CX28343 Просмотр технического описания (PDF) - Unspecified
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CX28343 Datasheet PDF : 195 Pages
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CX28342/3/4/6/8 Data Sheet
Dejitter Circuit Analysis
Analyzing the circuit in Figure A-1 the values for the resistors, capacitor, and the
VCO can be substituted into the derived equations.
Substituting the values for the
system shown in Figure A-1 result
in the coefficients shown to the
right. k1 is the phase detector built
into the CX28344 and is a constant.
k1
=
3
2Π
=
0.4775
(v/rad)
k3 is from the VCO and has a
frequency range of 300 ppm over
the control voltage range of 2.67
volts.
Substituting the values of 4.75 KΩ
for the resistors and 0.1 µF for the
capacitor:
k2
=
R2
R1 + R2
=
4.75KΩ
4.75KΩ + 4.75KΩ
=
1
2
k3
=
2Π∆f
∆v
= 31580
(rad/v-s)
a = 1 = 2105 (/s)
R2C1
b
=
(R1
1
+ R2 )C1
= 1053
(/s)
The result for the natural frequency
of the system is:
ωn =
k1k2k3a = 996
16
( ~159 Hz )
and the damping factor is:
ζ = (16b + k1k2k3 ) = 0.765
32ωn
The results from the analysis show a good damping factor of 0.765 and a natural
frequency of 996 rad/s. Although it would be better to get the natural frequency lower
so that more high frequency jitter would be filtered, the system response would suffer.
28348-DSH-001-B
Mindspeed Technologies™
A-7
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