Abstract: The invention provides a novel scheme to align data streams across multiple transmission channels and match multiple transmissions with one receiving rate. The channel aligning aspect of this invention detects the occurrence of an aligning character in a plurality of input channel character streams, buffers the character stream until an aligning character has been detected on every input channel. The channel aligning system transmits filler characters over every output channel corresponding to an input channel where an aligning character has been received if an aligning character has not been detected on every input channel. The aligning system then synchronously transmits the buffered characters, starting with the aligning character and proceeding with the subsequently received characters. The rate matching aspect of this invention receives a plurality of character streams synchronized by a first clock and buffers the character streams.

Abstract: A signal routing apparatus comprises a register bank to store a set of data signals. A delay locked loop generates a set of phase displaced clock signals. A phase controlled read circuit sequentially routes the set of data signals from the register bank in response to the phase displaced clock signals. A Low Voltage Differential Signaling buffer connected to the phase controlled read circuit transmits the data signals in a Low Voltage Differential Signaling mode. The phase displaced clock signals operate in lieu of a higher clock rate in order to reduce power consumption.

Abstract: A sampling frequency conversion apparatus which easily controls the phase difference (time difference) between the input data and the output data in converting the sampling frequency, includes a storage device 13 for continuously writing the input data or the data obtained by over-sampling the input data and for continuously reading out the data written maintaining a predetermined address difference relative to the writable address, and an interpolation processing unit 14 for interpolating the data read-out from the storage device 13 to obtain data of which the sampling frequency is converted. In converting the sampling frequency, an address difference between a writable address and a readable address in the storage device 13 is optimized, the address difference being optimized without limitation for a predetermined period of time from the start of supplying the input data and, then, being optimized by imposing a predetermined limitation after the passage of the predetermined period of time.

Abstract: A method and apparatus for analyzing and monitoring packet streams in “real time”. The packet analyzer comprises an input buffer, a real-time analysis unit, a non-real-time analysis unit, a graphics unit, a monitor and a flushing circuit. A packet stream is received into the input buffer where the data is either read by the real-time analysis unit or flushed by the flushing circuit. Messages are passed between the real-time analysis unit and the non-real-time analysis unit to report on detected errors or to update packet stream information. In turn, real time packet stream information are displayed and updated on a display via the graphic unit. A method of detecting framing errors in a packet stream is incorporated by setting a 9th bit in the input buffer for each byte of data in a packet.

Abstract: A reception interface unit in a transmission system wherein time series data is divided into data groups and a data packet with reproduction specification time data specifying a time at which each data piece in the data groups should be reproduced, added to the data groups is transmitted on a transmission bus in a time division manner.

Abstract: A circuit and method for distributing events in an event stream. A circuit for distributing events in a signal into a plurality of channels of circuitry capable of timestamping events is described. The circuit includes a first plurality of flip-flops arranged in a cascading configuration. The cascading configuration distributes a primary event stream into a first plurality of secondary event streams on each successive rising edge of the primary event stream. The circuit also includes a second plurality of flip-flops arranged in another cascading configuration for distributing the primary event stream. The primary event stream is distributed into a second plurality of secondary event streams on each successive falling edge of said primary event stream.

Abstract: A system for reliably receiving data includes a memory, write logic, and read logic. The write logic receives data and an unreliable clock signal and writes the data to the memory using the unreliable clock signal. The read logic generates a gapped clock signal and reads the data from the memory using the gapped clock signal. The read logic generates the gapped clock signal by turning on and off a constant local clock signal.

Abstract: Data transfer control circuitry includes a receive buffer for sequentially receiving received data, which are provided from a local processor together with a write control signal to store the data therein, and sequentially developing the stored data in response to a read control signal, which is provided from a host in the same order as stored. A transmit buffer sequentially receives data to be transmitted, which are provided from the host together with another write control signal, and sequentially develops the stored data in response to another read control signal provided from the local processor in the same order as stored. A counter increments a count in response to a clock signal and resets itself in response to either of the write control signals. A clock control circuit interrupts the clock signal when the count reaches a preset value.

Abstract: An apparatus for reducing the effects of pointer adjustments, wander, and jitter during desynchronization of a non-uniformly gapped data stream from a payload of a synchronized signal is disclosed. The apparatus utilizes a combination of two pointer adjustment signals embedded in the synchronized signal to determine a bit leak rate of bits from an elastic store following a pointer adjustment event such that the elastic store provides as an output a more-uniformly-distributed-gapped data stream.

Abstract: A digitally controlled circuit for reducing the phase modulation of a signal. The circuit has a multiphase clock generator that produces n phases of a clock that is m-times the signal. The circuit further has a multiplexer with n inputs for the n phases of the clock and with one output which supplies the output signal. The output signal and the signal are connected to the inputs of a phase comparator. The output signal of the comparator is supplied to a sigma-delta modulator whose output signals are used for controlling the multiplexer. A jittered input signal is compared in the phase comparator with a master clock. The determined phase difference is integrated in a sigma-delta modulator. The aim of the circuit is to generate a clock without jitter, digitally and without using external components. This circuit provides 20 dB/decade attenuation of the jitter received in the SYNC signal, based on the P-regulator characteristic.

Abstract: An integrated circuit (12) contains a serializing transmitter, including a phase locked loop (31) that supplies seven clocks (41) with different phases to a serializer circuit (32). The serializer circuit accepts 7-bit words at a parallel input (42), and outputs these words serially in an end-to-end manner on a twisted pair (17), as a clock signal. The serializer circuit also accepts 7-bit words on a further parallel input (43), and transmits them serially in an end-to-end manner on a twisted pair (18), as serialized data. The integrated circuit also includes a built-in self-test circuit (33), which can supply test information to the two parallel inputs of the serializer circuit, and which can monitor the two twisted pairs while the serializer circuit operates at high data rates typical of normal operation, in order to detect any errors introduced by the serializer circuit. The self-test circuit produces a single digital output (48) to indicate whether an error has been detected.

Abstract: An improved data acquisition system interface provides virtually constant sampling of input signals and provides those signals in a digitized format to a data acquisition unit that may not be able to sample at a constant rate without missing or “losing” some of the samples. The present invention acts as a front end interface that temporarily latches the sampled data, expands the data into multiple parallel signals, then stores the multiple parallel signals in a dual-port FIFO memory unit. Finally, the multiple parallel signals are transferred into the data acquisition unit at a lower frequency, and the transfer operations take place only when the data acquisition unit is ready to accept data. Since the front end misses no sampling intervals (i.e., it always takes a sample according to an extremely constant frequency crystal clock), then the data acquisition unit will be provided with all of these samples without losing any data.

Abstract: Methods and apparatus are provided for changing the rate of time-discrete signals. When changing the rate or for the interpolation of time-discrete input values (xn), output values (yk) of an output signal are produced. If the frequency of the output signal is greater than the frequency of the input signal and the shape of the output signal essentially corresponds to the shape of the input signal, the difference between a first and a second input value (xn, xn-1) subsequent to this is determined, interpolation values (PO . . . PN) of an interpolation progression (p) are scaled in dependence on the difference determined and output values (yk) in each case are produced by addition of the first input value (xn) to a scaled interpolation value (PC . . . PN).

Abstract: A symbol timing derivation system derives receiver timing from received symbols which avoids the need for a pilot tone, thereby reducing power consumption and expanding usable bandwidth. The system is implemented by using a calculation that finds the timing phase error. The timing phase error is then averaged and controls a phase locked loop (PLL). This PLL in turn controls a voltage-controlled oscillator, which handles the modem receiver timing. A centroid calculation can be included to bias the voltage-controlled oscillator to push the equalizer coefficients back to the ideal position. The system can be implemented in either a point-to-point modem environment or a multi-point environment, for example, but not limited to, MVL or DMT. The voltage-controlled oscillator may also be implemented to control transmitter timing, so that the central office modem and the remote modem will operate more-or-less synchronously, reducing the need for large equalizer corrections at either end.

Abstract: A system for recovering a clock signal from a data signal is described. The system uses an oscillator adapted to generate an oscillator output signal, a first detecting circuit for obtaining a coarse frequency-lock condition between the data signal and a recovered clock signal, a second detecting circuit for obtaining a phase-locked condition between the data signal and the recovered clock signal, a lock-detecting circuit responsive to the first detecting circuit for detecting an out-of-lock condition between the data signal and the recovered clock signal, and a control circuit responsive to the lock-detecting circuits and adapted to control the oscillator to generate an oscillator output signal on the basis of the first detecting circuit during an out-of-lock condition, and otherwise to generate the oscillator output signal on the basis of the second detecting circuit.

Abstract: For synchronising the data transmission between a CMOS circuit (1) and a bipolar circuit (2) a DLL (delayed lock loop) is provided which sets a phase deviation between the operating clocks (CLK1, CLK2) of the two circuits (1, 2), and changes the phase of at least one of the two clocks (CLK1, CLK2) according to this phase deviation, until said the two clocks are in phase, in such a way that the data (DATA1) provided by the first circuit (1) can then be taken on by the second circuit (2). To this end, the DLL circuit comprises a phase detector (6), a loop filter (7) and an adjustable element (8).

Abstract: An asynchronous transport stream receiver of a digital broadcasting receiving system connected to MPEG-2 (Moving Picture Experts Group-2) equipment, such as a VOD (Video On Demand) server is disclosed. The inventive receiver includes an FIFO section for storing MPEG-2 data generated from DVB-ASI (Digital Video Broadcasting Asynchronous Serial Interface) signals, an oscillator for generating clock signals for producing the MPEG-2 data from the DVB-ASI signals, and a read controller for reading and outputting the MPEG-2 data stored at the FIFO section in synchronization with clock signals of the oscillator. Accordingly, the MPEG-2 data can be processed and outputted regardless of the SD or HD leveled compression condition (bit rate) of the MPEG-2 data transmitted according to the DVB-ASI standard.

Abstract: A receiver for digital data is provided. The receiver comprises a ring buffer operable to store received data. The receiver also comprises a write pointer controller for the buffer, operable to control the writing of received data into the buffer, and a read pointer controller for the buffer, operable to control the reading of data from the buffer. The receiver further comprises a pointer adjustment controller operable, in response to a detection of a special data indicator, to control at least one of the write pointer controller and the read pointer controller using forward looking operable to foresee a data location within the buffer corresponding to a future read location of the buffer.

Abstract: A method and device is described for the numeric control of buffer and phase-locked loop for the recovery of the synchronism and the optimized management over communication networks having a high jitter like, e.g., networks in which the ATM mode (Asynchronous Transfer Mode), is used. The innovation resides in the buffer management which is carried out according to the input phase statistic characteristics (in part known a priori and in part measured by the system) as well as to its measured value (which is equivalent to the buffer filling level) thus introducing the concept of statistic pointers. This allows an optimal management thereof and also permits to control the buffer overflow and underflow probabilities. Moreover, by associating the present device with another phase locked device, it is possible to obtain a high frequency stability of the reconstructed sync signal, attenuating at a large extent the jitter introduced by the network, even at a very low frequency.

Abstract: A signal synchronization mapper for mapping an input data stream characterized by a first frequency (typically a SONET/SDH stream) into an output data stream characterized by a second frequency. A phase lock control loop containing a “delta-sigma” (&Dgr;-&Sgr;) modulator which functions as a voltage controller oscillator synchronizes the data rate of the output stream to that of the input stream in a manner which simplifies attenuation of jitter energy when the output data stream is desynchronized (demapped). The modulator generates an accurate pulse train by duty-cycle dithered modulation of the input stream, which the mapper interprets as stuff/nullide-stuff commands such that the mapping operation is lossless over time (i.e. the number of bits in equals the number of bits out over time) thus allowing utilization of a FIFO buffer without the need to monitor the buffer's depth or its pointers.

Abstract: An asynchronous sample rate estimator and a method for generating a rate estimate to track an asynchronous input sampled signal is disclosed. The present invention achieves lock quickly and maintains an optimum input buffer configuration and enhanced signal fidelity by responding quickly and accurately to changes in the incoming frequency. An asynchronous sample rate estimator receives and determines a measured sample period of an asynchronous input signal. Furthermore, a reciprocal frequency error signal and a current rate estimate signal are used to generate a rate estimate for tracking the read pointer to the write pointer of a FIFO buffer, as well as a phase correction signal for centering the write pointer in the FIFO buffer. An asynchronous sample rate estimator might also include an error gain generator for providing an error gain and a lock detector for indicating whether the system has achieved a locked condition.

Abstract: A filtering method for digital phase lock loop, comprises defining an ideal phase difference value between an input clock and a local recovery clock; calculating a phase difference between the input clock and the local recovery clock by a subtractor; and comparing the phase difference with the ideal phase difference value to adjust the local recovery clock to keep its phase difference stable in the ideal phase difference value. When adjusting the local recovery clock, taking the ideal phase difference value as a center, the phase difference is divided into different segments. For segments where the ideal phase difference value is located, the local recovery clock follows the phase difference with a minimum changing rate; and for segments farther apart from the ideal phase difference value, the local recovery clock follows the phase difference with a faster changing rate.

Abstract: Briefly, in accordance with one embodiment of the invention, a method of using a bypass buffer in a node coupled to a ringlet includes the steps of: writing a packet of binary digital signals on the ringlet into the bypass buffer; and retaining the packet of binary digital signals in the bypass buffer for a predetermined amount of time before transferring the packet to the ringlet. Briefly, in accordance with another embodiment, a node to be coupled to a ringlet includes: a transmit buffer and a receive buffer. The transmit and receive buffers are coupled in a configuration to transfer binary digital signals between the node and the ringlet via the transmit and receive buffers. The configuration further includes a bypass buffer to temporarily queue binary digital signals passing through the node. The bypass buffer is further coupled in the configuration to retain a packet of binary digital signals for a predetermined amount of time before transferring the packet to the ringlet.

Abstract: An apparatus configured to interface a first clock speed of a multiqueue storage device and a second clock speed of an interface. The apparatus may be configured to control a flow of variable size data packets.

Abstract: A novel and useful apparatus for and method of in-band clock compensation for use in synchronous communication systems. The clock compensation mechanism is implemented in each module and is operative to compensate for the differences between the clocks among the various modules in the system. The mechanism operates in band wherein special clock compensation symbols are periodically inserted into the data stream itself. Additional clock sync symbols are added to the data stream depending on the current level of the FIFO queue on the module or card. The insertion (or non-insertion) of additional symbols functions to compensate for the faster (or slower) clock of the module when compared to that of the reference.

Abstract: Systems and methods for converting a digital input data stream from a first sample rate to a second, fixed sample rate using a combination of hardware and software components. In one embodiment, a system includes a rate estimator configured to estimate the sample rate of an input data stream, a phase selection unit configured to select a phase for interpolation of a set of polyphase filter coefficients based on the estimated sample rate, a coefficient interpolator configured to interpolate the filter coefficients based on the selected phase, and a convolution unit configured to convolve the interpolated filter coefficients with samples of the input data stream to produce samples of a re-sampled output data stream. One or more hardware or software components are shared between multiple channels that can process data streams having independently variable sample rates.

Abstract: In the field of optical communications, the need to remove jitter from a Synchronous Digital Hierarchy (SDH) or Synchronous Optical NETwork (SONET) datastream is recognized. Consequently, the present invention provides a First-In-First-Out (FIFO) buffer having a read-out clock frequency that is controlled in response to a depth error of the FIFO buffer. The control of the read-out clock frequency is achieved by a hardware control loop coupled to the FIFO buffer. The period of the control loop is a product of the frequency at which the depth error of the FIFO buffer is acquired and another factor. The another factor is the number of states of logic employed by the control loop raised to an integer power.

Abstract: To synchronize a regularly occurring pulse train to the average of a bunched pulse train, an oscillator generates a plurality of differently phase shifted signals at a given frequency. One of the phase shifted signals is selected as an output signal. The output signal is compared with the bunched pulse train. The selected phase shifted signal is changed responsive to the comparison so the output signal occurs at the average frequency of the bunched pulse train. The oscillator is formed as a plurality of differential amplifier stages having equal controllable delays. The stages are connected together to form a ring oscillator. The output signal is compared with the bunched pulse train through a FIFO. A signal representative of the state of the FIFO is used as an error signal to control the selection of the phase shifted signal to be used as the output signal.

Abstract: Data reception circuit for receiving a serial input data stream, where the data reception circuit has a data stream separation circuit (4) for separating the serial input data stream into a plurality of separate data streams, a reference clock signal generation circuit (13) for generating a reference clock signal, a delay circuit (12) having a delay element chain (27) which comprises a plurality of series-connected delay elements, the first delay element (27-1) in the delay element chain (27) receiving the generated reference clock signal, and each delay element outputting a delayed reference clock signal (11), a first, asynchronously clocked register array (8), each register bank (26) in the first register array (8) being asynchronously clocked by an associated separate data stream and reading in the delayed reference clock signals from the delay circuit (12) in order to buffer-store a signal change in the separate data stream, a second, synchronously clocked register array (17), each register bank (28) in t

Abstract: A system and method of preventing metastability in conjunction with the receipt in a first clock domain of an asynchronous digital signal from a second clock domain when the first domain operates with a first clock frequency, and the second domain operates with a second clock frequency that is known within the first domain. The first domain sends information to the second domain, and includes a reference signal containing phase information known in the first domain. The information is clocked into the second domain utilizing the reference information. The second domain then sends the asynchronous digital signal to the first clock domain. A receiving unit in the first domain determines the phase information from the received signal with a known degree of maximum uncertainty that is less than one period of the reference signal. The first domain then stably reads the received asynchronous digital signal.

Abstract: A synchronization control apparatus and method enables synchronization control which can flexibly accommodate various frequencies using a simple circuit construction. A storage device that has a predetermined capacity, such as a FIFO, stores externally input data. A CPU controls an output frequency at which data stored in the storage device are output, based on an average frequency which is an average of the output frequency and on a coefficient for setting the average frequency at a fixed value, the first frequency controlling device calculating the average of the output frequency whenever a timing signal is input in accordance with a predetermined cycle and determining the coefficient depending on a free capacity of the storage device at a time of inputting of the timing signal.

Abstract: Data is transferred from a transmitter to a data buffer of a receiver according to the clock of the transmitter. When the amount of data in the data buffer exceeds an upper limit, the frequency of the reference clock of the receiver is increased to read the data faster, which is transferred to a digital-to-analog converting and audio amplifying section. When the amount of data falls below the upper limit, data is read at the original frequency of the reference clock of the receiver. When the amount of data falls below a lower limit, the frequency of the reference clock of the receiver is decreased.

Abstract: A data demodulating technique for binary data defined by a pulse code modulated signal. The technique involves digitizing the data signal read by a magnetic head from the stripe of a magnetic card. The time interval between peaks in the digitized signal is determined to provide peak interval values. The peak interval values form the basis for determining the end of a character and also by a pattern matching technique against idealized data form the basis for determining the character itself.

Abstract: The size of a Jitter Absorption Buffer (JAB) is automatically changed in response to changes in network conditions. The JAB size is changed based on the fullness of the JAB and the recent variations in JAB depth. Automatic adjustment allows for a balance of providing adequate correction for Packet Delay Variation (PDV) while avoiding unnecessary increases in Absolute Packet Delay (APD) from the prolonged use of an oversized JAB. This abstract is provided as a tool for those searching for patents, and not as a limitation on the scope of the claims.

Abstract: Systems and methods for enabling data transfers over communications links having a plurality of transmission lanes. In one embodiment, a system comprises a plurality of elastic buffers, each of which is coupled to one of the lanes in the communications link, and a buffer controller coupled to the buffers. Data is clocked into the elastic buffers using a first clock signal and is clocked out of the buffers by a second clock signal. The buffer controller is configured to monitor each of the buffers and to detect impending underflow or overflow conditions. In response to detect in one of these conditions, the buffer controller will cause the words to be added or deleted, respectively, to all of the elastic buffers rather than only the buffer in which the overflow/underflow condition was detected.

Abstract: Data, such as data received by a memory I/O from a memory unit in a DDR SDRAM system, is captured using a trigger signal, which may be a non free-running clock signal such as a DQS signal in a DDR SDRAM system, and is transferred to a host system, which may be part of an ASIC, using the host system's clock. The memory I/O includes a data capture register that latches the data received from the memory unit using DQS. The memory I/O also includes a FIFO buffer that latches the data output by the data capture register using a delayed version of DQS. A single edge of the delayed DQS is available to the FIFO for latching each set of data that corresponds to a single pulse of DQS. The FIFO transfers the data to the host system using the host system's clock, which represents a different clock domain than DQS.

Abstract: A network interface controller connects a processing system to receive data from a network fabric through a serial link. The data on the link is clocked in a link clock domain that is different than the core clock domain of the network interface controller. A physical interface operates in the link clock domain. It has a pipeline architecture partitioned into an input register block, a decoder block and a link synchronization manager. The input register block receives the link clock and the data on the link, and transfers the data into the link clock domain. The decoder block has dual cascaded 8B/10B decoders receiving and decoding the data transferred by the input register block. The link synchronization manager manages the synchronization of the serial link according to the decoded data. An elastic buffer is connected to the output of the link synchronization manager. It is configured to output the decoded data in the core clock domain.

Abstract: To provide a de-interleave circuit used for a BS digital broadcasting receiver. The de-interleave circuit is provided with less memory. An address data generator (3) supplies address data (A) to a de-interleave memory (4) in a de-interleave order. Each main signal is read from an address location in the de-interleave memory (4) specified by address data (A), and a following main signal is interleaved and written in that address location of the memory. As a result, the de-interleave memory (4) only requires space for one superframe.

Abstract: A system and method for synchronizing the skip pattern to two clock domains and initializing the clock skipping buffer which enables data transfers between the two clock domains. In one embodiment, a circuit comprises a pair of alignment detection units, a synchronous reset unit, a skip pattern generator, a counter reset unit and a data transfer buffer. Each of the alignment units is configured to detect the alignment of the clock signal in one of the clock domains with a reference clock signal and generate a signal indicative of the alignment. This signal is conveyed to the synchronous reset unit and the counter reset unit. The alignment signal generated by one alignment unit is also conveyed to the skip pattern generator. The synchronous reset unit accepts the alignment signals from the alignment units and generates concurrent reset signals (i.e., one for each of the two clock domains) to initialize the counter reset unit.

Abstract: In a clock switching circuit, a write address is generated based on a pre-switched clock, and the write address is employed to store input data in memory. Then, a read address is generated based on a post-switched clock, and the read address is employed to read data from memory, so that a clock synchronized with the data is changed. There are multiple pre-switched frequencies, and the frequency of a post-switched clock is higher than the frequency of a pre-switched clock. When the pre-switched clock frequency is lower than the post-switched clock frequency, the read address is updated in accordance with a ratio of the frequency of the pre-switched clock to the frequency of the post-switched clock.

Abstract: An apparatus for resynchronizing data between two modules sharing a common clock where the common clock is delayed at the second module has means for storing multiple copies of the data in the first module in a recirculating manner using a Johnson counter to cycle through storage locations. A multiplexer in the second module has the copies from the first module as inputs and selects in response to a select signal generated from the delayed version of the common clock and an enable signal from the Johnson counter synchronizing each of the copies in turn such that the copy selected has just not been written or is just not about to be written to assure that the data is in a stable state.

Abstract: A clock recovery circuit provides a reference clock signal and a plurality of clock pulses with phases different from the reference clock signal, and has an edge detecting circuit for detecting positions of edges of inputted serial random data. A detected edge selecting circuit selects whether the edges of the inputted serial random data are rising edges or falling edges of the reference clock signal. An edge position correcting circuit assures that the number of the selected edges is equal to the number of the edges of the inputted serial random data. Phase frequency detectors output pulses of a pulse width in proportion to the phase difference between the inputted serial random data and the reference clock signal.

Abstract: An interleaving/deinterleaving processing method, a channel encoding system using it and a computer readable recording media for realizing it is provided.

Abstract: The present invention provides a serial/parallel conversion circuit that has both a serial/parallel conversion function and a buffer function for absorbing clock frequency differences, together with a data transfer control device and electronic equipment. The serial/parallel conversion circuit (elasticity buffer) comprises a data holding register which holds serial data DIN that is input based on a CLK1 clock (480 MHz) in USB 2.0 HS mode; a determination circuit which determines whether or not held data is valid, by unit of a data cell; and a selector which outputs from the data holding register the data of data cells that have been determined to be valid, based on a CLK2 clock (60 MHz) having a frequency lower than that of CLK1. A data cell in which data of the first bit has been determined to be valid is deemed to be valid in the next CLK2 clock cycle.

Abstract: A modem for more efficiently processing a received analog signal into a digital output. The modem preferably estimates the carrier frequency offset in at least one stage, by receiving a synchronization field divided into at least two portions, calculating a difference of the phase between the portions, and then calculating the frequency offset from the phase difference. More preferably, the modem estimates the carrier frequency offset in two stages, with a first stage being a initial frequency estimate of the offset.

Abstract: The present invention provides a highly reliable synchronizer which provides excellent synchronization without using complicated PLL or DLL circuitry, which is simple to test, which is easily adaptable to systems which use bit-sliced data, and which does not require large chip area. The synchronizer is comprised of a first stage, a data capture circuit, preferably comprised of pair of master-slave flip-flops, that is electrically coupled to a second stage, a data selection circuit that preferably includes a FIFO comprised of N transparent latches that are electrically coupled to a multiplexer. The lack of complexity of the synchronizer design makes it smaller, faster, easier to test, and less prone to design error and manufacturing limits.

Abstract: A Universal Serial Bus repeater is provided, comprising a method and apparatus for detecting a specified data pattern and regenerating or retransmitting the recognized data pattern. In some embodiments, the invention recognizes an end of sync signal, and is operable to retransmit the end of sync signal and the following data that is presumed to be valid as a result of sync recognition. In other embodiments, the invention recognizes and retransmits a properly aligned end of packet signal, the size of which is dependent on detection of whether the end of packet signal is a part of a start of frame packet.

Abstract: An adapter that buffers received symbols and automatically determines and corrects for skew between lanes is disclosed herein. In one embodiment, the adapter is a part of a network that includes a first and second devices coupled together by a communications link having multiple independent serial lanes. The first device initiates communication by repeatedly transmitting a training sequence that includes a start symbol for each lane. An adapter in the second device includes a set of buffers each configured to receive the symbols conveyed by a corresponding serial lane. The buffers are coupled to a reconstruction circuit that removes one “symbol group” at a time from the buffers. A symbol group is made up of one symbol from each buffer. The reconstruction circuit removes symbol groups until a start symbol is detected. If the start symbol is not detected in all buffers, output from the buffers having start symbols is temporarily suspended.

Abstract: A source-synchronous data receiver includes a storage device for sequentially storing data received from a data source, a data output device for sequentially outputting the data that is stored in the storage device, and a control for controlling the data output device, so that the data output device makes available particular data previously stored by the data storage device a programmable predetermined number of clock states after data is called for, e.g., a read command to the data source is initiated.

Abstract: To synchronize a regularly occurring pulse train to the average of a bunched pulse train, an oscillator generates a plurality of differently phase shifted signals at a given frequency. One of the phase shifted signals is selected as an output signal. The output signal is compared with the bunched pulse train. The selected phase shifted signal is changed responsive to the comparison so the output signal occurs at the average frequency of the bunched pulse train. The oscillator is formed as a plurality of differential amplifier stages having equal controllable delays. The stages are connected together to form a ring oscillator. The output signal is compared with the bunched pulse train through a FIFO. A signal representative of the state of the FIFO is used as an error signal to control the selection of the phase shifted signal to be used as the output signal.