MT90401 Datasheet, PDF (19/38 Pages) Zarlink Semiconductor Inc – SONET/SDH System Synchronizer

MT90401
Data Sheet
SONET or SDH mode. For SONET mode the loop filter has a corner frequency of 70 millihertz and the output
phase slope is limited to 885 ns per second. For SDH mode the loop filter has a corner frequency of 1.1 Hertz and
a maximum phase slope of 53 ns per 1.326 milliseconds. If the input signal exceeds this rate, such as for very large
amplitude low frequency input jitter, the maximum output phase slope will be limited.
The MT90401 has ten outputs that can be locked to four possible input frequencies for a total of 40 possible jitter
transfer functions. Since all outputs are derived from the same internal signal, the jitter transfer values for the four
cases, 8 kHz to 8 kHz, 1.544 MHz to 1.544 MHz, 2.048 MHz to 2.048 MHz 19.44 MHz to 19.44 MHz can be applied
to all outputs.
Figure 10 - Jitter and Wander Transfer with SONET filter
Figure 11 - Jitter and Wander Transfer with SDH Filter
It should be noted that 1 UI at 1.544 MHz is 648 ns, which is not equal to 1 UI at 2.048 MHz, which is 488 ns.
Consequently, a transfer value using different input and output frequencies must be calculated in common units
(e.g., seconds) as shown in the following example.
Example: What is the T1 and E1 output jitter when the T1 input jitter is 20UI (T1 UI Units) and the T1 to T1 jitter
attenuation is 18 dB?
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