MT9041 Zarlink Semiconductor, MT9041 Datasheet - Page 7

• Manufacturer Part Number: MT9041
• Description: Single Reference Frequency Selectable Digital PLL With Multiple Clock Outputs For T1/E1 Trunk And Backplane Synchronization
• Manufacturer: Zarlink Semiconductor

It should be noted that 1UI at 1.544MHz is 644ns, which is not equal to 1UI at 2.048MHz, which is 488ns.
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.
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
18dB?
Using the above method, the jitter attenuation can be calculated for all combinations of inputs and outputs based on
the three jitter transfer functions provided.
Note that the resulting jitter transfer functions for all combinations of inputs (8kHz, 1.544MHz, 2.048MHz) and
outputs (8kHz, 1.544MHz, 2.048MHz, 4.096MHz, 8.192MHz, 16.384MHz) for a given input signal (jitter frequency
and jitter amplitude) are the same.
Since intrinsic jitter is always present, jitter attenuation will appear to be lower for small input jitter signals than for
large ones. Consequently, accurate jitter transfer function measurements are usually made with large input jitter
signals (e.g. 75% of the specified maximum jitter tolerance).
Frequency Accuracy
Frequency accuracy is defined as the absolute tolerance of an output clock signal when it is not locked to an
external reference, but is operating in a free running mode. For the MT9041B, the Freerun accuracy is equal to the
Master Clock (OSCi) accuracy.
Capture Range
Also referred to as pull-in range. This is the input frequency range over which the synchronizer must be able to pull
into synchronization. The MT9041B capture range is equal to ±230ppm minus the accuracy of the master clock
(OSCi). For example, a ±32ppm master clock results in a capture range of ±198ppm.
Lock Range
This is the input frequency range over which the synchronizer must be able to maintain synchronization. The lock
range is equal to the capture range for the MT9041B.
Phase Slope
Phase slope is measured in seconds per second and is the rate at which a given signal changes phase with respect
to an ideal signal. The given signal is typically the output signal. The ideal signal is of constant frequency and is
nominally equal to the value of the final output signal or final input signal.
OutputT
OutputT
OutputE
OutputE
1
1
1
1
=
=
=
=
Zarlink Semiconductor Inc.
InputT
20
OutputT
OutputT
×10
MT9041B


1
–
-------- -
20
18
×10
1
7
1


×
×


----------------------
(
(
=
–
------
20
(
-------------------
(
1UIT
1UIE
644ns
488ns
A
2.5UI T


1
1
)
)
)
)
(
=
1
3.3UI T
)
(
1
)
Data Sheet