International Business Machines Corporation

Michael B Spear

Frank David Ferraiolo

Robert J Reese

Susan M Eickhoff

Daniel Mark Dreps

Steven R Carlough

Gary A Van Huben

Steven John Baumgartner

Stephen Dale Wyatt

Patrick James Meaney

Michael Wayne Harper

Christian Jacobi

Kevin Charles Gower

Martin L Schmatz

Jieming Qi

John Francis Bulzacchelli

Eric Eugene Retter

Kenneth Lee Wright

Prasanna Jayaraman

Paul Allen Ganfield

Mack Wayne Riley

Michael Sperling

Glenn David Gilda

Jentje Leenstra

Michael Raymond Trombley

Timothy O Dickson

Peter L Buchmann

William Richard Kelly

Peter Matthew Thomsen

Erik English

Ashutosh Mishra

Logan I Friedman

Susan M Rubow

John G Rell, Iii

An enhanced quadrature receive serial interface circuit and methods are provided for calibrating the quadrature receive serial interface circuit. A quadrature receive serial interface circuit comprises a first phase rotator and a second phase rotator generating quadrature clocks of identical frequency. Calibration of the quadrature receive serial interface circuit uses a pseudo random bit sequence (PRBS) received by the quadrature receive serial interface circuit. For calibration, one-half of the received PRBS bits are sampled and the phase rotator generating in-phase 0° and 180° clock signals is adjusted to center the data eye for the sampled half of the PRBS bits. Then all data bits (even and odd data bits) of the received PRBS bits are sampled and the phase rotator generating quadrature phase 90° and 270° clock signals is adjusted to center the data eye of all data bits of the PRBS bits to complete calibration.

Calibrating a quadrature receive serial interface

Embodiments of the invention are directed to a computer-implemented method of operating a data transmission system. The data transmission system includes a transmitter and a receiver. The computer-implemented method includes using the transmitter to send serialized data from the transmitter through a plurality of lanes to the receiver. The transmitter sends the serialized data at a first serialization ratio. The receiver is configured to receive and load the serialized data at a second deserialization ratio, wherein the first serialization ration is greater than the second deserialization ratio.

Low-latency deserializer having fine granularity and defective-lane compensation

A calibration controller determines a latest arriving data strobe from at least one data chip at a first data buffer in a read data path between at least one memory chip and a host on a high speed interface. The calibration controller determines whether external feedback of the at least one data chip is required. The calibration controller, in response to determining that external feedback of the at least one data chip is required, aligns a chip clock distributed to a second data buffer in the read data path with the latest arriving data strobe by applying a 180 degree phase align of the chip clock through one or more latches, wherein data cross a first clock boundary from the first data buffer to the second data buffer, to minimize a latency in the read data path across the first clock boundary.

Reducing latency of memory read operations returning data on a read data path across multiple clock boundaries, to a host implementing a high speed serial interface

A method, system, and/or computer program product controls transitions from a first bandwidth to a second bandwidth in a bus within a multi-processor computer. A bus controller predicts a bandwidth transition requirement for a bus in a multi-processor computer, and transitions the bus from a first bandwidth to a second bandwidth based on the predicted bandwidth transition requirement. The bus controller checks an actual transitioning requirement of the bus in the computer, such that the bus controller checks the actual transitioning requirement for the bus at each occurrence of a predefined stage of operation of one or more processor processors in the computer. In response to the actual transitioning requirement matching the predicted bandwidth transition requirement, the bus controller directions a continuation of the transitioning of the bus from the first bandwidth to the second bandwidth.

Staged power on/off sequence at the I/O phy level in an interchip interface

A calibration controller of a receiving chip learns a difference between a first clock phase of an input clock for controlling inputs on a data path to a buffer of the receiving chip at a clock boundary and a second clock phase of a chip clock for controlling outputs from the buffer on the data path at the clock boundary. The calibration controller dynamically adjusts a phase of a reference clock driving a phase locked loop that outputs the chip clock to adjust the second clock phase of the chip clock with respect to the first clock phase to minimize a latency on the data path at the clock boundary to a half a cycle granularity.

Reducing chip latency at a clock boundary by reference clock phase adjustment

A calibration controller determines a latest arriving data strobe at a first data buffer in a read data path between at least one memory chip and a host on a high speed interface. The calibration controller aligns a chip clock distributed to a second data buffer in the read data path with the latest arriving data strobe, wherein data cross a first clock boundary from the first data buffer to the second data buffer, to minimize a latency in the read data path across the first clock boundary. The calibration controller aligns the chip clock with a high speed clock for controlling an unload pointer to unload the data from the second data buffer to a serializer in the read data path, wherein the data cross a second clock boundary from the second data buffer to the serializer, to minimize a latency in the read data path across a second clock boundary.

Method and apparatus for packeted analysis, comprising: testing a phase rotator at a plurality of phase rotator positions, by propagating a first series of bits of a first pattern through a channel of an integrated circuit; propagating a second series of bits of a second pattern through the channel; measuring, for the given phase rotator position, a value of each bit propagated through the channel; and in response to determining that measured values of the bits propagated through the channel conform to one of the first pattern and the second pattern, indicating that the given phase rotator position satisfies an accuracy threshold; determining a sequence of phase rotator positions of the plurality of phase rotator positions in which the accuracy threshold is satisfied; and in response to determining that the sequence of phase rotator positions does not satisfy an eye width threshold, failing the channel of the integrated circuit.

Built-in self-test for receiver channel

A system for memory management includes an incoming memory data strobe connecting a memory data interface, and a clock distribution network. The clock distribution network includes an internal clock aligned to the incoming memory data strobe. The system also includes an asynchronous clock domain that is asynchronous with the clock distribution network; and a strobe select circuit configured to align to the incoming memory data strobe. The clock distribution network is configured to propagate read data with reduced latency from the memory data interface to a second interface.

Double data rate (DDR) memory read latency reduction

A digital data communications mechanism includes multiple parallel lines, in which components of one or more lines are temporarily powered down to save power. Preferably, both the transmitter and receiver contain respective generators generating identical pre-determined pseudo-random bit streams, which are initially synchronized and which remain powered up when the line is temporarily powered down. Upon re-powering the line, the transmitter transmits the locally generated bit stream, and the receiver compares the received bit stream with its internally generated bit stream to determine an amount of shift required for re-synchronization.

Power reduction in a parallel data communications interface using clock resynchronization

A method includes modifying, at a bit error injection circuit, a multiplier value by a first value according to an occurrence of a first event. The method also includes, in response to a determination that the modified multiplier value matches a first threshold, modifying, at the bit error injection circuit, the offset value according to an occurrence of a second event. The method further includes, in response to a determination that the modified offset value matches a second threshold, asserting, at the bit error injection circuit, an error injection signal. The method further includes asserting a first error pattern to be transmitted via a bus lane based on the error injection signal.

System and method to inject a bit error on a bus lane

A communications link includes multiple continuously calibrated parallel lines, wherein one or more lines are at least partially powered down while being continuously calibrated to reduce power consumption. In one aspect, at least N+1 lines (where N is the logical bus width) are periodically recalibrated, and at least one redundant line is powered down between calibrations. The redundant line could be either a true spare available for use as a replacement, or an extra line which carries functional data while other lines are being calibrated in turn. In another aspect, the logical bus width is variable, but does not exceed N. When N&#x3c;N, lines not carrying functional data are partially powered down between calibrations.

Parallel data communications mechanism having reduced power continuously calibrated lines

A communications link of multiple parallel communications lines includes at least one redundant line. In a first aspect, the lines are periodically recalibrated one at a time while the others carry functional data. If a fault is detected, the faulty line is disabled and the remaining previously calibrated lines transmit functional data. In a second aspect, impending line malfunction is detected from anomalies during calibration. In a third aspect, line malfunction is detected from receiver circuit output by determining a logical lane upon which each detected error occurs, and by mapping the logical lane to a physical line currently carrying the logical lane data.

Dynamic fault detection and repair in a data communications mechanism

A parallel data link includes a redundant line. A bank of switches permits any arbitrary line of the link to be enabled or disabled for carrying functional data, each line being dynamically calibrated in turn by disabling the line and allowing other lines to carry the functional data. The switches are located downstream of alignment mechanisms so that data input to the switches is compensated for data skew. Preferably, receiver synchronization circuitry in each line operates in a respective independent clock domain, while the switches and calibration mechanism operate in a common clock domain. Preferably, the receiver synchronization circuits provide an adjustable delay corresponding to a variable number of clock cycles to align the outputs of the receiver synchronization circuits with respect to one another, which can accommodate high data skew.

Calibration of multiple parallel data communications lines for high skew conditions

A memory buffer, memory system and method for power-on initialization and test for a cascade interconnect memory system. The memory buffer includes a bus interface to links in a high-speed channel for communicating with a memory controller via a direct connection or via a cascade interconnection through an other memory buffer. The interface is operable in a SBC mode and a high-speed mode. The memory buffer also includes a field service interface (FSI) slave for receiving FSI signals from a FSI master. In addition, the memory buffer includes logic for executing a power-on and initialization training sequence initiated by the memory controller.

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Round Rock, TX, United States of America

Michael B Spear