Patent application number | Description | Published |
20080225734 | METHOD AND APPARATUS FOR DATA RATE DETECTION USING A DATA EYE MONITOR - Methods and apparatus are provided for data rate detection using a data eye monitor. The data rate is one of a plurality of data rates comprising a base rate and one or more divide-by-N multiples of the base rate, where N is an integer. The data rate of a received signal is detected by sampling the received signal; comparing the samples for a plurality of full rate data eyes associated with the received signal to determine if there is a mismatch between at least two predefined samples; and detecting the data rate by evaluating the comparison based on predefined criteria. The comparison can be performed by an exclusive or (XOR) logic gate for samples of at least two adjacent data eyes of a given rate. | 09-18-2008 |
20090086807 | METHODS AND APPARATUS FOR DETERMINING THRESHOLD OF ONE OR MORE DFE TRANSITION LATCHES BASED ON INCOMING DATA EYE - Methods and apparatus are provided for determining the threshold position of one or mote DFE latches using an evaluation of the incoming data eye. A threshold position is determined for one or more transition latches employed by a decision-feedback equalizer by obtaining a plurality of samples of a data eye using a data eye monitor; obtaining a vertical eye opening metric from the data eye monitor; and determining the threshold position for the one or more transition latches based on the vertical eye opening metric. A decision-feedback equalizer is also disclosed that comprises at least one data latch having a data threshold; and at least one transition latching having a transition threshold, wherein the transition threshold and the data threshold ate unequal | 04-02-2009 |
20090097538 | Methods And Apparatus For Adaptive Equalization Using Pattern Detection Methods - Methods and apparatus are provided for adaptive equalization using pattern detection methods. A signal is equalized by detecting one or more predefined patterns in the signal; and then changing one or more parameters of the equalization, such as an equalization adaptation rate, based on the detected predefined patterns. The equalization adaptation rate can be increased upon the detection of one or more predefined patterns and then gradually reduced to a steady state value. Equalization parameters that have been previously obtained for various patterns can optionally be loaded upon detection of a corresponding pattern The equalization can optionally be suppressed for one or more predefined patterns. The patterns can be detected, for example, by searching for the one or more predefined patterns in the signal, or by performing a statistical correlation of the signal to detect the one or more predefined patterns. | 04-16-2009 |
20090097541 | Methods And Apparatus For Determining Receiver Filter Coefficients For A Plurality Of Phases - Methods and apparatus are provided for determining receiver filter coefficients for a plurality of phases. One or more coefficients for a receiver filter are determined by determining a first coefficient for a first phase of a data eye; and determining a second coefficient for a second phase of the data eye. The receiver filter may be, for example, a decision-feedback equalizer. The first and second coefficients may be determined by performing an LMS adaptation of decision-feedback equalization coefficients. In another embodiment, the first and second coefficients may be determined by obtaining eye opening metrics from a data eye monitor corresponding to each of the respective first phase and the second phase; and determining the respective first and second coefficients based on the eye opening metrics. The first and second phases can correspond to odd and even phases. | 04-16-2009 |
20090110045 | METHOD AND APPARATUS FOR RATE-DEPENDENT EQUALIZATION - Methods and apparatus are provided fox equalizing a received signal. A received signal is equalized by determining a data rate of the received signal; obtaining one or more equalization parameters associated with the determined data rate; and equalizing the received signal using the obtained one or more equalization parameters. The equalization parameters may comprise, for example, one or more of a gain parameter, zero control for a high pass filter and one or more threshold settings for one or more latches used during the equalizing step, such as data latches or transition latches (or both). | 04-30-2009 |
20090110046 | METHOD AND APPARATUS FOR EQUALIZATION USING ONE OR MORE QUALIFIERS - Methods and apparatus are provided for equalizing a received signal. A received signal is equalized by updating one or more equalization parameters; and discarding the updated equalization parameters if one or more predefined qualifier conditions are detected during the equalizing step. The received signal can optionally be equalized using the updated equalization parameters if the predefined qualifier conditions are not detected during the equalizing step. The updated equalization parameters can optionally be stored if the one or more predefined qualifier conditions are not detected during the equalizing step | 04-30-2009 |
20090161747 | NOISE PREDICTION-BASED SIGNAL DETECTION AND CROSS-TALK MITIGATION - In an exemplary embodiment, noise prediction-based data detection is described with respect to a SERDES (serializer/deserializer) backplane primary channel subject to inter-symbol interference (ISI) noise and added cross-talk noise from other channels. Noise prediction-based data detection combines an added error component from inter-symbol interference (ISI) noise and an added error component from cross-talk noise into an overall noise prediction error term and cancels effects of residual ISI and cross-talk for various components of the exemplary embodiment. | 06-25-2009 |
20090167379 | Method and Apparatus for Digital VCDL Startup - Methods and apparatus are provided fox improved startup of a voltage controlled delay loop that has an injection clock and a return clock. A control signal is determined for a plurality of delay elements in a voltage controlled delay loop by obtaining a histogram count of a number of occurrences of at least one predefined logic value for a plurality of delay settings of the voltage controlled delay loop; determining a histogram count that approximately corresponds to an alignment of at least one edge in the injection and return clocks; and determining the control signal based on the determined histogram count that approximately corresponds to the alignment. The control signal can be, for example, a delay control current or a delay control voltage. The voltage controlled delay loop can be started using the determined control signal. The histogram count can be obtained for a plurality of PVT combinations and the control signal can then be determined for each PVT combination. The determined control signal can optionally be stored in a table for each of the plurality of PVT combinations | 07-02-2009 |
20090168862 | Methods and Apparatus for Detecting and Decoding Adaptive Equalization Training Frames - Methods and apparatus are provided for detecting and decoding adaptive equalization training frames (having a frame marker comprised of a string of binary ones and binary zeroes). Training frames are detected by shifting the received data; inserting at least one binary value at one end of the shifted received data to generate a modified version of the received data; applying a logic function to the received data and the modified version of the received data that identifies when corresponding bit positions have different values; and detecting the frame marker when an output of the logic function has a first binary value in an approximate middle of a string of a second binary value. The training frames are decoded using a distance between the approximate center of the frame maker and a predefined binary value in an output of the logic function. | 07-02-2009 |
20090168936 | Methods and Apparatus for Detecting a Loss of Lock Condition in a Clock and Data Recovery System - Methods and apparatus are provided for detecting a loss of lock condition in a clock and data recovery system. A loss of lock condition is detected in a clock and data recovery system that generates a recovered clock signal from a received signal by sampling the received signal for a plurality of different phases using one or more latches clocked by the recovered clock; evaluating the samples to monitor a data eye associated with the received signal; and detecting the loss of lock condition if the data eye does not satisfy one or more predefined conditions. Generally, the predefined conditions identify a loss of the data eye (e.g, when the data eye cannot be substantially detected), for example, based on a degree of opening of the data eye. The clock and data recovery system can optionally be restarted if the loss of lock condition is detected. | 07-02-2009 |
20090168940 | Methods and Apparatus for Improved Jitter Tolerance in an SFP Limit Amplified Signal - Methods and apparatus are provided for improving the jitter tolerance in an SFP limit amplified signal. Jitter tolerance is improved in a communications receiver by applying a received signal to an SFP limiting amplifier; and applying an output of the SFP limiting amplifier to a low pass filter to improve the jitter tolerance. The low pass filter optionally applies a programmable amount of attenuation to high frequency components of the output. The low pass filter slew rate controls (i.e., rotates) a data eye representation of the received signal to increase the data eye representation along a time axis. The noise margin of the received signal can optionally be improved by applying an output of the low pass filter to an all pass filter. A slew rate controller can evaluate the data eye statistics to determine a setting for the low pass filter. | 07-02-2009 |
20090219978 | Methods And Apparatus For Adaptive Link Partner Transmitter Equalization - Methods and apparatus are provided for adaptive link partner transmitter equalization. According to one aspect of the invention, a local transceiver adapts one ox more equalization parameters of a link partner by receiving a training frame over a channel between the link partner and the local transceiver, wherein the training frame is comprised of a predefined training pattern; adjusting one or more of the equalization parameters of the link partner; and determining whether the equalization of the channel satisfies one or more predefined criteria based on whether the predefined training pattern is properly received by the local transceiver The predefined training pattern can be a pseudo random pattern, such as a PN | 09-03-2009 |
20100054383 | METHODS AND APPARATUS FOR GENERATING EARLY OR LATE SAMPLING CLOCKS FOR CDR DATA RECOVERY - Methods and apparatus are provided for a clock phase generator for CDR data sampling that generates early and/or late sampling clocks, relative to ideal transition and sample points. An early sampling clock is generated by generating a plurality of transition and data sampling clock signals having a substantially uniform phase separation; and delaying at least one of the transition clock signals to generate one or more early clock signals. A late sampling clock is generated by generating a plurality of transition and data sampling clock signals having a substantially uniform phase separation; and delaying at least one of the data sampling clock signals to generate one or more late clock signals. The early clock signals can be employed, for example, in a threshold-based decision feedback equalizer. The late clock signals can be employed, for example, in a classical decision feedback equalizer. | 03-04-2010 |
20100125672 | PERSONAL BROADCAST AND CONTENT DELIVERY ENGINE - A communication system that enables a specified end-user device to obtain a media file corresponding to a delayed-play entry of a content-definition table prior to the scheduled play time. To deliver the media file to the end user, a service provider requests and receives the corresponding content from a content provider, generates the media file based on the received content, and temporarily stores the media file in a storage unit associated with the service provider. The service provider then breaks the media file into a plurality of data frames and transmits them to the end-user device during an appropriate delivery-opportunity window for storage in local storage unit (e.g., a hard drive) associated with the end-user device. At the play time, the service provider transmits to the end-user device a media-activation packet to initiate rendering thereat a copy of the media file assembled from the data frames stored in the local storage unit. | 05-20-2010 |
20100128828 | METHODS AND APPARATUS FOR ADAPTING ONE OR MORE EQUALIZATION PARAMETERS BY REDUCING GROUP DELAY SPREAD - Methods and apparatus are provided for adapting one or more equalization parameters in a communications system by reducing group delay spread. According to one aspect of the invention, one or more equalization parameters in a communications system are adapted by detecting one or more predefined run length patterns in a received signal, such as a plurality of consecutive same-valued bits; evaluating a transition latch value for each of the detected predefined run length patterns, wherein the transition latch value provides an indication of whether the received signal is under-equalized or over-equalized; and adjusting the one or more equalization parameters of the communications system based on the evaluation of the transition latch value. The adjusted equalization parameters may be employed to equalize intersymbol interference. A data eye monitor can be employed to evaluate the transition latch value. | 05-27-2010 |
20100176856 | METHOD AND APPARATUS FOR DETECTING AND ADJUSTING CHARACTERISTICS OF A SIGNAL - Disclosed is a circuit that adjusts a characteristic of a signal transmitted from a transmitter to a receiver over a communication channel (e.g., a wire, a backplane, etc.). The circuit includes a latch that receives the signal at a predetermined point in the circuit and samples a voltage of the signal many times after a threshold voltage is applied to the latch. The circuit also includes a processor that determines the characteristic of the signal when the sampled voltages indicate a transition point and that adjusts the threshold voltage when the sampled voltages do not indicate a transition point. The processor adjusts the characteristic of the signal by adjusting at least one of a current and a voltage of the transmitter when the characteristic of the signal is outside a predetermined range. | 07-15-2010 |
20100237915 | METHOD AND APPARATUS FOR DIGITAL VCDL STARTUP - Methods and apparatus are provided for improved startup of a voltage controlled delay loop that has an injection clock and a return clock. A control signal is determined for a plurality of delay elements in a voltage controlled delay loop by obtaining a histogram count of a number of occurrences of at least one predefined logic value for a plurality of delay settings of the voltage controlled delay loop; determining a histogram count that approximately corresponds to an alignment of at least one edge in the injection and return clocks; and determining the control signal based on the determined histogram count that approximately corresponds to the alignment. The voltage controlled delay loop can be started using the deter wined control signal. The histogram count can be obtained for a plurality of PVT combinations and the control signal can then be determined for each PVT combination. | 09-23-2010 |
20100289476 | METHOD AND APPARATUS FOR REGULATING A POWER SUPPLY OF AN INTEGRATED CIRCUIT - Disclosed is a circuit for adjusting a voltage supplied to an IC by a power supply circuit that produces a regulated-output voltage based on an output-control signal generated by a resistive voltage divider. The circuit includes a PVT detector configured to generate an interface control signal and an interface circuit (i) connected to PVT detector and to the resistive voltage divider and (ii) configured to adjust its resistance in response to the interface control signal. Adjusting the resistance of the interface circuit causes the voltage of the output-control signal to be adjusted, thus causing the power supply circuit to adjust the regulated output voltage. | 11-18-2010 |
20100329324 | METHODS AND APPARATUS FOR QUALIFICATION OF UPDATE OF CLOCK RECOVERY AND EQUALIZATION - Methods and apparatus are provided for CDR and equalization update qualification. A block of received data comprising a plurality of multiple tone patterns is processed. Equalization adaptation and/or updates to a timing recovery process can be selectively disabled if one or more of the multiple tone patterns exceed a corresponding predefined threshold. | 12-30-2010 |
20110296215 | Methods and Apparatus for Low Power Out-of-Band Communications - A signal generator circuit for reducing power consumption of message communications between a first device including the signal generator circuit and a second device coupled to the first device comprises a switching circuit and a controller coupled to the switching circuit. The controller is operative to receive a reference clock signal, to receive at least a first control signal indicative of a request for the first device to send a message to the second device when the first device is in a first mode of operation, and to generate an output control signal and an output data signal. The output control signal is operative as a function of the first control signal to selectively power up the switching circuit and a transmitter driver during the first mode. The output data signal includes the message supplied to the transmitter driver, via the switching circuit, for transmission to the second device during the first mode. | 12-01-2011 |
20120068762 | Method and Apparatus for Regulating a Power Supply of an Integrated Circuit - Disclosed is a circuit for adjusting a voltage supplied to an IC by a power supply circuit that produces a regulated-output voltage based on an output-control signal generated by a resistive voltage divider. The circuit includes a PVT detector configured to generate an interface control signal and an interface circuit (i) connected to PVT detector and to the resistive voltage divider and (ii) configured to adjust its resistance in response to the interface control signal. Adjusting the resistance of the interface circuit causes the voltage of the output-control signal to be adjusted, thus causing the power supply circuit to adjust the regulated output voltage. | 03-22-2012 |
20120170695 | Methods And Apparatus For Automatic Gain Control Using Samples Taken At Desired Sampling Phase And Target Voltage Level - Methods and apparatus are provided for automatic gain control in a receiver using samples taken at a desired sampling phase and target voltage level. The gain of a received signal is adjusted by obtaining a plurality of samples of the received signal substantially at a desired sampling phase (such as a center of a given unit interval), wherein at least one of the samples is taken substantially at a target voltage level; comparing the plurality of samples to determine whether the received signal has an amplitude that is substantially equal to the target voltage level; and adjusting a receiver gain based on whether the received signal amplitude is substantially equal to the target voltage level. The comparison can comprise the evaluation of a logic function, such as an exclusive OR function. The comparison can be performed over a plurality of samples to obtain an average gain update decision. The receiver gain can be adjusted based on a histogram of the average gain update decision, relative to a predefined threshold. | 07-05-2012 |
20120173914 | Methods and Apparatus for Trimming of CDR Clock Buffer Using Histogram of Clock-Like Data Pattern - Methods and apparatus are provided for trimming of one or more CDR clock buffers using a histogram of clock-like data patterns. One or more clock buffers in a clock and data recovery system are trimmed by receiving a first transmitted clock-like data pattern in a reduced rate mode, wherein the first transmitted clock-like data pattern is transmitted using a first rate mode and wherein the reduced rate mode divides the first rate mode by an integer value that is greater than one; locking the clock and data recovery system using the received version of the first transmitted clock-like data pattern in the reduced rate mode; receiving a second transmitted clock-like data pattern, wherein the second transmitted clock-like data pattern has a run-length that is an integer division of a run-length of the first transmitted clock-like data pattern, wherein the integer division is greater than one; and adjusting a phase of the one or more clock buffers using the second transmitted clock-like data pattern. The first and second transmitted clock-like data patterns can be transmitted by a local transmitter in a loopback mode. Generally, the received version of the first transmitted clock-like data pattern has edges that correspond to only positive or negative edges of the first transmitted clock-like data pattern. | 07-05-2012 |
20130156086 | METHODS AND APPARATUS FOR DETECTING AND DECODING ADAPTIVE EQUALIZATION TRAINING FRAMES - Methods and apparatus are provided for detecting and decoding adaptive equalization training frames (having a frame marker comprised of a string of binary ones and binary zeroes). Training frames are detected by shifting the received data; inserting at least one binary value at one end of the shifted received data to generate a modified version of the received data; applying a logic function to the received data and the modified version of the received data that identifies when corresponding bit positions have different values; and detecting the frame marker when an output of the logic function has a first binary value in an approximate middle of a string of a second binary value. The training frames are decoded using a distance between the approximate center of the frame marker and a predefined binary value in an output of the logic function. | 06-20-2013 |
20140023131 | METHODS AND APPARATUS FOR ADAPTING TRANSMITTER EQUALIZATION COEFFICIENTS BASED ON RECEIVER GAIN ADAPTATION - Methods and apparatus are provided for adapting transmitter equalization coefficients based on receiver gain adaptation. Equalization coefficients of a transmitter that communicates over a channel with a receiver are adapted by determining if a gain value for an amplifier in the receiver is within a limit of the amplifier; and preventing one or more adjustments to the transmitter equalization coefficients if the gain value does not satisfy the upper or lower limit of the amplifier. The gain adjustments comprise, for example, up and down requests for the transmitter equalization coefficients. One or more enable flags can optionally be set based on whether the gain value is within the limit of the amplifier. | 01-23-2014 |
20140132320 | LOSS OF LOCK DETECTOR FOR CLOCK AND DATA RECOVERY SYSTEM - An apparatus comprises a clock and data recovery system, and a loss of lock detector at least partially incorporated within or otherwise associated with the clock and data recovery system. The loss of lock detector is configured to generate a loss of lock signal responsive to phase adjustment requests generated for a clock signal in the clock and data recovery system. By way of example, the loss of lock signal may have a first logic level indicative of the phase adjustment requests occurring at a first rate associated with a lock condition and a second logic level indicative of the phase adjustment requests occurring at a second rate lower than the first rate. Absolute values of respective phase increments each associated with multiple up and down phase requests may be accumulated, and the loss of lock signal generated as a function of the accumulated phase increment absolute values. | 05-15-2014 |
20140211839 | Receiver Having Limiter-Enhanced Data Eye Openings - A communication system having a receiver with a linear path and a nonlinear path. As the receiver receives a data signal, it adaptively equalizes the received signal, and amplitude-limits the equalized signal in the nonlinear path using a saturable amplifier limiter or the like. A slicer extracts data from the limited equalized received signal. In the linear path, a clock recovery circuit generates a clock signal from the equalized received signal. A delay circuit in the linear path at least partially compensates for propagation delay in the limiter. Having the clock recovery occur in other than the nonlinear path, a low jitter clock is generated. The limiter enhances the vertical opening of the data eye by increasing the rise and fall times of the limited signal, providing more noise margin for the slicer to operate with and a greater timing margin in which to sample the sliced data. | 07-31-2014 |