摘要:
One of the advantages of direct frequency synthesis technique (e.g., flying-adder architecture) is its capability of generating arbitrary frequency by utilizing the time-average-frequency concept. In the clock output of the direct frequency synthesizer, instead of one type of cycle, there are two types of cycles. Unlike the conventional one-type-cycle clock wherein clock energy is concentrated at its designed frequency, Time-Average-Frequency based clock spreads some of its energy into spurious tones, which could be harmful to certain applications. The spurious tones are caused by the periodic carry sequence generated from a fractional part accumulator inside the frequency synthesizer. The invention suggests a method and an apparatus to break this periodicity and convert the spurious tones into broadband noise.
摘要:
One of the advantages of direct frequency synthesis technique (e.g., flying-adder architecture) is its capability of generating arbitrary frequency by utilizing the time-average-frequency concept. In the clock output of the direct frequency synthesizer, instead of one type of cycle, there are two types of cycles. Unlike the conventional one-type-cycle clock wherein clock energy is concentrated at its designed frequency, Time-Average-Frequency based clock spreads some of its energy into spurious tones, which could be harmful to certain applications. The spurious tones are caused by the periodic carry sequence generated from a fractional part accumulator inside the frequency synthesizer. The invention suggests a method and an apparatus to break this periodicity and convert the spurious tones into broadband noise.
摘要:
A Time-Average-Frequency direct period synthesizer is used to improve crystal-less frequency generator's frequency stability. It includes (a) a temperature sensor circuit to compensate temperature-induced frequency instability; (b) a voltage sensor circuit to compensate voltage-induced frequency instability; (c) a calibration circuit to correct manufacture-related frequency error; (d) a frequency control word update circuit to receive the temperature- and voltage-related frequency adjustments, and the calibration-related adjustment, to generate the corresponding frequency control word in a predetermined schedule; (f) a Time-Average-Frequency direct period synthesizer to receive said frequency control word in the predetermined schedule and produce a clock signal with a frequency that is stable and accurate by counteracting the frequency variation caused by crystal-less oscillators' temperature and voltage dependence and correcting the frequency error introduced in manufacture process. Methods of correcting crystal-less oscillators' frequency error and compensating its frequency variation are also disclosed.
摘要:
A lock detector for a phase lock loop (PLL) includes: first and second pulse width extenders, performing pulse width extension on first and second pulses for generating third and fourth pulses, respectively; first and second delay circuits, delaying the third and the fourth pulses into first and second sampling clocks, respectively; and a cross-sampling circuit, sampling the third pulse based on the second sampling clock and sampling the fourth pulse based on the first sampling clock to indicate whether the PLL is locked.
摘要:
Synchronous circuitry for processing digital data in which the data are filtered to compensate for expected jitter in time-average frequency clock signals. Time-average frequency synthesis circuitry generates internal clock signals of a desired frequency, for example as based on a recovered clock signal from an input data stream, in a manner in which not all periods of the clock signal are of uniform duration. A jitter precorrection filter is inserted into the data path to apply a variable delay to pre-correct for distortion caused by jitter in the clock cycle. In embodiments of the invention using a flying-adder architecture to generate the clock signal, coefficients of the digital filer realizing the jitter precorrection filter are calculated according to the currently-selected oscillator phase and according to a fractional portion of a digital frequency control word.
摘要:
To make Flying-Adder architecture even more powerful, a new concept, time-average-frequency, is incorporated into the clock generation circuitry. This is a fundamental breakthrough since it attacks the clock generation problem from its root: how is the clock signal used in real systems? By investigating from this direction, a much more powerful architecture, fixed-VCO-Flying-Adder architecture, is created. Furthermore, based on fixed-VCO-Flying-Adder frequency synthesizer and time-average-frequency, a new type of component called Digital-to-Frequency Converter (DFC) is born.
摘要:
An apparatus employing control words to present a synthesized output signal having an output frequency and a delay with respect to an input signal includes: (a) A multiplexer receiving the input signal and having an output and an address input. (b) An output unit generates the output signal in response to a drive signal from the multiplexer. (c) A first register coupled with the multiplexer output. (d) A second register coupled with the multiplexer and the first register. The first register responds to a multiplexer output signal to provide a first control signal to the second register based upon the control words. The second register responds to the multiplexer output signal to provide a second control signal to the address input based upon the first control signal and the control words. The multiplexer presents the drive signal in response to the second control signal.
摘要:
This invention uses a flying adder frequency synthesis circuit to provide the required frequency adjustments to accommodate the varying encoding density of a MPEG2 video data stream. This invention adjusts the local clock based on the information extracted from the program clock reference signal in the incoming data. This invention replaces an external or internal voltage-controlled crystal oscillator using a phase locked loop circuit on the video processing integrated circuit.
摘要:
An interface adapter for facilitating the data communication among computation modules in a Network-on-Chip SoC comprises 1) a FIFO block having certain number of storage cells for temporarily storing the data to be transported between two communicating modules; 2) a TAF-DPS clock generator and a multi-phase generator attached at the FIFO write side for generating the write clock for FIFO and the driving clock for the transmitter, a TAF-DPS clock generator and a multi-phase generator attached at the FIFO read side for generating the read clock for FIFO and the driving clock for the receiver; 3) a write pointer controller and a read pointer controller for reading the FIFO status and controlling the TAF-DPS clock generators at the write side and at the read side, respectively. A design scheme of using said interface adapters in Network-on-Chip SoC design includes a plurality of computation modules, routing modules, said interface adapters, a network of communication link, a network of global clock distribution. Methods of creating the interface adapter and using it in the Network-on-Chip SoC design are also disclosed.
摘要:
Circuits of a TAF-DPS clock generator implemented on programmable logic chip comprise: 1) a base time unit generator created from configurable blocks, or on-chip PLL, or on-chip DLL, said base time unit generator produces a plurality of phase-evenly-spaced-signals; 2) a TAF-DPS frequency synthesizer created by configuring configurable blocks of said programmable logic chip, said TAF-DPS frequency synthesizer takes said plurality of phase-evenly-spaced-signals as its input. Methods of creating flexible clock signal to drive application comprise: 1) selecting one or more strategic areas in said programmable logic chip; 2) creating one or more TAF-DPS clock generator for each said area by using the configurable resource in said area; 3) creating control function to control the frequency and duty-cycle of the TAF-DPS clock generator output, said control function can be circuit created from configuring configurable blocks, said control function can also be achieved by software; 4) driving the circuits in application by the flexible clock generated from said TAF-DPS clock generator.