CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 12/776,154 filed May 7, 2010, issued as U.S. Pat. No. 9,281,037 on Mar. 8, 2016, which is a divisional of U.S. patent application Ser. No. 11/899,738, filed Sep. 6, 2007, issued as U.S. Pat. No. 7,729,191 on Jun. 1, 2010, the applications and patents of which are incorporated herein by reference, in their entirety, for any purpose. 
     
    
     TECHNICAL FIELD 
       [0002]    This invention relates generally to memory devices, and, more particularly to decoding various reduced power commands in memory devices. 
       BACKGROUND OF THE INVENTION 
       [0003]    Memory devices, such as DRAM devices, have a large number of signal terminals for receiving command, address and write data signals and for transmitting read data signals. The large number of terminals is generally required for memory devices used in most electronic systems, such as computer systems, that include a large number of such memory devices. 
         [0004]    The command signals that are applied to memory devices are well-established and have been in common use for many years. Not only are users familiar with such commands, but devices used with memory devices, such as memory controllers, are specifically designed with such commands in mind. It would therefore be inconvenient to use or sell memory devices that use a command set that is different from this commonly used set of commands. Command signals for dynamic random access memory (“DRAM”) devices, for example, receive a number of command signals at respective terminals. These command signals are generally clock enable CKE#, chip select CS#, write enable WE#, row address strobe RAS# and column address strobe CAS# signals, where the “#” indicates the signal is active low. 
         [0005]    It would be desirable to reduce the number of signals and corresponding terminals that memory devices use to interface with other devices, such as processors or memory controllers. However, the currently used command signals are generally considered necessary to implement all of the desired functionality of memory devices. Therefore, it has been considered impractical to reduce the number of command signals that must be provided to memory devices. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a block diagram of a memory device according to one embodiment of the invention. 
           [0007]      FIG. 2  is a command decode table used by a command decoder in the memory device of  FIG. 1 . 
           [0008]      FIG. 3  is an embodiment of a portion of a command decoder in the memory device of  FIG. 1 . 
           [0009]      FIG. 4  is an embodiment of a portion of a command decoder in the memory device of  FIG. 1 . 
           [0010]      FIG. 5  is a block diagram of an embodiment of an electronic device having a CMOS image and the memory device of  FIG. 1  or some other embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]      FIG. 1  shows a dynamic random access memory (“DRAM”) device  10  according to one embodiment of the invention. The memory device  10  is a double-data rate (DDR) synchronous dynamic random access memory (“SDRAM”), although the principles described herein are applicable to any memory device that receives memory commands. The memory device  10  includes an address register  12  that receives row, column, and bank addresses over an address bus ADDR, with a memory controller (not shown) typically supplying the addresses. The address register  12  receives a row address and a bank address that are applied to a row address multiplexer  14  and bank control logic circuit  16 , respectively. The row address multiplexer  14  applies either the row address received from the address register  12  or a refresh row address from a refresh counter  18  to a plurality of row address latch and decoders  20   a - d . The bank control logic  16  activates the row address latch and decoder  20   a - d  corresponding to either the bank address received from the address register  12  or a refresh bank address from the refresh counter  18 , and the activated row address latch and decoder latches and decodes the received row address. In response to the decoded row address, the activated row address latch and decoder  20   a - d  applies various signals to a corresponding memory bank  22   a - d  to thereby activate a row of memory cells corresponding to the decoded row address. Each memory bank  22   a - d  includes a memory-cell array having a plurality of memory cells arranged in rows and columns, and the data stored in the memory cells in the activated row is stored in sense amplifiers in the corresponding memory bank. The row address multiplexer  14  applies the refresh row address from the refresh counter  18  to the decoders  20   a - d  and the bank control logic circuit  16  uses the refresh bank address from the refresh counter  18  when the memory device  10  operates in an auto-refresh or self-refresh mode of operation in response to an auto- or self-refresh command being applied to the memory device  10 , as will be appreciated by those skilled in the art. 
         [0012]    A column address is applied on the ADDR bus after the row and bank addresses, and the address register  12  applies the column address to a column address counter and latch  24  which, in turn, latches the column address and applies the latched column address to a plurality of column decoders  26   a - d . The bank control logic  16  activates the column decoder  26   a - d  corresponding to the received bank address, and the activated column decoder decodes the applied column address. Depending on the operating mode of the memory device  10 , the column address counter and latch  24  either directly applies the latched column address to the decoders  26   a - d , or applies a sequence of column addresses to the decoders starting at the column address provided by the address register  12 . In response to the column address from the counter and latch  24 , the activated column decoder  26   a - d  applies decode and control signals to an I/O gating and data masking circuit  28  which, in turn, accesses memory cells corresponding to the decoded column address in the activated row of memory cells in the memory bank  22   a - d  being accessed. 
         [0013]    During data read operations, data being read from the addressed memory cells is coupled through the I/O gating and data masking circuit  28  to a read latch  30 . The I/O gating and data masking circuit  28  supplies N bits of data to the read latch  30 , which then applies two N/2 bit words to a multiplexer  32 . A data driver  34  sequentially receives the N/2 bit words from the multiplexer  32  and also receives a data strobe signal DQS from a strobe signal generator  36  and a delayed clock signal from a delay-locked loop (“DLL”)  38 . The DQS signal is used by an external circuit such as a memory controller (not shown) in latching data from the memory device  10  during read operations. In response to the delayed clock signal from the DLL  38 , the data driver  34  sequentially outputs the received N/2 bits words as a corresponding data word on a data bus DQ. The data driver  34  also outputs the data strobe signal DQS having rising and falling edges in synchronism with the data word. 
         [0014]    During data write operations, an external circuit such as a memory controller (not shown) applies N/2 bit data words to the memory device  10  through the data bus DQ. The external circuit also applies the strobe signal DQS to the memory device  10 . A data receiver  48  receives each data word, and applies corresponding write data signals to input registers  50  that are clocked by the DQS signal. In response to a rising edge of the DQS signal, the input registers  50  latch a first N/2 bit word, and in response to a falling edge of the DQS signal the input registers latch the second N/2 bit word. The input register  50  provides the two latched N/2 bit words as an N-bit word to a write FIFO and driver  52 , which clocks the applied write data word into the write FIFO and driver  52  in response to the DQS signal. The write data word is clocked out of the write FIFO and driver  52  in response to the CK signal, and is applied to the I/O gating and masking circuit  28 . The I/O gating and masking circuit  28  transfers the DQ word to the addressed memory cells in the accessed bank  22   a - d.    
         [0015]    A control logic unit  64  receives a plurality of command and clock signals over a control bus  66 , typically from an external circuit such as a memory controller (not shown). The command signals include a write enable signal WE, a column address strobe signal CAS, and a row address strobe signal RAS, all of which are active high. These command and clock signals are decoded by a command decoder  70  in the control logic unit  64 , as described in greater detail below. The command decoder  70  causes address signals and data signals to be latched at both the rising edge of the CK signal (i.e., the crossing of CK from low-to-high) and the falling edge of the CK signal (i.e., the crossing of CK from high-to-low), while the data drivers  34  and the input registers  50  transfer data to and from, respectively, the data bus DQ in response to both edges of the data strobe signal DQS. The command decoder  70  receives signals from the address register  12  for reasons that will be explained below. The control logic unit  64  also includes mode registers  72  that can be programmed to control various operating modes, as is conventional in memory devices. The command decoder  70  also receives signals from the address register  12  for reasons that will be explained below. 
         [0016]    Unlike conventional DRAM devices, the memory device  10  does not receive a chip select signal CS# or a clock enable signal CKE#, thereby reducing the number of command signals by two. To preserve all of the functionality of the memory device  10 , the command decoder  70  should be adapted to perform all of the operations typically performed by a DRAM device without the use of the command signals that are typically decoded to designate those operations. The manner in which the command decoder  70  is able to perform those functions will be described in greater detail below. In response to the clock signal CK, the control logic unit  64  generates a sequence of clocking and control signals that control the components of the memory device  10  to perform the corresponding operations. 
         [0017]    One of the problems with the memory device  10  using a limited number of commands is that some of the operations performed responsive to respective commands place the memory device in a mode where it is no longer operating other than to retain data stored in the memory cells of the memory banks  22   a - d . The limited number of commands should be able to transition the memory device  10  back to a completely operable mode, and do so in a manner that does not result in spurious operations or other operations that might result in data loss. 
         [0018]    The power down operations performed by the memory device  10  are a precharge power down operation, an active power down operation and a deep power down operation. In both power down operations, power is removed from input buffers in the address register  12  and the data receiver  48 , and power is also removed from input buffers in the control logic unit  64  that receive some of the command signals. However, at least one input buffer in the control logic unit  64  remains powered to pass a signal that commands the memory device  10  to transition out of the power down mode. Also, in both power down modes, power continues to be applied to the components needed to refresh the memory cells in the banks  22   a - d . In the active power down mode, which is automatically entered responsive to a power down command if a row of memory cells is currently open, the row remains active so the memory cells in the row can be quickly read. Finally, in the deep power down mode, the entire memory device  10  is powered down except for a single input buffer needed to pass a command signal to maintain the memory device in that mode. The command decoder  70  in the control logic unit  64  can also decode other commands such a read, write, no operation, precharge, active, and refresh commands. 
         [0019]    In prior art memory devices, all three of these power down commands are normally signaled by the CKE# signal transitioning low in combination with other command signals. The power down modes are normally terminated by the CKE# signal transitioning high. Similarly, the auto-refresh command is normally differentiated from the self-refresh command by the state of the CKE# signal. However, in the memory device  10 , the CKE# command signal is not used. Moreover, the RAS, CAS and WE signals, which are used, are used for other purposes and are thus generally unavailable to take the place of the CKE# signal. This problem is solved by decoding the RAS, CAS and WE signals, along with certain address signals, according to the command decode table shown in  FIG. 2 . It is for this reason that the command decoder  70  receives signals from the address register  12 . 
         [0020]    With reference to  FIG. 2 , the command decoder  70  groups the commands into the 8 possible sets of commands that can be obtained from the 3 binary command signals RAS, CAS and WE. The Active command ACTV, the precharge command PREC and the auto refresh command RFSH all have unique combinations of the RAS, CAS and WE commands. Other commands are grouped together, with the commands in each group being differentiated from each other by address signals clocked into the command decoder  70  on either the rising edge of the falling edge of the CK signal. The commands that are grouped and differentiated from each other by address signals are chosen to be commands that do not require the decoding of at least some of the address signals. For example, the command decoder  70  differentiates between the power down and refresh commands PDE, all of which are signaled by the same combination of the RAS, CAS and WE commands, i.e., “110,” by examining the A 7  and A 6  address bits latched on the rising edge of the CK signal, which are designated as the A 7 R and A 6 R bits, respectively. The normal power down command (whether active power down or precharge power down) is signaled by decoding the A 7 R, A 6 R bits as “00,” the power down self-refresh command is signaled by decoding the A 7 R, A 6 R bits as “01,” and the deep power down command is signaled by decoding the A 7 R bit as “1.” 
         [0021]    The no operation command NOP is signaled by decoding RAS, CAS and WE signals as “111.” This decoding scheme is advantageous because the command “111” is differentiated from the command “110” for the power down and self-refresh modes only by the state of the WE signal. As a result, when the memory device  10  transitions out of one of the power down modes responsive to the WE signal transitioning from low-to-high, the command decoder  70  signals the memory device  10  to perform no operation, thereby avoiding spurious data from being written to or read from the memory device  10 . 
         [0022]    The READ commands are signaled by decoding the RAS, CAS and WE signals as “101,” and differentiated from each other by the state of the A 7  address signal latched on the falling edge of the CK signal, which is designated as the A 7 F bit. The normal read command is signaled by decoding the A 7 F signal as “0,” and the auto precharge read command is signaled by decoding the A 7 F signal as “1.” The addresses for a read command are applied to the address register  12  as A 7 -A 0  signals latched on the rising edge of the CK signal and the A 2 -A 0  signals latched on the falling edge of the CK signal, which are designated as the A 7 R-AOR and A 2 F-A 0 F bits, respectively. Similarly, the WRITE commands are signaled by decoding the RAS, CAS and WE signals as “100,” and also differentiated from each other by the state of the A 7  address signal latched on the falling edge of the CK signal, which is designated as the A 7 F bit. The normal write command is signaled by decoding the A 7 F signal as “0,” and the auto precharge write command is signaled by decoding the A 7 F signal as “1.” The addressing scheme for a write command is the same as the above-explained addressing scheme for a read command. 
         [0023]    There are also commands for loading the mode registers  72 , which are signaled by decoding the RAS, CAS and WE signals as “000,” and differentiated from each other by the state of the A 5  address signal latched on the rising edge of the CK signal, which is designated as the A 5 R bit. A first of the mode registers  72  is programmed responsive to the A 5 R bit being decoded as “0,” and a second of the mode registers  72  is programmed responsive to the A 5 R bit being decoded as “1.” The mode registers  72  are programmed with data applied to the address register  12  as A 7 , A 6  and A 4 -A 0  signals latched on the rising edge of the CK signal, and as A 7 -A 8  signals latched on the falling edge of the CK signal, which are designated as the A 7 R, A 6 R and A 4 R-AOR and A 7 F-A 8 F bits, respectively. 
         [0024]    Although the active command ACTV is signaled by uniquely decoding the RAS, CAS and WE signals, it requires an address to designate the row of memory cells that is to be activated. The addresses for the ACTV command are applied to the address register  12  as A 7 -A 0  signals latched on the rising edge of the CK signal and A 5 -A 0  signals latched on the falling edge of the CK signal. 
         [0025]    The command decoding scheme shown in  FIG. 2  allows the memory device  10  to perform all necessary operations despite the absence of the CKE# and CS# command signals typically found in DRAM memory devices. Although the absence of the chip select CS# signal can make it more difficult to use multiple memory devices  10  in a system, it is possible to provide commands to separate memory devices  10  in a system by applying a separate WE signal to each of the memory devices  10  in the same manner that the CS# signal is normally used. 
         [0026]    An embodiment of a portion of a decoder circuit  80  that may be used in the command decoder  70  to decode the RAS, CAS and WE commands is shown in  FIG. 3 . The decoder circuit  80  includes a NAND gate  82  that receives the RAS, CAS and WE signals through respective inverters  84 ,  86 ,  88 . The NAND gate  82  therefore outputs a low PowerDownF signal (with the “F” indicating the signal is active low) only if the RAS, CAS and WE signals are “111.” Otherwise, the PowerDownF signal is inactive high. The output of the NAND gate  82  is applied to a data input of a latch  90 , which also receives an output of a NAND gate  92 . The NAND gate  92  receives A 6 R and A 7 R signals from the address register  12  through respective inverters  96 ,  98 . As explained above, the A 6 R and A 7 R signals correspond to the A 6  and A 7  signals, respectively, latched on the rising edge of the CK signal, as shown in  FIG. 2 . It will be recalled that both of these signals will be high only when the power down command is a precharge power down command, i.e., not a self-refresh or a deep power down command. Therefore, the NAND gate  92  will output an active low AddPowerDownF signal only if the power down command is not a self-refresh or a deep power down command. If the signal applied to the Cmd and Add inputs to the latch  90  are both active low, which occurs responsive to a normal power down command, the latch  90  outputs an active high PDE command responsive to a Clk signal to indicate the normal power down command (either active power down or precharge power down depending upon the operation currently being performed). The Clk signal is generated responsive by delay circuitry (not shown) responsive to the CK signal after a suitable delay. 
         [0027]    The PowerDownF signal from the NAND gate  82  is also applied to the Cmd input of a second latch  100 , which receives an output from a NAND gate  102  at its Add input. The NAND gate  102 , in turn, receives the A 6 R signal at one input and the A 7 R signal through an inverter  104 . It will be recalled that, during a power down command, the A 6  signal latched on the rising edge of the CK signal is high and the A 7  signal latched on the rising edge of the CK signal is low only if the command is a power down self-refresh command. Therefore, in response to the decoding A 7 R, A 6 R as “01,” the NAND gate  102  outputs an active low AddSrefF signal. In response, to the low PowerDownF and AddSrefF signals, the latch  100  outputs an active high PDESR command in response to the Clk signal to indicate the power down self-refresh command. 
         [0028]    Similarly, a third latch  110  also receives the PowerDownF signal at its Cmd input. The latch  110  also receives the A 7 R signal through an inverter  112 . It will be recalled that the A 7  signal latched by the rising edge of the CK signal is high during a power down command only for a deep power down command. Therefore, in response to the Clk signal, the latch  110  outputs an active high PDEDP command responsive to decoding the A 7 R signal as “1.” 
         [0029]    An embodiment of a portion of a decoder circuit  120  that may be used in the command decoder  70  to terminate the power down and self-refresh operations responsive to the WE command transitioning high is shown in  FIG. 4 . In addition to the signals output from the decoder circuit  80  of  FIG. 3 , the decoder circuit  120  receives a BknOn signal that is passed through an inverter  122  to generate an BnkOnF signal that is active low whenever a row in a bank is open. The decoder circuit  120  also receives a We_Dpd signal at an input to an inverter  124 , which is active high whenever the memory device  10  is in the deep power down mode. Finally, the decoder circuit  120  receives a WeAsync signal and a WeSync signal. Both the WeAsync signal and the WeSync signal transition high when the WE signal is asserted high. The WeSync signal is generated at the output of a latch (not shown) in the command decoder  70 . As mentioned above, the latch is clocked by the CK signal. However, in the power down modes other than the active power down mode, the buffer (not shown) that passes the CK signal is not powered. Therefore, the rising edge of the WE signal latched by the CK signal could not be detected. For this reason, a WeAsync signal is generated at the output of a buffer (not shown) that passes the WE signal. This buffer, unlike the latch that receives the output of the buffer, remains powered in all power down and self-refresh modes. Thus, the WeSync signal transitions high responsive to the WE signal transitioning high in synchronism with the CK signal, and the WeAsync signal transitions high asynchronously responsive to the WE signal transitioning high. 
         [0030]    The decoder circuit  120  performs the function of generating signals that are active in the various modes to de-power certain circuits in the memory device  10 , as explained above. The PDE signal, which, as explained above, is high in the precharge power down mode or the active power down mode, is applied to one input of a NOR gate  130 . The other input of the NOR gate  130  receives the DPD signal, which, as explained above, is high in the deep power down mode. Thus, the NOR gate  130  outputs an active low PdCmdF signal in either the deep power down mode or in one of the other two power down modes. The low PdCmdF signal sets a flip-flop  134  formed by a pair of cross-coupled NAND gates  136 ,  138 . When the flip-flop is set, the NAND gate  136  outputs an active high POWER DOWN signal. The flip-flop  134  is reset responsive to the WE signal transitioning high, as explained below. 
         [0031]    A high POWER DOWN signal is used to generate several control signals. It is applied to one input of an OR gate  140 , which also receives the output of a delay circuit  142 , which receives the POWER DOWN signal through another delay circuit  144 . The delay circuits  142 ,  144  substantially respond to transitions of the low-to-high transition of the POWER DOWN signal, but they delay responding to transitions of high-to-low transition of the POWER DOWN signal. As a result, the output of the OR gate  140  substantially transitions high responsive to the low-to-high transition of the POWER DOWN signal. The output of the OR gate  140  is applied to one input of a NAND gate  146 , which also receives the BnkOn signal. It will be recalled that the BnkOn signal is high whenever a row is active. Therefore, the NAND gate  146  outputs a low, to cause the output of an inverter  148  to output an active high We_PdAct signal in the active power down mode. The high We_PdAct signal causes power to be removed from the components that are powered down in one of the active power down modes, as explained above. 
         [0032]    The POWER DOWN signal is also applied to an input of an AND gate  150 , which also receives the BnkOnF signal. The AND gate  150  therefore outputs a high in the power down mode only if a row of memory cells is not active, which occurs in the precharge power down mode. The output of the AND gate  150  is applied to an input of an OR gate  154 , which also receives a We_Sr signal. As explained below, the We_Sr signal is high in the self-refresh power down mode. Thus, the OR gate  154  outputs a low in either the precharge power down mode or the self-refresh power down mode. The output of the OR gate  154  is applied to an input of an inverter  158 , which outputs an active high We_PdSr signal in either the precharge power down mode or the self-refresh power down mode. The high We_PdSr signal causes power to be removed from the components that are de-powered in that mode. 
         [0033]    The We_Sr signal is generated at the output of a flip-flop  160  formed by NAND gates  164 ,  166 . The flip-flop  160  is set by a high PDESR signal coupled through an inverter  162 . As explained above, the PDESR signal is high in the power down self-refresh mode. Thus, as mentioned above, the We_Sr signal is high in the power down self-refresh mode. 
         [0034]    The decoder circuit  120  also generates an active high We_Dpd signal, which is high in the deep power down mode. The We_Dpd signal is generated at the output of a flip-flop  170 , which is formed by NAND gates  172 ,  174 . The flip-flop  170  is set by a high DPD signal coupled through an inverter  176 . As explained above, the DPD signal is high in the deep power down mode. Therefore, the We_Dpd signal is high in the power down self-refresh mode, and it removes power from almost all of the components of the memory device  10 . 
         [0035]    The We_Dpd signal applied to the inverter  124  is output to an input of a NAND gate  178 . This input to the NAND gate  178  is high whenever the memory device  10  is not in the deep power down mode. The NAND gate  178  also receives a We_PdAct signal, which, as explained below, is high in the active power down mode when the power down mode is entered with a row of memory cells active. Finally, the NAND gate  178  receives a PwrUp signal, which is high during normal operation. The output of the NAND gate  178  is applied to an input of an inverter  180 , which generates an active low AsyncF signal. An Async signal is therefore low and the AsyncF signal is low only when the memory device  10  is in the active power down mode. When the memory device  10  is in the deep power down mode, the Async signal is high and the AsyncF signal is low. The Async and AsyncF signals are used by circuitry that will now be explained. 
         [0036]    As explained above, the WeAsync signal transitions high asynchronously responsive to the WE signal transitioning high, and the WeSync signal transitions high responsive to the WE signal transitioning high in synchronism with the CK signal. The WeAsync signal is applied to an input of a NAND gate  182  and to the input of a first delay circuit  184 , which applies its output to the input of a second delay circuit  186 . The output of the second delay circuit  186  is applied to another input to the NAND gate  182 . When the WE signal is low, the WeAsync signal and the output of the delay circuit  186  are both low. As a result, the NAND gate  182  outputs a high, which is applied to an inverter  188 . The inverter  188  is enabled by the Async signal being high and the AsyncF signal being low. Therefore, as long as the memory device  10  is in the deep power down mode, the inverter  188  is enabled. When the WE signal is low, the inverter  188  outputs a low, which, after being inverted by an inverter  190 , causes a high to be applied to the flip-flops  134 ,  160 ,  170 . This high allows the flip-flops  134 ,  160 ,  170  to be set, as explained above. 
         [0037]    When the WE signal transitions high, the WeAsync signal asynchronously transitions high. After a delay time provided by the delay circuits  184 ,  186 , the output of the NAND gate  182  transitions low to cause the output of the inverter  190  to transition low. This low resets the flip-flops  134 ,  160 ,  170  to terminate the power down signals generated by the decoder circuit  120 . Therefore, in the deep power down mode, the power down mode is asynchronously terminated by the WE signal transitioning high. 
         [0038]    The WeSync signal, which transitions high in synchronism with the CK signal, is coupled through two inverters  192 ,  194  to the input of the inverter  190 . The inverter  194  is enabled by AsyncF being high and Async being low, which is the opposite state that enables the inverter  188 . Therefore, the inverter  194  is enable in all power down modes other than the deep power down mode. When the WeSync signal transitions high, the output of the inverter  190  transitions low to again reset the flip-flops  134 ,  160 ,  170 . 
         [0039]    In summary, in all power down modes but the deep power down mode, the flip-flops  134 ,  160 ,  170  are reset in synchronism with the CK signal responsive to the WE signal transitioning high to terminate the power down signals generated by the decoder circuit  120 . However, in the deep power down mode when the latch generating the WeSync signal is not powered, the flip-flops  134 ,  160 ,  170  are reset asynchronously responsive to the WE signal transitioning high. 
         [0040]    An embodiment of an electronic device  200  that may use the memory device  10  of  FIG. 1  or some other embodiment of the invention is shown in  FIG. 5 . The electronic device  200  may be, for example, a digital camera, a vehicle navigation system, a videophone, a cell phone, an audio player with imaging capabilities, or other devices that utilize CMOS image sensing technology. The electronic device  200  includes a CMOS imager  210  and a processor  212  that is connected to receive image data from the imager  210 . The processor  212  can then store the image data in the memory device  10  for subsequent read-out or display. The processor  212  may be, for example, a microprocessor, digital signal processor, or part of a larger central processing unit that performs other functions. The processor  212  is connected to the memory device  10  through a set of buses  220 , which may include a command bus, and address bus and a data bus. The electronic device  200  also includes a user interface  224  connected to the processor through a bus. The electronic device  200  also includes a display  230 , such as a cathode ray tube (CRT) or liquid crystal display (LCD), for displaying information captured by the CMOS imager  210 . The electronic device  200  may also include a data storage device  240 , such as removable Flash memory, capable of non-volatilely storing data processed by processor  212 , including, for example, digital image data. The consumer device  200  may optionally also have a peripheral device interface  250  so that the processor  212  may communicate with a peripheral device (not shown). Although the CMOS imager  210  is shown as a separate component, it may be combined with the processor  212  and/or with the memory device  10  on a single integrated circuit or on a different chip. 
         [0041]    From the foregoing it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention. Accordingly, the invention is not limited except as by the appended claims.
Systems, devices and methods are disclosed. In an embodiment of one such method, a method of decoding received command signals, the method comprises decoding the received command signals in combination with a signal provided to a memory address node at a first clock edge of a clock signal to generate a plurality of memory control signals. The received command signals, in combination with the signal provided to the memory address node at the first clock edge of the clock signal, represent a memory command. Furthermore, the signal provided to the memory address node at a second clock edge of the clock signal is not decoded in combination with the received command signals. The memory command may be a reduced power command and/or a no operation command.