Abstract:
An apparatus comprising a first bus, a second bus, a memory and one or more interconnections. The memory may be connected to the first bus and the second bus and may be configured to transfer data over the first bus and the second bus. The one or more interconnections may be connected between one or more data lines of the first bus and the second bus to control a bit-width of the first and second buses.

Description:
FIELD OF THE INVENTION 
     The present invention relates to post decoding of memory circuits generally and, more particularly, to a post decode method and/or architecture for memory circuits using an interdigitated array. 
     BACKGROUND OF THE INVENTION 
     Referring to FIG. 1, a conventional circuit  10  for post decoding of memory circuits is shown. The circuit  10  comprises a plurality of blocks  12   a - 12   n , a global data bus  14 , a multiplexer  16  and an I/O circuit  18 . Each block  12   a - 12   n  presents a signal to an input  20   a - 20   n  of the global data bus  14 . The global data bus  14  presents a signal to an input  22  of the multiplexer  16 . The multiplexer  16  presents a signal to the I/O circuit  18  in response to the signal received at the input  22  and a signal POST_DECODE_ADDR received at an input  24 . The I/O circuit  18  presents the signal OUTPUT in response to the signals received from the multiplexer  16 . 
     The blocks  12   a - 12   n  comprise an array  26   a - 26   n , a multiplexer  28   a - 28   n  and a sense amplifier  30   a - 30   n . The array  26   a  is connected to the multiplexer  28   a . The multiplexer  28   a  is connected to the sense amplifier  30   a  and will transfer data in response to the array  26   a . The sense amplifier  30   a  is connected to an input  20   a  of the global data bus  14  and will transfer data in response to the multiplexer  28   a.    
     Timing diagrams of the circuit  10  are shown in FIGS. 2 a ,  2   b  and  2   c . The timing diagrams display the problem of race conditions that occur during operation of the circuit  10 . The timing of the signal POST_ADDR is critical to the operation of the circuit  10 . FIG. 2 a  defines a simplified timing diagram for a non-atd variant of device  10 . The post decode address input to the multiplexer selects one of two bytes of data from the 16-bit global bus and passes the selected byte to the 8-bit I/O. As an example, a logic low level on post decode address will pass even bits of data, while a logic high level will pass odd bits of data. At some time (i.e., tau) after an address change, the data on the 16-bit global data bus will change to that of the selected address GQ(n). This data then passes through the multiplexer to the I/O. The timing of the post decode address is critical for proper functionality of the device. If the post decode address transitions prior to the global data transition, then the data from address n−1, GQ(n−1)odd, will be momentarily passed to the I/O. This will cause the outputs of the device to “glitch” to the incorrect data. This “glitch” is undesirable and can cause performance degradation and excessive noise. Conversely, if the post decode address transitions after the global data transition (FIG. 2 b ), then the data from address n is properly passed to the I/O. However, the time difference between the global data transition and the post decode data transition (i.e., phi) has a direct adverse impact on the access time of the device. Phi is directly additive to the Taa, or address access time of the device. 
     FIG. 2 c  defines a simplified timing diagram for an atd variant of device  10 . This type of device generates an atd pulse as a result of an address transition. This atd pulse is used to equalize the data path of the device. As a result, the global data bus is equalized high (or low) during the pulse duration. By necessity the I/O is forced into a high impedance state by the equalized data path. This allows for time during which the post decode address can transition without passing erroneous data to the I/O. The internal post decode address must be positioned within this equalized state in order to avoid the glitches described for the non-atd device. 
     SUMMARY OF THE INVENTION 
     The present invention concerns an apparatus comprising a first bus, a second bus, a memory and one or more interconnections. The memory may be connected to the first bus and the second bus and may be configured to transfer data over the first bus and the second bus. The one or more interconnections may be connected between one or more data lines of the first bus and the second bus to control a bit-width of the first and second buses. 
     The objects, features and advantages of the present invention include providing a method and/or architecture that may (i) transform a memory with an internal bus width of N to a device with an external bus width of N/2 m  using the same base design, (ii) multiplex a single ended data path without inducing unnecessary output data transitions, (iii) have an access time which is not dependent on a post decode address speed, and/or (iv) define post decoding of memories with interdigitated arrays. In one example, the present invention may be used with differential data and a non-interdigitated array. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects, features and advantages of the present invention will be apparent from the following detailed description and the appended claims and drawings in which: 
     FIG. 1 is a conventional block diagram for the post decoding of memory circuits; 
     FIGS. 2 a - 2   c  are timing diagrams of the circuit of FIG. 1; 
     FIG. 3 is a block diagram of a preferred embodiment of the present invention; 
     FIG. 4 is a detailed block diagram of a block array of FIG. 3; and 
     FIG. 5 is a timing diagram of the circuit of FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 3, a block diagram of a circuit  100  is shown in accordance with a preferred embodiment of the present invention. The circuit  100  may allow post decoding of memory circuits using an interdigitated array (i.e., an array that may be alternately accessed from two sides) and single-ended data path. The circuit  100  may multiplex an internal data bus (either up or down) to an external data bus. The circuit  100  may multiplex the internal data bus by implementing multiple metal masks to option the bit-width of a data word to be stored/retrieved. 
     The circuit  100  generally comprises a memory  101 , a memory  102 , a bus  104 , a bus  106 , an I/O block (or circuit)  108  and an I/O block (or circuit)  110 . While an example of the circuit  100  is described in connection with two memories (e.g., the memory  101  and the memory  102 ) a number of memories greater than two (or even a single memory) may be implemented accordingly to meet the design criteria of a particular implementation. The memories  101  and  102  may each be implemented, in one example, as interdigitated memory arrays. However, the memories  101  and  102  may be implemented as non-interdigitated arrays in certain design applications. The memories  101  and  102  (to be described in detail in connection with FIG. 4) generally allow the circuit  100  to operate efficiently without the use of a post decode address circuitry. The memories  101  and  102  may also eliminate critical timing problems associated with post decode address circuitry. Read and write circuitry (not shown) may be enabled in a selected memory  101  or  102  only during a particular read or write operation. An example of read and write circuitry that may be used with the present invention may be found in co-pending application (Ser. No. 09/398,735, filed Sep. 17, 1999), which is hereby incorporated by reference in its entirety. 
     In one example, the bus  104  may be implemented as a west global data bus and the bus  106  may be implemented as a east global data bus. However the bus  104  and the bus  106  may be implemented as any other bus type in order to meet the criteria of a particular implementation. The west global data bus  104  may be connected to the east global data bus  106  through one or more bi-directional connections (e.g., METAL MASK OPTIONS). The METAL MASK OPTIONS may allow change of the width of a data word. The METAL MASK OPTIONS may short particular portions (e.g., data lines) of the west and east global data buses  104  and  106 . Address transition detection pulses within the memories  101  and  102  may prevent potential crowbar conditions when switching between west and east global data buses  104  and  106 . 
     The memory  101  may present and/or receive data to and/or from the west global data bus  104  between an input/output  111  and an input/output  112 . The memory  101  may present and/or receive data to and/or from the east global data bus  106  between an input/output  113  and an input/output  114 . The memory  101  may present and/or receive data in response to a block enable signal (e.g., BLKEN( 101 )) received at an input  103  and an east/west address signal (e.g., AP 0 ) received at an input  180 . The memory  102  may present and/or receive data to and/or from the west global data bus  104  between an input/output  115  and an input/output  116 . The memory  102  may present and/or receive data to and/or from the east global data bus  106  between an input/output  117  and an input/output  118 . The memory  102  may present and/or receive data in response to the signal BLKEN( 102 ) received at an input  105  and an east/west address signal (e.g., AP 0 ) received at an input  181 . The signal BLKEN may enable the read and write circuitry (not shown) in a selected memory  101  or  102 . The signal AP 0  may enable the read or write circuitry on the east or west side of memory  101  or  102 . The memories  101  and  102  may each comprise an internal data bus (not shown). The internal data bus may have, in one example, a bit-width equal to two times the bit-width of the bus  104  and/or the bus  106 . However, other bit-widths may be implemented accordingly to meet the design criteria of a particular implementation. 
     The west global data bus  104  may present data received from the memories  101  and  102  to the I/O circuit  108  between an input/output  120  and an input/output  121 . The west global data bus  104  may also present data received from the I/O circuit  108  to the memories  101  and/or  102 . The I/O circuit  108  may present a signal (e.g., IN/OUTW) at the input/output  122 . The east global data bus  106  may present data received from the memories  101  and  102  to the I/O circuit  110  between an input/output  124  and an input/output  125 . The east global data bus  106  may also present data received from the I/O circuit  110  to the memories  101  and  102 . The I/O circuit  110  may present a signal (e.g., IN/OUTE) at an input/output  126 . The I/O circuits  108  and  110  may be implemented as 4-bit I/O circuits, 8-bit I/O circuits or any other bit-width I/O circuits that may be appropriate to meet the criteria of a particular implementation. 
     Referring to FIG. 4 a detailed block diagram of the memory  101  of FIG. 3 is shown. The memory  102  has similar components as the memory  101 . The memory  101  may comprise a memory array  130 , a sense amplifier  132 , a sense amplifier  134 , an inverter  136 , a nand gate  136  and a nand gate  165 . The memory array  130  may be implemented, in one example, as an interdigitated array having a size of 1024×16. However, the memory array  130  may be implemented as various sized memories in order to meet the criteria of a particular implementation. The sense amplifiers  132  and  134  may each access the memory array  130 . The sense amplifier  132  may present/receive data to/from the memory array  130  between an input/output  131  and an input/output  133 . The sense amplifier  134  may present/receive data to/from the memory array  130  between an input/output  135  and an input/output  137 . 
     The sense amplifiers  132  and  134  may be used in place of post decode address circuitry that may be found in conventional circuits. The sense amplifiers  132  and  134  may be implemented to transfer data to/from the array  130  to/from the west and east global data buses  104  and  106  in response to the BLKEN signal  103  and the AF 0  signal  150 . In one example, the sense amplifiers  132  and  134  may be implemented as 8-bit sense amplifiers. However, the sense amplifiers  132  and  134  may be implemented as any bit size in order to meet the criteria of a particular implementation. The memory array  130  may provide a similar operation for 8-bit sense amplifiers and 16-bit sense amplifiers. The sense amplifiers  132  and  134  may be implemented to multiplex, for example, a 16-bit memory array  130  to an 8-bit global data buses  104  (and/or  106 ). 
     The memory  101  may present the data at the input/output  111  and/or the input/output  113  in response to the signal BLKEN received at the input  103  and the AP 0  address signal  150 . The memory  101  may also receive data at the input/output  111  and/or the input/output  113 . The signal BLKEN may be presented to an inputs  160  and  161  of gates  166  and  165 , respectively. In one example, the gates  165  and  166  may be implemented as NAND gates. However, other gates may be implemented accordingly to meet the design criteria of a particular implementation. The gate  165  may present a signal to an input  142  of the sense amplifier  132 . The gate  166  may present a signal to an input  140  of the sense amplifier  134 . While input  140  of sense amplifier  134  or input  140  of sense amplifier  142  are inactive, the sense amplifiers  132  and  134  generally tristate and cease to drive the global data busses. The memory array  130  may present data to the sense amplifier  132  and/or the sense amplifier  134  in response to a bitline (e.g., BL) and a bitline bar (e.g., BLB). The memory array  130  may store data in response to the bitline BL and the bitline bar BLB. FIG. 5 details a timing diagram which may define the interaction of the signal AP 0  and the signal BLKEN on memory  101  and/or  102 . 
     While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the spirit and scope of the invention.