Rambus Inc.

Barry William Daly

Jared L Zerbe

John Cronan Eble, Iii

Lei Luo

John M Wilson

Brian S Leibowitz

Wayne D Dettloff

Jihong Ren

Teva J Stone

Brian Hing-Kit Tsang

Hsuan-Jung Su

Kambiz Kaviani

Anthony Chan Carusone

Dustin Tarl Dunwell

Yohan Usthavia Frans

Nhat M Nguyen

Yueyong Wang

Thomas J Giovannini

Masum Hossain

Robert E Palmer

William Franklin Stonecypher

Andrew M Fuller

Described are integrated circuits for equalizing parallel write-data and address signals from a memory controller. The integrated circuits each include a set of decision-feedback equalizers, one equalizer for each received signal. Each equalizer in a set has a main sampler and a monitor sampler, each of which samples the respective input signal on edges of a timing-reference signal (e.g. a clock or strobe) that is common to the set. The main sampler samples the input signal relative to a reference. The monitor sampler samples the input signal relative to an adjustable threshold calibrated to monitor one or more levels of the input signal. A feedback network adjusts the respective input signal responsive to one or more tap values that can be adjusted to equalize the signal. An adaptive tap-value generator for one or a collection of the equalizers adjusts the tap value or values as a function of least-mean squares of errors to one or more of the sampler input ports.

Circuits and methods for self-adaptive decision-feedback equalization in a memory system

The disclosed embodiments relate to a system that supports dynamic bursts to facilitate frequency-agile communication between a memory controller and a memory device. During operation, the system monitors a reference clock signal received at an interface between the memory device and the memory controller. Upon detecting a frequency change in the reference clock signal from a fullrate to a subrate, the interface operates in a burst mode, wherein data is communicated through bursts separated by intervening low-power intervals during which portions of the interface are powered down.

Using dynamic bursts to support frequency-agile memory interfaces

A low-power, high-performance source-synchronous chip interface which provides rapid turn-on and facilitates high signaling rates between a transmitter and a receiver located on different chips is described in various embodiments. Some embodiments of the chip interface include, among others: a segmented 'fast turn-on' bias circuit to reduce power supply ringing during the rapid power-on process; current mode logic clock buffers in a clock path of the chip interface to further reduce the effect of power supply ringing; a multiplying injection-locked oscillator (MILO) clock generator to generate higher frequency clock signals from a reference clock; a digitally controlled delay line which can be inserted in the clock path to mitigate deterministic jitter caused by the MILO clock generator; and circuits for periodically re-evaluating whether it is safe to retime transmit data signals in the reference clock domain directly with the faster clock signals.

Method and apparatus for source-synchronous signaling

Methods and apparatuses featuring a multiplying injection-locked oscillator are described. Some embodiments include a pulse-generator-and-injector and one or more injection-locked oscillators. The outputs of the pulse-generator-and-injector can be injected into corresponding injection points of an injection-locked oscillator. In embodiments that include multiple injection-locked oscillators, the outputs of each injection-locked oscillator can be injected into the corresponding injection points of the next injection-locked oscillator. Some embodiments reduce deterministic jitter by dynamically modifying the loop length of an injection-locked oscillator, and/or by using a duty cycle corrector, and/or by multiplexing/blending the outputs from multiple delay elements of an injection-locked oscillator.

Integrated circuit having a multiplying injection-locked oscillator

A signal on a transmitter tracks noise on a ground node in a manner decoupled from a positive node of a power supply. The signal is transmitted from the transmitter to the receiver. A reference voltage is generated on the receiver to track noise on a ground node in the receiver. Consequently, the received signal and the reference voltage have substantially the same noise characteristics, which become common mode noise that can be cancelled out when these two signals are compared against each other. In a further embodiment, the reference voltage is compared against a predetermined calibration pattern. An error signal is generated based on a difference between the sampler output and the predetermined calibration pattern. The error signal is then used to adjust the reference voltage so that the DC level of the reference voltage is positioned substantially in the middle of the received signal.

Reference voltage generation and calibration for single-ended signaling

A memory controller that extends the window when reading data from the memory device to compensate for fluctuations in a read strobe delay. The memory controller includes a communication port that receives a timing reference signal for reading data from a memory device. A control circuit generates a gating signal indicative of a read window. A gating adjustment circuit generates an adjusted gating signal indicative of an adjusted read window based on the gating signal and the timing reference signal. A gating circuit generates a first gated timing reference signal for reading data by gating a delayed version of the timing reference signal with the adjusted gating signal.

Read strobe gating mechanism

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Chapel Hill, NC, United States of America

Barry William Daly