Enhanced RF Power Leveling with FPGA-Based Instrumentation [Application Notes]

RF power amplifiers (PAs) exhibit nonlinear properties as their output power increases. These properties can degrade power efficiency, spectral quality, and modulation accuracy. In addition to nonlinear properties, the amplifier gain varies from device to device due to imperfections in the manufacturing process. During characterization, validation, and production testing, PAs are set to operate at specific output power levels before measuring the quality of their RF output and their power efficiency. Considering that the exact gain and nonlinear behavior of the PA under test is not fully known before it is tested, the test system must, therefore, adjust the power going into the device under test (DUT) to achieve the desired output power. This operation is often called "power leveling," "power servo," and in some cases "power search." This "Application Note" will use the term "power leveling." Consequently, DUT performance measurements cannot begin until power leveling is complete.