L M X 2 5 3 1 L Q 1 9 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
Phase Noise with Narrow Loop Filter (Internal Divide by 2 Enabled)
Fout = 917
MHz
Fout = 965
.5 MHz
Fout = 101
4 MHz
The plots to the left show the true
phase noise capability of the
VCO. In order to take these plots,
a 20 Hz loop bandwidth was used
with the E5052 spectrum
analyzer. This is the most
accurate and state of the art
equipment.
At lower offsets, the
measurements are more accurate
because the impact of the PLL is
removed. At higher offsets, the
measurements are also more
accurate because the E5052
spectrum analyzer has a much
lower noise floor than the E4445A
spectrum analyzer. Even though
the E4445A has a noise
cancellation feature, it only
cancels out thermal noise and not
cancel out the phase noise if the
LO inside this equipment.
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