WiMAX

WiMAX band: 2.4 GHz, 3.5 GHz, 5.8 GHz

Focus offers WLAN and WiMAX solutions to increase amplifier efficiency, linearity and gain.
Software capabilities range from basic stability testing through advanced CCDF, ACPR and EVM measurements including on-wafer multichip automation.

EVM is an important consideration when designing a PA for WiMAX or WLAN applications, and properly interfacing popular EVM measurement hardware with our software has been a substantial achievement. Focus' award-winning software can now communicate with Agilent VSA to perform EVM load pull.

The iCCMT-1220-2H-WiMAX is a "combo" tuner that covers 2-6 GHz Fo and 4-12 GHz 2Fo in one tuner. This allows for full coverage of WLAN and WiMAX frequencies as well as their second harmonic, the harmonic frequency which has the greatest effect on EVM.
Because both Fo and 2Fo are contained within one tuner as a complete WLAN/WiMAX solution, Focus can offer the highest VSWR and lowest losses of any harmonic solution.

The iMPT-1818-TC is a Multi-Purpose Multi-Frequency tuner designed specifically for WiMAX device testing.? Covering fundamental frequencies 1.8-6.0 GHz and 2Fo/3Fo up to 18 GHz, the iMPT-1818-TC offers full fundamental and harmonic tuning with full coverage of the Smith Chart (magnitude and phase).? This tuner truly represents the next evolution of microwave tuners.

Summary
A customized solution allows Error Vector Magnitude (EVM) measurements as a function of
input power as well as fundamental and harmonic impedances. A phase optimization at the second harmonic at Γ=0.9 can improve EVM by as much as fifty percent. Proper matching at the fundamental and the second harmonic is shown to achieve the lowest possible EVM while maintaining the desired output power.

The note describes in detail a test setup and test procedure used for load pulling transistors for WiMax applications, load pull, harmonic optimization and EVM over Input Power plots, allowing improvement of EVM from over 6% under power matched conditions to below 2% and extending the input power range by several dB.