[time-nuts] timing properties of "spectrum spreading" clocks
jimlux
jimlux at earthlink.net
Wed May 15 17:15:28 UTC 2019
Has anyone measured the details of the spread spectrum clocks used to
help meet emission limits (like FCC Part 15)?
It seems, superficially, that they do this with some sort of
deterministic process (like a linear feedback shift register), and so,
one might be able to "back out" the (Pseudo)randomization to get better
timing performance.
https://www.maximintegrated.com/en/app-notes/index.mvp/id/3503
seems to indicate that they use a up/down sweep approach.
https://www.maximintegrated.com/en/products/all-products/archive/MAX9492.html
https://www.idt.com/products/clocks-timing/application-specific-clocks/spread-spectrum-clocks/180-01-low-emi-clock-generator
"IDT's proprietary blend of analog and digital PLL technology"
https://www.idt.com/document/dst/idt5p50911-2-3-4-datasheet
seems to show a triangle wave frequency modulation
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