRX. Therefore, it is possible to prevent the pseudo SRAM from malfunctioning.
- the main word line MWLX selected for refresh is deactivated in synchronization with the redundant hit signal RHITX output from the fuse circuit 34, so that the pseudo SRAM having the redundant main word line RM WLX has However, the selected state of the main word line MWLX selected by the refresh operation can be maintained, and the corresponding main word line MWLX can be deselected when the redundant main word line RMWLX is accessed. [0081] When the refresh address is repeatedly executed by assigning the refresh address IAL0-12Z to the row block RBLK, the sub-word line SWL, and the main word line MWLX in order from the lower bit, the switching frequency of the main word line MWLX And the current consumption of pseudo SRA M can be reduced.
- FIG. 12 shows the main part of the second embodiment of the semiconductor memory of the present invention.
- This semiconductor memory is formed as pseudo SRAM on a silicon substrate using a CMOS process. Pseudo SRAM is used for work memory installed in mobile devices such as mobile phones.
- This embodiment has a flip-flop 40A instead of the flip-flop 40 (FIG. 2) of the first embodiment. Other configurations are the same as those of the first embodiment.
- the threshold voltage force of the nMOS transistor of the NAND gate that receives the exit pulse signal EXITPX is set lower than the threshold voltage of other nMOS transistors.
- the threshold voltage of a part of the transistors existing in the signal path where the entry signal ENTPX force is also fed back to the input via the node ND2 is set lower than the threshold voltage of the other transistors. Therefore, the flip-flop 40A can reliably change the node ND2 to a low level even when it receives the entry pulse signal ENTPX having a narrow pulse width (active period). That is, in this embodiment, the state of the flip-flop 40A can be prevented from becoming unstable, and the output can be reliably inverted.
- the entry pulse signal ENTPX is generated using a plurality of signals WLS PX, CEX, REFZ, and WLCHCTLZ having different timings.
- the chip enable signal CEX and the internal refresh signal REFZ are generated asynchronously with each other, so the generation timing may be shifted. For this reason, the pulse width of the entry pulse signal ENTPX is easy to change. Therefore, by lowering the threshold voltage, the internal operation of the flip-flop 40A can be speeded up, and malfunction of the flip-flop 40A can be prevented.
- FIG. 13 shows an essential part of a third embodiment of the semiconductor memory of the present invention.
- This semiconductor memory is formed as pseudo-SRAM on a silicon substrate using a CMOS process. Pseudo SRAM is used for work memory installed in mobile devices such as mobile phones.
- This embodiment has a filter 42B instead of the filter 42 (FIG. 2) of the first embodiment. Other configurations are the same as those in the first embodiment.
- the filter 42B has an AND circuit that receives the node ND1 and the inverted logic of the node ND2.
- the filter effect is greater than that of the filter 42 of the first embodiment. That is, even when the entry pulse signal ENTPX has a plurality of fine pulses due to noise or the like, it is possible to prevent the pre-reset inhibition signal PNORSTZ from being activated.
- the filter 42B can surely remove noise added to the entry pulse signal ENTPX, that is, it can prevent malfunction of the pseudo SRAM.
- FIG. 14 shows a fourth embodiment of the semiconductor memory of the present invention.
- This semiconductor memory is formed as pseudo SRAM on a silicon substrate using a CMOS process.
- the pseudo SRAM is used, for example, as a work memory mounted on a mobile device such as a mobile phone.
- the pseudo SRAM includes an external command input circuit 10C, a refresh request generation circuit 12, a refresh address generation circuit 14, an arbiter Z operation control circuit 16, an external address input circuit 22, an external data input / output circuit 24, and an internal row address generation circuit. 26, predecoders 28C, 30, 32, fuse circuit 34, memory core CORE and test control circuit TC (first and second test control circuits).
- the external command input circuit 10C When the external command input circuit 10C receives a test command at the command terminal CMD, the external command input circuit 10C activates one of the test activation signal signals TM1Z and TM2Z according to the test command, and receives the test release command. When activated, the test activation signals TM1Z and TM2Z are deactivated.
- the pseudo SRAM shifts to the normal operation mode test mode when it receives a test command, and shifts from the test mode to the normal operation mode when it receives a test release command.
- Other functions of the external command input circuit 10C are the same as those of the external command input circuit 10 of the first embodiment.
- the predecoder 28C is different from the predecoder 28 of the first embodiment in that it generates a pulsed predecode signal X23PZ ⁇ 0: 3>.
- the word decoder WDEC is different from that of the first embodiment.
- the test control circuit TC activates the first test signal TOPENZ and the second test signal TSWLZ in response to the activation of the test activation signals TM1Z and TM2Z, respectively. Other configurations are the same as those in the first embodiment.
- FIG. 15 shows details of the word decoder WDEC shown in FIG.
- the difference from the word decoder WDEC (Fig. 5) in the first embodiment is that it does not receive the reset signal RSTX, the block latch control circuit RSTC uses the address latch signal AINZ, instead of the circuit that outputs the block reset signal SRSTX, Having an address latch control circuit ALC that outputs AINX, having an address latch circuit ADLT that latches the predecode signals X67Z ⁇ 0: 3>, X89Z ⁇ 0: 3>, X101112Z ⁇ 0: 7>, and main
- the word decoder MWD and the redundant main word decoder RMWD are different.
- Other configurations are the same as those in the first embodiment.
- the row block selection signal RBLKSELPZ has a pulse waveform that is synchronized with the pulsed predecode signal X23PZ 0: 3>.
- the address latch control circuit ALC generates address latch signals AINZ and AINX in synchronization with the pulse-like row block selection signal RBLKSELPZ.
- the address latch signals AINZ and AINX are complementary to each other.
- the address latch circuit ADLT passes through the predecode signals X67Z, X89Z, and X101112Z and outputs them to the main word decoder MWD as the latch decode signals LX67Z, LX89Z, and LX101112Z when the address latch signal AINZ is high.
- the predecode signals X67Z, X89Z, and X101112Z are latched in synchronization with the change of AINZ to a low level.
- the main word decoder MWD selects the main word line MWLX using latch decode signals LX67Z, LX89Z, and LX101112Z.
- FIG. 16 shows details of the address latch control circuit ALC and the address latch circuit ADLT. is doing.
- the address latch control circuit ALC outputs the low level address latch signal AINX and the high level address latch signal AINZ while the row block selection signal RBLKSELPZ or the first test signal TOPENZ is high level.
- the first test signal TOPENZ is a signal common to the address latch control circuit ALC of the row blocks RBLK0-15.
- the first test signal TOPENZ is activated when the main word lines MWLX of a plurality of row blocks RBLK are simultaneously selected in the test mode in order to perform a word line multiple selection test or a disturb test.
- the word lines MWLX and SWL adjacent to the focused word lines MWLX and SWL are selected, and the influence on the focused word lines MWLX and SWL is examined.
- the first test signal TOPENZ is fixed at a low level in the normal operation mode.
- the address latch circuit ADLT is turned on when the address latch signal AINZ is at a high level and transmits a predecode signal ( ⁇ 67 ⁇ ⁇ 0>, etc.), and a latch connected to the output of the CMOS transmission gate. And an AND circuit that outputs a latch decoding signal (LX67X ⁇ 0>, etc.) with one input connected to the output of the latch.
- the latch is activated while the address latch signal AINZ is low and holds the received predecode signal.
- the AND circuit outputs a positive logic latch decode signal (LX67Z ⁇ 0> etc.).
- the other input of the AND circuit receives the second test signal TSWLZ via an inverter.
- the second test signal TSWLZ is a signal common to the address latch circuits ADLT and all the main word decoders MWD of all the row blocks RBLK0-15.
- the second test signal TSWLZ is activated when all the main word lines MWLX are selected in the test mode in order to efficiently execute the burn-in test mode.
- the second test signal T SWLZ is fixed at a low level in the normal operation mode.
- FIG. 17 shows details of the main word decoder MWD and the redundant main word decoder RMWD.
- latch decode signals LX67Z, LX89Z, and LX101112Z indicate one of the latch decode signals LX67Z ⁇ 0: 3>, LX89Z ⁇ 0: 3>, and LX101112Z ⁇ 0: 7>, respectively.
- the common circuit COM is a circuit common to the main word decoders MWD and RMWD.
- the common circuit COM is the level converter LEVC 1 for the main word decoder MWD and the level converter for the redundant main word decoder RMWD. Have LEVC2! /
- the level converter LEVC1 converts the high level of the latch decode signal LX67Z from the internal power supply voltage VII to the boost voltage VPP to generate the latch decode signal PRLX67Z.
- the level converter LEVC1 fixes the latch decode signal PRLX67Z to a low level in order to select all the main word lines MWLX during the activation of the redundant hit signal RHITX.
- the latch decode signal RLX67Z is generated in response to the latch signal LX67Z during the inactive state of the redundant hit signal RHITX.
- the level converter LEVC2 converts the high level of the redundancy selection signal RWSZ (RWSOZ—RWS 15Z shown in Fig. 3! Or the second test signal TSWLZ from the internal power supply voltage VII to the boost voltage VPP, and selects the redundancy. Output as signal PRWSZ.
- the main word decoder MWD includes a pMOS transistor that receives the latch decode signal PRLX67Z at the gate, an nMOS transistor that receives the latch decode signals RLX67Z, LX89Z, and LX101112Z at the gate, and a latch connected to the drain of the pMOS transistor. And a reset circuit which also has an nMOS transistor power connected to the output of the latch and receiving latch decode signals LX89Z and LX101112Z at the gates.
- the pMOS transistor and the nMOS transistor that receive the latch decode signals PRLX67Z, RLX67Z, LX89Z, and LX101112Z are connected in series between the boost power supply line VPP and the ground line VSS.
- the output of the latch is connected to the main word line MWLX via an inverter. When the reset circuit (nMOS transistor) is turned on, the main word line MWLX is not selected.
- the redundant main word decoder RMWD is the same circuit as that of the first embodiment (FIG. 6). For this reason, defect relief is performed in units of main word lines MWLX. Redundant main word decoder RMWD pMOS transistor receives redundant selection signal PRWSZ at its gate. The nMOS transistor of the redundant main word decoder RMWD receives the redundant selection signal RWSZ and internal power supply voltage VII at the gate.
- the latch decode signal PRLX67Z and the redundancy selection signal PRWSZ are the only signals that use the boost voltage VPP at a high level. By minimizing the signal that uses the boost voltage VPP, the power consumption of the boost circuit that generates the boost voltage VPP can be reduced. wear. As a result, in particular, the standby current of the pseudo SRAM can be reduced.
- FIG. 18 shows operations of the main word decoder MWD and the redundant main word decoder RMWD when a read operation or a write operation is executed in the fourth embodiment. Detailed descriptions of the same operations as those in FIG. 7 are omitted. In this example, the case where the redundant hit signal RHITX without a defect in the main word line MWLX or the memory cell MC is not activated! / Is shown.
- the access signal ACTPZ is activated (FIG. 18 (a)).
- the predecode signals X67Z, X89Z, and X101112Z to be accessed (ACT) are activated in synchronization with the activation of the access signal ACTPZ (Fig. 18 (b)).
- the internal row address generation circuit 26 holds for the refresh operation !, and the row address RAO—12Z (internal address IALO—12Z) switches, so the refresh target (REF) predecode signals X67Z, X89Z, X101112Z force S is deactivated (Fig. 18 (c)).
- the row block selection signal RBLK SELPZ is activated, and the address latch signal AINZ is activated in synchronization with the row block selection signal RBLKSELPZ (Fig. 18 (d)).
- the address latch circuit ADLT of the row block RBLK that executes the access operation latches the predecode signals X67Z, X89Z, and X101112Z, and outputs them as latch decode signals LX67Z, LX89Z, and LX101112Z (FIG. 18 (e)).
- the latch decode signals LX67Z, LX89Z, LX101112Z, and PRL X67Z that are activated to perform the refresh operation are deactivated.
- the selected main word line MWLX is deselected (Fig. 18 (f)).
- the latch decode signals LX67Z, LX89Z, LX101112Z, and PRLX67Z to be accessed (ACT) are activated, and the main word line MWLX for executing the access operation is not selected (FIG. 18 (g)). Since the main word line MWLX is not selected and is selected at the same time, the time from the activation of the access signal ACTPZ to the selection of the main word line MWLX is T2, which is shorter than T1 in the first embodiment.
- the row block selection signal RB Since LKSELPZ is not activated and the address latch signals AINZ and AINX are not output, the address latch circuit ADLT continues to activate the latch decode signals LX67Z, LX89Z, and LX101112Z for executing refresh. In other words, the main word line MWLX to be refreshed is deselected only in the row block RBLK for which an access request has occurred.
- FIG. 19 shows another example of the operation of the main word decoder MWD and redundant main word decoder RMWD when a read or write operation is performed!
- the main word line MWLX or the memory cell MC has a defect, and the redundant hit signal RHITX is activated.
- Detailed descriptions of the same operations as those in Fig. 18 are omitted.
- the fuse circuit 34 receives the row address RA6-12Z and activates the redundant hit signal RH ITX (FIG. 19 (a)).
- the activation of the redundant hit signal RHITX deactivates the latch decode signal PRLX67Z that is activated / refreshed for the refresh operation (Fig. 19 (b)).
- the redundancy selection signal RWSZ (not shown) is activated, and the redundancy main word line RMWLX is selected (FIG. 19 (c)).
- the time from the activation of the access signal ACTPZ to the selection of the redundant main word line RMWLX is equal to T1 in the first embodiment. A shorter T2.
- the address latch circuit ADLT uses the latch decode to execute refresh. Continue to activate signals LX67Z, L X89Z, and LX101112Z. That is, the non-selection of the main word line MWLX to be refreshed is performed only in the row block RBLK where the access request has occurred.
- FIG. 20 shows the operation of the memory core CORE in the fourth embodiment. Detailed description of the same operation as in FIG. 11 is omitted.
- FIG. 20 shows the operation of the memory core CORE in the fourth embodiment. Detailed description of the same operation as in FIG. 11 is omitted.
- FIG. 20 shows the operation of the memory core CORE in the fourth embodiment. Detailed description of the same operation as in FIG. 11 is omitted.
- FIG. 11 an example with four core blocks RBLK0-3 and two sub word lines SWL0-1 is shown! / RU Number assigned to refresh signal REFPZ Indicates the number of the row block RBLK where the refresh operation REF is executed! /
- This embodiment is different from the first embodiment in the following points.
- the main word line MWLX selected for the refresh operation is deselected and the main word line MWLX for the access operation is simultaneously selected.
- the main word line MWLX continues to be selected until the next operation is executed.
- the refresh operation of the last sub word line SWL1 (actually SWL3)
- the main word line MWLX continues to be selected even after REF.
- the address latch circuit ADL T is formed corresponding to the decode signals X67Z ⁇ 0: 3>, X89Z ⁇ 0: 3>, and X101112Z ⁇ 0: 7> for selecting the main word decoder MWD.
- the word line MWLX can be selected or not selected according to the latch decode signals LX67Z, LX89Z, and LX101112Z held in the address latch circuit ADLT. Therefore, the state of the address latch circuit ADLT changes according to the external address EAL supplied in response to the access request, so that the main word line MWLX selected for refresh can be deselected and at the same time the main address for access Word line MWLX can be selected.
- the circuit for generating the reset inhibition signal PNORSTZ, the reset signal RSTX, and the block reset signal SRSTX of the first embodiment is not necessary. That is, a simple logic circuit can maintain the selected state of the main word line MWLX after the refresh operation, and can switch the main word line MWLX to be selected in response to an access request for each memory block. Since the circuit configuration is simplified, the operation verification time during circuit design can be shortened. Unselection of two main word lines MWLX Since Z selection can be switched at the same time, the access demand can also shorten the time T2 until the access operation starts. That is, the access time can be shortened.
- the first test signal TOPENZ common to the address latch control circuit ALC is activated and the address latch signals AIN Z and AINX are generated in synchronization with the activation of the first test signal TOPENZ.
- the address latch circuit ADLT of each row block RBLK can be operated simultaneously.
- a multiple selection test and a disturb test can be performed on the word line SWL.
- the second test signal TSWLZ common to the main word decoder MWD By activating the second test signal TSWLZ common to the main word decoder MWD during the test mode, all the main word lines MWLX are synchronized with the activation of the second test signal TSWLZ. You can select at the same time. As a result, the test time for the burn-in test can be shortened.
- FIG. 21 and FIG. 22 show the main part of the fifth embodiment of the semiconductor memory of the present invention.
- This semiconductor memory is formed as a pseudo-RAM on a silicon substrate using a CMOS process. Pseudo SRAM is used for work memory installed in mobile devices such as mobile phones.
- This embodiment is different from the fourth embodiment in the address latch circuit ADLT, the main word decoder MWD, and the redundant main word decoder RMWD. Other configurations are the same as those in the first embodiment.
- the operations of the main word decoder MWD and redundant main word decoder RMWD and the operation of the memory core CORE are the same as those in the fourth embodiment (FIGS. 18 to 20).
- the address latch circuit ADLT receives a predecode signal (X67Z ⁇ 0>, etc.) when the address latch signal AINZ is high, and a signal received when the address latch signal AINZ is low. Is a differential input type latch that holds The received predecode signal is output as a latch decode signal (LX67X ⁇ 0> etc.).
- the address latch circuit ADLT has a level shifter that converts the high level of the received predecode signal from the internal power supply voltage VII to the boosted voltage VPP. That is, the high level of all latch decode signals output from the address latch circuit ADLT is set to the boost voltage VPP.
- the main word decoder MWD has a redundant hit in which the latch decode signals PLX67Z, PLX89Z, PLX101112Z whose high level is set to the boost voltage VPP and the high level is converted to the boost voltage VPP by the level converter LEVC. It consists of a 4-input NAND gate that receives the signal RHITX and two inverters connected in series. The final inverter is connected to the main word line MWLX.
- the redundant main word decoder RMWD is the same circuit as the main word decoder MWD.
- the 4-input NAND gate of the redundant main word decoder RMWD receives the boost voltage VPP and the redundancy selection signal RWSZ whose high level is converted to the boost voltage VPP by the level converter LEVC.
- the final stage inverter is connected to the redundant main word line RMWLX.
- the main word decoder MWD and redundant main word decoder RMWD are configured with simple logic gates by aligning the high level voltage of all latch decode signals (PLX67Z, etc.) with the boost voltage VPP. it can.
- the main word decoder MWD is a circuit formed in large numbers in the memory core CORE, and the chip size reduction effect is significant by simplifying the circuit of the word decoder MWD.
- the same effect as in the first and fourth embodiments can be obtained. Furthermore, by forming a level shifter in the address latch circuit ADLT, the address voltage (high level voltage) supplied to the main word decoder MWD and the redundant main word decoder RMWD can all be set to the same value. As a result, the main word decoder MWD and the redundant main word decoder RMWD can be easily configured, and the chip size of the pseudo SRAM can be reduced. As a result, the chip cost can be reduced.
- FIG. 23 shows a sixth embodiment of semiconductor memory according to the present invention.
- This semiconductor memory is formed as pseudo SRAM on a silicon substrate using a CMOS process.
- the pseudo SRAM is used, for example, as a work memory mounted on a mobile device such as a mobile phone.
- the pseudo SRAM of this embodiment has two banks BANK0-1 having memory cores CORE operating independently of each other, and a bank decoder 46 for selecting the bank BANK0-1.
- the external address input circuit 22D is configured by adding an input buffer for receiving the 1-bit bank address BA0 to the external address input circuit 22 of the first embodiment.
- the bank decoder 46 generates bank selection signals BRAS0Z and BRAS1Z from the bank address BA0 in synchronization with the basic timing signal RASZ.
- Each bank BANK0-1 includes a reset signal generation circuit (reset inhibition control circuit) 20, a predecoder 28D for selecting a row block RBLK, a predecoder 30D for selecting a main word line MWLX, a predecoder 32, and The memory core CORE of the first embodiment is included.
- the reset signal generation circuit 20 operates by receiving a bank selection signal BRAS0Z (or BRAS 1Z) instead of the basic timing signal RASZ. That is, the reset signal generation circuit 2 formed in each bank BANK0-1 With 0, only the bank BANK that received the access request activates the reset signal RSTX in response to the deactivation signal of the reset inhibit signal NORSTZ.
- the predecoders 28D and 30D are the same as the predecoders 28 and 30 of the first embodiment except that they have a latch function. Other configurations are the same as those in the first embodiment.
- FIG. 24 shows details of the bank BANKO-1 shown in FIG.
- Each bank BANKO — 1 has a timing control circuit 48. Since bank BANKO-1 has the same configuration, only bank BANKO will be described.
- the timing control circuit 48 activates the bank active signal BACTPOZ for a predetermined period in synchronization with the rising edge of the bank selection signal BRASOZ.
- the predecoders 28D and 30D receive the row addresses RAO-3Z and RA6-12Z during the high level period of the bank active signal BACTPOZ, and latch the received signals in synchronization with the falling edge of the bank active signal BACTPOZ.
- FIG. 25 shows the operation of the pseudo SRAM of the sixth embodiment.
- a feature of this embodiment is that the reset signal RSTX is generated only in the bank BANK that requested access. Therefore, the non-selection of the main word line MWL X that has been selected for the refresh request is performed only in the row block RBLK for which an access request has been issued in synchronization with the activation of the block reset signal SRSTX (FIG. 25). (a, b)). The reset signal RSTX is activated in response to the deactivation of bank BANK (Fig. 25 (c)). The block reset signal SRSTX is deactivated in response to the deactivation of the row block RBLK due to the deactivation of the bank BANK (Fig. 25 (d)).
- the reset signal generation circuit 20 formed in each bank BANKO-1 transmits the reset signal RSTX only to the bank BANK selected according to the bank address, so that when each bank BANK receives an access request, The main word line MWLX can be deselected independently. In bank BANK, which is not involved in access requests, unnecessary deselection of main word line MWLX can be prevented, thus reducing power consumption.
- FIG. 26 shows a seventh embodiment of the semiconductor memory of the present invention.
- This semiconductor memory is formed as pseudo-SRAM on a silicon substrate using a CMOS process. It is. Pseudo SRAM is used, for example, for work memory installed in mobile devices such as mobile phones.
- the pseudo SRAM of this embodiment has two banks BANK0-1 having memory cores CORE operating independently of each other, and a bank decoder 46 for selecting the bank BANK0-1.
- the predecoder 30 for selecting the main word line MWLX is formed in common in the banks BANK0-1.
- the predecoder 30 does not have a latch function.
- a predecoder 28E for selecting the row block RBLK is formed for each bank BANK 0-1.
- Other configurations are the same as those of the fourth embodiment.
- FIG. 27 shows details of the bank BANK0-1 shown in FIG.
- Each bank BANK0-1 has the same timing control circuit 48 as in the sixth embodiment and the same block reset control circuit RSTC as in the fourth embodiment.
- the predecoder 28E is composed of a predecoder 28E-1 common to the banks BAN0-1 and a predecoder 28E-2 formed in each bank BANK0-1.
- the predecoder 28E-1 predecodes the row address RA2-3Z and generates a decode signal X23Z 0: 3>.
- Decode signal X23Z 0: 3> is not a pulse signal, unlike decode signal X23PZ ⁇ 0: 3> in the fourth embodiment!
- the predecoder 28E-2 receives the row address RA0-1Z during the high level period of the bank active signal BACTP0Z (or BACTP1Z) and generates the bank decode signal BX01Z 0: 3>.
- the row block selection signal RBLKSELPZ is selected by the NAND logic of the bank decode signal X01Z ⁇ 0: 3> and the predecode signal X23Z ⁇ 0: 3>.
- the address latch signals AINZ and AINX are generated in synchronization with the block reset control circuit RSTC power low block selection signal RBLKSELPZ.
- the pseudo SRAM of this embodiment is similar to the fourth embodiment (Fig. 15).
- Each row block RBLK of the bank BANK0-1 is pre-decoded with the pre-decode signal pre-synchronized with the address latch signals AINZ and AINX. It has an address latch circuit ADLT that latches the decode signals X67Z, X89Z, and X101112Z.
- the address latch signals AINZ and AINX are activated only in the bank BANK selected according to the bank address BA0-1Z. Not selected! Address latch circuit ADLT in bank BANK does not latch!
- predecode signal for selecting main word line MWLX X67Z ⁇ 0: 3>, X89Z ⁇ 0: 3>, X101112Z ⁇ 0 : 7> Can be wired in common to the address latch circuit ADLT of bank BANKO-1.
- the signal line of the predecode signal X23Z ⁇ 0: 3> Can be wired in common to the address latch circuit ADL T in bank BANKO-1.
- the number of predecode signal lines wired to the bank BANKO-1 can be reduced from 48 to 28 in the sixth embodiment.
- FIG. 28 shows an operation of the pseudo SRAM according to the seventh embodiment.
- the feature of this embodiment is that the non-selection of the main word line MWLX that is continuously selected for the refresh request is performed in synchronism with the activation of the block reset signal SRSTX in the row block RBLK of the bank BAN K that requested the access. (Fig. 28 (a, b)).
- the same effect as in the first, fourth, and sixth embodiments can be obtained.
- only the address latch circuit ADLT of the bank BANK selected according to the bank address BAO can latch the external address EAL, so that the main word line MWLX can be selected and deselected independently for each bank BANK.
- the bank BANK which is not involved in access requests, can prevent unnecessary deselection of the main word line MWLX, thus reducing power consumption.
- the address latch signals AINZ and AINX can be generated using only the non-bank BANK that received the access request. Unselected bank BANK address latch circuit ADLT does not latch! Therefore, predecode signals X67Z ⁇ 0: 3>, X89Z> 0: 3>, X101112Z ⁇ 0: 7> signal lines are connected to bank BANKO— 1 can be wired in common. As a result, the number of signal lines for the predecode signals X23PZ, X67Z, and X101112Z can be almost halved, and the chip size of the pseudo SRAM can be reduced.
- FIG. 29 shows the main part of the eighth embodiment of the semiconductor memory of the present invention.
- This semiconductor memory is formed as pseudo-SRAM on a silicon substrate using a CMOS process. Pseudo SRAM is used for work memory installed in mobile devices such as mobile phones.
- This embodiment is a substitute for the refresh address generation circuit 14 of the first embodiment. Instead, it has a refresh address generation circuit 14A. Further, the word decoder WDEC is different from that of the first embodiment. Other configurations are the same as those in the first embodiment.
- the refresh address generation circuit 14A is different from the first embodiment in address assignment. That is, of the refresh addresses IAL0-12Z, the lower 4 bits IALO-3Z are used to select the row block RBLKO-15, and the next 7 bits are used to select the main word line MWLX. The upper 2 bits are used to select the sub word line SWL.
- the 13-bit refresh address is assigned to IALO-3Z (row block selection address), IAL6-12Z (main word selection address), and IAL4 in order from the lower order. — 5Z (subword selection address).
- the refresh address generation circuit 14A outputs a refresh address for selecting the last main word line MWLX127 out of 128 main word lines MWL XO-127 (both bits IAL6-12Z are both high). During the level period), the refresh counter signal SRTXZ is held high. Other functions of the refresh address generation circuit 14A are the same as those of the refresh address generation circuit 14 of the first embodiment.
- FIG. 30 shows a main part of the memory core CORE shown in FIG.
- the word decoder WD EC selects the sub word selection decoder SWDgen for selecting the sub word selection signal SWDZ 0: 3> (sub word selection signal line) according to the decode signal X45Z ⁇ 0: 3> for each row block RBLK0-15.
- the sub word selection signals SWDZ 0: 3> are supplied to sub word decoders SWD arranged in a distributed manner in each block RBLK.
- Other configurations are the same as those of the first embodiment (FIG. 4). Since the sub word selection signal line SW DZ is connected to the sub word decoder SWD distributed in the row block RBLK, its wiring length is long.
- FIG. 31 shows details of each word decoder WDEC shown in FIG. Block reset control circuit RSTC timing signal generation circuit
- the block reset signal SRSTX is supplied to the sub word selection decoder SWDgen, which is not the main word decoder MWD.
- the subword selection decoder SWDgen generates a subword selection signal SWDZ ⁇ 0: 3> in response to the decode signal x45Z ⁇ 0: 3>.
- the subword selection decoder SWDgen selects (activates) the subword selection signal SWDZ and deselects the subword selection signal SWDZ in response to the activation of the block reset signal SRSTX.
- Other configurations are the same as those of the first embodiment (FIG. 5).
- FIG. 32 shows details of the subword selection decoder SWDgen.
- the subword selection decoder SWDgen has a pMOS transistor and nMOS transistor that receive the block reset signal PRSTX at the gate, an nMOS transistor that receives the predecode signal X45Z at the gate, a latch connected to the drain of the pMOS transistor, and the latch output. It has a buffer consisting of two connected inverters!
- the power supply line of the sub-word selection decoder SW Dgen is connected to the boost voltage line VPP.
- FIG. 33 shows an operation of the sub word selection decoder SWDgen when a read operation or a write operation is executed in the eighth embodiment.
- This example shows a case where the redundant hit signal RHITX in which there is no defect in the main node line MWLX or the memory cell MC is not activated.
- the same operations as those in the first embodiment (FIG. 7) are denoted by the same reference numerals.
- the difference from the first embodiment is that, in response to the block reset signal SRSTX, the sub-word selection signal SWDZ which is not selected and selected is not selected and selected.
- the pMOS transistor of the sub-word selection decoder SWDgen is turned on, and the sub-word selection signal SWDZ that continues to be selected to perform the refresh operation is deselected (see FIG. 33 (F)).
- the subword selection signal SWDZ corresponding to the access request is selected and the access operation is executed (Fig. 33 (I)).
- the pMOS transistor of the subword selection decoder SWDgen is turned on and selected for access operation !, and the subword selection signal SWDZ is deactivated (Fig. 7 ( M)). From activation of access signal ACTPZ The time until selection of the subword selection signal SWDZ is T3. Time ⁇ 3 is substantially the same as time T1 in the first embodiment (FIG. 7). Other operations are the same as those in the first embodiment.
- FIG. 34 shows operations of the arbiter / operation control circuit 16, reset control circuit 18 and reset signal generation circuit 20 in the eighth embodiment.
- the order of the word lines selected in response to the refresh request is different from that of the first embodiment (FIG. 10). That is, in this embodiment, for each refresh request, the row block RBLK is switched first, then the main word line MWLX is switched, and finally the sub word line SWL is switched. Further, while the refresh address generation circuit 14 outputs the high-level refresh counter signal SRTXZ, that is, while the last main word line MWLX1 27 is specified by the refresh address, the reset signal RSTX generates the refresh request SRTZ. Output every time. Other operations are the same as those in the first embodiment.
- the charge / discharge current can be reduced, and the power consumption of the pseudo SRAM can be reduced.
- FIG. 35 shows the essential parts of a ninth embodiment of semiconductor memory according to the present invention.
- This semiconductor memory is formed as pseudo SRAM on a silicon substrate using a CMOS process. Pseudo SRAM is used for work memory installed in mobile devices such as mobile phones.
- This embodiment has a refresh address generation circuit 14A in place of the refresh address generation circuit 14 of the fourth embodiment.
- the refresh address generation circuit 14A is the same as that in the eighth embodiment.
- the word decoder WDE C is different from that of the fourth embodiment.
- Other configurations are the same as those of the fourth embodiment.
- FIG. 36 shows details of the word decoder WDEC shown in FIG.
- the mode decoder WDEC shown in FIG. 36 is formed in each row block RBLK0-15.
- the word decoder WDEC uses four subword selection decoders SW Dgen and subword selection decoder SWDgen to select the subword selection signal SWDZ 0: 3> (subword selection signal line) according to the decode signal X45Z ⁇ 0: 3>.
- an address latch circuit ADLT an address latch circuit
- Address latch circuit ADLT synchronizes the predecode signal ⁇ 67 ⁇ ⁇ 0: 3>, ⁇ 89 ⁇ ⁇ 0: 3>, ⁇ 101112 ⁇ ⁇ 0: 7>, and the predecode signal ⁇ 45 ⁇ ⁇ 0: 3> to the address latch signal ⁇ , ⁇ Latch and output the latch decode signal LX45Z 0: 3>.
- the timing signal WLENZ generated by the timing signal generation circuit TSC of the block reset control circuit RST C is supplied to the main word decoder MWD.
- Other configurations are the same as those of the fourth embodiment (FIG. 15).
- the> is connected to the sub word decoder SWD distributed in the row block RBLK, so that the wiring length is long. For this reason, a large charge / discharge current occurs due to the selection Z deselection of the subword selection signal line SWDZ.
- the charge / discharge current is reduced and the power consumption is reduced.
- FIG. 37 shows details of the address latch control circuit ALC and the address latch circuit ADLT.
- the address latch control circuit ALC is the same as that of the fourth embodiment (FIG. 16).
- the address latch circuit ADLT is configured by changing the logic of the address latch circuit ADLT (FIG. 16) of the fourth embodiment in order to output a positive logic latch decode signal LX45Z ⁇ 0: 3>.
- the address latch circuit ADLT fixes all the latch decode signals LX45Z ⁇ 0: 3> to high level when the second test signal TSWLZ is high level.
- FIG. 38 shows details of the subword selection decoder SWDgen.
- the sub-word selection decoder SWDgen has a level converter LEVC1 and a buffer that also has two inverters connected to the output of the level converter LEVC1.
- the power line of the subword selection decoder SWDgen is connected to the boost voltage line VPP.
- the level converter LEVC1 converts the high level of the latch decode signal LX45Z from the internal power supply voltage VII to the boost voltage VPP and outputs it to the buffer.
- FIG. 39 shows an operation of the sub word selection decoder SWDgen when a read operation or a write operation is executed in the ninth embodiment.
- the redundant hit signal RHITX that activates the main node line MWLX or the memory cell MC is activated. The case where it is not displayed is shown.
- the same operations as those in the fourth embodiment (FIG. 18) are denoted by the same reference numerals.
- the difference from the fourth embodiment is that, in response to the block reset signal SRSTX, the sub word selection signal SWDZ, which is not the main word line MWLX, is not selected or selected.
- the subword selection signal SWDZ that has been selected to perform the refresh operation is deselected (FIG. 39 (F)), and at the same time, the access request is responded.
- Sub-node selection signal SWDZ is selected (Fig. 39 (G)).
- the time from activation of access signal ACTPZ to selection of subword selection signal SWDZ is T4.
- Time T4 is almost the same as time T2 in the fourth embodiment (Fig. 18). Since the sub-word selection signal SWDZ is not selected and selected simultaneously, the time from the activation of the access signal ACTPZ to the selection of the sub-word selection signal SWDZ is T4 shorter than T3 in the eighth embodiment.
- Other operations are the same as those in the fourth embodiment.
- FIG. 40 shows the operation of the memory core CORE in the ninth embodiment.
- the memory core CORE has four row blocks RBLK0—3, two main node lines MWLX0—1, and two sub word lines SWL0—1! /.
- the number attached to the refresh signal REFPZ indicates the number of the row block RBLK where the refresh operation REF is executed.
- the refresh address IAL0-12Z generated by the refresh address generation circuit 14A first switches the row block RBLK, then switches the main word line MWLX, and finally switches the sub-word line SWL ( Subword decoder SWD) is switched. Therefore, every time a refresh request is made, the sub word selection signal SWDZ in the row blocks RBLK0-3 is sequentially selected on the main word line MWLX. Other operations are almost the same as those in the fourth embodiment.
- the same effect as in the first, fourth, and eighth embodiments can be obtained. That is, by reducing the frequency of selection Z deselection of the subword selection signal line SWDZ, the charge / discharge current can be reduced and the power consumption of the pseudo SRAM can be reduced.
- the present invention is applied to a pseudo SRAM having hierarchical word lines MWLX and SWL has been described. That is, the main word line MWLX, which is selected for the refresh operation, is requested to be accessed for each row block RBLK.
- An example of non-selection in response to was described.
- the invention is not limited to the powerful embodiments. For example, as shown in FIGS.
- the present invention may be applied to a pseudo SRAM having a non-hierarchized V ⁇ word line WL (or redundant word line RWL). That is, the first word decoder WD1 that receives the predecode signal and generates the decode signal WDS, and the second word decoder WD2 that receives the decode signal WDS and the row address RA4-5Z and selects one of the word lines WL
- the decode signal WDS that is continuously selected for the refresh operation may be deselected in response to the access request for each row block RBLK.
- the word lines WL that are not hierarchized are generally composed of a polysilicon wiring for forming the gate of the transfer transistor of the memory cell MC and a metal wiring running on the polysilicon wiring.
- the example in which the sub word line SWL3 is not selected every refresh of the main word line MWLX when the sub word line SWL3 is a refresh target has been described.
- the present invention is not limited to such embodiments.
- the sub word line SWLO becomes a refresh target
- the main word line MWLX that has been selected until then may be deselected and a new main word line MWLX to be refreshed may be selected.
- the example in which the predecode signal is latched by the address latch circuit ADLT in order to keep the main word line MWLX activated is described.
- the invention is not limited to the powerful embodiments.
- the next external address EAL or refresh address IAL is received, and the redundancy of the received address is judged. By determining the redundancy of the next refresh operation or access operation during the refresh operation or access operation, the cycle time can further shorten the access time.
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Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
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PCT/JP2004/011267 WO2006013632A1 (ja) | 2004-08-05 | 2004-08-05 | 半導体メモリ |
JP2006531067A JP4579247B2 (ja) | 2004-08-05 | 2004-08-05 | 半導体メモリ |
CN200480043556A CN100592420C (zh) | 2004-08-05 | 2004-08-05 | 半导体存储器 |
US11/641,767 US7379370B2 (en) | 2004-08-05 | 2006-12-20 | Semiconductor memory |
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PCT/JP2004/011267 WO2006013632A1 (ja) | 2004-08-05 | 2004-08-05 | 半導体メモリ |
Related Child Applications (1)
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US11/641,767 Continuation US7379370B2 (en) | 2004-08-05 | 2006-12-20 | Semiconductor memory |
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WO2006013632A1 true WO2006013632A1 (ja) | 2006-02-09 |
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PCT/JP2004/011267 WO2006013632A1 (ja) | 2004-08-05 | 2004-08-05 | 半導体メモリ |
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US (1) | US7379370B2 (ja) |
JP (1) | JP4579247B2 (ja) |
CN (1) | CN100592420C (ja) |
WO (1) | WO2006013632A1 (ja) |
Cited By (3)
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JP2008084428A (ja) * | 2006-09-27 | 2008-04-10 | Fujitsu Ltd | 半導体メモリおよびシステム |
JP2009043373A (ja) * | 2007-08-10 | 2009-02-26 | Fujitsu Microelectronics Ltd | 半導体記憶装置及びワードデコーダ制御方法 |
CN1851825B (zh) * | 2006-05-10 | 2010-05-12 | 威盛电子股份有限公司 | 高效能存储器及相关方法 |
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Publication number | Priority date | Publication date | Assignee | Title |
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US7444577B2 (en) * | 2005-08-04 | 2008-10-28 | Rambus Inc. | Memory device testing to support address-differentiated refresh rates |
JP4816911B2 (ja) * | 2006-02-07 | 2011-11-16 | 日本電気株式会社 | メモリの同期化方法及びリフレッシュ制御回路 |
JP4813937B2 (ja) * | 2006-03-20 | 2011-11-09 | ルネサスエレクトロニクス株式会社 | 半導体装置 |
KR100878307B1 (ko) * | 2007-05-11 | 2009-01-14 | 주식회사 하이닉스반도체 | 멀티 워드라인 테스트 제어 회로 및 그의 제어 방법 |
CN102194513B (zh) * | 2010-03-11 | 2013-07-31 | 复旦大学 | 自动调整存储器刷新操作频率的电路、方法及其存储器 |
US8547777B2 (en) * | 2010-12-22 | 2013-10-01 | Intel Corporation | Nor logic word line selection |
JP5932236B2 (ja) * | 2011-04-13 | 2016-06-08 | ピーエスフォー ルクスコ エスエイアールエルPS4 Luxco S.a.r.l. | 半導体装置及びシステム |
KR20130117424A (ko) * | 2012-04-17 | 2013-10-28 | 삼성전자주식회사 | 반도체 메모리 장치의 리프레쉬 회로 |
KR20160119588A (ko) * | 2015-04-06 | 2016-10-14 | 에스케이하이닉스 주식회사 | 반도체 메모리 장치 |
KR102550685B1 (ko) * | 2016-07-25 | 2023-07-04 | 에스케이하이닉스 주식회사 | 반도체장치 |
KR102471500B1 (ko) * | 2018-03-12 | 2022-11-28 | 에스케이하이닉스 주식회사 | 반도체 장치 및 이를 포함하는 테스트 시스템 |
KR102627228B1 (ko) * | 2018-09-14 | 2024-01-22 | 에스케이하이닉스 주식회사 | 반도체 장치의 퓨즈 래치 |
US10998022B2 (en) * | 2019-08-16 | 2021-05-04 | Micron Technology, Inc. | Apparatuses and methods for reducing access device sub-threshold leakage in semiconductor devices |
CN113129976B (zh) * | 2021-06-17 | 2021-09-03 | 中天弘宇集成电路有限责任公司 | 行译码电路及存储器 |
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- 2004-08-05 WO PCT/JP2004/011267 patent/WO2006013632A1/ja active Application Filing
- 2004-08-05 CN CN200480043556A patent/CN100592420C/zh not_active Expired - Fee Related
- 2004-08-05 JP JP2006531067A patent/JP4579247B2/ja not_active Expired - Fee Related
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2006
- 2006-12-20 US US11/641,767 patent/US7379370B2/en active Active
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JPH08315598A (ja) * | 1995-05-12 | 1996-11-29 | Mitsubishi Electric Corp | テスト機能内蔵メモリ集積回路 |
JPH08315569A (ja) * | 1995-05-16 | 1996-11-29 | Hitachi Ltd | 半導体記憶装置、及びデータ処理装置 |
JP2002184182A (ja) * | 2000-10-05 | 2002-06-28 | Fujitsu Ltd | 半導体メモリおよびその制御方法 |
JP2002133865A (ja) * | 2000-10-27 | 2002-05-10 | Seiko Epson Corp | 半導体メモリ装置内のワード線の活性化 |
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CN1851825B (zh) * | 2006-05-10 | 2010-05-12 | 威盛电子股份有限公司 | 高效能存储器及相关方法 |
JP2008084428A (ja) * | 2006-09-27 | 2008-04-10 | Fujitsu Ltd | 半導体メモリおよびシステム |
JP2009043373A (ja) * | 2007-08-10 | 2009-02-26 | Fujitsu Microelectronics Ltd | 半導体記憶装置及びワードデコーダ制御方法 |
Also Published As
Publication number | Publication date |
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CN1985330A (zh) | 2007-06-20 |
JP4579247B2 (ja) | 2010-11-10 |
CN100592420C (zh) | 2010-02-24 |
US20070121410A1 (en) | 2007-05-31 |
US7379370B2 (en) | 2008-05-27 |
JPWO2006013632A1 (ja) | 2008-05-01 |
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