Table of Contents
Advertisement
Carrier Offset (Hz)
Residual Phase
Noise
The tuning sensitivity of the YTF is about 75 MHz/mA, with a measured
phase sensitivity of 10 rad/mA. This tuning sensitivity sets the noise current
requirements on the YTF driver. Given a goal of only a 0.5 dB degradation
or less due to YTF tune-current noise, the tune-current noise must be 10 dB
less than the YTF phase noise. The noise current contribution to phase noise
can be calculated by:
Table 13-14
YTF tune current noise goal
Carrier Offset (Hz)
Noise Current (pA)
The YTF is equipped with an internal heater to help maintain frequency
stability and tuning repeatability over the module's operating temperature
range.
The tuning algorithm is designed to minimize magnetic hysteresis. The YTF
is tuned to a frequency below all usable frequencies, before it is tuned to the
desired frequency. This relaxes the magnetic hysteresis. The YTF is then
tuned to the new frequency by increasing the magnetic field until the new
frequency is reached.
Frequency calibration data is stored in the EE PROM on the microprocessor
assembly. The calibration data contains DAC current settings for each comb
line frequency, and an interpolation algorithm generates DAC settings for the
second YTF in the HP 70428 opt 002. The module can measure its own
frequency calibration data by accessing the YTF Calibration screen (see
Chapter 15).
GaAs Amplifier Preamp & Power Amp
The YTF output is amplified by the GaAs amplifiers. The amplifier input
range is 2.4 to 26.4 GHz, with a input level of –25 dBm to 0 dBm.
HP 70428A Microwave Deck Assembly
Table 13-13
YTF's typical residual phase noise
performance at 9.6 GHz
1
–92
β
C
---- -
=
20
log
-- - whereβ
sb
2
βrms
=
noi
sec
1
1120
HP 70427A/HP 70428A User's Guide 13-35
10
100
1 k
10 k
–110
–125
–135
–143
=
peakphasedeviation
(
)x
urrent rms
10
100
1 k
10 k
141
25.1
7.95
3.16
Block Diagram
>100 k
–152
>100 k
1.12
Advertisement
Table of Contents
