LMX2320 National Semiconductor, LMX2320 Datasheet - Page 20

• Manufacturer Part Number: LMX2320
• Description: Frequency Synthesizer for RF Personal Communications
• Manufacturer: National Semiconductor

http
Application Information
MEASUREMENT RESULTS (Example
The reference spurious level is
filter attenuation and the low spurious noise level of the
LMX2320
The phase noise level at 20 kHz offset is
www national com
FIGURE 12 PLL Phase Noise 20 kHz Offset
FIGURE 10 PLL Reference Spurs
k
b
65 dBc due to the loop
(Continued)
2)
b
80 dBc Hz
TL W 12339– 34
TL W 12339– 36
20
ure 13 shows the switching waveforms for a frequency jump
The phase noise level at 150 Hz offset is
The spurs at 60 and 180 Hz offset are due to 60 Hz line
noise from the power supply
Of concern in any PLL loop filter design is the time it takes
to lock in to a new frequency when switching channels Fig-
of 1650 9 MHz to 1683 9 MHz By narrowing the frequency
span of the HP53310A Modulation Domain Analyzer en-
ables evaluation of the frequency lock time to within
frequency jump of 33 MHz
g
1 kHz The lock time is seen to be less than 500 s for a
FIGURE 11 PLL Phase Noise
FIGURE 13 Frequency Jump Lock Time
150 Hz Offset
b
81 1 dBc Hz
TL W 12339 – 35
TL W 12339 – 37