Keysight Technologies E Series - Page 22

1Introduction
22 Keysight E-Series E9300 Operating and Service Guide
technique achieves wide dynamic range capability, it is limited to continuous
wave (CW) signals outside the square law region. Modulated signals must be
padded down or at low levels, with their average and peak power levels within the
diode square law region, to be measured accurately. Accurate, average power
measurement of high level signals carrying modulation cannot be obtained using
a CW correction factor technique. Specialized modulation sensors provide
accurate measurements but are bandwidth limited.
The Keysight E-Series E9300 power sensors are true average, wide dynamic range
RF microwave power sensors. They are based on a dual sensor diode pair/
attenuator/diode pair proposed by Szente et. al. in 1990
[1]
. Figure 1-2 shows a
block diagram of this technique.
Figure 1-2 Simplified block diagram of diode pair/attenuator/diode pair
This technique ensures the diodes in the selected signal path are kept in their
square law region, thus the output current (and voltage) is proportional to the
input power. The diode pair/attenuator/diode pair assembly can yield the average
of complex modulation formats across a wide dynamic range, irrespective of
signal bandwidth.
[1] US Patent #4943764, assigned to Keysight Technologies.
RF in
Low Sense
+
Low Sense
-
High Sense
+
High Sense
-
Upper Range
(-10 dBm to +20dBm)
Lower Range
(-60 dBm to -10dBm)