HP 70427A User Manual page 438

NOTE
Table 13-1
Frequency
Specified
Typical
Table 13-2
Frequency
Specified
Typical
General Theory of Operation: 600 MHz Reference Chain
transverse wave oscillator (STWO) is now controlled by the front panel
voltage control. The 10 and 100 MHz auxiliary outputs are turned on, with
the 100 MHz clean-up loop locked to the 10 MHz timebase. The timebase is
set to 0 ppm/V.
The tuning sensitivity must be adequate to acquire and maintain phase-lock
with the device under test (DUT) during a phase noise measurement, without
degrading the measurement of the DUT. The 600 MHz Reference phase
noise, close to the carrier, degrades as the tuning sensitivity is increased
above 0.05 ppm/V, but allows for a greater drift tracking range to be used
with noisy DUTs.)
The module's noise performance is set by the 600 MHz Reference and its
associated circuitry. The 10, 100, and 600 MHz oscillators contribute to the
noise of the 600 MHz Reference output at different carrier offsets. The 10
MHz timebase is responsible for the noise close to the carrier, between 0.01
and 300 Hz. The 100 MHz VCXO contributes the noise between 50 Hz and
20 kHz carrier offsets. The 600 MHz STWO sets the noise performance
between 5 kHz and 20 MHz offsets.
The phase noise performance of the 600 MHz Reference is specified for
three conditions:
1. The 600 MHz loop locked to the 100 MHz loop, with the 100 MHz loop
locked to the 10 MHz timebase. (tuning sensitivity: 0.05 ppm/V)
1 Hz 10 Hz 100 Hz
–59 –89 –109
–67 –97 –116
2. The 600 MHz loop locked to the 100 MHz VCXO
( tuning sensitivity: 1 ppm/V)
1 Hz 10 Hz 100 Hz
–7 –57 –107
–50 –88 –118
1 kHz 10 kHz 100 kHz
–137 –149 –159
–142 –156 –170
1 kHz 10 kHz 100 kHz
–137 –149 –159
–143 –157 –170
HP 70427A/HP 70428A User's Guide 13-3
Block Diagram
1 MHz 40 MHz
–163 –163
–177 –177
1 MHz 40 MHz
–163 –163
–177 –177