National Semiconductor LMK03002C, Руководство по эксплуатации

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L M K 0 3 0 0 2 C
E V A L U A T I O N B O A R D O P E R A T I N G I N S T R U C T I O N S
17
Appendix A: VCO Performance
The internal VCO performance is measured by using a narrow bandwidth loop filter. By default
the narrow loop bandwidth filter is stuffed as Loop Filter #2 in positions C1_AUX, C2_AUX,
C2p_AUX, and R2_AUX and has a loop bandwidth of 55 Hz.
See the Loop Filter section in Board Options for more detail about switching between the two
different loop filters.
Loop Filter #2
Phase Margin
58º K
φφφφ
100 uA
Loop Bandwidth 55 Hz Fcomp 500 kHz
Crystal Frequency 16 MHz Output Frequency 1566 to 1724 MHz
Supply Voltage 3.3 Volts VCO Gain 13 MHz/Volt
VCO
8
2
0
n
F
1
0
u
F
8
2
0
ΩΩΩΩ
150 pF 110 pF
600
Ω
Ω Ω
Ω
200
Ω
Ω Ω
Ω
CPout
Charge Pump
C
1
C
2
R
2
R3 R4
C3 C4
This loop filter is located on the top side of the PCB and is selected by placing a
0 ohm resistor on pad R5.
This loop filter has been designed with a very small loop bandwidth to minimize
the PLL from interacting with the noise of the VCO to permit a VCO phase noise
measurement.