A data receiver circuit may include: a delay circuit suitable for delaying first and second strobe signals and generating delayed first and second strobe signals; a first receiver circuit suitable for sampling data in synchronization with the delayed first strobe signal; a second receiver circuit suitable for sampling the data in synchronization with the delayed second strobe signal; an enable signal generation circuit suitable for generating an enable signal indicating whether the data transitioned; a transition level generation circuit suitable for generating a transition level signal indicating a transition direction of the data; a phase shift circuit suitable for shifting the phase of the delayed first strobe signal by a set degree and generating a shifted first strobe signal; a sampling circuit suitable for sampling the data in synchronization with the shifted first strobe signal and generating a sampling result; and a control logic suitable for changing a delay value of the delay circuit in response to the transition level signal and the sampling result of the sampling circuit, when the enable signal is activated.

A method for measuring one-way delays in a communications network, the method comprising: maintaining, at a third node having a reference clock, a first virtual clock state emulating a first node clock located at a first node and a second virtual clock state emulating a second node clock located at a second node; registering a timeset comprising transmission and reception times at the first node and the second node, respectively, for each packet of a plurality of packets that are transmitted from the first node to the second node and reflected from the second node back to the first node; converting times in the timeset, responsive to the first and/or second virtual clocks, into times in accordance with the reference clock; calculating, for each packet of the plurality of packets, a forward one-way delay (FOWD) and a reverse one-way delay (ROWD), responsive to the converted timeset.

According to one embodiment, an interface system includes a receiver, a first clock generator, a second clock generator, and a sampling circuit. The receiver is configured to receive a first clock and serial data from a host. The first clock generator includes a first voltage controlled oscillator (VCO) and is configured to generate a second clock on the basis of the first clock. The second clock generator includes a second voltage controlled oscillator (VCO) and is configured to generate a third clock on the basis of the serial data. The sampling circuit is configured to sample reception data on the basis of the third clock and the serial data.

A receiver with clock phase calibration is disclosed. A first sampling circuit generates first digital data based on an input signal, a sampling phase of the first sampling circuit controlled by a first clock signal. A second sampling circuit generates second digital data based on the input signal, a sampling phase of the second sampling circuit controlled by a second clock signal. Circuitry within the receiver calibrates the clocks in different stages. During a first calibration stage, a phase of the second clock signal is adjusted while the first digital data is selected for generating the output data. During a second calibration stage, a phase of the first clock signal is adjusted while the first digital data is selected for the output data path.

Systems and methods related to phase-locked loops circuitry and lock-detect circuitry are provided. Some of the systems and methods allow sharing of lock-detect circuitries between multiple phase-locked loops or other suitable circuitry. Others allow multiple circuitries to select from multiple lock-detect circuitries that may use different lock-detect techniques.

The present disclosure relates to registration methods and devices. One example method includes obtaining, by a line card, line card information of the line card, the line card comprising a fabric interface chip optically interconnected to a switch fabric chip in at least one switch fabric card by using an optical fiber, and sending, by the line card, the line card information to the at least one switch fabric card through an optical interconnect path. The at least one switch fabric card registers the line card based on the line card information.

A CDR circuit for use in an optical receiver is provided that performs automatic rate negotiation. The CDR circuit is configured to determine whether the incoming data signal has a first, second or third data rate. If the CDR circuit determines that the incoming data signal has the first data rate, the CDR circuit places itself in a bypass mode of operations so that CDR is not performed. If the CDR circuit determines that the incoming data signal has the second or third data rates, the CDR circuit places itself in a CDR mode of operations and performs CDR on the incoming data signal.

A method and system that provides for execution of a first calibration sequence, such as upon initialization of a system, to establish an operation value, which utilizes an algorithm intended to be exhaustive, and executing a second calibration sequence from time to time, to measure drift in the parameter, and to update the operation value in response to the measured drift. The second calibration sequence utilizes less resources of the communication channel than does the first calibration sequence. In one embodiment, the first calibration sequence for measurement and convergence on the operation value utilizes long calibration patterns, such as codes that are greater than 30 bytes, or pseudorandom bit sequences having lengths of 2.sup.N1 bits, where N is equal to or greater than 7, while the second calibration sequence utilizes short calibration patterns, such as fixed codes less than 16 bytes, and for example as short as 2 bytes long.

A receiver with clock phase calibration. A first sampling circuit generates first digital data based on an input signal, a sampling phase of the first sampling circuit controlled by a first clock signal. A second sampling circuit generates second digital data based on the input signal, a sampling phase of the second sampling circuit controlled by a second clock signal. Circuitry within the receiver calibrates the clocks in different stages. During a first calibration stage, a phase of the second clock signal is adjusted while the first digital data is selected for generating the output data. During a second calibration stage, a phase of the first clock signal is adjusted while the first digital data is selected for the output data path.

System and method of frame alignment at a receiver with power optimization mechanisms. A framer is configured to perform a frame alignment process on a data stream and enter an inactive state after frame alignment is achieved. In the inactive state, the circuits used to perform the frame alignment process in the framer can be powered down or otherwise placed in a power reduction mode. Responsive to an indication that data processing at the receiver becomes out-of-frame again, the framer can wake up from the inactive state and restart the frame alignment process. An out-of-frame indication may be generated by error detection logic (e.g., forward error correction (FEC) decoder) when it detects an excessive number of uncorrectable errors.