International Business Machines Corporation

Marvell Asia Pte., Ltd.

William Richard Kelly

Hayden C Cranford, Jr

Michael Anthony Sorna

Troy James Beukema

Eugene R Atwood

Matthew B Baecher

Daniel Mark Dreps

Todd Morgan Rasmus

Minhan Chen

Daniel W Storaska

Louis L Hsu

Frank David Ferraiolo

Joseph Franklin Logan

Robert J Reese

Sergey Vladimirovich Rylov

Karl David Selander

Joseph Natonio

Steven Mark Clements

Robert Michael Bunce

Michael B Spear

Pinping Sun

Louis T Fasano

Kevin G Kramer

Victor Moy

Dinesh B Nair

Susan M Rubow

Chun-Ming Hsu

Elizabeth M May

Embodiments of the present disclosure provide an apparatus including: a phase detector for detecting a write frequency of a deserializer and a read frequency of a serializer, such that the phase detector outputs a first code sequence in response to the write frequency being greater than the read frequency, or a second code sequence at the rotator input in response to the write frequency being less than the read frequency; and a phase rotator for receiving the first code sequence or the second code sequence from the phase rotator to transmit a pacing signal having the read frequency to the deserializer, wherein the pacing signal causes the read frequency to increase or decrease based on whether the read frequency is different from the write frequency.

Apparatus and related method to synchronize operation of serial repeater

A system for detecting one or more signals at a PCI Express interface includes a receiver configured to receive a signal at the PCI Express interface, and a peak detector configured to detect one or more signals based on level sensing, and identify one or more data sampling points to set an amplitude threshold. A comparator is configured to compare an amplitude of the received signal with the amplitude threshold, and a processor is configured to confirm that the received signal is a valid signal when the amplitude of the signal is at least one of greater than or equal to the amplitude threshold over a predefined period of time. The processor is also configured to disable a signal detector that can detect one or more low frequency signals. The system also includes a tester configured to test whether the detected signal is correct.

Systems for signal detection

Methods for detecting one or more signals at a PCI Express interface includes receiving, a signal by a receiver at the PCI Express interface. The methods further include identifying one or more data sampling points to set an amplitude threshold. Further, the method includes comparing an amplitude of the received signal with the amplitude threshold. The method also includes confirming that the received signal is a valid signal when the amplitude of the signal is at least one of greater than or equal to the amplitude threshold over a predefined period of time. The method also includes disabling a signal detector of the PCI Express interface to save power. The signal detector is configured to detect one or more low frequency signals; and testing whether the detected signal is correct.

Systems and methods for signal detection

Testing a Decision Feedback Equalizer ('DFE'), the DFE including a summing amplifier operatively coupled to a plurality of latches and an input signal line for receiving a data signal, including: preventing a differential data signal from being received by the summing amplifier; and iteratively for each tap to be tested: setting a tap coefficient for each tap to zero; setting an output of the plurality of latches to a predetermined value; setting a tap coefficient for the tap to be tested to a full scale value; and determining whether a resultant output signal from the DFE matches a predetermined expected output signal.

Testing a decision feedback equalizer ('DFE')

Testing a digital-to-analog converter (DAC), where the test is carried out iteratively for a plurality of digital test signal values, includes: providing the digital test signal to a DAC under test and to a servo; providing, by the DAC under test to a summer, an analog test signal, including converting the digital test signal to the analog test signal; providing, by the summer to an observation latch, a summed signal, including summing the analog test signal and an analog offset signal, the analog offset signal received from a second DAC; providing, by the observation latch to the servo, a sample of the summed signal; providing, by the servo to the second DAC in dependence upon the sample and the digital test signal, a digital offset signal, where the second DAC converts the digital offset signal to the analog offset signal; and storing, as a digital observation, the digital offset signal.

Testing a digital-to-analog converter

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 serial data receiver includes an amplitude path including a first signal conditioner that adds a first offset or subtracts a second offset based on a selection input, a preamp configured to receive a signal from a transmitter and provide an input signal to the amplitude path, an amplitude latch coupled to the amplitude path, a data latch having a data output and a decision feedback equalization (DFE) logic block coupled to the first conditioning element and the data output and configured to generate the selection output based on the data output of the data latch.

Post-equalization amplitude latch-based channel characteristic measurement

A system and method for closed loop clock correction includes adjusting two or more input signals comprising at least one in-phase clock and one quadrature clock, and applying adjusted quadrature clock signals to a device capable of generating a 4-quadrant interpolated output clock phase. An interpolated output clock phase is delayed to form a clock for a measurement device. Two or more adjusted input signals are measured on a measurement device over a range of interpolated output clock phases. Errors are determined on the in-phase clock and the quadrature clock using sampled information from the measurement device. The in-phase clock and the quadrature clock are adapted using determined error information.

Dynamic quadrature clock correction for a phase rotator system

Systems and methods for adaptive clock and equalization control are provided for data receivers, which are based on a 'closed loop' sampling clock framework that employs controllable and dynamically adapted time offsets on both local data and amplitude clocks. The controllable clock offsets are dynamically adapted using signal processing methods adapted to achieve optimum sampling of data and amplitude sampling clock signals to accurately detect data bits and optimize system equalization settings, including, decision-feedback equalizer and/or an optional linear equalizer preceding a decision-feedback equalizer.

Adaptive clock and equalization control systems and methods for data receivers in communications systems

Illustrative embodiments provide a computer implemented method and an apparatus for data decorrelation in a line equalizer adaptive system. The apparatus comprises an input and an output, forming a data path there between, wherein the input capable of receiving data to create received data and the output capable of sending data. The apparatus further comprises an adaptive equalizer capable of equalizing the received data, connected to the data path, and a synchronous decorrelator connected to the data path, in communication with the adaptive equalizer, wherein the synchronous decorrelator evaluates an adapt enable output for each received data input to the adaptive equalizer to determine whether the adaptive equalizer can update settings of the line equalizer adaptive system.

Apparatus for stabilizing convergence of an adaptive line equalizer

An eyewidth of a data signal is determined by steps including: (a) recovering a phase of a clock from a data signal as a sampling clock; (b) shifting the phase of the sampling clock away from the first phase by a count multiplied by predetermined phase amount; (c) sampling the data signal with the shifted sampling clock phase to obtain sample data; d) determining whether the sample data contains error; (e) when the sample data does not contain error, recovering the phase of the clock from the data signal again for use as the first phase of the sampling clock, increasing the count value and repeating steps (b) through (e); and f) when the sample data contains error, determining the eyewidth based on the last shifted phase of the sampling clock prior to determining that the sample data contains error.

System for measuring an eyewidth of a data signal in an asynchronous system

A method for on-chip detection of data lock and measurement of data lock time in a high-speed serial data link, including: permitting one or more incoming data streams into the high-speed data link; establishing a pattern to be searched in the one or more incoming data streams; comparing patterns in the one or more incoming data streams to a programmable data pattern; holding a repetitive pattern of bits in the one or more incoming data streams by one or more programmable data pattern registers, wherein when one or more occurrences of a byte are detected, an appropriate bit in the one or more programmable data pattern registers is set to indicate the byte's relative position; and filtering false indications in the repetitive pattern by using a byte detection state machine, the state machine controlling and keeping track of a search progress.

On-chip detection and measurement of data lock in a high-speed serial data link

The present invention provides a robust global timing resynchronization architecture, a multi-link communications system including the same, and a method for minimizing the effects of resynchronization signal skew, reference clock skew, and PLL static phase error variations on resynchronization of multi-link communications systems.

Multi-channel synchronization architecture

A transmitter for driving a transmission medium employs pre-distortion to predistort the signals leaving the driver so that they will have an acceptable shape when they reach their destination and have been distorted by imperfections in the transmission medium. The change to pulse height is accomplished by means of a current steering unit that directs a controllable amount of current into the line for each pulse while maintaining the total sum of current that is generated constant in order to reduce noise. Control coefficients for the current steering unit are manipulated in an nxm register that automatically maintains the total number of bits constant while bits are moved from a location that controls a first current driver to a location that controls a second current driver with different properties.

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Verbank, NY, United States of America

William Richard Kelly