US20050071707A1 - Integrated circuit with bi-modal data strobe - Google Patents

Integrated circuit with bi-modal data strobe Download PDF

Info

Publication number
US20050071707A1
US20050071707A1 US10676648 US67664803A US2005071707A1 US 20050071707 A1 US20050071707 A1 US 20050071707A1 US 10676648 US10676648 US 10676648 US 67664803 A US67664803 A US 67664803A US 2005071707 A1 US2005071707 A1 US 2005071707A1
Authority
US
Grant status
Application
Patent type
Prior art keywords
signal
data
mode
controller
data strobe
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US10676648
Inventor
Craig Hampel
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Rambus Inc
Original Assignee
Rambus Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Family has litigation

Links

Images

Classifications

    • GPHYSICS
    • G06COMPUTING; CALCULATING; COUNTING
    • G06FELECTRIC DIGITAL DATA PROCESSING
    • G06F13/00Interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units
    • G06F13/14Handling requests for interconnection or transfer
    • G06F13/16Handling requests for interconnection or transfer for access to memory bus
    • G06F13/1668Details of memory controller
    • G06F13/1694Configuration of memory controller to different memory types
    • GPHYSICS
    • G06COMPUTING; CALCULATING; COUNTING
    • G06FELECTRIC DIGITAL DATA PROCESSING
    • G06F13/00Interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units
    • G06F13/14Handling requests for interconnection or transfer
    • G06F13/16Handling requests for interconnection or transfer for access to memory bus
    • G06F13/1668Details of memory controller
    • G06F13/1689Synchronisation and timing concerns

Abstract

A memory device that has two operating modes. In the first mode the data strobe is source synchronous and is driven by the memory device when data is being transmitted. In the second mode the data strobe is not driven by the memory device. In this mode the data strobe signal is used as a free running clock to sample write data. The capture of read data by the controller is timed by the controller with a calibrated internal timing reference from the system clock.

Description

    BRIEF DESCRIPTION OF THE INVENTION
  • The present invention pertains generally to integrated circuit technologies. More specifically, the present invention pertains to integrated circuit devices with bi-modal data strobes.
  • BACKGROUND
  • A source synchronous data strobe serves to compensate for the delays in the transmit path of a device that is transmitting data and the receive path of a device receiving this data. The size of these delays are a function of the speed, and variation in path speed, of a semiconductor device over its operating conditions and manufacturing tolerances.
  • Typically the data strobe interconnect lines between devices are left in a tristate, or quiet state, when responsibility for generating a data strobe is transferred from one device to another. As a result of these quiet periods, the data strobe does not have a predetermined, constant frequency, but resembles a clock being briefly turned on and off. During periods that multiple cycles of the data strobe are generated by a single device, the data strobe signal suffers from standing wave phenomena. The first edge, and perhaps the first few edges of a data strobe will typically arrive in-phase with respect to the data. However, subsequent edges of the data strobe may shift due to reflections of previous data strobe edges, and therefore will not be in phase with respect to the data. In other words, the data strobe would begin to appear more like a free running clock.
  • As memory bus speeds have increased, the benefits of using source synchronous data strobes in memory systems have decreased. Over time it is apparent that data strobes will need to be modified to accommodate systems that run faster. Due to manufacturing costs and economies of scale, it would be beneficial if a new system design that addresses the problems with data strobes were compatible with products using source synchronous data strobes.
  • SUMMARY
  • A controller for a memory system is coupled to a data strobe bus, a data bus, and a clock bus. The controller includes an output buffer configured to assert a first data strobe signal on the data strobe bus when the output buffer is enabled. The controller also includes a register to store a mode of controller operation. The output buffer is enabled only during transfers from the controller of a first data signal over the data bus when the mode of controller operation is set to a first mode of controller operation. The output buffer is, however, continuously enabled when the mode of controller operation is set to a second mode of controller operation. Further, the controller is configured to receive a clock signal over the clock bus and to clock receipt of a second data signal over the data bus with the clock signal.
  • In another aspect, a memory device is coupled to a data strobe bus, a data bus, and a clock bus. The memory device is configured to receive over the data strobe bus a data strobe signal that is continuously, remotely asserted on the data strobe bus. The memory device is also configured to receive over the data bus a first data signal in conjunction with the data strobe signal and to clock receipt of the first data signal with the data strobe signal. The memory device is further configured to receive a clock signal over the clock bus. In a first mode of operation, the memory device is configured to transmit over the data bus a second data signal in conjunction with the clock signal and to clock transmission of the second data signal with the clock signal. In a second mode of operation the memory device is configured to clock transmission of the second data signal with the data strobe signal.
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • Aspects of the present invention will be more readily apparent from the following description and appended claims when taken in conjunction with the accompanying drawings, in which:
  • FIG. 1 illustrates a memory system.
  • FIG. 2 illustrates a controller of the memory system illustrated in FIG. 1.
  • FIG. 3 illustrates a DRAM that may be included in the memory system illustrated in FIG. 1.
  • FIG. 4 illustrates another DRAM that may be included in the memory system illustrated in FIG. 1.
  • FIG. 5A illustrates another controller that may be included in the memory system illustrated in FIG. 1.
  • FIG. 5B illustrates another DRAM that may be included in the memory system illustrated in FIG. 1.
  • DESCRIPTION OF EMBODIMENTS
  • A number of embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described. It will be appreciated that in the development of any such embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.
  • FIG. 1 illustrates a memory system 100 that includes a master system clock or global clock 140, a clock buffer 142, a controller 110/425, one or more memory modules 120 (120-1, 120-2), one or more control and address (“C/A”) leads 150, eight data (“DQ”) leads 160 (160-1 to 160-8) and eight data strobe (“DS”) leads 170 (170-1 to 170-8). The memory module 120-1 in some embodiments is a DIMM (dual in-line memory module) that includes eight DRAMs 130/440/450 (130-1 to 130-8), and a configuration storage device 132. While the memory module 120-1 shown in FIG. 1 has a single column of DRAMs, one or more of the memory modules in the system 100 may be a multi-rank memory module having two or more columns (also called ranks) of DRAMs. In such memory modules, a single column or rank of the DRAMs is accessed during each memory operation that employs the memory module. Each memory module 120 optionally includes a register 152, a phase locked loop (“PLL”) clock buffer 144. These optional support circuits are helpful, for instance, in systems supporting large fan-outs (i.e., large numbers of DRAMs). In particular, these optional circuits support the distribution of clock, control and address signals among the DRAMs 130.
  • In some embodiments, the memory module configuration storage device 132 (sometimes called a mode register or configuration register) is implemented as a serial presence detect (SPD) device such as a PROM (programmable read only memory). The configuration storage device 132 is typically read by the controller upon power up or system reset to determine the capabilities and/or configuration of the memory module 120. In some embodiments, a bit within the memory module configuration storage device 132 stores a data strobe mode value (also herein called a directional mode value), indicative of whether the memory devices within the memory module can be configured to disable driving of the data strobe, in addition to other mode values. The information read from the memory module configuration storage device 132 is used by the controller 110 to set mode bits within the controller 110 and the DRAMs 130. In some embodiments the number of data leads, data strobes and DRAMs may be larger or smaller. Except where otherwise noted, discussions provided here with respect to controller 110 are also applicable to controller 425, and discussions with respect to DRAM 130 are also applicable to DRAMs 440 and 450.
  • The C/A leads 150 function as a control and address bus, having as many parallel signal paths as needed by the memory system 100. Similarly, each of the DQ leads 160 function as a data bus, having as many parallel signal paths (or as few as one signal path) as needed by the memory system 100. When the memory system 100 has two or more memory modules, the C/A leads 150, DQ leads 160 and DS leads 170 connect the controller 110 to each of the memory modules.
  • In some embodiments, the DS leads 170 transmit data strobes that act as source synchronous bi-directional timing references. The set of leads 150, 160, 170 interconnecting the controller 110/425 and the memory module 120 are sometimes collectively called a memory bus or, more generally, an interconnect. The DS leads 170 separately connect the controller 110 to each DRAM 130 in the memory module 120. When the controller 110 transmits data to a DRAM 130 over a given DQ lead 160, the transmission and receipt of the data is clocked by the data strobe transmitted by the controller 110 over a corresponding DS lead 170. Similarly, in some embodiments, when a DRAM 130 transmits data to the controller 110 over a given DQ lead 160, the transmission and receipt of the data is clocked by the data strobe transmitted by the DRAM 130 over a corresponding DS lead 170.
  • In other embodiments, the DS leads 170 in the memory system 100 are configured to operate in a unidirectional manner. More specifically, data strobes transmitted by the DS leads 170 are unidirectional—generated and transmitted by the controller 110 only. The DRAMs 130, therefore, may receive a data strobe but not generate and transmit a data strobe. In these embodiments, when a DRAM 130 transmits data to the controller 110 over a given DQ lead 160, the transmission and receipt of the data is clocked by the clock signal received from the clock buffer 142.
  • As described in more detail below, the memory system 100 includes a controller 110 and a DRAM 130 that may be configured to operate in conjunction with DS leads 170 that are bidirectional or unidirectional. The embodiments described here are not limited to a controller 110 and/or a DRAM 130 that operate in a unidirectional manner. A single part (e.g., a controller 110, DRAM 130/440/450, or memory module 120) may be configurable so as to satisfy past, present, and future needs of the memory system market. In other words, these devices are capable of providing improved performance while also maintaining backwards compatibility.
  • Though not illustrated, the controller 110 (sometimes called a memory controller) preferably sends and receives data to and from external components (i.e., components not illustrated in FIG. 1). Additionally, the controller 110 sends and receives this same data to and from the memory module 120, which stores this data, via the DQ leads 160. More specifically, each of the DQ leads 160 connects the controller 110 to a DRAM 130 within the memory module 120. And as illustrated in FIG. 1, the DQ leads 160 are bi-directional. More specifically, the controller 110 transmits data to and receives data from the DRAMs 130 via the DQ leads 160.
  • The controller 110 controls the operation of the memory module 120, and thus the DRAMs 130, via the C/A lead 150, with control and address signals. These signals enable the controller 110 to select one of possibly two or more memory modules 120 to which the controller 110 is coupled. The memory module 120 is configured to receive over the control and address bus 150 control and address signals in conjunction with the clock signal asserted on the clock bus, the clock signal clocking receipt of the control and address signals. The transmission of the control and address signals to the DRAMs 130 is synchronous and operates in parallel with the synchronous transmission of data signals over the DQ leads 160.
  • The global clock 140 generates a clock (sometimes called the system clock or reference clock) that is transmitted to the clock buffer 142, which drives the clock to the controller 110 and the memory module 120. The clock buffer is typically PLL based in order to phase align the clock. Other bus structures for distributing the system or reference clock may be used, such as the configuration shown in U.S. Pat. No. 5,485,490, which is hereby incorporated by reference. Within the memory module 120, a PLL clock buffer 144 receives the clock from the clock buffer 142. The PLL clock buffer 144 aligns the phase of the module clock (used internally within the memory module) with the received reference clock, and transmits the module clock to the register 152 and the DRAMs 130. The transfer of data and control signals to the memory module 120 is thus synchronous to the clock generated by the global clock 140.
  • Controller with Directional Mode Control
  • FIG. 2 illustrates a controller 110 of the memory system 100 in greater detail. It is noted that FIG. 2 is a conceptual representation of a small subset of the components of a typical controller. The controller 110 includes a write indicator 380, a data-out register 388, an output buffer 390, another write indicator 392, an output buffer 394, a data-in register 395, a read indicator 396, an input buffer 397, another read indicator 398, and an input buffer 399. In some implementations, the two read indicators 396, 398 are the same read control signal, and the two write indicators 380, 392 are the same write control signal.
  • In some embodiments, the controller further includes a calibration selector 382, a calibration array 384, a clock calibrator 386, while in other embodiments these elements are not included. In those embodiments in which these elements are not include, the clock from the clock buffer 142 is coupled to the output buffer 394.
  • The controller 110 also includes a mode register 510, an OR gate 515, a calibration selector 555, a calibration array 560, a clock calibrator 565, and a clocking multiplexor 570. Additional control logic 580 generates the control signals shown in FIG. 2, and also performs control functions of the controller 110 that are not relevant to the present discussion. The mode register 510 stores a directional mode. Generally, this mode determines whether the DS leads 170 are unidirectional or bidirectional. The mode register 510 may preferably be set during operation of the controller 110 by one or more external components (not illustrated) or during the manufacture of the controller 110. The directional mode stored by the mode register 510 is transmitted to the OR gate 515 and to the clocking multiplexor 570.
  • The OR gate 515, as indicated in the preceding paragraph, receives input from the mode register 510. The OR gate 515 also receives input from the write indicator 380. The output of the OR gate 515 is, therefore, high if either the directional mode is high or the write indicator 380 is high. Preferably, the write indicator 380 is high when the controller 110 writes data to a DRAM, and the directional mode is high when the controller 110 is configured to operate in a unidirectional mode (regardless of whether the controller 110 is writing data, reading data, or is otherwise inactive). The output of the OR gate 515 is connected to the output buffer 394 to enable or disable the output buffer 394. So when the controller 110 writes data to a DRAM or when the controller 110 is configured to operate in a unidirectional mode, the output buffer 394 is enabled. When the output buffer 394 is not enabled, its output is tristated (i.e., set to a high impedance state), which leaves the DS lead 170 floating if no other device is asserting a signal on the DS lead, and more generally allows the DS lead 170 to be driven by another device (e.g., a memory device in a memory module).
  • As indicated above, the controller 110 sets the write indicator 380 to enable the output of the output buffer 394 when transmitting data to a DRAM 130. Additionally, the controller 110 stores calibration data for each memory module 120 to which the controller 110 is connected. In the memory systems illustrated in the present application, only one memory module 120 is shown. Memory systems, however, may include more than one memory module 120. The various connections of the controller 110 to the memory modules 120 may be different. For example, the length and impedance of such connections may vary. As a result, the timing signals (e.g., clock or data strobe) may be calibrated or adjusted.
  • As noted above, in some embodiments, the controller includes a calibration selector 382, a calibration array 384, a clock calibrator 386 for adjusting the timing signals used when writing data to a memory device. The calibration array 384 stores calibration data for this purpose. The calibration selector 382 carries a signal generated by the controller 110 that selects a specific calibration based upon which memory module 120 is being written to by the controller 110. The calibration selector 382 may transmit, for example, an address to select a specific calibration value stored by the calibration array 384.
  • The selected calibration value is transmitted by the calibration array 384 to the clock calibrator 386, which also receives a clock from the clock buffer 142. The clock calibrator 386 uses the selected calibration value to adjust the phase of the clock received thereby. In some embodiments each stored calibration value specifies a delay to offset state transitions of the clock signal. In some embodiments the stored calibration values each specify a clock phase. The adjusted clock is the basis of a data strobe generated by the controller 110. This data strobe is transmitted by the clock calibrator 386 to the data-out register 388 and to the output buffer 394. As indicated above, the output buffer 394 transmits the data strobe to a DS lead 170. The data strobe clocks the output of data from the data-out register 388 to the output buffer 390, which is connected to the DQ lead 160 and enabled by the write indicator 392.
  • In one mode of operation, the data-in register 395 of the controller 110 receives a data strobe from the input buffer 397 and data from the input buffer 399. The input buffer 397 is enabled by the read indicator 396 and the input buffer 399 is enabled by the read indicator 398. The input buffer 397 receives input (i.e., a data strobe) from the DS lead 170 and the input buffer 399 receives input (i.e., data) from the DQ lead 160. The control logic 580 controller 110 sets the read indicators 396, 398 to enable the input buffers 397, 399 when receiving data from a DRAM 130. The received data strobe, therefore, clocks the receipt of the data.
  • When the controller 110 is configured to use the DS leads in a bidirectional manner, the data strobe is source synchronous and is driven by a DRAM while the DRAM transmits data. In this mode, the controller 110 is compatible with conventional DRAM (e.g., DRAM 130) memory modules. But when the controller is configured to use the DS leads 170 in a unidirectional manner, the data strobe is not source synchronous and is not driven by a DRAM. In this mode the data strobe may be used by a DRAM as a free running clock to sample data transmitted by the controller 110.
  • As described above, the memory module 120 includes a plurality of DRAMs 130. Accordingly, the controller 110 may include (though not illustrated for simplicity) a data-out register 388 for each DRAM 130 within the memory module 120. The output of the clock calibrator 386 is connected to each of the data-out registers 388. Additionally, an output buffer 390, which is in turn connected to a respective DQ lead 160, is included for each data-out register 388. The write indicator 392 is preferably connected to each of these data-out registers 388 so that the output of each data-out register 388 is clocked by the same data strobe and enabled by the same write indicator 392. Additionally, an output buffer 394 is included for each DRAM 130 within the memory module 120. The output of the clock calibrator 386 is connected to each of the data-output buffers 394, which are in turn connected to a respective DS lead 170. This configuration enables the controller to transmit separate data to each DRAM 130 of a memory module 120 simultaneously.
  • A given calibration value, therefore, applies to each of the data-out registers 388 simultaneously clocked by the data strobe. Each set of DS 170 and DQ leads 160 connected to a given set of output buffers 390, 394 may also be connected to more than one memory module 120. Calibration values, therefore, are typically derived for each memory module 120, not each DRAM 130 within a memory module 120. When a specific memory module 120 is selected, this selection is reflected in the control and address signals transmitted to each memory module 120 in order to set the selected memory module 120 to receive data.
  • Similarly, the controller 110 may include (though not illustrated for simplicity) a data-in register 395, input buffer 397, and input buffer 399 for each DRAM 130 within the memory module 120 (i.e., each set of DS 170 and DQ leads 160). This configuration enables the controller to receive separate data from each DRAM 130 of a memory module 120 simultaneously. When a specific memory module 120 is selected to transmit data to the controller, only this memory module 120 puts data and a data strobe on the DQ 160 and DS leads 170, respectively.
  • The calibration selector 555 carries a signal generated by the control logic 580 of controller 110 depending on which memory module is being read from by the controller 110 (i.e., depending on which memory module is transmitting data over the DQ lead 160 to the controller 110). The calibration selector 555 may transmit an address to select a specific calibration value stored by the calibration array 560.
  • The selected calibration value is transmitted by the calibration array 560 to the clock calibrator 565, which also receives a clock from the clock buffer 142. The clock calibrator 565 uses the selected calibration value to adjust the phase of the clock received thereby. The adjusted clock is transmitted by the clock calibrator 565 to the clocking multiplexor 570. It should be noted that the calibration selector 555, calibration array 560 and clock calibrator 565 are used only when the directional mode is unidirectional, and are used to generate a phase adjusted receive clock that is adjusted or calibrated in accordance with the memory device from which data is being received. In some embodiments, operation of the clock calibrator 565 is disabled when the directional mode is bidirectional in order to reduce power usage.
  • The clocking multiplexor 570 is configured to transmit either the phase adjusted clock transmitted by the clock calibrator 565 or a data strobe transmitted over the DS lead 170. The output of the clocking multiplexor 570 may be called a clock signal or reference signal, even though in some circumstances this signal may be derived from the received data strobe. The selection of the signal output by the clocking multiplexer 570 is controlled by the mode register 510, which as stated above outputs a directional mode to the clocking multiplexor 570. The output of the clocking multiplexor 570 is transmitted to the input buffer 397, which as stated above is enabled by the read indicator 396 and connected to the data-in register 395. The data received by the data-in register 395 is, therefore, clocked by either the adjusted clock produced by the clock calibrator 565 or the data strobe transmitted over the DS lead 170. The clocking multiplexor 570 transmits the data strobe transmitted over the DS lead 170 to the input buffer 397 when the controller 110 is configured to operate in a bidirectional mode. Additionally, the clocking multiplexor 570 transmits the adjusted clock produced by the clock calibrator 565 to the input buffer 397 when the controller 110 is configured to operate in a unidirectional mode.
  • When the controller 110 is configured to use the DS leads in a bidirectional manner, therefore, the data strobe may be used by the controller 110 to sample data transmitted by a DRAM. But when configured to operate in a unidirectional manner, the capture of read data by the controller 110 is timed or clocked with a calibrated internal timing reference (e.g., the adjusted clock).
  • Dram with Directional Mode Control
  • FIG. 3 illustrates a DRAM 130 of the memory system 100. As illustrated in FIG. 3, the DRAM 130 includes a mode register 302, C/A register 310, a transmit (Tx) indicator 320, an output buffer 325, a receive (Rx) indicator 330, an input buffer 335, a data-in register 340, a receive indicator 350, an input buffer 355, a transmit (Tx) indicator 360, an output buffer 365, a data-out register 370 and an AND gate 304. In some embodiments, the two receive indicators 330 and 350 are the same receive control signal, and the two transmit indicators 320 and 360 are the same transmit control signal. Furthermore, the receive and transmit indicators may be complements of each other.
  • It is noted that FIG. 3 is a conceptual representation of a small subset of the components of a DRAM chip. For instance, the data in and data out registers 340, 370 shown in this Figure represent circuitry in the interface to the storage array of the DRAM, such as in the sense amplifier arrays of the DRAM, and that circuit may or may not strictly meet the definition of “registers” (as opposed, for instance, to latches and other clocked circuits). Furthermore, the data in and data out registers 340, 370, while shown separately in FIG. 3, may be implemented in part or in whole with the same circuitry.
  • The C/A register 310 receives a clock (typically from the PLL clock buffer 144, FIG. 1) and control and address signals, via the C/A lead 150, from the controller 110. The clock clocks or times the receipt of these control and address signals.
  • The first set of input and output buffers 335, 325 are connected to a DS lead 170 to receive and transmit, respectively, a data strobe. As illustrated, the data strobe transmitted by the output buffer 325 is generated by the DRAM 130 from the clock.
  • The DRAM mode register 302 stores a directional mode when used in conjunction with the DRAM 130 (or the DRAM 440 of FIG. 4). The directional mode determines whether the DS leads 170 are unidirectional or bidirectional. The mode register 302 may preferably be set during operation of the DRAM 130 by the controller 110 or during the manufacture of the DRAM 130 or memory module 120. In some embodiments, the controller 110 and DRAM 130 are configured so that the controller may send a command over the control and address lines 150 that directs the DRAM to store a particular mode value in the mode register 302. The directional mode stored by the mode register 302 is transmitted to the AND gate 304.
  • The AND gate 304, as indicated in the preceding paragraph, receives input from the DRAM mode register 302. The AND gate 304 also receives input from the transmit (Tx) indicator 320. The output of the AND gate 304 is high if the directional mode is high and the transmit (Tx) indicator 320 is high. Preferably, the transmit (Tx) indicator 320 and the directional mode are high when the DRAM 130 transmits a data strobe to the controller and the DRAM 130 is configured to operate in a bidirectional mode. The output of the AND gate 304 is connected to the output buffer 325 to enable or disable the output buffer 325. So when the DRAM 130 transmits data and, in addition, the DRAM 130 is configured to operate in a bidirectional mode, the output buffer 325 is enabled and drives the received clock signal onto the DS lead 170 as the data strobe for the data being transmitted from the data out register 370. Conversely, when the DRAM 130 is configured to operate in a unidirectional mode, the output of the AND gate 304 is low such that the output buffer 325 is disabled. When the output buffer 325 is not enabled, its output is tristated (i.e., set to a high impedance state), which leaves the DS lead 170 floating if no other device is asserting a signal on the DS lead, and more generally allows the DS lead 170 to be driven by another device (e.g., the memory controller 110, or another memory device in another memory module on the same memory bus as the memory module 120 in which the DRAM 130 resides).
  • The data strobe received by the input buffer 335 is generated and transmitted by the controller 110. Additionally, the input buffer 335 is enabled (or set to transmit a data strobe from the DS lead 170 to the data-in register 340) by the receive (Rx) indicator 330. Thus, when the DRAM receives data from the controller 110, the receive (Rx) indicator 330 is set so that the input buffer 335 is enabled. The receipt of data by the data-in register 340 is clocked, therefore, by the data strobe received over the DS lead 170.
  • The second set of input and output buffers 355, 365 is connected to a data signal (DQ) lead 160 to receive and transmit, respectively, data. As illustrated in FIG. 3, the data transmitted by the output buffer 365 is transmitted from the data-out register 370, which receives data from storage elements within the DRAM 130. Additionally, the output buffer 365 is enabled (or set to transmit data to the DQ lead 160) by the transmit (Tx) indicator 360. Thus, when the DRAM transmits data to the controller 110, the transmit (Tx) indicator 360 is set so that the output buffer 365 is enabled. The data received by the input buffer 355 is transmitted by the controller 110. Additionally, the input buffer 355 is enabled to transmit data from the DQ lead 160 to the data-in register 340, which transmits data to storage elements within the DRAM 130, by the receive (Rx) indicator 350. Thus, when the DRAM receives data from the controller 110, the receive (Rx) indicator 350 is set so that the input buffer 355 is enabled. The transmission of data by the data-out register 370 is clocked, therefore, by the clock (not the data strobe received over the DS lead 170).
  • As indicated above, when the DRAM 130 is configured to use the DS leads in a bidirectional manner, the data strobe is source synchronous and is driven by the DRAM 130 while the DRAM 130 transmits data. The transmission delays associated with the strobe output buffer 325 and the data output buffer 365 are preferably the same, or very close to being the same. As a result, the phase relationship of the transmitted data and data strobe will be preserved when those signals arrive at the controller. In this mode, the DRAM 130 is compatible with conventional controllers (e.g., controller 110, FIG. 1). But when the DRAM 130 is configured to use the DS leads in a unidirectional manner, the data strobe is not source synchronous and is not driven by the DRAM. In this mode, the DRAM 130 is compatible with controllers described herein (e.g., controllers with calibrated timing to receive data from the DRAM 130).
  • FIG. 4 illustrates another embodiment of a DRAM 440 of the memory system 100. In addition to those components described above in connection with the DRAM 130 illustrated in FIG. 3, the DRAM 440 illustrated in FIG. 4 includes a multiplexor 410.
  • The multiplexor 410 receives the clock (typically from the PLL clock buffer 144) and a data strobe transmitted by the DS lead 170. The output of the multiplexor is transmitted to the data-out register 370. So depending on the selection by the multiplexor 410, the output of data by the data-out buffer is timed or clocked by the clock or the data strobe transmitted by the DS lead 170. This selection is made by the mode register 302, which transmits the directional mode as selection input to the multiplexor 410.
  • As indicated above, when the DRAM 440 is configured to use the DS leads 170 in a unidirectional manner, the data output by the DRAM 440 is clocked by the data strobe generated by a controller (e.g., controller 110). This is possible because the data strobe is always transmitted by the controller. Additionally, the data strobe typically suffers from less phase shift than the clock, and as a result the rate of data transmission over the memory bus may be increased over that of prior systems. In this mode, the DRAM 440 is compatible with controllers (such as the controllers described herein) configured to continuously transmit a data strobe to the DRAM 440. But when the DRAM 440 is configured to use the DS leads 170 in a unidirectional manner, the data strobe is not available while the DRAM 440 transmits data. Instead, the data output by the DRAM 440 is clocked by the clock. In this mode, the DRAM 440 is compatible with conventional controllers (e.g., controller 110).
  • Additional Embodiments
  • FIG. 5A illustrates another embodiment of a controller 425 for use in the memory system 100. Unlike the controller 110 illustrated in FIG. 2, the controller 425 illustrated in FIG. 5A does not operate in bidirectional mode. Accordingly, this controller 425 does not include a mode register 510, a write indicator 380, an OR gate 515, or a clocking multiplexor 570. These components are not needed because the output of the clock calibrator 386 is continuously applied to the DS lead 170. Alternately, the controller may include a mode register that stores various mode values, but not a directional mode value.
  • Optionally, this embodiment of the controller 425 includes data strobe output buffer 394, to provide a signal delay that matches, or approximately matches, the transmission delay associate with data-out register 388 and output buffer 390. Additionally, input to the data-in register is always clocked by the output of the clock calibrator 565. This controller 425 is compatible with the DRAMs described herein (e.g., DRAM 130, DRAM 440, and DRAM 450), but is not compatible with conventional DRAMs.
  • FIG. 5B illustrates another embodiment of a DRAM 450 for use in the memory system 100. Unlike the DRAMs 130, 440 of FIGS. 3 and 4, this DRAM 450 does not include an AND gate 304 or an output buffer 325. This is because this DRAM 450 does not transmit a data strobe over the DS lead 170. Additionally, this DRAM 450 does not include a multiplexor 410 because the output of the data-out register 370 is not clocked or timed by the clock. Instead, the data-out register 370, like the data-in register 340, is always clocked by a data strobe transmitted over the DS lead 170. Preferably, only control and address signals transmitted over the C/A lead 150 are clocked by the clock. This DRAM 450 is compatible with controllers described herein (e.g., controller 110 and controller 425), but is not compatible with conventional controllers.
  • The foregoing descriptions of specific embodiments are presented for purposes of illustration and explanation. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, to thereby enable others skilled in the art to best utilize the invention. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Various modifications may occur to those skilled in the art having the benefit of this disclosure without departing from the inventive concepts described herein.
  • For example, the various data strobes and clocks (i.e., clock signals) described above are illustrated as single ended signals. In alternate embodiments, however, these data strobes and clocks are differential signals. The use of differential signals enables greater clock speeds and data rates. Accordingly, it is the claims, not merely the foregoing illustration, that are intended to define the exclusive rights of the invention.

Claims (25)

  1. 1. A controller for a memory system, said controller coupled to a data strobe bus, to an interconnect, and to a clock bus, said controller comprising:
    an output buffer configured to assert a first data strobe signal on the data strobe bus when said output buffer is enabled, said first data strobe signal generated by the controller;
    a register configured to store information representing a mode of controller operation, the output buffer enabled during transfers from the controller of a first data signal over the interconnect when said mode of controller operation is set to a first mode of controller operation, the output buffer continuously enabled when said mode of controller operation is set to a second mode of controller operation; and
    the controller configured to receive a clock signal over the clock bus, said controller further configured to clock receipt of a second data signal over the interconnect with said clock signal.
  2. 2. The controller of claim 1, wherein the controller is configured to adjust, when the mode of controller operation is set to the second mode of controller operation, a phase of the clock signal in accordance with a pre-existing calibration while receiving the second data signal over the interconnect.
  3. 3. The controller of claim 1, wherein the controller is configured to use, when the mode of controller operation is set to the first mode of controller operation, a second data strobe signal remotely asserted on the data strobe bus as a phase reference while receiving the second data signal over the interconnect.
  4. 4. The controller of claim 1, further comprising:
    a circuit configured to receive as a first input a mode of controller operation from the register, said first input at a first logic level when said mode of controller operation is set to the first mode of controller operation and said first input at a second logic level when said mode of controller operation is set to the second mode of controller operation;
    the circuit configured to receive as a second input an operational state of said controller, said operational state set to the second logic level during the transfers of the first data signal over the interconnect from the controller; and
    an output of the circuit coupled to the output buffer such that said output buffer is enabled by said circuit when either the first input or the second input is set to the second logic level.
  5. 5. A method of operating a memory system controller, comprising:
    maintaining a mode of controller operation;
    generating a first data strobe signal;
    enabling, when the mode of controller operation is set to a first mode of controller operation, transmission of the first data strobe signal while transferring a first data signal;
    enabling, when the mode of controller operation is set to a second mode of controller operation, continuous transmission of the first data strobe signal;
    receiving a clock signal; and
    clocking receipt of a second data signal with a reference signal.
  6. 6. The method of claim 5, further comprising:
    adjusting, when the mode of controller operation is set to the second mode of controller operation, a phase of the clock signal in accordance with a pre-existing calibration so as to generate the reference signal while receiving the second data signal.
  7. 7. The method of claim 5, further comprising:
    using, when the mode of controller operation is set to the first mode of controller operation, a second data strobe signal remotely transmitted by a memory device as the reference signal, and using the reference signal as a phase reference while receiving the second data signal.
  8. 8. A memory device to store data in a memory system, the memory device coupled to a data strobe bus, an interconnect, and a clock bus, wherein
    the memory device is configured to receive over the data strobe bus a data strobe signal continuously, remotely asserted on said data strobe bus;
    the memory device is configured to receive over the interconnect a first data signal in conjunction with the data strobe signal, said memory device further configured to clock receipt of said first data signal with the data strobe signal;
    the memory device is configured to receive over the clock bus a clock signal; and
    the memory device is configured to transmit over the interconnect a second data signal in conjunction with the clock signal, said memory device further configured to clock transmission of said second data signal with the clock signal.
  9. 9. A method of operating a memory device to store data in a memory system, comprising:
    receiving a continuous data strobe signal;
    intermittently receiving a first data signal in conjunction with the continuous data strobe signal;
    clocking receipt of the first data signal with the data strobe signal;
    receiving a clock signal;
    intermittently transmitting a second data signal in conjunction with the clock signal; and
    clocking transmission of the second data signal with the clock.
  10. 10. A memory device to store data in a memory system, the memory device coupled to a data strobe bus, an interconnect, and a clock bus, wherein
    the memory device is configured to receive over the data strobe bus a data strobe signal continuously, remotely asserted on said data strobe bus;
    the memory device is configured to receive over the interconnect a first data signal in conjunction with the data strobe signal, said memory device further configured to clock receipt of said first data signal with the data strobe signal; and
    the memory device is configured to transmit over the interconnect a second data signal in conjunction with the data strobe signal, said memory device further configured to clock transmission of said second data signal with the data strobe signal.
  11. 11. A method of operating a memory device to store data in a memory system, comprising
    receiving a continuous data strobe signal;
    intermittently receiving a first data signal for storage in conjunction with the continuous data strobe signal;
    clocking receipt of the first data signal with the data strobe signal;
    intermittently transmitting from storage a second data signal in conjunction with the data strobe signal; and
    clocking transmission of the second data signal with the data strobe signal.
  12. 12. A memory device to store data in a memory system, the memory device coupled to a data strobe bus and an interconnect, said memory device comprising:
    an output buffer configured to transmit a first data strobe signal when enabled;
    circuitry to transmit over the interconnect a first data signal, said first data signal transmitted in conjunction with the first data strobe signal when the output buffer is enabled;
    a register to store a mode of memory device operation, the memory device configured to enable the output buffer when said mode of memory device operation is set to a first mode of memory device operation, the memory device configured to disable the output buffer when said mode of memory device operation is set to a second mode of memory device operation; and
    additional circuitry configured to receive over the interconnect a second data signal in conjunction with a second data strobe signal remotely asserted on the data strobe bus, said second data strobe signal clocking receipt of said second data signal.
  13. 13. A method of operating a memory device to store data in a memory system, comprising
    intermittently receiving a first data signal in conjunction with a first data strobe signal, said first data strobe signal clocking receipt of said first data signal;
    intermittently transmitting a second data signal;
    storing a mode of memory device operation;
    setting an output to a second data strobe signal while transmitting the second data signal when the stored mode of memory device operation is a first mode of memory device operation; and
    preventing output of the second data strobe when the mode of memory device operation is set to a second mode of memory device operation.
  14. 14. A memory device to store data in a memory system, the memory device coupled to a data strobe bus, an interconnect, a clock bus, and a control and address bus, wherein
    the memory device is configured to receive over the control and address bus a control and address signal in conjunction with a clock signal remotely asserted on the clock bus, said clock signal clocking receipt of said control and address signal;
    the memory device is configured to receive over the interconnect a first data signal in conjunction with a first data strobe signal remotely asserted on the data strobe bus, said first data strobe signal clocking receipt of said first data signal; and
    the memory device is configured to transmit over the interconnect a second data signal, the first data strobe signal clocking transmission of said second data signal.
  15. 15. A method of operating a memory device to store data in a memory system, comprising:
    intermittently receiving a control and address signal in conjunction with a clock signal, said clock signal clocking receipt of said control and address signal;
    intermittently receiving a first data signal in conjunction with a first data strobe signal, said first data strobe signal clocking receipt of said first data signal;
    intermittently transmitting from storage a second data signal, said first data strobe signal clocking transmission of said second data signal.
  16. 16. A memory device to store data in a memory system, the memory device coupled to a data strobe bus, an interconnect, and a clock bus, wherein
    the memory device is configured to receive over the interconnect a first data signal in conjunction with a first data strobe signal remotely asserted on the data strobe bus, said first data strobe signal providing a phase reference while receiving said first data signal; and
    the memory device includes a register to store a reference mode;
    the memory device is configured to receive over the clock bus a clock signal;
    the memory device is configured to transmit over the interconnect a second data signal;
    the memory device is configured to use, when the reference mode is set to a first reference mode, the first data strobe signal as a phase reference while transmitting the second data signal; and
    the memory device is configured to use, when the reference mode is set to a second reference mode, the clock signal as the phase reference while transmitting the second data signal.
  17. 17. A method of operating a memory device to store data in a memory system, comprising
    intermittently receiving a first data signal in conjunction with a remotely asserted first data strobe signal, said first data strobe signal providing a phase reference while receiving said first data signal;
    storing a reference mode;
    receiving a clock signal;
    intermittently transmitting a second data signal;
    using, when the reference mode is set to a first reference mode, the first data strobe signal as a phase reference while transmitting the second data signal; and
    using, when the reference mode is set to a second reference mode, the clock signal as the phase reference while transmitting said second data signal.
  18. 18. A memory system, comprising
    a controller, a memory device, and a clock signal generator;
    a data strobe bus coupling the controller to the memory device;
    an interconnect coupling the controller to the memory device;
    the clock signal generator configured to transmit a clock signal to the controller;
    the controller configured to use the clock signal in conjunction with a pre-existing calibration to clock a first data signal received from the memory device over the interconnect;
    the controller further configured to continuously assert a data strobe signal on the data strobe bus; and
    the memory device configured to use the data strobe signal to clock a second data signal received from the controller over the interconnect.
  19. 19. The memory system of claim 18, wherein the calibration comprises a delay to offset state transitions of the clock signal that otherwise time sampling of the first data signal by the controller.
  20. 20. The memory system of claim 18, wherein the memory device is further configured to use the data strobe signal as a phase reference while transmitting the second data signal.
  21. 21. The memory system of claim 18, wherein
    the clock signal generator is further configured to transmit the clock signal to the memory device; and
    the memory device is further configured to use the clock signal as a phase reference while transmitting the second data signal.
  22. 22. A controller for a memory system, said controller coupled to a data strobe bus, to an interconnect, and to a clock bus, said controller comprising:
    a bimodal data strobe interface configured to connect the controller to the data strobe bus; and
    means for storing information representing a mode of controller operation;
    wherein the bimodal data strobe interface includes means for utilizing the data strobe bus as a unidirectional data strobe bus when the mode of controller operation is set to a first mode and for utilizing the data strobe bus as a bidirectional data strobe bus when the mode of controller operation is set to a second mode.
  23. 23. A controller for a memory system, said controller coupled to a data strobe bus, to an interconnect, and to a clock bus, said controller comprising:
    means for asserting a first data strobe signal on the data strobe bus when said asserting means is enabled;
    means for storing information representing a mode of controller operation;
    wherein the asserting means is enabled during transfers from the controller of a first data signal over the interconnect when said mode of controller operation is set to a first mode of controller operation, and wherein the asserting means is continuously enabled when said mode of controller operation is set to a second mode of controller operation; and
    the controller configured to receive a clock signal over the clock bus, said controller further configured to clock receipt of a second data signal over the interconnect with said clock signal.
  24. 24. A memory device to store data, the memory device coupled to a data strobe bus, an interconnect, and a clock bus, the memory device comprising:
    a bimodal data strobe interface configured to connect the memory device to the data strobe bus; and
    a storage circuit for storing information representing a mode of operation;
    wherein the bimodal data strobe interface includes means for utilizing the data strobe bus as a unidirectional data strobe bus when the mode of operation is set to a first mode and for utilizing the data strobe bus as a bidirectional data strobe bus when the mode of operation is set to a second mode.
  25. 25. A memory module, comprising:
    a plurality of dynamic memory random access memory devices (DRAMs); and
    a serial presence device configured to store information indicating whether the memory devices are bimodal with respect to use of a set of data strobe busses, wherein each of the memory devices, if bimodal, includes a configuration mechanism for configuring the memory device to drive a respective data strobe bus while transmitting data in one mode of operation and for configuring the memory device to not drive the data strobe bus while transmitting data in another mode of operation.
US10676648 2003-09-30 2003-09-30 Integrated circuit with bi-modal data strobe Abandoned US20050071707A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US10676648 US20050071707A1 (en) 2003-09-30 2003-09-30 Integrated circuit with bi-modal data strobe

Applications Claiming Priority (9)

Application Number Priority Date Filing Date Title
US10676648 US20050071707A1 (en) 2003-09-30 2003-09-30 Integrated circuit with bi-modal data strobe
JP2006533897A JP4783290B2 (en) 2003-09-30 2004-09-03 Integrated circuit having a bimodal data strobe
EP20040783434 EP1668523B2 (en) 2003-09-30 2004-09-03 Integrated circuit with bi-modal data strobe
KR20067008404A KR101110469B1 (en) 2003-09-30 2004-09-03 Integrated circuit with bi-modal data strobe
DE200460007674 DE602004007674T3 (en) 2003-09-30 2004-09-03 Integrated circuit with bimodal data strobe
KR20117006938A KR101108297B1 (en) 2003-09-30 2004-09-03 Integrated circuit with bi-modal data strobe
PCT/US2004/029186 WO2005033958A1 (en) 2003-09-30 2004-09-03 Integrated circuit with bi-modal data strobe
US12103640 US8352696B2 (en) 2003-09-30 2008-04-15 Integrated circuit with bi-modal data strobe
JP2011050556A JP5191555B2 (en) 2003-09-30 2011-03-08 Integrated circuit having a bimodal data strobe

Related Child Applications (1)

Application Number Title Priority Date Filing Date
US12103640 Continuation US8352696B2 (en) 2003-09-30 2008-04-15 Integrated circuit with bi-modal data strobe

Publications (1)

Publication Number Publication Date
US20050071707A1 true true US20050071707A1 (en) 2005-03-31

Family

ID=34377433

Family Applications (2)

Application Number Title Priority Date Filing Date
US10676648 Abandoned US20050071707A1 (en) 2003-09-30 2003-09-30 Integrated circuit with bi-modal data strobe
US12103640 Active 2026-01-19 US8352696B2 (en) 2003-09-30 2008-04-15 Integrated circuit with bi-modal data strobe

Family Applications After (1)

Application Number Title Priority Date Filing Date
US12103640 Active 2026-01-19 US8352696B2 (en) 2003-09-30 2008-04-15 Integrated circuit with bi-modal data strobe

Country Status (6)

Country Link
US (2) US20050071707A1 (en)
EP (1) EP1668523B2 (en)
JP (2) JP4783290B2 (en)
KR (2) KR101108297B1 (en)
DE (1) DE602004007674T3 (en)
WO (1) WO2005033958A1 (en)

Cited By (32)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20060031698A1 (en) * 2004-03-17 2006-02-09 Rambus, Inc. Drift tracking feedback for communication channels
US20060052961A1 (en) * 2004-08-20 2006-03-09 Best Scott C Individual data line strobe-offset control in memory systems
US20060095620A1 (en) * 2004-10-29 2006-05-04 International Business Machines Corporation System, method and storage medium for merging bus data in a memory subsystem
US20060136769A1 (en) * 2004-12-21 2006-06-22 Kizer Jade M Interface circuit for strobe-based systems
US20060203602A1 (en) * 2005-03-14 2006-09-14 Rambus, Inc. Self-timed interface for strobe-based systems
US20070217559A1 (en) * 2006-03-16 2007-09-20 Rambus Inc. Signaling system with adaptive timing calibration
US20070276976A1 (en) * 2006-05-24 2007-11-29 International Business Machines Corporation Systems and methods for providing distributed technology independent memory controllers
US20070288671A1 (en) * 2006-06-07 2007-12-13 Bohm Mark R Low power and low pin count bi-directional dual data rate device interconnect interface
US20080162991A1 (en) * 2007-01-02 2008-07-03 International Business Machines Corporation Systems and methods for improving serviceability of a memory system
US20090094476A1 (en) * 2005-10-31 2009-04-09 International Business Machines Corporation Deriving clocks in a memory system
US20090150636A1 (en) * 2004-10-29 2009-06-11 International Business Machines Corporation Memory subsystem with positional read data latency
US20090300314A1 (en) * 2008-05-29 2009-12-03 Micron Technology, Inc. Memory systems and methods for controlling the timing of receiving read data
US20100005376A1 (en) * 2008-07-02 2010-01-07 Micron Technology, Inc. Method and apparatus for repairing high capacity/high bandwidth memory devices
US7669086B2 (en) 2006-08-02 2010-02-23 International Business Machines Corporation Systems and methods for providing collision detection in a memory system
US7685392B2 (en) 2005-11-28 2010-03-23 International Business Machines Corporation Providing indeterminate read data latency in a memory system
WO2010078383A1 (en) * 2008-12-31 2010-07-08 Rambus Inc. Active calibration for high-speed memory devices
US7765368B2 (en) 2004-07-30 2010-07-27 International Business Machines Corporation System, method and storage medium for providing a serialized memory interface with a bus repeater
US20100268901A1 (en) * 2007-09-27 2010-10-21 Ian Shaeffer Reconfigurable memory system data strobes
US7844771B2 (en) 2004-10-29 2010-11-30 International Business Machines Corporation System, method and storage medium for a memory subsystem command interface
US7870459B2 (en) 2006-10-23 2011-01-11 International Business Machines Corporation High density high reliability memory module with power gating and a fault tolerant address and command bus
US20110260767A1 (en) * 2010-04-21 2011-10-27 Narendra Devta-Prasanna System and device for reducing instantaneous voltage droop during a scan shift operation
US8140942B2 (en) 2004-10-29 2012-03-20 International Business Machines Corporation System, method and storage medium for providing fault detection and correction in a memory subsystem
US8533416B2 (en) 2008-07-21 2013-09-10 Micron Technology, Inc. Memory system and method using stacked memory device dice, and system using the memory system
US8539312B2 (en) 2008-08-15 2013-09-17 Microns Technology, Inc. Memory system and method using a memory device die stacked with a logic die using data encoding, and system using the memory system
US8799726B2 (en) 2008-06-03 2014-08-05 Micron Technology, Inc. Method and apparatus for testing high capacity/high bandwidth memory devices
US8861246B2 (en) 2010-12-16 2014-10-14 Micron Technology, Inc. Phase interpolators and push-pull buffers
US9032356B2 (en) 2013-03-06 2015-05-12 Lsi Corporation Programmable clock spreading
US9142281B1 (en) 2007-12-21 2015-09-22 Rambus Inc. Method and apparatus for calibrating write timing in a memory system
US9171597B2 (en) 2013-08-30 2015-10-27 Micron Technology, Inc. Apparatuses and methods for providing strobe signals to memories
US9628257B2 (en) 2004-01-28 2017-04-18 Rambus Inc. Communication channel calibration for drift conditions
US9659630B2 (en) 2008-07-02 2017-05-23 Micron Technology, Inc. Multi-mode memory device and method having stacked memory dice, a logic die and a command processing circuit and operating in direct and indirect modes
US9667359B2 (en) 2004-01-28 2017-05-30 Rambus Inc. Periodic calibration for communication channels by drift tracking

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4267002B2 (en) 2006-06-08 2009-05-27 エルピーダメモリ株式会社 Controller and system comprising a memory
RU2623801C1 (en) 2013-07-26 2017-06-29 Интел Корпорейшн Interface of non-volatile memory
US9660847B2 (en) 2014-11-26 2017-05-23 Rambus Inc. Equalized multi-signaling mode driver

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6188638B1 (en) * 1998-08-27 2001-02-13 Siemens Aktiengesellschaft Integrated semiconductor memory with control device for clock-synchronous writing and reading
US20010054135A1 (en) * 2000-06-16 2001-12-20 Nec Corporation Memory control technique
US6397312B1 (en) * 1997-07-04 2002-05-28 Fujitsu Limited Memory subsystem operated in synchronism with a clock
US6502173B1 (en) * 2000-09-29 2002-12-31 Ati Technologies, Inc. System for accessing memory and method therefore
US20030026161A1 (en) * 2001-08-03 2003-02-06 Fujitsu Limited Semiconductor memory
US6621496B1 (en) * 1999-02-26 2003-09-16 Micron Technology, Inc. Dual mode DDR SDRAM/SGRAM
US20050018494A1 (en) * 2003-07-22 2005-01-27 Wu Chung-Hsiao R. Double data rate (ddr) data strobe receiver
US7134960B1 (en) * 2000-08-23 2006-11-14 Nintendo Co., Ltd. External interfaces for a 3D graphics system

Family Cites Families (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5721860A (en) * 1994-05-24 1998-02-24 Intel Corporation Memory controller for independently supporting synchronous and asynchronous DRAM memories
US5692165A (en) * 1995-09-12 1997-11-25 Micron Electronics Inc. Memory controller with low skew control signal
JP3922765B2 (en) 1997-07-22 2007-05-30 富士通株式会社 The semiconductor device system and a semiconductor device
US6085285A (en) * 1997-11-13 2000-07-04 International Business Machines Corporation Intermixing different devices along a single data communication link by placing a strobe signal in a parity bit slot
US6487647B1 (en) * 1997-12-29 2002-11-26 Intel Corporation Adaptive memory interface timing generation
US6510503B2 (en) * 1998-07-27 2003-01-21 Mosaid Technologies Incorporated High bandwidth memory interface
JP2000163965A (en) * 1998-11-27 2000-06-16 Mitsubishi Electric Corp Synchronous semiconductor storage
US6643787B1 (en) 1999-10-19 2003-11-04 Rambus Inc. Bus system optimization
US20020144173A1 (en) * 2001-03-30 2002-10-03 Micron Technology, Inc. Serial presence detect driven memory clock control
JP2003007069A (en) * 2001-06-18 2003-01-10 Mitsubishi Electric Corp Semiconductor memory and semiconductor integrated circuit device
JP2003050739A (en) * 2001-08-06 2003-02-21 Matsushita Electric Ind Co Ltd Memory controller
US7062625B1 (en) * 2001-09-14 2006-06-13 Denali Software, Inc. Input/output cells for a double data rate (DDR) memory controller
US7032092B2 (en) * 2001-10-09 2006-04-18 Via Technologies, Inc. Memory controller for supporting a plurality of different memory accesse modes
US6944738B2 (en) * 2002-04-16 2005-09-13 Sun Microsystems, Inc. Scalable design for DDR SDRAM buses
US20040003194A1 (en) * 2002-06-26 2004-01-01 Amit Bodas Method and apparatus for adjusting DRAM signal timings
US7093082B2 (en) * 2003-06-11 2006-08-15 Matsushita Electric Industrial Co., Ltd Microprogrammable SDRAM memory interface controller
JP4660129B2 (en) * 2003-07-21 2011-03-30 三星電子株式会社Samsung Electronics Co.,Ltd. A semiconductor memory device and a memory module
EP2130055B1 (en) 2007-03-20 2011-05-18 Rambus Inc. Integrated circuit having receiver jitter tolerance ("jtol") measurement

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6397312B1 (en) * 1997-07-04 2002-05-28 Fujitsu Limited Memory subsystem operated in synchronism with a clock
US6188638B1 (en) * 1998-08-27 2001-02-13 Siemens Aktiengesellschaft Integrated semiconductor memory with control device for clock-synchronous writing and reading
US6621496B1 (en) * 1999-02-26 2003-09-16 Micron Technology, Inc. Dual mode DDR SDRAM/SGRAM
US20010054135A1 (en) * 2000-06-16 2001-12-20 Nec Corporation Memory control technique
US7134960B1 (en) * 2000-08-23 2006-11-14 Nintendo Co., Ltd. External interfaces for a 3D graphics system
US6502173B1 (en) * 2000-09-29 2002-12-31 Ati Technologies, Inc. System for accessing memory and method therefore
US20030026161A1 (en) * 2001-08-03 2003-02-06 Fujitsu Limited Semiconductor memory
US20050018494A1 (en) * 2003-07-22 2005-01-27 Wu Chung-Hsiao R. Double data rate (ddr) data strobe receiver

Cited By (98)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9628257B2 (en) 2004-01-28 2017-04-18 Rambus Inc. Communication channel calibration for drift conditions
US9667359B2 (en) 2004-01-28 2017-05-30 Rambus Inc. Periodic calibration for communication channels by drift tracking
US9667406B2 (en) 2004-01-28 2017-05-30 Rambus Inc. Communication channel calibration for drift conditions
US9710011B2 (en) 2004-03-17 2017-07-18 Rambus Inc. Drift tracking feedback for communication channels
US7640448B2 (en) 2004-03-17 2009-12-29 Rambus, Inc. Drift tracking feedback for communication channels
US7159136B2 (en) * 2004-03-17 2007-01-02 Rambus, Inc. Drift tracking feedback for communication channels
US8504863B2 (en) 2004-03-17 2013-08-06 Rambus Inc. Drift tracking feedback for communication channels
US20070088968A1 (en) * 2004-03-17 2007-04-19 Rambus, Inc. Drift Tracking Feedback for Communication Channels
US20100058100A1 (en) * 2004-03-17 2010-03-04 Rambus, Inc. Drift tracking feedback for communication channels
US20070204184A1 (en) * 2004-03-17 2007-08-30 Rambus Inc. Drift tracking feedback for communication channels
US7526664B2 (en) 2004-03-17 2009-04-28 Rambus, Inc. Drift tracking feedback for communication channels
US20060031698A1 (en) * 2004-03-17 2006-02-09 Rambus, Inc. Drift tracking feedback for communication channels
US7765368B2 (en) 2004-07-30 2010-07-27 International Business Machines Corporation System, method and storage medium for providing a serialized memory interface with a bus repeater
US10056130B2 (en) 2004-08-20 2018-08-21 Rambus Inc. Strobe-offset control circuit
US8135555B2 (en) 2004-08-20 2012-03-13 Rambus Inc. Strobe-offset control circuit
US9111608B2 (en) 2004-08-20 2015-08-18 Rambus Inc. Strobe-offset control circuit
US20070109908A1 (en) * 2004-08-20 2007-05-17 Best Scott C Individual Data Line Strobe-Offset Control in Memory Systems
US7668679B2 (en) 2004-08-20 2010-02-23 Rambus Inc. Individual data line strobe-offset control in memory systems
US7171321B2 (en) 2004-08-20 2007-01-30 Rambus Inc. Individual data line strobe-offset control in memory systems
US8688399B2 (en) 2004-08-20 2014-04-01 Rambus Inc. Strobe-offset control circuit
US20060052961A1 (en) * 2004-08-20 2006-03-09 Best Scott C Individual data line strobe-offset control in memory systems
US20100118627A1 (en) * 2004-08-20 2010-05-13 Best Scott C Strobe-offset control circuit
US8311761B2 (en) 2004-08-20 2012-11-13 Rambus Inc. Strobe-offset control circuit
US8140942B2 (en) 2004-10-29 2012-03-20 International Business Machines Corporation System, method and storage medium for providing fault detection and correction in a memory subsystem
US8296541B2 (en) 2004-10-29 2012-10-23 International Business Machines Corporation Memory subsystem with positional read data latency
US8589769B2 (en) 2004-10-29 2013-11-19 International Business Machines Corporation System, method and storage medium for providing fault detection and correction in a memory subsystem
US20090150636A1 (en) * 2004-10-29 2009-06-11 International Business Machines Corporation Memory subsystem with positional read data latency
US7844771B2 (en) 2004-10-29 2010-11-30 International Business Machines Corporation System, method and storage medium for a memory subsystem command interface
US20060095620A1 (en) * 2004-10-29 2006-05-04 International Business Machines Corporation System, method and storage medium for merging bus data in a memory subsystem
US7543172B2 (en) 2004-12-21 2009-06-02 Rambus Inc. Strobe masking in a signaling system having multiple clock domains
US9105325B2 (en) 2004-12-21 2015-08-11 Rambus Inc. Memory controller for strobe-based memory systems
US9728247B2 (en) 2004-12-21 2017-08-08 Rambus Inc. Memory controller for strobe-based memory systems
US20060136769A1 (en) * 2004-12-21 2006-06-22 Kizer Jade M Interface circuit for strobe-based systems
US9390777B2 (en) 2004-12-21 2016-07-12 Rambus Inc. Memory controller for strobe-based memory systems
US9905286B2 (en) 2004-12-21 2018-02-27 Rambus Inc. Memory controller for strobe-based memory systems
US8151133B2 (en) 2004-12-21 2012-04-03 Rambus Inc. Method for calibrating read operations in a memory system
US8743635B2 (en) 2004-12-21 2014-06-03 Rambus Inc. Memory controller for strobe-based memory systems
US20060203602A1 (en) * 2005-03-14 2006-09-14 Rambus, Inc. Self-timed interface for strobe-based systems
US7688672B2 (en) 2005-03-14 2010-03-30 Rambus Inc. Self-timed interface for strobe-based systems
US7934115B2 (en) 2005-10-31 2011-04-26 International Business Machines Corporation Deriving clocks in a memory system
US20090094476A1 (en) * 2005-10-31 2009-04-09 International Business Machines Corporation Deriving clocks in a memory system
US8145868B2 (en) 2005-11-28 2012-03-27 International Business Machines Corporation Method and system for providing frame start indication in a memory system having indeterminate read data latency
US8151042B2 (en) 2005-11-28 2012-04-03 International Business Machines Corporation Method and system for providing identification tags in a memory system having indeterminate data response times
US8495328B2 (en) 2005-11-28 2013-07-23 International Business Machines Corporation Providing frame start indication in a memory system having indeterminate read data latency
US8327105B2 (en) 2005-11-28 2012-12-04 International Business Machines Corporation Providing frame start indication in a memory system having indeterminate read data latency
US7685392B2 (en) 2005-11-28 2010-03-23 International Business Machines Corporation Providing indeterminate read data latency in a memory system
US20070217559A1 (en) * 2006-03-16 2007-09-20 Rambus Inc. Signaling system with adaptive timing calibration
US9432179B2 (en) 2006-03-16 2016-08-30 Rambus Inc. Signaling system with adaptive timing calibration
US8121237B2 (en) 2006-03-16 2012-02-21 Rambus Inc. Signaling system with adaptive timing calibration
US20070276976A1 (en) * 2006-05-24 2007-11-29 International Business Machines Corporation Systems and methods for providing distributed technology independent memory controllers
KR101429782B1 (en) * 2006-06-07 2014-08-18 스탠다드 마이크로시스템즈 코포레이션 Low power and low pin count bi-directional dual data rate device interconnect interface
US8352657B2 (en) * 2006-06-07 2013-01-08 Standard Microsystems Corporation Digital device interconnect interface and system
US8055825B2 (en) * 2006-06-07 2011-11-08 Standard Microsystems Corporation Digital device interconnect method
US8060678B2 (en) * 2006-06-07 2011-11-15 Standard Microsystems Corporation Digital device interconnect system
US20070288671A1 (en) * 2006-06-07 2007-12-13 Bohm Mark R Low power and low pin count bi-directional dual data rate device interconnect interface
US7702832B2 (en) * 2006-06-07 2010-04-20 Standard Microsystems Corporation Low power and low pin count bi-directional dual data rate device interconnect interface
US20120137032A1 (en) * 2006-06-07 2012-05-31 Bohm Mark R Digital Device Interconnect Interface and System
US20100205337A1 (en) * 2006-06-07 2010-08-12 Bohm Mark R Digital device interconnect system
US20100205339A1 (en) * 2006-06-07 2010-08-12 Bohm Mark R Digital device interconnect method
US7669086B2 (en) 2006-08-02 2010-02-23 International Business Machines Corporation Systems and methods for providing collision detection in a memory system
US7870459B2 (en) 2006-10-23 2011-01-11 International Business Machines Corporation High density high reliability memory module with power gating and a fault tolerant address and command bus
US7721140B2 (en) 2007-01-02 2010-05-18 International Business Machines Corporation Systems and methods for improving serviceability of a memory system
US20080162991A1 (en) * 2007-01-02 2008-07-03 International Business Machines Corporation Systems and methods for improving serviceability of a memory system
US9703503B2 (en) 2007-09-27 2017-07-11 Rambus Inc. Reconfigurable memory system data strobes
US8868873B2 (en) 2007-09-27 2014-10-21 Rambus Inc. Reconfigurable memory system data strobes
US20100268901A1 (en) * 2007-09-27 2010-10-21 Ian Shaeffer Reconfigurable memory system data strobes
US9177632B2 (en) 2007-12-21 2015-11-03 Rambus Inc. Method and apparatus for calibrating write timing in a memory system
US9263103B2 (en) 2007-12-21 2016-02-16 Rambus Inc. Method and apparatus for calibrating write timing in a memory system
US9881662B2 (en) 2007-12-21 2018-01-30 Rambus Inc. Method and apparatus for calibrating write timing in a memory system
EP2232493B1 (en) * 2007-12-21 2018-05-09 Rambus Inc. Method and apparatus for calibrating write timing in a memory system
US9142281B1 (en) 2007-12-21 2015-09-22 Rambus Inc. Method and apparatus for calibrating write timing in a memory system
US9552865B2 (en) 2007-12-21 2017-01-24 Rambus Inc. Method and apparatus for calibrating write timing in a memory system
US9165638B2 (en) 2007-12-21 2015-10-20 Rambus Inc. Method and apparatus for calibrating write timing in a memory system
US9411538B2 (en) 2008-05-29 2016-08-09 Micron Technology, Inc. Memory systems and methods for controlling the timing of receiving read data
US20090300314A1 (en) * 2008-05-29 2009-12-03 Micron Technology, Inc. Memory systems and methods for controlling the timing of receiving read data
US8521979B2 (en) 2008-05-29 2013-08-27 Micron Technology, Inc. Memory systems and methods for controlling the timing of receiving read data
US8751754B2 (en) 2008-05-29 2014-06-10 Micron Technology, Inc. Memory systems and methods for controlling the timing of receiving read data
US8799726B2 (en) 2008-06-03 2014-08-05 Micron Technology, Inc. Method and apparatus for testing high capacity/high bandwidth memory devices
US9146811B2 (en) 2008-07-02 2015-09-29 Micron Technology, Inc. Method and apparatus for repairing high capacity/high bandwidth memory devices
US8756486B2 (en) 2008-07-02 2014-06-17 Micron Technology, Inc. Method and apparatus for repairing high capacity/high bandwidth memory devices
US20100005376A1 (en) * 2008-07-02 2010-01-07 Micron Technology, Inc. Method and apparatus for repairing high capacity/high bandwidth memory devices
US9659630B2 (en) 2008-07-02 2017-05-23 Micron Technology, Inc. Multi-mode memory device and method having stacked memory dice, a logic die and a command processing circuit and operating in direct and indirect modes
US9275698B2 (en) 2008-07-21 2016-03-01 Micron Technology, Inc. Memory system and method using stacked memory device dice, and system using the memory system
US8793460B2 (en) 2008-07-21 2014-07-29 Micron Technology, Inc. Memory system and method using stacked memory device dice, and system using the memory system
US8533416B2 (en) 2008-07-21 2013-09-10 Micron Technology, Inc. Memory system and method using stacked memory device dice, and system using the memory system
US8539312B2 (en) 2008-08-15 2013-09-17 Microns Technology, Inc. Memory system and method using a memory device die stacked with a logic die using data encoding, and system using the memory system
US8826101B2 (en) 2008-08-15 2014-09-02 Micron Technology, Inc. Memory system and method using a memory device die stacked with a logic die using data encoding, and system using the memory system
WO2010078383A1 (en) * 2008-12-31 2010-07-08 Rambus Inc. Active calibration for high-speed memory devices
US8667347B2 (en) 2008-12-31 2014-03-04 Rambus Inc. Active calibration for high-speed memory devices
US20110239063A1 (en) * 2008-12-31 2011-09-29 Rambus Inc. Active calibration for high-speed memory devices
US20110260767A1 (en) * 2010-04-21 2011-10-27 Narendra Devta-Prasanna System and device for reducing instantaneous voltage droop during a scan shift operation
US8627160B2 (en) * 2010-04-21 2014-01-07 Lsi Corporation System and device for reducing instantaneous voltage droop during a scan shift operation
US8861246B2 (en) 2010-12-16 2014-10-14 Micron Technology, Inc. Phase interpolators and push-pull buffers
US9899994B2 (en) 2010-12-16 2018-02-20 Micron Technology, Inc. Phase interpolators and push-pull buffers
US9602080B2 (en) 2010-12-16 2017-03-21 Micron Technology, Inc. Phase interpolators and push-pull buffers
US9032356B2 (en) 2013-03-06 2015-05-12 Lsi Corporation Programmable clock spreading
US9437263B2 (en) 2013-08-30 2016-09-06 Micron Technology, Inc. Apparatuses and methods for providing strobe signals to memories
US9171597B2 (en) 2013-08-30 2015-10-27 Micron Technology, Inc. Apparatuses and methods for providing strobe signals to memories

Also Published As

Publication number Publication date Type
JP2007507794A (en) 2007-03-29 application
US8352696B2 (en) 2013-01-08 grant
DE602004007674T3 (en) 2015-05-28 grant
JP5191555B2 (en) 2013-05-08 grant
DE602004007674D1 (en) 2007-08-30 grant
KR101108297B1 (en) 2012-01-25 grant
KR101110469B1 (en) 2012-01-31 grant
JP2011146063A (en) 2011-07-28 application
KR20110038184A (en) 2011-04-13 application
US20080195885A1 (en) 2008-08-14 application
JP4783290B2 (en) 2011-09-28 grant
DE602004007674T2 (en) 2008-04-10 grant
KR20060111465A (en) 2006-10-27 application
EP1668523A1 (en) 2006-06-14 application
EP1668523B2 (en) 2014-12-10 grant
EP1668523B1 (en) 2007-07-18 grant
WO2005033958A1 (en) 2005-04-14 application

Similar Documents

Publication Publication Date Title
US5815462A (en) Synchronous semiconductor memory device and synchronous memory module
US6618319B2 (en) Synchronous semiconductor memory device allowing control of operation mode in accordance with operation conditions of a system
US6636110B1 (en) Internal clock generating circuit for clock synchronous semiconductor memory device
US7019555B2 (en) Circuit for performing on-die termination operation in semiconductor memory device and its method
US6854043B2 (en) System and method for multi-modal memory controller system operation
US7089412B2 (en) Adaptive memory module
US6337832B1 (en) Operable synchronous semiconductor memory device switching between single data rate mode and double data rate mode
US7024518B2 (en) Dual-port buffer-to-memory interface
US6968419B1 (en) Memory module having a memory module controller controlling memory transactions for a plurality of memory devices
US7007130B1 (en) Memory system including a memory module having a memory module controller interfacing between a system memory controller and memory devices of the memory module
US6970968B1 (en) Memory module controller for providing an interface between a system memory controller and a plurality of memory devices on a memory module
US6742098B1 (en) Dual-port buffer-to-memory interface
US6715096B2 (en) Interface circuit device for performing data sampling at optimum strobe timing by using stored data window information to determine the strobe timing
US20130083611A1 (en) Fast-wake memory
US20060149857A1 (en) Memory system including a memory module having a memory module controller
Kushiyama et al. A 500-megabyte/s data-rate 4.5 M DRAM
US20080005518A1 (en) Synchronous memory read data capture
US20030174569A1 (en) System and method for translation of SDRAM and DDR signals
US7590008B1 (en) PVT compensated auto-calibration scheme for DDR3
US6658523B2 (en) System latency levelization for read data
US20070028027A1 (en) Memory device and method having separate write data and read data buses
US20030105932A1 (en) Emulation of memory clock enable pin and use of chip select for memory power control
US6680866B2 (en) Clock synchronous semiconductor memory device
US6930932B2 (en) Data signal reception latch control using clock aligned relative to strobe signal
US6877079B2 (en) Memory system having point-to-point bus configuration

Legal Events

Date Code Title Description
AS Assignment

Owner name: RAMBUS INC., CALIFORNIA

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:HAMPEL, CRAIG E.;REEL/FRAME:014581/0778

Effective date: 20030930