Working With Pa Fem Measurements; Test Challenges Faced By Power Amplifier Testing - Keysight Technologies M9393A Programming Manual

Working with PA FEM Measurements

The RF front end of a product includes all of the components between an antenna
and the baseband device. The purpose of an RF front end is to upconvert a
baseband signal to RF that can be used for transmission by an antenna. An RF front
end can also be used to downconvert an RF signal that can be processed with ADC
circuitry. As an example, the RF signal that is received by a cellular phone is the
input into the front end circuitry and the output is a down-converted analog signal
in the intermediate frequency (IF) range. This down-converted signal is the input to
a baseband device, an ADC. For the transmit side, a DAC generates the signal to be
up-converted, amplified, and sent to the antenna for transmission. Depending on
whether the system is a Wi-Fi, GPS, or cellular radio will require different
characteristics of the front end devices.
RF front end devices fall into a few major categories: RF Power Amplifiers, RF
Filters and Switches, and FEMs [Front End Modules].

Test Challenges Faced by Power Amplifier Testing

The following are the test challenges faced by power amplifier testing:
Keysight M9393A PXIe Performance Vector Signal Analyzer
RF Power Amplifiers and
following:
PA[Power Amplifier] – Production Tests which include:
Channel Power - Power Acquisition Mode is used to return
one value back through the API.
ACPR [Adjacent Channel Power Ratio]
ACPR measurements, "Baseband Tuning" is used to digitally
tune the center frequency in order to make channel power
measurements, at multiple offsets, using the Power
Acquisition interface.
Servo Loop- When measuring a power amplifier, one of the
key measurements is performing a Servo Loop because when
you measure a power amplifier:
it is typically specified at a specific output power
there is a need to adjust the source input level until you
measure the exact power level - to do this, you will
continually adjust the source until you achieve the
specified output power then you make all of the ACPR
and harmonic parametric measurements at that level.
FEMs [Front End Modules] – which could be a combination of multiple front
end functions in a single module or even a "Switch Matrix" that switches
various radios (such as Wi-Fi, GSM, PCS, Bluetooth, etc.) to the antenna.
The need to quickly adjust power level inputs to the device under test (DUT).
The need to assess modulation performance (i.e., ACPR and EVM) at high
output power levels.
RF Filters and Switches typically require the
– When making fast
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