AN2638 Freescale Semiconductor / Motorola, AN2638 Datasheet - Page 5

• Manufacturer Part Number: AN2638
• Description: Effects of Clock Jitter on the MPC8260 (HiP3 and HiP4)
• Manufacturer: Freescale Semiconductor / Motorola

Table 3provides a brief description for each transfer function elements.
The PLL low pass filter of the first order has the following transfer function:
Therefore, the PLL closed loop transfer function is as follows:
The damping factor and loop bandwidth defined as:
The loop gain (K) and loop bandwidth ( ) cannot be independently selected because a change in one of the
parameters will have an adverse effect on the other parameter. Therefore, to allow independent change in
(K) and ( ), a component of R
MOTOROLA
Vin
H
LPF
G
K
s
Effects of Clock Jitter on the MPC8260 (HiP3 and HiP4)
(s)
n
Transfer Function
Freescale Semiconductor, Inc.
For More Information On This Product,
Rint
xfc
Table 3. PLL Transfer Function Elements
n
is added to the PLL low pass filter.
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Figure 6. PLL Loop Filter
Cint
Damping function
Loop bandwidth
Feedback Transfer function
Low Pass Filter
Forward transfer function
Loop Gain
Input frequency
Remark
Cxfc
Phase Lock Loop (PLL)
Vout
5