Patent Document

BACKGROUND  
       [0001]     Synchronous dynamic random access memory (SDRAM) chips are produced in a variety of storage capacities including, 128-Mbit, 256-Mbit, and 512-Mbit. In general, each memory chip includes at least one array of memory cells. The memory cells are arranged in rows and columns, with the rows extending along an x-direction and the columns extending along a y-direction. Conductive word lines extend across the array of memory cells along the x-direction and conductive bits lines extend across the array of memory cells along the y-direction. A memory cell is located at each cross point of a word line and bit line. Memory cells are accessed using a row address and a column address.  
         [0002]     Memory chips are often manufactured with larger storage capacities and reduced to smaller storage capacities for sale. Reducing the storage capacity can occur for a number of reasons, including the chip contains more memory cell defects than can be repaired using normal redundancy techniques or a smaller capacity memory chip provides a larger profit margin.  
         [0003]     For memories with storage capacities such as 128-Mbit and 256-Mbit storage capacities, doubling the storage capacity of the memory means doubling the number of memory cells. The additional memory cells can be addressed by doubling the number of rows. An additional row address bit is therefore required. For these memories, it is simple to halve the storage capacity by shorting the most significant row address bit to either a logic high level or a logic low level. If the most significant row address bit is shorted to a logic high level, the lower half of the memory is disabled. If the most significant row address bit is shorted to a logic low level, the upper half of the memory is disabled. For example, to disable the lower half of a 256-Mbit chip, the most significant row address bit is shorted to a logic low level, resulting in a 128-Mbit chip.  
         [0004]     For conforming memories with 512-Mbit storage capacities and higher (i.e. one that complies with Joint Electron Device Engineering Council (JEDEC) standards), the addressable cells are doubled by doubling the number of columns and adding an additional column address, rather than adding rows. A conforming 512-Mbit chip has a page length of 16 k bits (equal to the number of columns) while a conforming 256-Mbit chip has a page length of 8 k bits. Therefore, simply shorting the most significant row address bit to a logic high level or logic low level to reduce the addressable memory cells results in a nonconforming SDRAM. Nonconforming memory chips cannot be sold in the commodity SDRAM market. For example, if a 512-Mbit chip is reduced to a 256-Mbit chip by shorting the most significant row address bit to a logic high level or logic low level, the resulting 256-Mbit chip still has a page length of 16 k bits, which is nonconforming.  
         [0005]     In addition, shorting the most significant column address bit of a 512-Mbit chip to a logic high level or a logic low level results in a chip in which array addressing can conflict with data pad organizations. SDRAM chips typically have one die solutions for multiple data pad (DQ) organizations. Depending upon whether the memory chip has 4, 8, or 16 DQs (×4, ×8, ×16 DQ organization), the number of column address bits will vary. For example, assuming a 512-Mbit DDR SDRAM with ×16 organization, 16 k array cells are connected to an activated row and 32 bits are addressed per memory access. Therefore, nine column address bits are needed to access all the data in one row. For a 512-Mbit DDR SDRAM with ×8 organization, ten column address bits are needed to access all the data in one row. The most significant column address bit depends on the DQ organization. To short the most significant column address bit to a logic high level or a logic low level would require coordination with the DQ organization.  
         [0006]     A lower column address bit can be shorted to a logic high level or a logic low level to reduce the size of the addressable memory, but this has several disadvantages. Using a lower column address bit limits the addressable block size. Limiting the addressable block size limits the size of cluster fails that can be bypassed as a cluster fail could extend beyond one block. In addition, using a lower column address bit can interfere with or destroy normal column redundancy techniques, as a redundant column could be located in a deactivated section leaving a column in an addressable section without a redundant column.  
       SUMMARY  
       [0007]     One aspect of the present invention provides a random access memory. The random access memory comprises a plurality of data pads and an array of memory cells comprising a first portion of memory cells and a second portion of memory cells. The random access memory comprises a first line configured to receive first data signals between the first portion of memory cells and the data pads and a second line configured to receive second data signals between the second portion of memory cells and the data pads. The first portion of memory cells is configured to be made inaccessible to eliminate the first data signals and a first number of the data pads and the second portion of memory cells is configured to be made inaccessible to eliminate the second data signals and a second number of the data pads. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     Embodiments of the invention are better understood with reference to the following drawings. The elements of the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding similar parts.  
         [0009]      FIG. 1  is a block diagram illustrating an exemplary embodiment of a DDR SDRAM, according to the present invention.  
         [0010]      FIG. 2  is a diagram illustrating an exemplary embodiment of a memory cell.  
         [0011]      FIG. 3  is a block diagram illustrating an exemplary embodiment of a DDR SDRAM with multiple memory banks.  
         [0012]      FIG. 4  is a block diagram illustrating an exemplary portion of two memory banks of a DDR SDRAM including two cut down options.  
         [0013]      FIG. 5  is a block diagram illustrating an exemplary embodiment of redundancy for a block of memory cells.  
         [0014]      FIG. 6  is a block diagram illustrating an exemplary embodiment of a data line multiplexing circuit for cut down options in a DDR SDRAM.  
         [0015]      FIGS. 7   a  and  7   b  are diagrams illustrating an exemplary embodiment of a 512-Mbit×16 DDR SDRAM reduced to a 256-Mbit×8 DDR SDRAM. 
     
    
     DETAILED DESCRIPTION  
       [0016]      FIG. 1  is a block diagram illustrating a random access memory  10 . In one embodiment, random access memory  10  is a double data rate synchronous dynamic random access memory (DDR SDRAM). The DDR SDRAM  10  includes a memory controller  20  and at least one memory bank  30 . Memory bank  30  includes an array of memory cells  32 , a row decoder  40 , a column decoder  44 , sense amplifiers  42 , and data in/out circuit  46 . In other embodiments, data in/out circuit  46  is separate from memory bank  30 . Memory controller  20  is electrically coupled to memory bank  30 , indicated at  22 .  
         [0017]     Conductive word lines  34 , referred to as row select lines, extend in the x-direction across the array of memory cells  32 . Conductive bit lines  36 , controlled by the column select lines, extend in the y-direction across the array of memory cells  32 . A memory cell  38  is located at each cross point of a word line  34  and a bit line  36 . Each word line  34  is electrically coupled to row decoder  40  and each bit line  36  is electrically coupled to a sense amplifier  42 . The sense amplifiers  42  are electrically coupled to column decoder  44  through conductive column decoder lines  45  and to data in/out circuit  46  through data lines  47 .  
         [0018]     Data in/out circuit  46  includes data input/output (I/O) circuitry and pins (DQs) to transfer data between memory bank  30  and an external device. Data to be written into memory bank  30  is presented as voltages on the DQs from an external device. The voltages are translated into the appropriate signals and stored in selected memory cells  38 . Data read from memory bank  30  is presented by memory bank  30  on the DQs for an external device to retrieve. Data read from selected memory cells  38  appears at the DQs once access is complete and the output is enabled. At other times, the DQs are in a high impedance state.  
         [0019]     The array of memory cells  32  includes a first portion of memory cells and a second portion of memory cells. A first portion of data lines  47  are configured to pass first data signals between a first portion of DQs and the first portion of memory cells and a second portion of data lines  47  are configured to pass second data signals between a second portion of DQs and the second portion of memory cells. The first and second portions of memory cells are configured to be made inaccessible to eliminate the first and second data signals respectively and the first and second portions of DQs respectively.  
         [0020]     Memory controller  20  controls reading data from and writing data to memory bank  30 . During a read operation, memory controller  20  passes the row address of a selected memory cell  38  to row decoder  40 . Row decoder  40  activates the selected word line  34 . As the selected word line  34  is activated, the value stored in each memory cell  38  coupled to the selected word line  34  is passed to the respective bit line  36 . The value of each memory cell  38  is read by a sense amplifier  42  electrically coupled to the respective bit line  36 . Memory controller  20  also passes a column address of the selected memory cell  38  to column decoder  44 . Column decoder  44  selects which sense amplifiers  42  pass data to data in/out circuit  46  for retrieval by an external device.  
         [0021]     During a write operation, the data to be stored in array  32  is placed in data in/out circuit  46  by an external device. Memory controller  20  passes the row address for the selected memory cell  38  where the data is to be stored to row decoder  40 . Row decoder  40  activates the selected word line  34 . Memory controller  20  passes the column address for the selected memory cell  38  where the data is to be stored to column decoder  44 . Column decoder  44  selects which sense amplifiers  42  are passed the data from data in/out circuit  46 . Sense amplifiers  42  write the data to the selected memory cell  38  through bit lines  36 .  
         [0022]      FIG. 2  illustrates an exemplary embodiment of one memory cell  38  in the array of memory cells  32 . Memory cell  38  includes a transistor  48  and a capacitor  50 . The gate of transistor  48  is electrically coupled to word line  34 . The drain-source path of transistor  48  is electrically coupled to bit line  36  and capacitor  50 . Capacitor  50  is charged to represent either a logic 0 or a logic 1. During a read operation, word line  34  is activated to turn on transistor  48  and the value stored on capacitor  50  is read by a corresponding sense amplifier  42  through bit line  36  and transistor  48 . During a write operation, word line  34  is activated to turn on transistor  48  and the value stored on capacitor  50  is written by a corresponding sense amplifier  42  through bit line  36  and transistor  48 .  
         [0023]     The read operation on memory cell  38  is a destructive read operation. After each read operation, capacitor  50  is recharged with the value that was just read. In addition, even without read operations, the charge on capacitor  50  discharges over time. To retain a stored value, memory cell  38  is refreshed periodically by reading the value from and then writing the value back to the memory cell  38 . All memory cells  38  within the array of memory cells  32  are periodically refreshed to maintain their values.  
         [0024]     In DDR SDRAM, the read and write operations are synchronized to a system clock. The system clock is supplied by a host system including the DDR SDRAM  10 . Operations are performed on both the rising and falling edges of the system clock. DDR SDRAM uses a double data rate architecture to achieve high speed operation. The double data rate architecture is essentially a 2 n prefetch architecture with an interface designed to transfer two data words per clock cycle at the DQs. A single read or write access for the DDR SDRAM effectively consists of a single 2 n bit wide, one clock cycle data transfer at the internal memory array and two corresponding n bit wide, one half clock cycle data transfers at the DQs.  
         [0025]     A bidirectional data strobe (DQS) is transmitted externally along with data for use in data capture at data in/out circuit  46 . DQS is a strobe transmitted by the DDR SDRAM during read operations and by an external memory controller during write operations. DQS is edge aligned with data for read operations and center aligned with data for write operations. Input and output data is registered on both edges of DQS.  
         [0026]     DDR SDRAM operates from a differential clock, CK and bCK. The crossing of CK going high and bCK going low is referred to as the positive edge of CK. Commands such as read and write operations, including address and control signals, are registered at the positive edge of CK.  
         [0027]     Read and write accesses to the DDR SDRAM are burst oriented. Accesses start at a selected location and continue for a programmed number of locations in a programmed sequence. Accesses begin with the registration of an active command, which is followed by a read or write command. The address bits registered coincident with the active command are used to select the bank and row to be accessed. The address bits registered coincident with the read or write command are used to select the bank and the starting column location for the burst access.  
         [0028]      FIG. 3  is a block diagram illustrating an exemplary embodiment of DDR SDRAM  10  with an array of memory banks  31 . The array of memory banks  31  includes four memory banks, bank zero through bank three, indicated at  30   a - 30   d . Each memory bank  30   a - 30   d  includes all of the circuitry of memory bank  30  illustrated in  FIG. 1  and previously described. In one embodiment, a single data in/out circuit  46  is shared by memory banks  30   a - 30   d . Multiple memory banks  30   a - 30   d  increase the storage capacity of DDR SDRAM  10  and reduce the access time of DDR SDRAM  10  as one bank can be prepared for access while another bank is being accessed.  
         [0029]      FIG. 4  illustrates a portion of bank zero  100   a  and a portion of bank one  100   b  of DDR SDRAM  10 . In the exemplary embodiment, DDR SDRAM  10  is in a ×16 DQ organization. The portion of bank zero  100   a  includes word line  34   a , multiple bit lines, blocks of memory cells  110   a ,  112   a ,  114   a , and  116   a , even and odd data dividing line  102   a , and data lines  120   a ,  122   a ,  124   a , and  126   a . The portion of bank one  100   b  includes word line  34   b , multiple bit lines, blocks of memory cells  110   b ,  112   b ,  114   b , and  116   b , even and odd data dividing line  102   b , and data lines  120   b ,  122   b ,  124   b , and  126   b . The portion of bank zero  100   a  and the portion of bank one  100   b  use data lines DL 1 &lt;0:7&gt; 130 , DL 2 &lt;0:7&gt; 132 , DL 1 &lt;8:15&gt; 134 , and DL 2 &lt;8:15&gt; 136 .  
         [0030]     In the portion of bank zero  100   a , each block of memory cells  110   a ,  112   a ,  114   a , and  116   a , includes at least eight memory cells  38  along word line  34   a  The memory cells  38  of block  110   a  are electrically coupled to data line  120   a  through sense amplifiers  42  of bank zero  30   a . The memory cells  38  of block  112   a  are electrically coupled to data line  122   a  through sense amplifiers  42  of bank zero  30   a . The memory cells  38  of block  114   a  are electrically coupled to data line  124   a  through sense amplifiers  42  of bank zero  30   a  and the memory cells  38  of  116   a  are electrically coupled to data line  126   a  through sense amplifiers  42  of bank zero  30   a . Data line  120   a  is electrically coupled to data line DL 1 &lt;0:7&gt; 130 . Data line  122   a  is electrically coupled to data line DL 2 &lt;0:7&gt; 132 . Data line  124   a  is electrically coupled to data line DL 1 &lt;8:15&gt; 134  and data line  126   a  is electrically coupled to data line DL 2 &lt;8:15&gt; 136 .  
         [0031]     For the portion of bank one  100   b , each block of memory cells  110   b ,  112   b ,  114   b , and  116   b , includes at least eight memory cells  38  along word line  34   b . The memory cells  38  of block  110   b  are electrically coupled to data line  120   b  through sense amplifiers  42  of bank one  30   b . The memory cells  38  of block  112   b  are electrically coupled to data line  122   b  through sense amplifiers  42  of bank one  30   b . The memory cells  38  of block  114   b  are electrically coupled to data line  124   b  through sense amplifiers  42  of bank one  30   b  and the memory cells  38  of  116   b  are electrically coupled to data line  126   b  through sense amplifiers  42  of bank one  30   b . Data line  120   b  is electrically coupled to data line DL 1 &lt;0:7&gt; 130 . Data line  122   b  is electrically coupled to data line DL 2 &lt;0:7&gt; 132 . Data line  124   b  is electrically coupled to data line DL 1 &lt;8:15&gt; 134  and data line  126   b  is electrically coupled to data line DL 2 &lt;8:15&gt; 136 .  
         [0032]     Data lines  120   a ,  122   a ,  124   a ,  126   a ,  120   b ,  122   b ,  124   b ,  126   b , DL 1 &lt;0:7&gt; 130 , DL 2 &lt;0:7&gt; 132 , DL 1 &lt;8:15&gt; 134 , and DL 2 &lt;8:15&gt; 136  are data busses or other suitable data transmission lines for carrying at least eight data bits at a time to pass data into or out of the portion of bank zero  100   a  and the portion of bank one  100   b . In other embodiments, the data lines are configured for carrying any suitable number of data bits. Word lines  34   a  and  34   b  activate the selected memory cells  38  during a read or write operation as previously described.  
         [0033]     In the exemplary embodiment, DDR SDRAM  10  is in a ×16 DQ organization and  32  data bits are read, two per DQ, per memory read access. Likewise, 32 data bits are written, two per DQ, per memory write access. The first 16 data bits on the DQs are referred to as the even data bits. The second 16 data bits on the DQs are referred to as the odd data bits. The array of memory cells  32  in each bank  30   a - 30   d  of DDR SDRAM  10  is divided into even and odd sections to facilitate the data transfer.  
         [0034]     Even and odd data dividing line  102   a  divides the upper and lower half of bank zero portion  100   a . The lower half of bank zero portion  100   a  includes block  110   a  and block  114   a , which represent the even data. The upper half of bank zero portion  100   a  includes block  112   a  and block  116   a , which represent the odd data.  
         [0035]     Even and odd data dividing line  102   b  divides the upper and lower half of bank one portion  100   b . The lower half of bank one portion  100   b  includes block  110   b  and block  114   b , which represent the even data. The upper half of bank one portion  100   b  includes block  112   b  and block  116   b , which represent the odd data.  
         [0036]     Data line  120   a  passes data from the memory cells  38  in block  110   a  to data line DL 1 &lt;0:7&gt; 130  during a read operation. Data line  120   a  passes data from data line DL 1 &lt;0:7&gt; 130  to memory cells  38  in block  110   a  during a write operation. Data line  120   b  passes data from the memory cells  38  in block  110   b  to data line DL 1 &lt;0:7&gt; 130  during a read operation. Data line  120   b  passes data from data line DL 1 &lt;0:7&gt; 130  to memory cells  38  in block  110   b  during a write operation.  
         [0037]     Data lines  122   a  and  122   b  with data line DL 2 &lt;0:7&gt; 132  perform the same finction for their respective blocks  112   a  and  112   b  as data lines  120   a  and  120   b . Data lines  124   a  and  124   b  with data line DL 1 &lt;8:15&gt; 134  perform the same finction for their respective blocks  114   a  and  114   b  as data lines  120   a  and  120   b  and data lines  126   a  and  126   b  with data line DL 2 &lt;8:15&gt; 136  perform the same function for their respective blocks  116   a  and  116   b  as data lines  120   a  and  120   b.    
         [0038]     Data line DL 1 &lt;0:7&gt; 130  passes data from data lines  120   a  and  120   b  to the first eight DQs (eight least significant DQs) to output as even data. Data line DL 2 &lt;0:7&gt; 132  passes data from data lines  122   a  and  122   b  to the first eight DQs to output as odd data. Data line DL 1 &lt;8:15&gt; 134  passes data from data lines  124   a  and  124   b  to the second eight DQs (eight most significant DQs) to output as even data. Data line DL 2 &lt;8:15&gt; 136  passes data from data lines  126   a  and  126   b  to output as odd data. On the rising edge of a clock pulse, the data on data lines DL 1 &lt;0:7&gt; 130  and DL 1 &lt;8:15&gt; 134  is output to the 16 DQs and on the falling edge of the clock pulse, the data on data lines DL 2 &lt;0:7&gt; 132  and DL 2 &lt;8:15&gt; 136  is output to the 16 DQs.  
         [0039]     One of the banks  30   a - 30   d  is read from or written to during each memory access. Further, one portion of one bank  30   a - 30   d , such as the portion of bank zero  100   a  or the portion of bank one  100   b , is read from or written to during each memory access. The other portions of bank zero  30   a  and bank one  30   b  are treated similar to the portion of bank zero  100   a  and the portion of bank one  100   b . In addition, bank two  30   c  and bank three  30   d  of DDR SDRAM  10  are treated similar to bank zero  30   a  and bank one  30   b.    
         [0040]     To reduce the size of DDR SDRAM  10 , one of at least two options, cut option one  140  and cut option two  142 , can be selected.  FIG. 4  illustrates cut options  140  and  142  for the portion of bank zero  100   a  and the portion of bank one  100   b . In the portion of bank zero  100   a , cut option one  140  includes blocks  114   a  and  116   a  and cut option two  142  includes blocks  110   a  and  112   a . Likewise, in the portion of bank one  100   b , cut option one  140  includes blocks  114   b  and  116   b  and cut option two  142  includes blocks  110   b  and  112   b.    
         [0041]     If cut option one  140  is selected, blocks  114   a ,  116   a ,  114   b , and  116   b  are no longer used. Selecting cut option one  140  also makes data lines  124   a ,  126   a ,  124   b , and  126   b  no longer needed. With data lines  124   a ,  126   a ,  124   b , and  126   b  no longer needed, data lines DL 1 &lt;8:15&gt; 134  and DL 2 &lt;8:15&gt; 136  also are no longer needed and the second eight DQs are no longer needed.  
         [0042]     If cut option two  142  is selected, blocks  110   a ,  112   a ,  110   b , and  112   b  are no longer used. Selecting cut option two  142  makes data lines  120   a ,  122   a ,  120   b , and  122   b  no longer needed. With data lines  120   a ,  122   a ,  120   b , and  122   b  no longer needed, data lines DL 1 &lt;0:7&gt; 130  and DL 2 &lt;0:7&gt; 132  also are no longer needed and the first eight DQs are no longer needed.  
         [0043]     Selecting cut option one  140  deactivates the portions of the array of memory cells  32  of banks  30   a - 30   d  that are electrically coupled to the upper eight DQs. Selecting cut option two  142  deactivates the portions of the array of memory cells  32  of banks  30   a - 30   d  that are electrically coupled to the lower eight DQs. Selecting either cut option one  140  or cut option two  142  reduces the addressable memory size of DDR SDRAM  10  by one half. Therefore, with cut option one  140  or cut option two  142  selected, 16 data bits are accessed per read or write operation instead of the original 32 data bits. The DDR SDRAM  10  in a ×16 DQ organization is reduced to a ×8 organization.  
         [0044]      FIG. 5  is a diagram illustrating an exemplary embodiment of block  114   a  and an associated redundant block  214   a . Block  114   a  includes word line  34   a , data line  124   a , and part of cluster fail  150 . Block  214   a  includes word line  34   a , data line  224   a , and part of cluster fail  150 . The data lines  124   a  and  224   a  are electrically coupled to data line DL 1 &lt;8:15&gt; 134 .  
         [0045]     Block  214   a  and data line  224   a  include the same features as block  114   a  and data line  124   a  previously described. Block  214   a  and data line  224   a , however, are not used unless a defect, such as a cluster fail, in block  114   a  or data line  124   a  prevents block  114   a  from being used. Similarly, blocks  110   a ,  112   a ,  116   a ,  110   b ,  112   b ,  114   b , and  116   b  shown in  FIG. 4  also have an associated redundant block and data line.  
         [0046]     In the exemplary embodiment, cluster fail  150  extends into block  114   a  and  214   a . Therefore, neither block  114   a  nor block  214   a  can be used. Cluster fail  150  renders DDR SDRAM  10  defective, preventing DDR SDRAM  10  from being sold in a ×16 DQ organization. By selecting cut option one  140 , however, blocks  114   a  and  214   a  are no longer used and cluster fail  150  is bypassed. The resulting DDR SDRAM  10  in a ×8 organization is not defective and can be sold.  
         [0047]      FIG. 6  is a block diagram illustrating an exemplary embodiment of a data line multiplexing circuit  306  for cut option one  140  and cut option two  142 . Multiplexing circuit  300  is part of data in/out circuit  46  and is used to route data to the lower eight DQs if either cut option one  140  or cut option two  142  is selected. Multiplexing circuit  300  includes multiplexers  302  and  304 . Multiplexer  302  receives input data lines DL 1 &lt;0:7&gt; 130  and DL 2 &lt;0:7&gt; 132  and select lines cut option one  140  select line (SC 1 ) and cut option two  142  select line (SC 2 ). Multiplexer  304  receives input data lines DL 1 &lt;8:15&gt; 134  and DL 2 &lt;8:15&gt; 136  and select lines SC 1  and SC 2 .  
         [0048]     If SC 1  is true, indicated as a logic high level (logic 1), and SC 2  is false, indicated as a logic low level (logic 0), cut option one  140  is selected. If SC 2  is true, indicated as a logic high level (logic 1), and SC 1  is false, indicated as a logic low level (logic 0), cut option two  142  is selected. SC 1  and SC 2  are not both set true as that would result in none of DDR SDRAM  10  being addressable. SC 1  and SC 2  are shorted to a logic high level or a logic low level during the manufacturing and testing process of DDR SDRAM  10 .  
         [0049]     Selecting cut option one  140  results in data on data lines DL 1 &lt;8:15&gt; 134  and DL 2 &lt;8:15&gt; 136  being ignored, indicated at  312 , and data on data lines DL 1 &lt;0:7&gt; 130  and DL 2 &lt;0:7&gt; 132  passing through to data lines DL 1 / 2 &lt;0:7&gt; 306 , indicated at  314 . Selecting cut option two  142  results in data on data lines DL 1 &lt;8:15&gt; 134  and DL 2 &lt;8:15&gt; 136  being passed through to data lines DL 1 / 2 &lt;0:7&gt; 306 , indicated at  310 , and data on data lines DL 1 &lt;0:7&gt; 130  and DL 2 &lt;0:7&gt; 132  being ignored, indicated at  316 . Selecting neither cut option one  140  nor cut option two  142  results in the data on data lines DL 1 &lt;0:7&gt; 130  and DL 2 &lt;0:7&gt; 132  passing to data lines DL 1 / 2 &lt;0:7&gt; 306  and data on data lines DL 1 &lt;8:15&gt; 134  and DL 2 &lt;8:15&gt; 136  passing to data lines DL 1 / 2 &lt;8:15&gt; 308 .  
         [0050]      FIGS. 7   a  and  7   b  are block diagrams illustrating an exemplary embodiment of the portion of bank zero lOOa before and after cut option one  140  is selected. In this embodiment the portion of bank zero  100   a  illustrated in  FIG. 7   a  is a portion of a 512-Mbit×16 DDR SDRAM with 32 data bits per memory access. The portion of bank zero  100   a  illustrated in  FIG. 7   b  is a portion of the 512-Mbit×16 DDR SDRAM after it is reduced to a 256-Mbit×8 DDR SDRAM with 16 data bits per memory access.  
         [0051]     As illustrated in  FIG. 7   a,  32 data bits can be accessed during a read or write operation of the 512-Mbit×16 DDR SDRAM. When the 512-Mbit×16 DDR SDRAM is cut down to the 256-Mbit×8 DDR SDRAM illustrated in  FIG. 7   b,  16 of the data bits can no longer be accessed. The memory cells within blocks  114   a  and  116   a  are no longer addressable. In addition, data lines DL 1 &lt;8:15&gt; 134  and DL 2 &lt;8:15&gt; 136  are no longerused. The portions of memory array  32  of banks  30   a - 30   d  that are included in cut option one  140  are deactivated (made inaccessible) by blowing fuses for the corresponding bit lines  36 , by blowing fuses for the corresponding data lines, or in any other suitable manner.  
         [0052]     The 512-Mbit×16 DDR SDRAM with 16 DQs and a 16 k page size is cut down to produce a conforming 256-Mbit×8 DDR SDRAM with eight DQs and an 8 k page size. This same method can apply to other DQ organizations as well. For example, a 512-Mbit×8 DDR SDRAM can be cut down to produce a conforming 256-Mbit×4 DDR SDRAM.

Technology Category: g