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| LMX2487E Datasheet, PDF (39/47 Pages) Texas Instruments – Low-Power Dual PLLatinum Frequency Synthesizers | |||
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www.ti.com
LMX2487E
SNAS404B â MAY 2007 â REVISED JANUARY 2016
9.2.1 Design Requirements
Table 47 lists the design parameters of the LMX2487E.
PM
BW
T3/T1
T4/T3
KPD
fPD
fVCO
Vcc
KVCO
CVCO
C1_LF
C2_LF
C3_LF
C4_LF
R2_LF
R3_LF
R4_LF
PARAMETER
Phase Margin
Loop Bandwidth
Pole Ratio
Charge Pump Gain
Phase Detector Frequency
VCO Frequency
Supply Votlage
VCO Gain
VCO Input Capacitance
Loop Filter Component
Table 47. Design Requirements
VALUE
48.6 degrees
9.3 KHz
39.70%
39.20%
8X (760 µA)
20 MHz
6000-6030
3V
20 MHz/V
50 pF
2.2 nF
39 nF
220 pF
100 pF
1.2 kΩ
4.7 kΩ
10 kΩ
9.2.2 Detailed Design Procedure
The design of the loop filter involves balancing requirements of lock time, spurs, and phase noise. This design is
fairly involved, but the TI website has references, design tools, and simulation tools cover the loop filter design
and simulation in depth.
9.2.3 Application Curves
Figure 26. Phase Noise
Figure 27. Fractional Spurs at 200-kHz Offset
Copyright © 2007â2016, Texas Instruments Incorporated
Product Folder Links: LMX2487E
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