U.S. patent application number 12/838835 was filed with the patent office on 2010-11-04 for multi-bank memory.
Invention is credited to David R. Brown, Brian M. Shirley.
Application Number | 20100277964 12/838835 |
Document ID | / |
Family ID | 25201685 |
Filed Date | 2010-11-04 |
United States Patent
Application |
20100277964 |
Kind Code |
A1 |
Shirley; Brian M. ; et
al. |
November 4, 2010 |
MULTI-BANK MEMORY
Abstract
A multi-bank memory device includes rows and columns of memory
cores. Each row includes memory cores from one bank interleaved
with memory cores from another bank. Banks in different rows can be
simultaneously accessed.
Inventors: |
Shirley; Brian M.; (Boise,
ID) ; Brown; David R.; (Allen, TX) |
Correspondence
Address: |
SCHWEGMAN, LUNDBERG & WOESSNER/MICRON
P.O. BOX 2938
MINNEAPOLIS
MN
55402
US
|
Family ID: |
25201685 |
Appl. No.: |
12/838835 |
Filed: |
July 19, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11861959 |
Sep 26, 2007 |
7760532 |
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12838835 |
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11379194 |
Apr 18, 2006 |
7292497 |
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11861959 |
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09809586 |
Mar 15, 2001 |
7088604 |
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11379194 |
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Current U.S.
Class: |
365/51 ;
365/230.03 |
Current CPC
Class: |
G11C 7/1042 20130101;
G11C 11/4087 20130101; G11C 11/4097 20130101; G11C 7/065 20130101;
G11C 2207/002 20130101; G11C 2207/005 20130101; G11C 7/18 20130101;
G11C 8/12 20130101; G11C 11/4091 20130101 |
Class at
Publication: |
365/51 ;
365/230.03 |
International
Class: |
G11C 5/02 20060101
G11C005/02; G11C 8/00 20060101 G11C008/00 |
Claims
1. A memory device comprising: memory cores from different banks
interleaved in a strip in an alternating fashion; and sense
amplifiers shared between the different banks.
2. The memory device of claim 1, wherein memory cores from
different banks interleaved within rows in an alternating
fashion.
3. The memory device of claim 1, wherein memory cores from
different banks interleaved within columns in an alternating
fashion.
4. The memory device of claim 1, wherein sense amplifiers are
shared between two different banks in the strip.
5. The memory device of claim 1, wherein each sense amp is coupled
to two cores, each core from a different bank.
6. A memory device comprising: memory cores from different banks
interleaved in a number of rows in an alternating fashion; sense
amplifiers shared between the different banks; and a single column
decoder associated with each row in the number of rows.
7. The memory device of claim 6, wherein each row in the number of
rows supports only one access at a time.
8. The memory device of claim 6, wherein each column decoder is
associated with two banks.
9. The memory device of claim 6, wherein each row includes more
than two memory cores.
10. The memory device of claim 6, wherein two memory cores are
associated with a sense amplifier.
11. A memory device comprising: memory cores from different banks
interleaved in a number of columns in an alternating fashion; sense
amplifiers shared between the different banks; and a single row
decoder associated with each column in the number of columns.
12. The memory device of claim 11, wherein each column in the
number of columns supports only one access at a time.
13. The memory device of claim 11, wherein each row decoder is
associated with two banks.
14. The memory device of claim 11, wherein each column includes
more than two memory cores.
15. The memory device of claim 11, wherein two memory cores are
associated with a sense amplifier.
16. A memory device comprising: a two dimensional array of memory
cores; wherein, memory cores from different banks are interleaved
in multiple strips along a first dimension in an alternating
fashion; wherein one or more strips along the first dimension
includes a sense amplifier shared between different banks; and
wherein memory cores from different banks are not interleaved in a
second direction, orthogonal to the first dimension.
17. The memory device of claim 16, wherein memory cores from
different banks are interleaved in multiple rows, and wherein
memory cores from different banks are not interleaved in
columns.
18. The memory device of claim 16, wherein memory cores from
different banks are interleaved in multiple columns, and wherein
memory cores from different banks are not interleaved in rows.
19. The memory device of claim 16, wherein two or more strips are
configured to be accessed in parallel.
20. The memory device of claim 16, wherein each strip includes a
single decoder.
Description
CROSS REFERENCES TO RELATED APPLICATIONS
[0001] This application is a Continuation of U.S. application Ser.
No. 11/861,959, filed Sep. 26, 2007, which is a Continuation of
U.S. application Ser. No. 11/379,194, filed on Apr. 18, 2006, now
issued as U.S. Pat. No. 7,292,497, which is a Continuation of U.S.
application Ser. No. 09/809,586, filed on Mar. 15, 2001, now issued
as U.S. Pat. No. 7,088,604; the specifications of which are hereby
incorporated by reference in their entirety.
TECHNICAL FIELD OF THE INVENTION
[0002] The present invention relates generally to memory devices,
and in particular, the present invention relates to memory devices
having multiple banks.
BACKGROUND OF THE INVENTION
[0003] Direct Rambus Dynamic Random Access Memories, hereinafter
referred to as DRDRAMs, are very fast, highly pipelined memory
devices that are becoming an industry standard in high speed
processing systems. DRDRAMs include a considerable amount of
internal circuitry that supports the pipelined architecture so as
to provide for very high communication bandwidths at the device
boundary. DRDRAM sustained data transfer rates exceed 1 GB/s.
[0004] DRDRAMs, like most commercially available memories, include
memory cells that are arranged in rows and columns. Unlike many
commercially available memories, however, DRDRAMs are multi-bank
devices that have memory cells logically arranged into banks that
can be independently accessed. This results in multiple banks
within each DRDRAM, each including a number of memory cells.
Gathering the memory cells into banks, and allowing different banks
to undergo separate operations simultaneously, increases the
overall data transfer rate of the device.
[0005] Each bank is associated with one or more sense amplifiers
that function to read data from, and write data to, the memory
cells within the bank. The sense amplifiers serve as a data
communications bridge between the banks of memory cells and the
data buses external to the device. Banks are separately activated,
possibly simultaneously, or overlapping in time, prior to a read or
write operation. When a bank is activated, it communicates with one
or more sense amplifiers. When the read or write operation is
complete, the bank is deactivated, and the sense amplifiers are
precharged, which readies the sense amplifiers for another
operation.
[0006] Examples of DRDRAMs are described in: "Rambus Direct RDRAM
128/144-Mbit (256k.times.16/18.times.32s) Preliminary Information,"
Document DL0059, V1.11, June 2000; and "Rambus Direct RDRAM
256/288-Mbit (1Mx16/18.times.16d) Preliminary Information,"
Document DL0105, V 1.1, August 2000. The contents of the
aforementioned documents are hereby incorporated by reference.
[0007] FIG. 1 shows a prior art multi-bank memory device. Memory
device 100 includes memory cells arranged in rows and columns. Each
column is shown as a vertical strip of memory cells, and each row
is shown as a horizontal strip of memory cells. For example, strip
102 is a column that includes memory cells 120, 124, and 128, and
strip 104 is a column that includes memory cells 130, 134, and 138.
In memory device 100, each column corresponds to a single bank of
memory cores. For example, memory cores 120, 124, and 128 of strip
102 are part of Bank 0, and memory cores 130, 134, and 136 of strip
104 are part of Bank 1. In similar fashion, strips 106 and 108
contain similar memory cells, such as 131, to form bank 2 and bank
n-1 respectively. As shown in FIG. 1, memory device 100 is arranged
into "n" banks labeled Bank 0 through Bank (n-1).
[0008] Each bank shares sense amplifiers with at least one other
bank. For example, sense amplifiers 140, 142, and 144 are shared
between memory cores in Bank 0 and memory cores in Bank 1, and
sense amplifiers 146, 148, and 150 are shared between memory cores
in Bank 1 and memory cores in Bank 2.
[0009] Local row decoders are arranged within the array of memory
cores. Each local row decoder provides wordline addressing to
memory cores in close proximity. For example, in FIG. 1, each of
row decoders 122 and 126 provide row decoding for one or more of
the memory cores in strip 102. Similarly, row decoders 132 and 163
provide row decoding for one or more of the memory cores in strip
104.
[0010] Column decoding, in contrast to row decoding, is performed
globally. Column decode lines driven by column decoders typically
traverse an entire row of memory cores, rather than only memory
cores nearby. For example, column decoder 110 drives column decode
lines 160 shown schematically in FIG. 1 as an arrow. One or more of
column decode lines 160 traverse multiple memory cells of the row
to enable sense amplifiers within the row across from the column
decoder. For example, a column decode line that enables sense
amplifiers 146 to read from memory core 131 in Bank 2 will
typically travel over, under, or past memory cores 120 and 130 from
Banks 0 and 1, respectively.
[0011] In memory devices that allow simultaneous access to multiple
banks, such as DRDRAMs, column decode lines that traverse memory
cores from multiple banks can be problematic, in part because
column decode lines addressed to one bank can cause electrical
noise in memory cores of other banks being accessed. If noise is
great enough, data errors can result.
[0012] FIG. 2 shows a prior art sense amplifier suitable for use in
a multi-bank memory. Sense amplifier 200 includes N-sense amplifier
202 and P-sense amplifier 204 coupled between sense nodes 232 and
234, isolation transistors 206A, 206B, 208A, and 208B, column
decode transistors 210 and 212, and bank select transistors 216 and
218. Sense nodes 232 and 234 are coupled to input output (I/O)
lines 224 and 222 through the column decode and bank select
transistors. A column decode signal (Y-GATE) on node 214 is coupled
to column decode transistors 210 and 212, and a bank select signal
(BANK) on node 220 is coupled to bank select transistors 216 and
218. Other column decode lines 230 driven by the column decoder 110
(FIG. 1) pass nearby sense amplifier 200. Other column decode lines
230 are coupled to other sense amplifiers (not shown) in the same
manner that Y-GATE is coupled to sense amplifier 200 on node
214.
[0013] The operation of sense amplifier 200 is well known. When
data from a memory core either to the left or right of sense
amplifier 200 is to be read, the appropriate isolation transistors
are turned on by either signal ISOL or ISOR, and the N-sense and
P-sense amplifiers are activated using signals NLAT and ACT,
respectively. The data value (and its complement) being read
appears on sense nodes 232 and 234. When both the column decode
signal (Y-GATE) on node 214 and the bank select signal (BANK) on
node 220 are asserted, transistors 210, 212, 216, and 218 turn on
and couple sense amplifier 200 to I/O lines 222 and 224.
[0014] When sense amplifier 200 is used in a multi-bank memory
device that allows simultaneous operations among banks, the other
column decode lines 230 can be actively changing during the
operation of sense amplifier 200, causing noise that can
potentially cause a data error. For example, referring now back to
FIG. 1, if sense amplifier 140 is sensing data from memory core 120
in bank 0 while a column decode line addressing sense amplifier 146
is changing, a data error in sense amplifier 140 can result. As
memory devices become larger, and more banks are added, the problem
becomes worse.
[0015] For the reasons stated above, and for other reasons stated
below which will become apparent to those skilled in the art upon
reading and understanding the present specification, there is a
need in the art for alternate multi-bank memory devices.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a diagram of a prior art multi-bank memory
device.
[0017] FIG. 2 is a diagram of a prior art sense amplifier.
[0018] FIG. 3 is a diagram of a multi-bank memory device of the
present invention.
[0019] FIG. 4 is a diagram of a sense amplifier in accordance with
the present invention.
[0020] FIG. 5 is a diagram of a processing system in accordance
with the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0021] In the following detailed description of the invention,
reference is made to the accompanying drawings which form a part
hereof, and in which is shown, by way of illustration, specific
embodiments in which the invention may be practiced. In the
drawings, like numerals describe substantially similar components
throughout the several views. These embodiments are described in
sufficient detail to enable those skilled in the art to practice
the invention. Other embodiments may be utilized and structural,
logical, and electrical changes may be made without departing from
the scope of the present invention. The following detailed
description is, therefore, not to be taken in a limiting sense, and
the scope of the present invention is defined only by the appended
claims, along with the full scope of equivalents to which such
claims are entitled.
[0022] FIG. 3 shows a multi-bank memory device in accordance with
the present invention. Memory device 300 includes memory cells
arranged in rows and columns. Each column is shown as a vertical
strip of memory cells, and each row is shown as a horizontal strip
of memory cells. For example, strip 302 is a column that includes
memory cells 320, 324, and 328 (and similarly strips 304, 306 and
308 include memory cells such as 331, 334 and 338), and strip 370
is a row that includes memory cells 320 and 330. As shown in FIG.
1, memory device 100 is arranged into "n" banks labeled Bank 0
through Bank (n-1).
[0023] Each row in memory device 300 includes memory cores from two
banks interleaved together. For example, strip 370 includes memory
cores from Bank 0 and Bank 1 alternating across the strip. Also for
example, strip 372 includes memory cores from Bank 2 interleaved
with memory cores from Bank 3.
[0024] Each row includes sense amplifiers that are shared between
two banks of memory cores. For example, sense amplifiers 340 and
346 are shared between memory cores in Bank 0 and memory cores in
Bank 1, and sense amplifiers 342 and 348 are shared between memory
cores in Bank 2 and memory cores in Bank 3.
[0025] Local row decoders are arranged within the array of memory
cores. Each local row decoder provides wordline addressing to
memory cores in close proximity. For example, in FIG. 3, each of
row decoders 322 and 326 provide row decoding for one or more of
the memory cores in strip 302, while row decoders 332 and 336
provide similarly for strip 304. In some embodiments, row decoders
are shared among multiple memory cores, with latches and row
drivers dedicated to each bank. For example, in the embodiment of
FIG. 3, row decoders can be shared between Bank 0 and Bank 2. In
operation, each of these row decoders performs a row decode
operation, and the result is steered into a latch for Bank 0 or a
latch for Bank 2.
[0026] Column decode lines driven by column decoders typically
traverse an entire row of memory cores, rather than only memory
cores nearby. For example, column decoder 310 drives column decode
lines 360 shown schematically in FIG. 3 as an arrow. One or more of
column decode lines 360 traverse multiple memory cells of the row
to enable sense amplifiers within the row across from the column
decoder. For example, a column decode line that enables sense
amplifiers 346 to read from memory core 331 in Bank 0 will
typically travel over, under, or past memory cores 320 and 330 from
Banks 0 and 1, respectively. In similar fashion, sense amplifiers
344 and 350 may read from memory cores in Banks n or n-1.
[0027] Multi-bank memory device 300 is useful in part because each
row includes memory cores from banks that cannot be simultaneously
accessed. For example, memory cores from Bank 0 and Bank 1 are
interleaved in a single row. Because memory cores from Bank 0 and
Bank 1 share sense amplifiers, they cannot be simultaneously
accessed. Banks in other rows, however, may be accessed at the same
time or overlapping in time with an access of memory cores in Bank
0 or Bank 1. Each row has at least one column decoder dedicated
thereto. For example, row 370 has column decoder 310 dedicated
thereto. Because each row supports only one access at a time,
column decode lines driven by each column decoder change only
during an access to that particular row, and the noise problem
associated with memory device 100 (FIG. 1) is avoided.
[0028] Multi-bank memory device 300 is arranged as a two
dimensional array of memory cores. One dimension of the array
includes strips of memory cores, each strip having interleaved
memory cores from two separate banks. The other dimension of the
array contains strips that do not include memory cores from common
banks. In the embodiment shown in FIG. 3, each strip that includes
interleaved memory cores from two banks is situated in a row, and
strips that do not include memory cores from common banks are
situated in columns. In other embodiments, columns include
interleaved memory cores rather than rows.
[0029] FIG. 4 shows a sense amplifier in accordance with the
present invention. Sense amplifier 400 includes N-sense amplifier
402 and P-sense amplifier 404 coupled between sense nodes 432 and
434, isolation transistors 406A, 406B, 408A, and 408B, and column
decode transistors 410 and 412. Sense nodes 432 and 434 are coupled
to input output (I/O) lines 424 and 422 through the column decode
transistors. A column decode signal (Y-GATE) on node 414 is coupled
to column decode transistors 410 and 412.
[0030] Other column decode lines 430 driven by the column decoder
pass nearby sense amplifier 400. Other column decode lines 430 are
coupled to other sense amplifiers (not shown) in the same manner
that Y-GATE is coupled to sense amplifier 400 on node 414. Because
each row includes interleaved memory cores from two banks, the
sense amplifiers in the same row as sense amplifier 400 access
memory cores from the same two banks as sense amplifier 400. As a
result, other column decode lines 430 are not changing when sense
amplifier 400 is sensing.
[0031] In operation, when data from a memory core either to the
left or right of sense amplifier 400 is to be read, the appropriate
isolation transistors are turned on by either signal ISOL or ISOR,
and the N-sense and P-sense amplifiers are activated using signals
NLAT and ACT, respectively. The data value (and its complement)
being read appears on sense nodes 432 and 434. When the column
decode signal (Y-GATE) on node 414 is asserted, transistors 410 and
412 turn on and couple sense amplifier 400 to I/O lines 422 and
424.
[0032] Sense amplifier 400 does not include bank select transistors
such as bank select transistors 216 and 218 (FIG. 2). This is
because each row only includes memory cores from two banks that
cannot be simultaneously accessed, and there is no need to identify
which bank is being accessed with a bank decode signal. As a
result, sense amplifier 400 can be made significantly smaller than
sense amplifier 200 (FIG. 2).
[0033] Node 414 and other column decode lines 430 are conductors
that run substantially parallel to a row of memory cores and sense
amplifiers. For example, referring now back to FIG. 3, column
decode lines 160 run substantially parallel to row 370. The
conductors can be made from metal, poly, or any other suitable
material. For example, in a two-layer metal process, the column
decode lines can be dedicated to a single metal layer. Also for
example, in a single layer metal process, the column decode lines
can be buried on poly layers.
[0034] FIG. 5 is a diagram of a processing system in accordance
with the present invention. System 500 includes processor 505 and
memory device 510. Memory device 510 includes memory array 515,
address circuitry 520, and read circuitry 530, and is coupled to
processor 505 by address bus 535, data bus 540, and control bus
545. Memory array 515 includes memory cells and circuits arranged
in accordance with those embodiments discussed above with reference
to FIGS. 3 and 4.
[0035] Memory device 510 is typically mounted on a motherboard.
Processor 505, through address bus 535, data bus 540, and control
bus 545 communicates with memory device 510. In a read operation
initiated by processor 505, address information, data information,
and control information are provided to memory device 510 through
busses 535, 540, and 545. This information is decoded by addressing
circuitry 520 and read circuitry 530. Successful completion of the
read operation results in information from memory array 515 being
communicated to processor 505 over data bus 540.
CONCLUSION
[0036] A multi-bank memory device has been described that includes
rows and columns of memory cores. Each row includes memory cores
from one bank interleaved with memory cores from another bank.
Banks in different rows can be simultaneously accessed without
noise coupling from one access to the other.
[0037] In one embodiment, a memory device includes a plurality of
banks, each including a plurality of memory cores, and also
includes a plurality of sense amplifiers shared among memory cores
of different ones of the plurality of banks. The memory cores from
two of the different ones of the plurality of banks are interleaved
in a strip with the plurality of shared sense amplifiers.
[0038] In another embodiment, an integrated circuit includes an
array of memory cores having a first dimension and a second
dimension, where a strip of memory cores in the first dimension
includes memory cores from a first bank interleaved with memory
cores from a second bank. In this embodiment, a plurality of sense
amplifiers are arranged between memory cores from the first bank
and memory cores from the second bank.
[0039] In another embodiment, a computer system includes a
processor and a memory device coupled to the processor. The memory
device includes a plurality of rows and columns of memory cores,
and also includes a plurality of sense amplifiers positioned
between memory cores within each row, wherein every other memory
core within each row is assigned to a bank.
[0040] Although specific embodiments have been illustrated and
described herein, it will be appreciated by those of ordinary skill
in the art that any arrangement which is calculated to achieve the
same purpose may be substituted for the specific embodiment shown.
This application is intended to cover any adaptations or variations
of the present invention. Therefore, it is manifestly intended that
this invention be limited only by the claims and the equivalents
thereof.
* * * * *