Xilinx, Inc.

Alcatel

Paolo Novellini

Giovanni Guasti

Silvio Cucchi

Antonello Di Fresco

David Taylor

Anthony Torza

Martin Johann Kellermann

Alastair J Richardson

A fast clock domain crossing architecture for high frequency trading includes a receiver that recovers data and a clock of a first clock domain from a communication from an exchange, functional circuitry that generates and a buy/sell command based on the recovered data and the recovered clock, format circuitry that formats the command in a second clock domain, and a transmitter that transmits the formatted command to the exchange. The architecture further includes error detection circuitry that detects bit errors that arise from an asynchronous boundary of the clock domains without increasing a round-trip latency, and/or synchronization circuitry that synchronizes the clock domains, where the synchronization circuitry includes a cleanup PLL that filters input jitter and a phase detector and variable delay line that compensate for latency within the architecture.

Fast clock domain crossing architecture for high frequency trading (HFT)

Methods and apparatus for quickly changing line rates in PCIe analyzers without resetting the receivers. One example circuit for multi-rate reception generally includes: a receiver having a data input, a data output, and a clock input configured to receive a clock signal from a clock generator, the receiver being configured to switch between receiving data at a first data rate and at least one second data rate and to sample data according to the first data rate, wherein the first data rate is higher than the at least one second data rate; a phase detector having an input coupled to the data output of the receiver; and a filter having an input coupled to an output of the phase detector and having an output configured to effectively control a phase of the sampling by the receiver when the data is at the at least one second data rate.

Fast line rate switching in peripheral component interconnect express (PCIe) analyzers

A method for measuring asynchronous timestamp requests includes receiving a timestamp ('TS') request from a client device during a first interval of a time of day ('TOD') clock, and calculating, using the TOD clock, at a next interval of the TOD clock, a TS correction of the TS request relative to a reference point of the first TOD clock interval. The method further includes adding the TS correction to the reference point of the first interval of the TOD clock, and outputting the corrected TS to the client device.

Method for time stamping with increased accuracy

A circuit for processing a data stream is described. The circuit comprises a burst phase detector configured to receive a data input signal; a clocking circuit coupled to the burst phase detector, wherein the clocking circuit is configured to receive a delayed data input signal and to receive a data stream phase signal and a data stream detect signal; and a programmable clock generator configured to receive a plurality of clock signals; wherein a selected clock signal of the plurality of clock signals is generated by the programmable clock generator and provided to the burst phase detector and the clocking circuit.

Circuit for and method of processing a data stream

A receiver implemented in an integrated circuit device is described. The receiver circuit comprises a first receiver circuit configured to receive first data, wherein the first receiver circuit comprises a first memory element configured to receive the first data in response to a first clock signal; a latency mirror circuit configured to receive second data, wherein the latency mirror circuit comprises a second memory element configured to receive the second data in response to a second clock signal; and a latency control circuit configured to detect a latency in the second data, wherein the latency control circuit adjusts a phase of the first clock signal used to receive the first data in the first receiver circuit.

Receiver for and method of implementing a receiver in an integrated circuit device

A device includes a physical medium attachment (PMA), a physical coding sublayer (PCS), a phase detector, and an oscillator. The PMA receives data at a first speed and overclocks the received data to a second speed, wherein the second speed is higher than the first speed. The PCS receives the data at the second speed. The phase detector receives another data from the PCS wherein the another data is based on the received data at the second speed or the phase detector is configured to receive the data at the second speed directly from the PMA. The phase detector adjusts a phase based on bit transitions. The oscillator is coupled to the phase detector and generates a reference clock signal wherein a phase of the reference clock is adjusted by the phase detector. The oscillator clocks the PMA based on the adjusted clock.

Low latency receiver

An example circuit includes: a transmitter configured to transmit a clock pattern based on a transmit clock; a receiver, coupled to the transmitter, configured to sample the clock pattern based on a receive clock to generate a bit pattern, where there is a non-zero frequency difference between the transmit clock and the receive clock; a phase interpolator (PI) configured to add a phase shift to a source clock to supply one of the transmit clock or the receive clock; and a test circuit configured to apply adjustments to the phase shift over a time period and determine a phase distribution of the PI based on changes in the bit pattern over the time period.

Self-measurement of phase interpolator non-linearity in a transceiver

A circuit for receiving data is described. The circuit comprises a phase detector circuit comprising a detector having a first input configured to receive a sum of an oscillator phase and a phase error, and a second input coupled to an output of a first sample selector; a second sample selector having an input coupled to receive the input data and generate output data; and an eye detection circuit comprising a third sample selector having an input coupled to receive the input data and a comparator for comparing outputs of the second sample selector and the third sample selector to determine how much an eye is open for a plurality of channels. A method of implementing a receiver is also described.

Circuit for and method of implementing a bursty clock and data recovery circuit using an eyescan detection circuit

An integrated circuit (IC) includes a first device and a second device. A latency measurement circuit is configured to determine a first latency of the first device; and determine a second latency of the second device based on the first latency.

Systems and methods for measuring latency of data buffers

A receiver for processing a data stream includes: a bursty phase detector having a first voltage-controlled oscillator configured to provide a first VCO phase, a signal stream detector configured to provide a data stream phase and a data stream detect signal, and a delay component configured to receive the data stream; a clocking circuit coupled to receive an output of the delay component, the data stream phase, and the data stream detect signal, the clocking circuit configured to provide a second VCO phase at an output of the clocking circuit, wherein the clocking circuit is configured to operate based on a fractional relationship between a reference clock frequency and an output frequency; and a data sample selector with a first input coupled to the output of the delay component, and a second input coupled to the output of the clocking circuit.

Numerically controlled oscillator for fractional burst clock data recovery applications

An apparatus relates generally to serializer-deserializers. In such an apparatus, a first serializer-deserializer has a first data path and a data eye path. The first data path is coupled to a first data out interface of the first serializer-deserializer. A second serializer-deserializer has a second data path. The second data path is coupled to a second data out interface of the second serializer-deserializer. The data eye path of the first serializer-deserializer is coupled to the second data path of the second serializer-deserializer.

SERDES receiver oversampling rate

In a method relating generally to starting a plurality of transmitters, a sequence is initiated for each of the plurality of transmitters having corresponding data buffers. Latency is set for each of the data buffers responsive to execution of the sequence. The sequence includes: obtaining a read address associated with a read clock signal; obtaining a write address associated with a write clock signal; determining a difference between the read address and the write address; asserting a flag signal associated with the difference; and adjusting the read clock signal to change the difference to locate a change of state location for the flag signal to set the latency for a data buffer of the data buffers.

Lane-to-lane de-skew for transmitters

A data recovery unit includes a phase locked loop configured to receive data samples and generate an output; a first sample selector coupled to the phase locked loop; and an eye scanner coupled to the phase locked loop. The first sample selector is configured to receive the data samples and the output of the phase locked loop. The eye scanner comprises a second sample selector coupled to the phase locked loop via a first horizontal shift module.

Non-disruptive eye scan for data recovery units based on oversampling

A data recovery unit (DRU) includes: an oscillator; a phase detector unit configured to receive a reference phase and to receive input data through N wires, where N is an integer, to compare the reference phase with the input data to obtain phase errors, and to determine an average of the phase errors; a subtractor to subtract an output of the oscillator from the average of the phase errors to obtain an unbiased phase error; a delay unit to receive the input data; and a sample selector configured to receive an output from the delay unit and the output of the oscillator, and to output recovered data.

Data recovery unit (DRU) based on free running oversampling with zero-latency loop

The methods and apparatus disclosed herein provide an operative system for increasing the resolution of serial DRUs based on interleaved free running oversamplers. In particular, this system uses incoming data to measure and to compensate the skew between two or more free running oversamplers (e.g., SerDes), without the need for any hardware design requirement relating to the precision of the relative skew of the oversamplers.

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Gorgonzola, Italy

Paolo Novellini