Texas Instruments LMK04208, Руководство пользователя

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Offset (Hz)
P
h
a
se
No
is
e
(d
B
c/
Hz)
10 100 1000 10000 100000 1000000 1E+7 5E+7
-170
-160
-150
-140
-130
-120
-110
-100
-90
-80
-70
-60
-50
D001
Epson 122.88 MHz VCXO, LVPECL (120 ohm em), VG-4513CA-122.8800M-GFCT3
Crystek 122.88 MHz VCXO, LVCMOS, CVHD-950-122.88
www.ti.com
VCXO Phase Noise 122.88 MHz
29 SNAU200 – September 2016
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Copyright © 2016, Texas Instruments Incorporated
Typical Phase Noise Performance Plots
B.1 VCXO Phase Noise 122.88 MHz
The phase noise of the reference is masked by the phase noise of this VCXO by using a narrow loop
bandwidth for PLL1 while retaining the frequency accuracy of the reference clock input. This VCXO sets
the reference noise to PLL2.
Figure 18 shows the open loop typical phase noise performance of the VG-
4513CA-122.8800M-GFCT3 Epson VCXO and CVHD-950-122.88 Crystek VCXO.
120 ohm em refers to the emitter resistors of the AC coupled LVPECL output are 120 Ω .
Figure 18. VCXO Phase Noise at 122.88 MHz
Table 8. VCXO Phase Noise at 122.88 MHz (dBc/Hz)
Offset Epson Crystek
10 Hz -74.1 -76.6
100 Hz -108.2 -108.9
1 kHz -130.4 -137.4
10 kHz -148.9 -153.3
100 kHz -153.3 -162.0
1 MHz -153.4 -165.7
5 MHz -153.3 -167.5
10 MHz -153.6 -168.1
20 MHz -153.5 -168.0
40 MHz -153.7 -168.1
Table 9. VCXO Jitter at 122.88 MHz (fs RMS)
Offset Epson Crystek
100 Hz to 20 MHz 185.6 60.5
12 kHz to 20 MHz 174.6 35