Product specifications

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The IMD calibration includes R1 receiver calibration, source 1 and source 2 power
calibration, and B receiver calibration when port 1 for the DUT input and port 2
for the DUT output are selected. If 2-port error correction is used during an IMD
calibration, the power sensor mismatch during R1 receiver calibration is corrected
and the transmission response term is used to transfer the R1 receiver calibration
to the B receiver. IMD calibration without 2-port calibration ignores the power
sensor mismatches during R1 receiver calibration and uses a response calibra-
tion to transfer to the B receiver. Calibrating at all receiver frequencies is recom-
mended for wide tone spacing; otherwise it can be at only the center frequency
of each stimulus setup. Often recommended in wideband pulse measurements,
is to calibrate all frequencies due to the fact that wider IF bandwidth requires
wider tone spacing, easily wider than 1 MHz or often several megahertz. The
frequency responses of the receivers at each tone frequency can be different from
the center frequency with wide tone spacing. The pulse modulation must switch
to CW before the swept IMD calibration. Note that both f1 (port 1) and f2 (port 1
source 2) source leveling mode must be changed to receiver leveling in Swept IMD
Measurement class.
Figure 30a and 30b show the measurement example of wideband pulse swept-
frequency IMD with open loop and receiver leveling respectively. The 12 us pulse
width is selected based on the minimum pulse width for 100 kHz IF bandwidth
shown in Table 1. With open loop leveling mode the input powers are inconsistent
across the frequency range and a few dB off from the set power level, which can
be corrected with receiver leveling mode.
Figure 30a. Wideband pulse swept-frequency IMD measurements with open loop
leveling