摘要:
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. The invention concerns non-error code and vibration minimization at the same time, so vibration tolerance is better raised, vibration transfer characteristics are very good, and net output vibration indicators at low band and high band parts is improved.
摘要:
The present invention relates to a system and method for adaptively adjusting delays along selected signal paths in order to equalize the signal delays at various distributed points within an integrated circuit. Where a signal traverses an initial outgoing path and a return path, delay elements disposed in each of the paths may be adjusted in order to set the entirety of the delay of the signal having traveled the entire signal trajectory equal to the delay present in a deliberately introduced delay element of known value. Alternatively, the inventive mechanism may control a selected one of two (or other plurality of) delay elements so as to automatically and adaptively adjust the delay value of the selected delay element so as to equalize the signal delay incurred along two or more signal paths.
摘要:
An apparatus including a sampling circuit to generate sampling clocks from a local clock and the sampling clocks to sample incoming data and a quarter clock, a phase detector to detect a phase difference between a data transition in sampled data and the local clock, and a delay line adapted to delay the sampled data by the detected phase difference.
摘要:
A system for the generation and distribution a plurality of coherently phased system clocks comprises a local clock generator and a plurality of remote clock generators. Each clock generator has a local input and a plurality of remote inputs coupled to a plurality of phase detectors, a cost function coupled to each phase detector and producing a control output, and the control output coupled to a voltage controlled oscillator and producing a local clock output, which is distributed to each local and remote clock generator. The cost function comprises a linear or non-linear combination of phase error and offset. A clock selection circuit comprises a control input which changes a propagation time away from the coherently phased edges of the system clock, thereby selecting a system clock in a glitch-free manner.
摘要:
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.
摘要:
A circuit combines the outputs of two or more phase locked loops to reduce jitter to a level below that of an individual phase locked loop. A digital version of the circuit uses a majority function to determine the median value of the phase locked loops. An analog version of the circuit averages the outputs of the phase locked loops.
摘要:
A fraction part control circuit of a frequency synthesizer apparatus including a PLL circuit is of a plural-n-th-order delta-sigma modulator circuit for controlling a fraction part of a number of frequency division to a variable frequency divider of the PLL circuit. An adder adds data of the fraction part to an output data from a multiplier and outputs the resultant data to a quantizer through a second-order integrator. The quantizer quantizes input data with a quantization step and outputs the quantized data to the multiplier through a feedback circuit. The quantized data is used as data of the controlled fraction part. The multiplier multiplies data from the feedback circuit by the quantization step and outputs the resultant data to the adder. The fraction part control circuit periodically changes the data of the fraction part, thereby setting a frequency of an output signal from a VCO according to an average value of the period.
摘要:
A clock identification and reproduction circuit which synchronizes a clock signal with an input signal includes a voltage controlled generator for generating a clock signal, a phase comparator for detecting a phase difference between an input signal and a clock signal to generate a phase difference signal according to the phase difference, and a filter for synchronizing a clock signal of the voltage controlled generator in response to a phase difference signal, in which the phase comparator generates a phase difference signal when a specific pulse waveform of a pulse of an input signal changes.
摘要:
A data clock generator, a data clock generating method and a storage medium therefor are provided, which make it possible to reduce burden on a PLL circuit and substantially reduce jitter in the generated data clock signal, as well as achieve a sufficiently wide lock range of the PLL circuit. Data packets are supplied, which include at least a plurality of data samples and time stamps which are smaller in number than the number of the plurality of data samples. Time samples are generated, respectively, for the data samples from the time stamps of the supplied data packets. A PLL circuit generates a data clock signal based on the time samples for the respective data samples.
摘要:
A communication apparatus includes a phase-locked loop circuit which receives a first signal having a frequency and converts it into an output signal having a transmission frequency, and includes a current output type phase comparator which converts a phase difference between the first signal and a second signal into a current signal, a low pass filter which filters the current signal of the current output type phase comparator to produce an output signal, a voltage controlled oscillator which produces an output signal having a transmission frequency corresponding to the output signal of the low pass filter, the output signal of the voltage controlled oscillator constituting the output signal of the phase-locked loop circuit, a frequency converter which frequency-converts the output signal of the voltage controlled oscillator to produce the second signal, and a current source which supplies a current to an input of the low pass filter.