LMX25313010EVAL National Semiconductor, LMX25313010EVAL Datasheet - Page 8

• Manufacturer Part Number: LMX25313010EVAL
• Description: BOARD EVAL FOR LMX25131LQ 3010
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LMX25313010EVAL

• Main Purpose: Timing, Frequency Synthesizer
• Embedded: No
• Utilized Ic / Part: LMX2531LQ3010
• Primary Attributes: Low Band 1455 - 1566 MHz, High Band 2910 - 3132 MHz
• Secondary Attributes: 2.8 V ~ 3.2 V Supply
• Silicon Manufacturer: National
• Silicon Core Number: LMX2531
• Kit Application Type: Clock & Timing
• Application Sub Type: Frequency Synthesizer
• Kit Contents: Board, Cable, CD
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

L M X 2 5 3 1 L Q 3 0 1 0 E
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
Free-Running VCO Phase Noise (Internal Divide by 2 Enabled)
The plots to the left show the true phase
noise capability of the VCO. In order to
take these plots, the E5052 phase nose
analyzer was used.
The method was to
lock the PLL to the proper frequency, then
disable
the
EN_PLL,
EN_PLLLDO1,
EN_PLLLDO2,
EN_DIGLDO,
and
EN_OSC bits. The equipment needs to be
able to track the VCO phase noise to
measure in this way, and one can not let
the VCO drift too far off in frequency. If this
kind of equipment is not available, the
VCO phase noise can also be measured
by making a very narrow loop bandwidth
filter.
When divide by 2 is enabled, the phase
noise at lower offsets is about 6 dB better;
but at high offsets, the phase noise
improvement may be less because the
divider is noise floor is adding to the phase
noise.
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