Specifications

23
Innovative
Applications
Simplified test of I/Q
converters and modu-
lators, and differential
mixers
(Option 089)
I/Q and differential converter measurement challenges
• Requires signals with 90% or 180% phase difference
• Traditional approach uses hybrid couplers and/or baluns which are:
• Inherently band-limited, requiring multiple components for broadband measurements
• Limited to fixed phase offsets, preventing phase sweeps to determine optimum alignment
• Lossy and inaccurate (+/- 3% to 12% typically)
• Difficult to use with on-wafer setups
PNA-X differential and I/Q devices application
• Provides accurate phase control of internal and external sources, eliminating the need for
hybrid couplers and baluns
• Tunes receivers to all user-specified output frequencies needed to fully characterize the DUT
• Sweeps frequency to measure operating bandwidth or sweeps phase and power at a fixed
frequency to measure quadrature or differential imbalance
• Includes match-corrected power measurements for highest accuracy
The I/Q inputs of this
modulator can be directly
driven with the internal
sources of the PNA-X,
eliminating the need for
a 90 ° hybrid coupler
Tips from the experts
• Two additional external sources can be used to create differential I/Q drive signals.
The external sources must be routed through the PNA-X test set to measurement
receivers in order to achieve the desired phase offsets.
• For I/Q modulators, DC power supplies or source-measurement units (SMUs) can
be routed through the bias tees to the I/Q inputs of the DUT. Voltage sweeps can
then be performed to help find the optimum I/Q-voltage offsets for the greatest
amount of LO suppression.
• Measure harmonics and total-harmonic distortion (THD) of differential amplifiers by
establishing a true-differential drive and tuning the PNA-X receivers to all desired
harmonics
• Measure compression of differential mixers using power sweeps