LMX2325 datasheet(18/22 Pages) NSC

Part #	LMX2325

Description	Frequency Synthesizer for RF Personal Communications

PDF	22 Pages

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Manufacturer	NSC [National Semiconductor (TI)]

Direct Link	http://www.national.com

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18 / 22 page

Application Information (Continued)

MEASUREMENT RESULTS (Example

TLW12339 – 47

FIGURE 5 PLL Reference Spurs

The reference spurious level is k b74 dBc due to the loop

filter attenuation and the low spurious noise level of the

LMX2315

TLW12339 – 49

FIGURE 6 PLL Phase Noise 10 kHz Offset

The phase noise level at 10 kHz offset is b80 dBcHz

TLW12339 – 48

FIGURE 7 PLL Phase Noise

1 kHz Offset

The phase noise level at 1 kHz offset is b795 dBcHz

TLW12339 – 50

FIGURE 8 Frequency Jump Lock Time

Of concern in any PLL loop filter design is the time it takes

to lock in to a new frequency when switching channels

Fig-

ure 8 shows the switching waveforms for a frequency jump

of 865 MHz to 915 MHz By narrowing the frequency span

of the HP53310A Modulation Domain Analyzer enables

evaluation of the frequency lock time to within g500 Hz

The lock time is seen to be less than 500 ms for a frequency

jump of 50 MHz

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LMX2325 Datasheet(PDF) 18 Page - National Semiconductor (TI)