Keysight E6680A - Page 381

3 IQ Analyzer (Basic) Mode
3.2 IQ Waveform Measurement
IF Path Auto
When IF Path Auto is ON, the measurement automatically selects between the IF
Paths based on the current measurement’s Digital IF Bandwidth setting. When the
measurement tries to set a Digital IF Bandwidth between 10 and 25 MHz, the IF Path
parameter automatically switches from 10MHz to 25MHz . When the
measurement sets the Digital IF Bandwidth back to a value narrower than 10 MHz,
then the IF Path automatically switches from 25MHz to 10MHz . This is the same
for the other paths as well. If the instrument has options B25 and B1X installed but
not B40, when the IF Path Auto is set ON and the current measurement sets the IF
Bandwidth from 14MHz to 26MHz, the IF Path automatically switches from 25MHz
to 140MHz since the 40MHz path is not available.
When reducing the Digital IF Bandwidth, the selected IF Path is the narrowest
possible path applicable.
For example, an instrument with B25, B40 and B1X installed, and you currently have
IF Path Auto set to ON and the Digital IF Bandwidth is 50MHz, the IF Path selection
will be 140MHz . If the bandwidth decreases and the value is 40MHz or narrower
(but above 25MHz), the IF Path will automatically change to 40MHz . Similarly, for
bandwidths equal to or narrower than 25MHz (but above 10MHz), the 25MHz path
is selected. For bandwidths equal to or narrower than 10MHz, the 10MHz path is
selected.
These rules apply even for DIF configurations of Swept DIF + WBDIF.
If the External path is available in the IF Path menu (see "Connecting an Oscilloscope
as an External Digitizer" on page 377), it will be automatically selected when IF Path
is set to AUTO and you increase the Digital IF Bandwidth above the widest IF Path
that was listed above External.
381 IQ Analyzer Mode User's &Programmer's Reference