Abstract: Nodes in a network include a pseudo-timestamp in messages or packets, derived from local pseudo-time clocks. When a packet is received, a first time is determined representing when the packet was sent and a second time is determined representing when the packet was received. If the difference between the second time and the first time is greater than a predetermined amount, the packet is considered to be stale and is rejected, thereby deterring replay. Because each node maintains its own clock and time, to keep the clocks relatively synchronized, if a time associated with a timestamp of a received packet is later than a certain amount with respect to the time at the receiver, the receiver's clock is set ahead by an amount that expected to synchronize the receiver's and the sender's clocks. However, a receiver never sets its clock back, to deter attacks.

Abstract: A communication channel includes a first component having a transmitter coupled to a normal signal source, and a second component having a receiver coupled to a normal signal destination. A communication link couples the first and second components. Calibration logic provides for setting an operation value for a parameter of the communication channel, such as by executing an exhaustive calibration sequence at initialization of the link. A tracking circuit, including a monitoring function, tracks drift in the parameter by monitoring a feedback signal that has a characteristic that correlates with drift in the communication channel, and updates, or indicates the need for updating of, the operation value of the parameter in response to the monitoring function.

Abstract: A multiphase encoded protocol has sufficient density of commands to allow a rich language to be realized on a bus. When ten field bits are dedicated to commands, it is possible to have more than six million words to choose from per clock. Architecture to implement the multiphase encoded protocol and synchronize the bus includes an extracted clock, a command element, and a data element. One-bit multipliers are used as correlation elements to provide feedback into slaved delay-locked loop (DLL) devices, which provides precise phase alignment for successful data extraction of several channels.

Abstract: A structure for performing cross-chip communication with mesochronous clocks. The structure includes: a data delay line; a remote clock delay line; a structure that captures at least one value of a state of a delayed remote clock signal on the remote clock delay line; and a control that influences a delay associated with the data delay line and the remote clock delay line.

Abstract: A memory device is provided. The memory device includes a plurality of memory chips coupled in series, and a register serially coupled to the memory chips. The register includes an integrated delay-locked loop. The memory device may be included in a processing system. Moreover, a method for improving timing budgets in a registered dual in-line memory module (RDIMM) may be implemented using the memory device having a register with an integrated delay-locked loop.

Abstract: Integrated circuits such as programmable logic device integrated circuits with memory interface circuitry are provided. The memory interface circuitry measures the timing characteristics of an associated memory during a series of dummy read operations. A multiplexer and phase detector are used to measure phase shifts of memory group clock signals compared to a system clock signal. The memory interface circuitry uses these measurements to adjust a delay-locked-loop circuit. The delay-locked-loop circuit produces a capture clock that is used to read data from the memory.

Abstract: A method for adjusting clock frequency is disclosed. The method includes halting a central processing unit (CPU) while tuning a clock frequency, thereby enabling multiple clock signals with the tuned clock frequency to be generated.

Abstract: Methods and system for reducing latency associated with a read operation in a processor memory system are provided. In one implementation, the method includes receiving an early indicator corresponding to read data from a memory, delaying the early indicator in accordance with a pre-determined delay such that the early read indicator is passed to a bus in advance of the read data; and dynamically adjusting the pre-determined delay using an adjustment delay circuit, the pre-determined delay being adjusted responsive to a change in operational speed of the bus or change in operational speed of a processor coupled to the bus.

Abstract: An apparatus and method for generating a delayed clock signal is provided. The clock signal generator includes a synchronizing circuit for generating an output clock signal from an input clock signal and further includes a delay circuit having an input coupled to the output of the synchronizing circuit. The delay circuit provides an output clock signal having a delay with respect to the clock signal from the synchronizing circuit according to one of a plurality of programmable time delays selected in accordance with a selection signal. The method of generating a clock signal includes synchronizing an internal clock signal to an external clock signal, and delaying the internal clock signal different amounts based on a selection value indicative of external clock frequency to provide the clock signal.

Abstract: A digital registered data buffer is disclosed that has data paths each with a data input for receiving a digital data input signal (Dn), a clock input for receiving a clock input signal (CLK) and a data output providing a digital data output signal (Qn) for application to a data destination device such as memory devices. The buffer further has a clock output for providing an output clock signal (QCLK) to the data destination device and a phase-locked loop (PLL) with a clock input, a feedback input, a feedback output and a plurality of clock outputs. The buffer uses a pair of data registers, i.e. flip-flops (FF1, FF2) connected in series in each data path. The first data register in each data path is clocked by the clock input signal (CLK) and the second data register in each data path is clocked by one of the clock outputs (PDCLK) from the PLL.

Abstract: A serial bus system for data communication between devices according to a master-slave protocol has a data bus connecting master and slave devices and a shared clock system arranged to provide a shared-clock signal to the master and slave devices. The master and slave devices are arranged to derive device-individual clock signals which are synchronized with data received on the data bus, from the shared-clock signal and a data-timing indication on the data bus.

Abstract: An interface apparatus is provided having a first register device and a second register device, which is connected in parallel with it. The register devices are configured to receive a data word. The interface apparatus includes a synchronization circuit, to which a first and a second clock signal is supplied and which is configured to emit a selection signal, which is derived from the first clock signal, for selection of the first or second register device for storage of a data word. The synchronization circuit is also configured to emit a control signal derived from the selection signal and the second clock signal, at a control output. The control output is coupled to a selection circuit, by means of which the output of one of the two register devices can be connected to the data output of the interface apparatus. Comparison of the selection signal with the second clock signal means that there is no need for an additional registration device.

Abstract: A method and circuit for precisely synchronizing clocks in separate nodes on a communication network is provided by adjusting timestamps and related data in network messages. The circuit will allow a daisy-chain connection of the nodes and will forward time synchronization frames while accounting for delays in a manner that does not use boundary clocks, but does not depart from the IEEE 1588 standard protocol. The delays will be added on the fly to synchronization packets and the IP checksum and frame CRC will be adjusted. Deterministic data delivery and redundant data paths are also provided in a full duplex Ethernet network.

Abstract: A semiconductor integrated circuit including a first power supply region supplied with a first power supply voltage, and having a first clock distribution network, a second power supply region supplied with a second power supply voltage, and having a second clock distribution network, a first phase synchronizer which provides a first output signal obtained by making a phase of a reference clock signal for controlling a data input/output coincident with a phase of a clock signal at a first point of the first clock distribution network, to a second point of the second clock distribution network, and a second phase synchronizer which provides a second output signal obtained by making the phase of the clock signal at a third point of the first clock distribution network coincident with a phase of a clock signal at a first point of the second clock distribution network, to a second point of the first clock distribution network.

Abstract: A multi-clock system-on-chip (D) comprises i) a core (CE) comprising asynchronous clock domains provided for exchanging test data therebetween, ii) a clock generator unit (CGU) arranged for delivering primary clock signals (clk1-clko) for at least some of the clock domains, and iii) clock control modules (CCl-CCo), arranged respectively for defining the functional clock signals from the primary clock signals and from control signals (intended for setting the clock control modules (CCl) in a normal mode allowing test data transmission from the corresponding emitter clock domain to at least one receiver clock domain or a shift mode forbidding such a test data transmission).

Abstract: Programmable logic device integrated circuits are provided that have configurable receivers with dynamic phase alignment capabilities. In situations in which receivers require dynamic phase alignment circuitry, programmable logic elements can be configured to implement a dynamic phase alignment data capture and synchronization circuit. In situations in which dynamic phase alignment receiver circuitry is not required, resources are made available for implementing other user logic. Multiple dynamic phase alignment receiver circuits can share an eight-phase dynamic phase alignment clock signal that is generated by a phase-locked-loop circuit. Switches may be configured to selectively route the dynamic phase alignment clock signal to desired locations on the programmable logic device integrated circuit.

Abstract: A communication channel includes a first component having a transmitter coupled to a normal signal source, and a second component having a receiver coupled to a normal signal destination. A communication link couples the first and second components. Calibration logic provides for setting an operation value for a parameter of the communication channel, such as by executing an exhaustive calibration sequence at initialization of the link. A tracking circuit, including a monitoring function, tracks drift in the parameter by monitoring a feedback signal that has a characteristic that correlates with drift in the communication channel, and updates, or indicates the need for updating of, the operation value of the parameter in response to the monitoring function.

Abstract: An information processing apparatus includes a versatile Operating System (OS) that performs a time measurement process in response to a request from an application, a storage unit that stores a process load of the versatile OS and a delay time of the time measurement process in combination, a detecting unit that detects a process load of the versatile OS when the application requests the time measurement process, an acquiring unit that acquires a delay time that corresponds to the process load, which is detected by the detecting unit, as an expected delay time from the storage unit, and a requesting unit that requests the versatile OS to measure a requested measurement time that is obtained by subtracting the expected delay time, which is acquired by the acquiring unit, from a measurement time that is requested by the application.

Abstract: The asynchronous circuit insensitive to delays comprises at least one time delay insertion circuit on the propagation path of a signal. The delay insertion circuit comprises, between an input and an output of the signal, a Muller C-element and a plurality of delay circuits connected in series to an output of the Muller C-element. The outputs of the delay circuits are connected to corresponding inputs of a multiplexing circuit having an output constituting the output of the delay insertion circuit. The Muller C-element comprises an input connected to the output of the last delay circuit via an inverter gate, and an input constituting the input of the signal to the delay insertion circuit. The multiplexing circuit control circuit preferably comprises a random generator.

Abstract: A fast data access circuit that has both a standard clock mode and a fast data access mode. The mode is selectable through a mode/configuration register. A configuration word loaded into the register has bits to indicate the desired mode and the input clock frequency. In the fast data access mode, a clock delay circuit uses the clock frequency setting bits to select a delay to be added to the input clock. The higher the clock frequency, the less the added delay. The delayed clock generates FIFO control signals to control a data FIFO register. During the fast data access mode, the data is output from the data FIFO register at a faster rate than in the standard clock mode.

Abstract: Apparatus and method support the synchronization and calibration of a plurality of clocks in a medical device system that may provide treatment to a patient with a nervous system disorder. The plurality of clocks, which may be located at different components of the medical device system, comprises a first clock and a second clock. The second clock may be synchronized to a first clock by disabling a run mode operation and setting the second clock to a selected time. When a reference time of the first clock approximately equals the selected time, the second clock enables the run mode operation. Additionally, a drift time that is indicative of a time difference between the first clock and the second clock is determined. If the drift time is greater than a predetermined amount, an indication to resynchronize the first and second clocks is provided.

Abstract: A programmable local clock buffer for integrated circuit devices which is capable of varying initial settings is provided. The illustrative embodiments allow a single type of local clock buffer (LCB) to be used throughout an integrated circuit design while still being able to provide differing initial offsets and pulse widths for different local circuitry portions of the integrated circuit design. Delay circuit paths are provided, which provide discreet delay values, within the LCB that can be chained together when the LCB is instantiated to set the initial offset and pulse width values. When an LCB is instantiated in the integrated circuit device design, various ones of the delay circuit paths are connected together with the existing circuit paths of the LCB, i.e. the circuit paths that provide the pre-established offset and pulse width values, in order to set the initial offset and pulse width values for the LCB.

Abstract: A semiconductor integrated circuit including a first power supply region supplied with a first power supply voltage, and having a first clock distribution network, a second power supply region supplied with a second power supply voltage, and having a second clock distribution network, a first phase synchronizer which provides a first output signal obtained by making a phase of a reference clock signal for controlling a data input/output coincident with a phase of a clock signal at a first point of the first clock distribution network, to a second point of the first clock distribution network, and a second phase synchronizer which provides a second output signal obtained by making the phase of the reference clock signal coincident with a phase of a clock signal at a first point of the second clock distribution network, to a second point of the second clock distribution network.

Abstract: An apparatus and method for generating a delayed clock signal is provided. The clock signal generator includes a synchronizing circuit for generating an output clock signal from an input clock signal and further includes a delay circuit having an input coupled to the output of the synchronizing circuit. The delay circuit provides an output clock signal having a delay with respect to the clock signal from the synchronizing circuit according to one of a plurality of programmable time delays selected in accordance with a selection signal. The method of generating a clock signal includes synchronizing an internal clock signal to an external clock signal, and delaying the internal clock signal different amounts based on a selection value indicative of external clock frequency to provide the clock signal.

Abstract: An apparatus and method for generating a delayed clock signal is provided. The clock signal generator includes a synchronizing circuit for generating an output clock signal from an input clock signal and further includes a delay circuit having an input coupled to the output of the synchronizing circuit. The delay circuit provides an output clock signal having a delay with respect to the clock signal from the synchronizing circuit according to one of a plurality of programmable time delays selected in accordance with a selection signal. The method of generating a clock signal includes synchronizing an internal clock signal to an external clock signal, and delaying the internal clock signal different amounts based on a selection value indicative of external clock frequency to provide the clock signal.

Abstract: A high-speed video serializer has an X bit parallel input bus and a Y bit parallel output bus, where X and Y are multiples of one another (e.g., 2). A multiplexer is connected between the input bus and the output bus and is operated such that a frequency of the signals on the output bus is a multiple of the frequency of the signals on the input bus. A circuit provides a clock signal substantially in sync with the signals on the output bus. A high speed video deserializer is also disclosed as are methods of operating the serializer and deserializer.

Abstract: The tracking of the phase of a received signal having a known preamble is accomplished by the steps of: initializing a phase-locked loop in accordance with estimated phase parameters, which are generated during an estimation interval by processing samples of the known preamble; delaying the preamble; generating phase error parameters by processing samples of the delayed preamble; and training the phase locked loop by tracking the phase-tracked signal in accordance with the tracking error parameters during a training interval after the estimation interval. The timing of the sampling is likewise trained in a closed timing loop in accordance with timing error parameters generated during the training interval after the timing loop has been initialized by estimated timing parameters generated during the estimation interval. The duration of the delay of the preamble is one-half the duration of the estimation interval.

Abstract: A non-volatile semiconductor memory device, comprising: an interface for receiving commands issued by a controller, the commands including an erase command; a functional entity with circuit components and having a terminal; a node; switchable circuitry capable of controllably switching between a first operational state in which the terminal is electrically connected to the node and a second operational state in which the terminal is electrically decoupled from the node, the node being configured to have a signal for the functional entity communicated through it when the switchable circuitry is in the first operational state; and a command processing unit configured to recognize the commands issued by the controller and, in response to recognizing the erase command, to cause the switchable circuitry to switch from the first operational state to the second operational state.

Abstract: Receiver architectures and related bias circuits for a data processor are provided. One embodiment of a receiver architecture includes a linear receiver portion having a first input node for a data (DQ) signal, a second input node for a reference voltage, and output nodes for a differential output signal. The linear receiver portion is configured to compare the DQ signal to the reference voltage, and to generate the differential output signal in response to the comparison. A sense amplifier portion is coupled to the linear receiver portion. The sense amplifier portion has input nodes connected to the output nodes of the linear receiver portion, and an output node for a binary output signal having voltage characteristics compatible with the computer processor. The sense amplifier portion is configured to transform the differential output signal into the binary output signal.

Abstract: Embodiments for positioning transitions in one or more data signals in relation to a data strobe signal are disclosed. For an example embodiment, a receiving device may return a test value to a transmitting device. Timing for one or more data signals may be adjusted in relation to a clock signal according, at least in part, to the test value returned from a receiving device.

Abstract: A data transmission error reduction circuit is formed including a delay circuit, a detection circuit and a control circuit. In one embodiment, the delay circuit includes n delay element and multiplexor pairs, selectively employable to apply an aggregate amount of time delay to a data signal. The detection circuit includes circuit elements to detect a critical reference time distance between a reference point of a data signal and at least a selected edge of a clock signal being smaller than a desired threshold. The control circuit includes circuit elements to dynamically control the aggregate amount of time delay applied by the delay circuit based at least in part on the detection of the detection circuit. In one application, m units of the data transmission error reduction circuit are correspondingly employed to reduce data transmission errors on m high speed parallel data signals of a data interface.

Abstract: A system and method of deterministically transferring data across a first clock domain to a second clock domain includes receiving a resynchronize command, initiating a corresponding one of a plurality of read delays in each one of a second plurality of devices in the second clock domain, counting down the plurality of read delays to zero, receiving a training pattern after the plurality of read delays count down to zero in each one of the second plurality of devices, recovering a clock data in each of the second plurality of devices, receiving a synch byte by each of the second plurality of devices, selecting one of a plurality of serial lanes as a reference lane, wherein the plurality of serial lanes couple the first clock domain to the second clock domain, initiating a write pointer, writing n bytes of serial data to a buffer and converting the n bytes of data from serial data to parallel data in a serial to parallel converter such that the serial n byte data in the buffer are aligned in time.

Abstract: A method of calibrating read operations in a memory system is disclosed. The method involves placing a memory controller in a calibration mode, and performing a series of dummy read operations. Each of the read operations performs a read of pre-specified data stored in at least one memory component while using different ones of delayed enable signals. Data read from respective dummy read operations is compared to identify successful read operations while the timing information from successful read operations is compared to identify a suitable delayed enable signal.

Abstract: The invention relates to a method for synchronizing clock pulse devices. According to this method, an emission unit emits at least one narrow-band distant signal; clock pulse devices of receiving units are pre-synchronized by coupling the same to the source of one such distant signal; the emission unit emits a wide-band measured signal after a defined waiting time, and the receiving units receive said signal; and the receiving units correlate the wide-band measuring signal with a homogeneously modulated comparison signal, the receiving time of the wide-band measuring signal and the deviation in the synchronization of the clock pulse devices being determined and compensated on the basis of the correlation result.

Abstract: The present invention is directed to circuitry for detecting and protecting against over-clocking attacks on hardware modules. The circuitry preferably comprises a test signal, a delay path for providing a delayed signal of the test signal, and circuitry for comparing the logical state of the test signal and the delayed signal and issuing an attack indication whenever the signals are different.

Abstract: Circuits, methods, and apparatus for deskewing rising and falling edges of a clock signal. One embodiment of the present invention utilizes a delay element in a data path to adjust a data signal such that a clock signal is centered relative to the data. A further embodiment of the present invention recovers a double-data rate signal using two flip-flops, one clocked by clock rising edges, the other clocked by clock falling edges. An additional delay element is inserted in front of one or both flip-flop clock inputs. If two additional delay elements are used, they are independently adjustable such that each edge can be independently adjusted for improved data recovery.

Abstract: A semiconductor integrated circuit, including a data input unit for receiving an input data signal to be supplied to an external data input terminal, a storage unit for storing the input data signal received by the data input unit, a timing generating unit for generating a timing signal in response to an output request signal, a data output unit for outputting, in synchronization with the timing signal, the input data signal stored in the storage unit as an output data signal, a test output control unit for outputting, in synchronization with the timing signal, and a data selector for outputting the output data signal supplied from the data output unit to the external data output terminal in a normal operation mode and outputting the input data signal supplied from the test output control unit to the external data output terminal in a test mode.

Abstract: A circuit comprising: clock circuitry for supplying a first faster clock signal to a first circuit portion and a second slower clock signal to a second circuit portion, and varying the relative frequency of the first and second clock signals. Synchronisation logic generates pulses which indicate when to transfer data between the first and second circuit portions. The clock circuitry generates a first control signal at a predetermined time in each cycle of the first clock signal prior to a predetermined edge, and a second control signal at a predetermined time in each cycle of the second clock signal prior to a predetermined edge. A change in the relative frequency is conditional on a coincidence of the first and second control signals. The synchronisation generates the pulses such that there is at least one cycle of the first clock signal between those pulses, and such that there is only one of those pulses per cycle of the second clock signal.

Abstract: A protocol conversion circuit performing a protocol conversion between a preceding stage circuit and a succeeding stage circuit includes a data storing unit storing input data from the preceding stage circuit, an output enable signal generating unit generating an output enable signal outputting data stored in the data storing unit to the succeeding stage circuit by using one or more parameters for the protocol conversion which are externally fed and can take a different value each time interval externally specified, and an address specifying unit specifying an address for read of an output data for the data storing unit based on the output enable signal.

Abstract: To synchronize units of a formation evaluation/drilling operation evaluation system, a time delay associated with a communications link between a master unit and a slave unit of the formation evaluation/drilling operation evaluation system is determined. The master unit has a master time clock that provides universal time. The time delay associated with the communications link is used to enable synchronization of time provided by a slave time clock in the slave unit to the universal time.

Abstract: Techniques for organizing and displaying timing data derived from an EDA tool are provided that allows users to easily extract, analyze, and manipulate portions of the timing data relevant to particular user requirements. Relevant portions of signal waveforms are displayed on an interactive graphical user interface (GUI). Time points on the waveforms are marked with pointers so that users can easily visualize the relationships between different signals. A user can also extract relevant timing data from the EDA tool by manipulating the GUI. Manipulating and understanding circuit design requirements affects all of the design cycle and the quality of the final result from an EDA tool. A user can visualize all aspects of timing analysis on the GUI, such as clock skew, and the setup/hold relationship. A data entry approach is provided that can be used for natural and intuitive manipulation of various timing relationships.

Abstract: In a method and apparatus for synchronizing the receiver and the emitter in an autocompensating quantum cryptography system it is allowed to one of the stations (for example the emitter) to define the timing of all its operations (for example the application of a signal onto the modulator used to encode the values of the bits) as a function of a time reference. This time reference can either be transmitted using a channel from the other station (for example the receiver). It can also consist of a time reference synchronized with that of the other station through using information transmitted along a channel and a synchronization unit. Preferably a time reference unit is provided at each station. One of these time reference units functions as a master, while the other one function as a slave. The slave is synchronized with the master using information transmitted over a communication channel by a synchronization unit.

Abstract: A method for balancing clock trees in a multi-voltage synchronous digital environment is provided that includes generating a first source clock signal in a first voltage domain based on a first mirrored clock signal in a second voltage domain. Similarly, a second source clock signal is generated in the second voltage domain based on a second mirrored clock signal in the first voltage domain.

Abstract: A spread spectrum clock generator includes a non-volatile memory to store control codes corresponding to a predetermined delay. A delay circuit receives a control code having a predetermined number of bits that determine a delay to apply to a fixed clock signal a period of time. The delay mitigates the electromagnetic interference caused by a periodic clock signal.

Abstract: A component of a computing device such as a processor is operated based on a clock signal oscillating at a frequency. Power management for the computing device is performed by adjusting the frequency of the clock signal applied to the component when warranted and also by idling the component when the component experiences a period of inactivity longer than an idle detection metric scaled according to the adjusted frequency.

Abstract: A semiconductor integrated circuit comprises: a first area, formed on a semiconductor chip, which operates at a first predetermined voltage and a first predetermined frequency; a second area, formed on the semiconductor chip, which operates at a second voltage and a second frequency lower than the first voltage and the first frequency, respectively, and also operates after a shift to the first voltage and the first frequency; and a third area, formed on the semiconductor chip, which operates at the first voltage and a frequency which operates the second area and transmits and receives signals sent between the first area and the second area; the third area possessing a delay analysis endpoint that can analyze each of a first delay occurring between the first area and the third area and a second delay occurring between the second area and the third area.

Abstract: In one embodiment, the present invention includes a method for receiving data from a second device in a first device, forwarding the data from an input/output (I/O) clock domain to a system clock domain of the first device, and providing the data to a functional unit of the first device at a deterministic time. In such manner, the two devices may operate in lockstep fashion. Other embodiments are described and claimed.

Abstract: This invention relates to multiprocessor arrangements with shared non-volatile memory and the design of the access control of this memory, in particular to such memories embedded or integrated into circuits (ICs) as used in mobile phones, PDAs or laptop computers. To reduce power consumption, the processor clock rates are often varied depending on the current performance requirements. Differing clock rates of processors sharing a non-volatile memory leads to relatively long read access times of the latter, since the particular microprocessor fetching the data from the memory is usually halted until the data are available. When dual or multi-port non-volatile memory and multiple asynchronous clocks are used, access times are even longer since clock synchronization between the ports is necessary. The present invention overcomes this problem by providing a plurality of wait timers, preferably one dedicated to each processor, advantageously each being clocked synchronously with its associated processor.

Abstract: A signal generator can control phase relationship between output signals of the channels without stopping clocks provided to the channels to enable the circuit operation fast. First and second channels 20 and 22 have signal generation blocks 10 and 12 that have clock phase shift circuits 26 and 28, memories, parallel to serial converters and DACs respectively. A phase comparator 24 compares data reading clocks from the signal generation blocks 10 and 12 to produce a phase difference signal wherein the data reading clocks are used to read waveform data from the memories within the signal generation blocks 10 and 12. A CPU controls the clock phase shift circuits 26 and 28 according to the phase difference signal to shift phases of the clocks provided to the signal generation blocks 10 and 12 and then makes phase relationship between the output signals of the first and second channels 20 and 22 as desired.

Abstract: A method and apparatus is provided for transmitting multi-bit data across asynchronous time domains. In one embodiment, the apparatus includes a first delay circuit to generate a selector signal based upon an input reference signal of a first time domain, a second delay circuit to generate a delayed data signal based upon an input data signal, and selection logic coupled to the first and second delay circuits to select one of the data signal and the delayed data signal based upon the state of the selector signal in accordance with an input clock signal of a second time domain, such that at any given sampling point of the input clock signal, the selector signal indicates valid data.