Manufacturers of WiMAX output devices need a much larger signal than the typical vector signal generator can produce for WiMAX testing. These tests are done to verify the linearity of the amplifier device and the fidelity of the signal amplified. An amplifier is needed to produce these signals with sufficient power to do the testing while maintaining the original signal quality. The main limiting factor is the Peak Envelope Power (PEP) of the WiMAX signal. The peak power can be as much as 18 dB above the average power, thus the need for amplification. There are two signal quality criteria that need to be maintained in this process, including Adjacent Channel Power (ACP) and Relative Constellation Error (RCE).
AR RF/Microwave Instrumentation offers two amplifier series that cover the frequency range of WiMAX. Very linear amplification is available from 800 MHz to 4.2 GHz (1 to 700 W) and another series that covers 4 to 8 GHz (1 to 60 W).
Rohde & Schwarz (R&S) recently made its WiMAX test system available to make measurements for this application on two AR amplifiers – 50S1G4A (50 W, 0.8 to 4.2 GHz) and 10S4G11 (10 W, 4 to 10.6 GHz). The measurement system consists of a the R&S Model SMU200 Vector Signal Generator and the R&S Model FSQ Signal Analyzer, both outfitted with the WiMAX generation and analysis software. Measurements were made at 3.7 and 5.8 GHz, although the same performance is assured across the entire bandwidth of the amplifiers. AR RF/Microwave Instrumentation’s “S” series amplifier performance provides more 1 dB compression power and higher third-order intercepts that allow the test engineer to get more useable power than competitive units.