Classifications

• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11C—STATIC STORES
  • G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
  • G11C11/21—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements
  • G11C11/34—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements using semiconductor devices
  • G11C11/40—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements using semiconductor devices using transistors
  • G11C11/401—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements using semiconductor devices using transistors forming cells needing refreshing or charge regeneration, i.e. dynamic cells
  • G11C11/406—Management or control of the refreshing or charge-regeneration cycles
  • G11C11/40622—Partial refresh of memory arrays
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11C—STATIC STORES
  • G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
  • G11C11/21—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements
  • G11C11/34—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements using semiconductor devices
  • G11C11/40—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements using semiconductor devices using transistors
  • G11C11/401—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements using semiconductor devices using transistors forming cells needing refreshing or charge regeneration, i.e. dynamic cells
  • G11C11/406—Management or control of the refreshing or charge-regeneration cycles

Definitions

• This invention relates to memory architectures. Specifically, the present invention relates to memory architectures used in communication systems.
• Modern cell phones typically use flash RAM (random access memory) for nonvolatile memory applications, such as program storage, and volatile static RAM also known as "SRAM” for nonvolatile data storage. While SRAM has heretofore been adequate for cellular telephony applications, dynamic RAM or “DRAM” has been preferred for numerous other applications, such as personal computing, due to the smaller size thereof. That is, while SRAM typically requires six transistors per cell, DRAM typically requires only a single transistor per cell. The smaller size of DRAM memory cells allows for greater storage capacity per chip or die unit area.
• the inventive system includes a mechanism for selectively refreshing elements of a memory array in response to signals from a conventional memory management system.
• the memory is dynamic random access memory and the inventive system is adapted to provide for selective refresh of those DRAM memory elements to which data has been or will be stored.
• This allows for the use of advantageous DRAM memory elements while minimizing the power consumption thereof. Consequently, the utility of DRAM memory elements is extended to a variety of power sensitive applications including cellular telephony and mobile computing.
• the inventive system includes a first counter for counting clock pulses and providing a first count in response thereto; a first comparator for comparing the count to a refresh interval and providing refresh pulses in response thereto; a second counter for generating a reset the signal in response to the refresh pulses and a refresh address range; and a third counter for generating a refresh address pointer in response to the refresh signal and the reset signal.
• the memory elements are dynamic random access memory elements. Nonetheless, the present teachings are not limited thereto.
• the novel wireless indication system includes a transceiver for transmitting and receiving electromagnetic signals; a modem for converting the electromagnetic signals to digital signals and vice versa; memory and a memory management system for storing at least some of the digital signals in predetermined memory elements; a system for selectively refreshing the predetermined memory elements; and an arrangement for providing user input and output.
• the wireless communication system includes dynamic random access memory.
• Figure 1 is a block diagram showing an illustrative embodiment of a wireless communication system implemented in accordance with the teachings of the present invention.
• Figure 2 is a block diagram showing an illustrative implementation of the refresh control logic of Figure 1.
• Figure 3 is a block diagram of an illustrative implementation of the second counter circuit shown in Figure 2.
• FIG. 1 is a block diagram showing an illustrative embodiment of a wireless communication system implemented in accordance with the teachings of the present invention.
• the system 10 includes an antenna 20 coupled to a transceiver 30.
• the transceiver 30 includes a radio frequency transmitter and receiver along with circuitry for up converting and down converting signals as is well known in the art.
• the transceiver circuit 30 communicates demodulator/decoder 35 which converts the received signals to baseband and converts baseband signals to RF frequencies.
• the demodulator/decoder 35 communicates with a data modem 40 of conventional design and construction.
• the data modem 40 sends digital signals to and receives digital signals from a system controller 50.
• the system controller 50 is implemented on a single chip as mobile station modem application specific integrated circuit (MSM ASIC).
• the system controller 50 includes a microprocessor 60 which, in accordance with the present teachings, communicates with dynamic random access memory (DRAM) 100 and other memory 110 via a bus interface 170.
• DRAM dynamic random access memory
• EDRAM embedded dynamic random access memory
• a refresh control logic 80 which operates under control of the microprocessor 60 via the interface bus 70 in response to inputs from a memory manager or controller 90.
• the memory manager 90 is typically implemented in software in an operating system running on the communication system 10.
• the communication system 10 further includes user input and output devices which are represented generally at 120.
• FIG. 2 is a block diagram showing an illustrative implementation of the refresh control logic 80 of Figure 1.
• the refresh control logic 80 is implemented as a state machine with a first counter 122 that counts clock pulses and provides a first count to a first comparator 126.
• the comparator 126 compares the first count to a refresh interval stored in a register 124.
• the refresh interval stored in the register 124 is provided by the memory manager 90 and represents the terminal count for the comparator 126.
• the compare 126 outputs a refresh pulses to the DRAM 100 via conventional DRAM refresh logic 127.
• the refresh pulses are also counted by a second counter 128 disposed within the refresh control logic 80.
• the second counter 128 is implemented with a logic circuit as illustrated more fully in Figure 3 below.
• Figure 3 is a block diagram of an illustrative implementation of the second counter circuit shown in Figure 2.
• the second counter circuit 128 includes an incremental counter 132, which receives the refresh pulses from the first comparator 126 of Figure 2.
• the output of the counter 132 is supplied to a second comparator 140.
• the second comparator 140 generates a reset address pointer signal 'RAP' when the count of the counter 132 exceeds the address range stored in the register 130.
• the refresh address range is supplied by the memory manager 90.
• the refresh address range may be the memory cells in the DRAM 100 to which data has been or will be written by the memory manager 90.
• a default minimum address is utilized, only the upper limit on the range need be specified. This approach is utilized in the illustrative embodiment. Consequently, a register 130 is used in conjunction with the counter 128 to supply the upper limit on the refresh address range thereto. In the illustrative embodiment, this upper limit is represented by the label 'max_row_size'.
• the register 130 includes a buffer register 134 for storing a new value for the address range and a second register 136 for storing the current value of the refresh address range 'max_row_size'.
• the second counter 128 generates one RAP pulse every 'max_row_size'.
• a logic circuit 138 compares the output of the to register is 134 and 136 and implements the algorithm set forth below to ensure that as max_row_size is updated, it is set such that every row gets refreshed within the data retention time: [0019] if new size > old size, counter 2 counts to old size, generates RAP, wrap-around to zero, then uses new size as the terminal count [0020] if new size ⁇ old size,
• the output of the logic circuit 138 is compared to the output of the counter 132 by the comparator 140.
• the comparator 140 outputs a reset address pointer signal 'RAP'.
• the refresh interval controls how often DRAM is refreshed and therefore the refresh current consumed by the DRAM. It should be chosen as large as possible while still satisfying equation [1]. This results in minimum refresh current compatible with the size of the memory. Max_row_size controls the amount of memory refreshed and can be determined from the data memory requirement of the system by the memory manager.
• the third counter 142 is implemented on the DRAM chip.
• the third counter 132 provides a refresh address pointer to the DRAM refresh logic 127.
• the DRAM refresh logic 127 refreshes the DRAM row specified by the third counter when a refresh pulse is received.
• the third counter 142 is reset by the RAP signal from the second counter 128.

Landscapes

• Engineering & Computer Science (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Computer Hardware Design (AREA)
• Dram (AREA)
• Mobile Radio Communication Systems (AREA)
• Storage Device Security (AREA)

Priority Applications (3)

Applications Claiming Priority (4)

Publications (2)

Family

ID=26935419

Family Applications (1)

Country Status (6)

Cited By (1)

Families Citing this family (8)

Family Cites Families (2)

• 2002
  • 2002-09-11 US US10/242,878 patent/US20030053361A1/en not_active Abandoned
  • 2002-09-19 CA CA002461018A patent/CA2461018A1/en not_active Abandoned
  • 2002-09-19 JP JP2003529478A patent/JP2005528717A/ja not_active Withdrawn
  • 2002-09-19 WO PCT/US2002/030000 patent/WO2003025947A2/en not_active Ceased
  • 2002-09-19 BR BRPI0212659-1A patent/BR0212659A/pt not_active IP Right Cessation
  • 2002-09-19 RU RU2004111785/09A patent/RU2004111785A/ru not_active Application Discontinuation

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