Xilinx, Inc.

John D Logue

F Erich Goetting

David P Schultz

Vasisht Mantra Vadi

John E McGrath

Anthony J Collins

Andrew K Percey

Austin H Lesea

Joseph H Hassoun

Wei Guang Lu

Alvin Y Ching

Shawn K Morrison

Steven P Young

James M Simkins

Greg W Starr

Robert M Ondris

Nicholas J Sawyer

Paul G Hyland

James J Koning

Andrew R Percey

Method and device for arbitration for time division multiple access using delta-sigma modulation for an integrated circuit are described. A method for arbitrating access to a shared resource among multiple devices includes obtaining a first arbitration factor. The first arbitration factor is first delta-sigma modulated to produce a first slot signal. The first slot signal is for Time Division Multiple Access-arbitrated access to the shared resource.

Arbitration for time division multiple access using delta sigma modulation

In one embodiment, a monitor circuit is disclosed. For example, the monitor circuit includes a first delay line circuit having a plurality of delay taps for receiving data from a data channel, and a second delay line circuit having a plurality of points for sampling the data received from the first delay line circuit, where the plurality of points comprises an input point, a middle point and an output point. The monitor circuit further includes a voltage control circuit for providing a control voltage to the second delay line circuit, and a data compare circuit for comparing a data value of the input point and a data value of the middle point to produce a first out-of-bounds signal, and for comparing the data value of the middle point and a data value of the output point to produce a second out-of-bounds signal.

Method and apparatus for providing a monitor using an auxiliary delay line

An automatic calibration scheme is provided, which calibrates the equivalent taps per period ETT/P every time a delay lock loop is used. More specifically, a digital phase shifter is used to measure equivalent taps per period ETT/P. Alternately, the digital phase shifter is used to directly measure the signal delay through a clock phase shifter of the delay lock loop, thereby directly determining the high frequency and low frequency overhead constants.

Automatic tap delay calibration for precise digital phase shift

Preventing transistor damage to an integrated circuit is described. The circuit includes a switch with a first pair of p-type transistors respectively coupled in source-drain parallel with second pair of p-type transistors for preventing Negative Bias Temperature Instability ('NBTI') damage to the second pair of p-type transistors. The switch is configured to such that when in a state associated with causing, or potentially causing, NBTI damage, both of the second pair of p-type transistors are in an OFF state for preventing NBTI damage thereto.

Preventing transistor damage

Method and apparatus for an interface to a system monitor () is described. A controller () accessible via a port interface thereof () is configured for read/write access to configuration memory cells () and for read access to status registers (). The configuration memory cells () are addressable via a first address space, and the status registers () are addressable via a second address space different from the first address space. The port interface () is configured to receive a plurality of signals including a data address signal () and a data clock signal (). The data address signal () has address information for accessing either the first address space or the second address space.

Reconfiguration port for dynamic reconfiguration-system monitor interface

Method and apparatus for dynamic configuration of function block logic of an integrated circuit is described. The integrated circuit includes a reconfiguration port coupled to a controller. The controller is coupled to an array of memory cell. A portion of the array of memory cells is coupled for read/write communication with the controller, and another portion of the array of memory cells is not coupled for read/write communication with the controller. The portion of the array of memory cells is configurable at an operational frequency of the integrated circuit for dynamic reconfiguration of the function block logic of the integrated circuit.

Reconfiguration port for dynamic reconfiguration

A digital clock manager is provided. The digital clock manager generates an output clock signal that causes a skewed clock signal to be synchronized with a reference clock signal. Furthermore, the digital clock manager generates a frequency adjusted clock signal that is synchronized with the output clock signal during concurrence periods. The digital clock manager includes a delay lock loop and a digital frequency synthesizer. The delay lock loop generates a synchronizing clock signal that is provided to the digital frequency synthesizer. The output clock signal lags the synchronizing clock signal by a DLL output delay. Similarly, the frequency adjusted clock signal lags the synchronizing clock signal by a DFS output delay. By matching the DLL output delay to the DFS output delay, the digital clock manager synchronizes the output clock signal and the frequency adjusted clock signal.

Synchronized multi-output digital clock manager

A low jitter digital frequency synthesizer includes a first counter module, a second counter module, a snapshot module, an error value generation module, and a tapped delay line. The first counter module counts intervals of M cycles of an input clock to produce a first count. The second counter module count intervals of D cycles of an output clock to produce a second count, wherein a rate of the output clock corresponds to M/D times a rate of the input clock. The snapshot module periodically takes a snapshot of the first and second counts to produce snapshots. The error value generation module generates an error value based on the snapshots. The tapped delay line module produces the output clock based on the error value.

Low jitter digital frequency synthesizer and control thereof

Method and apparatus for sub-frame bit access for reconfiguring a logic block of a programmable logic device is described. A reconfiguration port in communication with a controller is provided. The controller is in communication with configuration memory for configuring the logic block. Configuration information is provided via the reconfiguration port. A single data word stored in the configuration memory is read via the controller, modified with the configuration information, and written back into configuration memory. Accordingly, by reading a single data word, in contrast to an entire frame, on-the-fly reconfiguration is facilitated.

Reconfiguration port for dynamic reconfiguration&#x2014;sub-frame access for reconfiguration

Method and apparatus for a controller for dynamic configuration is described. The controller comprises a port interface, a read/write interface, and a plurality of flip-flops. The flip-flops, couple the port interface to the read/write interface. The port interface is configured to receive a plurality of signals, where portion of the plurality of signals are pipelined through the plurality of flip-flops responsive to a data clock signal of the plurality of signals. This facilitates reading and writing to storage elements at a rate which is at least approximately a frequency of the data clock signal while operating a device at approximately such frequency in which the controller is instantiated.

Reconfiguration port for dynamic reconfiguration-controller

The frequency of a skew clock signal is dithered around a base frequency, thereby enabling this clock signal to comply with FCC requirements for electromagnetic emissions within a specified window. Delay is introduced such that the clock signals exhibits slightly different frequencies in successive periods. For example, the frequency of a 100 MHz clock signal can be adjusted to have frequencies of approximately 98, 98.5, 99, 99.5, 100, 100.5, 101, 101.5, and 102 MHz during different periods. Because the frequencies are spread in 0.5 MHz increments, only three frequencies are included in any 1 MHz window. As a result, &#x2154; of the energy of the clock signal is not included when determining whether the clock signal meets the FCC electromagnetic emission requirements. By spreading the frequencies above and below the base frequency in a regular manner, the average frequency of the clock signal becomes equal to the base frequency.

Digital spread spectrum circuitry

Method and apparatus for providing a measure of jitter and skew of a clock signal is described. The clock signal may be used as an input to a digital circuit. In one embodiment, a digital delay circuit is used in conjunction with a processing circuit to continuously measure the jitter of an input clock signal, thus providing clock signal performance measurement over time. In another embodiment, a pair of digital delay circuits are used to continuously measure the skew or delay between a reference clock signal and a input clock signal, thus providing a measurement of the skew of the input clock signal over time. The digital delay circuit(s) are formed on-chip, and thus an on-chip determination of jitter or skew may be provided.

Method and apparatus for clock signal performance measurement

After a delay lock loop synchronizes a reference clock signal with a skewed clock signal, a digital phase shifter can be used to shift the skewed clock signal by a small amount with respect to the reference clock signal. The tap/trim settings of a delay line in the main path of the delay lock loop can be transmitted to the digital phase shifter, thereby informing the digital phase shifter of the period of the reference clock signal. In response, the digital phase shifter provides a phase control signal that introduces a delay, which is referenced to the period of the reference clock signal, to either the reference clock signal or the skew clock signal. The phase control signal is proportional to a predetermined fraction of the period of the reference clock signal. The digital phase shifter can be controlled to operate in several modes. In a first fixed mode, the digital phase shifter introduces delay to the skew clock signal. In a second fixed mode, the digital phase shifter introduces delay to the reference clock signal. In a first variable mode, the digital phase shifter can cause the reference clock signal to lead or lag the skew clock signal by controlling the delay of the reference clock signal. In a second variable mode, the digital phase shifter can cause the reference clock signal to lead or lag the skew clock signal by controlling the delay of the skew clock signal.

Digital phase shifter

Method and apparatus for providing a controlled voltage to an integrated circuit is described. A first frequency value indicative of a first voltage is compared to a second frequency value indicative of a second voltage. The second frequency value is adjusted by the second voltage until the second frequency value is within a range of the first frequency value. Additionally, the second voltage may be adjusted to maintain the second frequency value within the range.

Method and apparatus for controlling supply voltage levels for integrated circuits

A delay lock loop uses a clock phase shifter with a delay line to synchronize a reference clock signal with a skewed clock signal. The delay line is coupled to a reference input terminal of the delay lock loop and generates a delayed clock signal that is provided to the clock phase shifter. The clock phase shifter generates one or more phase-shifted clock signals from the delayed clock signal. An output generator coupled to the delay line, the clock phase shifter, and an output terminal of the delay lock loop provides either the delayed clock signal or one of the phase-shifted clock signals as an output clock signal of the delayed lock loop. The propagation delay of the delay line is set to synchronize the reference clock signal with the skewed clock signal, which is received on a feedback input terminal of the delay lock loop. A phase detector compares the reference clock signal and the skewed clock signal to determine the appropriate propagation delay.

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Placerville, CA, United States of America

John D Logue