October 3, 2009

converting ppm to frequency

Filed under: ASIC Design, Embedded Design — paritycheck @ 6:42 am

Oscillators and other frequency control devices specify their frequency variation in units of parts per million (ppm).  The equation for this relationship is,

delta_frequency = (f x ppm)/ 10^6

where ppm is the peak variation (expressed as +/-),f is the center frequency (in Hz), and delta_frequency is the peak frequency variation (in Hz).

For example, 100 ppm of 100 MHz represents a variation in frequency(delta_frequency) of 10 kHz.  The maximum and minimum frequencies are therefore 100.01 and 99.99 MHz, respectively.


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