Jitter attenuator fifo overflow-underflow protection using digital-phase locked loop's bandwidth adaptation
OwnerManop Thamsirianunt, Tony Wonginventors
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Abstract
The present invention provides a jitter attenuator that has a phase locked loop (PLL), the PLL having a programmable bandwidth setting. The jitter attenuator also has a first-in/first-out (FIFO) buffer for storing data, a write clock for providing a write pulse to the FIFO, a read clock for providing a read pulse to the FIFO, and a pointer generator for controlling the programmable bandwidth in response to the difference between the frequencies of the write and read clocks.
Claims12
A jitter attenuator comprising:
- a phase locked loop (PLL), the PLL having a programmable bandwidth setting;
- a first-in/first-out (FIFO) buffer for storing data;
- a write clock for providing a write pulse to the FIFO;
- a read clock for providing a read pulse to the FIFO;
- and
- a pointer generator for controlling the programmable bandwidth in response to the difference between the frequencies of the write and read clocks.
A method for attenuating jitter in an integrated circuit, the method comprising:
- storing data in a first-in/first-out (FIFO) buffer;
- providing a write pulse to the FIFO, with a write clock;
- providing a read pulse to the FIFO, with a read clock;
- taking difference between the frequencies of the write and read clocks;
- and
- controlling a programmable bandwidth, with a pointer generator, in response to the difference between the frequencies of the write and read clocks.
A method for attenuating jitter in an integrated circuit, the method comprising:
- storing data in a first-in/first-out (FIFO) buffer;
- providing a write pulse to the FIFO, with a write clock;
- providing a read pulse to the FIFO, with a read clock;
- providing a read pointer and a write pointer;
- determining the location of the read pointer and the location of the write pointer;
- and
- adjusting the bandwidth of a PLL to higher frequency, when the FIFO approaches an overflow or underflow condition, to keep up with jitter amplitude and offset frequencies.
A method for attenuating jitter in an integrated circuit, the method further comprising:
- providing a write pointer and a read pointer, with the pointer generator;
- providing a first pulse and a second pulse, with the pointer generator, wherein the first and second pulses are derived from the write pulse;
- providing a sample pulse, with the pointer generator, wherein the sample pulse is derived from the read pulse;
- comparing relative locations of the pulses, with the pointer generator;
- and
- sending a signal to the programmable bandwidth setting, with the pointer generator, to the PLL for adjusting the programmable bandwidth setting when one of the first and second pulses overlaps the sample pulse, wherein the speed of the read pointer tracks the speed of the write pointer.
Dependencies are inferred from the claim text.