Abstract:
A system has a plurality of memory devices arranged in a fly-by topology, each having on-die termination (ODT) circuitry for connecting to an address and control (RQ) bus. The ODT circuitry of each memory device includes a set of one or more control registers for controlling on-die termination of one or more signal lines of the RQ bus. A first memory device includes a first set of one or more control registers storing a first ODT value, for controlling termination of one or more signal lines of the RQ bus by the ODT circuitry of the first memory device, and a second memory device includes a second set of one or more control registers storing a second ODT value different from the first ODT value, for controlling termination of one or more signal lines of the RQ bus by the ODT circuitry of the second memory device.
Abstract:
A system that calibrates timing relationships between signals involved in performing write operations is described. This system includes a memory controller which is coupled to a set of memory chips, wherein each memory chip includes a phase detector configured to calibrate a phase relationship between a data-strobe signal and a clock signal received at the memory chip from the memory controller during a write operation. Furthermore, the memory controller is configured to perform one or more write-read-validate operations to calibrate a clock-cycle relationship between the data-strobe signal and the clock signal, wherein the write-read-validate operations involve varying a delay on the data-strobe signal relative to the clock signal by a multiple of a clock period.
Abstract:
A memory system includes a memory controller coupled to multiple memory devices. Each memory device includes an oscillator that generates an internal reference signal that oscillates at a frequency that is a function of physical device structures within the memory device. The frequencies of the internal reference signals are thus device specific. Each memory device develops a shared reference signal from its internal reference signal and communicates the shared reference signal to the common memory controller. The memory controller uses the shared reference signals to recover device-specific frequency information from each memory device, and then communicates with each memory device at a frequency compatible with the corresponding internal reference signal.
Abstract:
A memory device comprising a programmable command-and-address (CA) interface and/or a programmable data interface is described. In an operational mode, two or more CA interfaces may be active. In another operational mode, at least one, but not all, CA interfaces may be active. In an operational mode, all of the data interfaces may be active. In another operational mode, at least one, but not all, data interfaces may be active. The memory device can include circuitry to select: an operational mode; a sub-mode within an operational mode; one or more CA interfaces as the active CA interface(s); a main CA interface from multiple active CA interfaces; and/or one or more data interfaces as the active data interfaces. The circuitry may perform these selection(s) based on one or more bits in one or more registers and/or one or more signals received on one or more pins.
Abstract:
A system that calibrates timing relationships between signals involved in performing write operations is described. This system includes a memory controller which is coupled to a set of memory chips, wherein each memory chip includes a phase detector configured to calibrate a phase relationship between a data-strobe signal and a clock signal received at the memory chip from the memory controller during a write operation. Furthermore, the memory controller is configured to perform one or more write-read-validate operations to calibrate a clock-cycle relationship between the data-strobe signal and the clock signal, wherein the write-read-validate operations involve varying a delay on the data-strobe signal relative to the clock signal by a multiple of a clock period.
Abstract:
In a reconfigurable data strobe-based memory system, data strobes may be re-tasked in different modes of operation. For example, in one mode of operation a differential data strobe may be used as a timing reference for a given set of data signals. In a second mode of operation, one of the components of the differential data strobe may be used as a timing reference for a first portion of the set of data signals and the other component used as a timing reference for a second portion of the set of data signals. Different data mask-related schemes also may be invoked for different modes of operation. For example, in a first mode of operation a memory controller may generate a data mask signal to prevent a portion of a set of data from being written to a memory array. Then, in a second mode of operation the memory controller may invoke a coded value replacement scheme or a data strobe transition inhibition scheme to prevent a portion of a set of data from being written to a memory array.
Abstract:
A memory system includes a memory controller coupled to multiple memory devices. Each memory device includes an oscillator that generates an internal reference signal that oscillates at a frequency that is a function of physical device structures within the memory device. The frequencies of the internal reference signals are thus device specific. Each memory device develops a shared reference signal from its internal reference signal and communicates the shared reference signal to the common memory controller. The memory controller uses the shared reference signals to recover device-specific frequency information from each memory device, and then communicates with each memory device at a frequency compatible with the corresponding internal reference signal.
Abstract:
A memory module comprises a module interface having module data-group ports to communicate data as respective data groups, a command port to receive memory-access commands, a first memory device including a first device data-group port, a second memory device including a second device data-group port, and a signal buffer coupled between the module interface and each of the first and second devices. In a first mode, in response to the memory-access commands, the signal buffer communicates the data group associated with each of the first and second device data-group ports via a respective one of the module data-group ports. In a second mode, in response to the memory-access commands, the signal buffer alternatively communicates the data group associated with the first device data-group port or the data group associated with the second device data-group port via the same one of the module data-group ports.
Abstract:
A system has a plurality of memory devices arranged in a fly-by topology, each having on-die termination (ODT) circuitry for connecting to an address and control (RQ) bus. The ODT circuitry of each memory device includes a set of one or more control registers for controlling on-die termination of one or more signal lines of the RQ bus. A first memory device includes a first set of one or more control registers storing a first ODT value, for controlling termination of one or more signal lines of the RQ bus by the ODT circuitry of the first memory device, and a second memory device includes a second set of one or more control registers storing a second ODT value different from the first ODT value, for controlling termination of one or more signal lines of the RQ bus by the ODT circuitry of the second memory device.
Abstract:
A memory device or module selects between alternative command ports. Memory systems with memory modules incorporating such memory devices support point-to-point connectivity and efficient interconnect usage for different numbers of modules. The memory devices and modules can be of programmable data widths. Devices on the same module can be configured select different command ports to facilitate memory threading. Modules can likewise be configured to select different command ports for the same purpose.