摘要:
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, ⅔ 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.
摘要:
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.
摘要:
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.
摘要:
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 for the delay line.
摘要:
Method and apparatus for an interface to a system monitor (1600) is described. A controller (102) accessible via a port interface thereof (110) is configured for read/write access to configuration memory cells (1500) and for read access to status registers (1602). The configuration memory cells (1500) are addressable via a first address space, and the status registers (1602) are addressable via a second address space different from the first address space. The port interface (110) is configured to receive a plurality of signals including a data address signal (124) and a data clock signal (121). The data address signal (124) has address information for accessing either the first address space or the second address space.
摘要:
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.
摘要:
A precision trim circuit for a tuneable delay line is provided. The precision trim circuit provides delays greater than the base delay of the tuneable delay line. By using larger delays than conventional trim circuits, the precision trim circuit of the present invention can use components that react to process and environmental variations in the same manner as the components of the tuneable delay line. Specifically, one embodiment of the precision trim circuit comprises a first delay element providing a delay greater than or equal to the base delay of the tuneable delay line. The precision trim circuit also comprises a second delay element providing a greater delay than the first delay element. A multiplexer coupled to the first delay element and the second delay element is used to select the amount of delay provided by the precision trim circuit. Other embodiments include additional delay elements providing varying delay values.
摘要:
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.
摘要:
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.
摘要:
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.