HP 8340B Manual page 45

4-9. SINGLE SIDEBAND PHASE NOISE (Cont'd)
PHASE NOISE MEASUREMENT obtains phase noise data for DUT frequencies of 2.202, 6.902,
13.402,19.S02 and, in the case of the HP 8340B, 26.032 GHz. These specific frequencies typically
have the worst case phase noise for the HP 8340B/41B. The DUT is adjusted for the test frequency
and then the LO frequency is adjusted to obtain a 1 MHz
phase noise level at 30 Hz, 100 Hz 1 kHz, 10 kHz, and 100 kHz offsets from IF) measurement is
performed using the OFFSET and NOISE LVL functions of the HP 3585A and the results are recorded
as the Measured Noise Level (MNL, measured in dBc).
PHASE NOISE CALCULATION takes the data obtained for MNL and adds and subtracts the calibra-
tion data and a 3 dB correction factor to obtain the actual phase noise. The formula that is used is:
IFCD is the response of the 1 MHz notch filter at 1 MHz. Since the filter is not installed during the 10 Hz,
100 Hz and 1 kHz measurements IFCD
notch filter attenuates the IF causing the power difference between the IF and the phase noise to be
smaller than it actually is, therefore IFCD must be added to MNL to correct this. The system's fre-
quency response (LCD) causes the difference between the IF level and the phase noise level to be
greater than it actually is, therefore CD must be subtracted from MNL. A factor of 3 dB is subtracted
from MNL to correct for the LOs phase noise contribution.
4-46 Performance Tests
Actual Phase Noise MNL
0. During the 10 kHz and 100 kHz offset measurements the
=
Figure 4-9. Single Sideband Phase Noise Test Setup
signal to noise level (IF to
0.9 Hz IF. A
±
IFCD CD
3 dB
t
— —
SPECTRUM ANALYZER
ADAPTER
f)
APC—3.5(
to N(n)
(8341B ONLY)
HP 8340B/41B