ACTIVE TUNING SYSTEM ANALYZES POWER TRANSISTORS

DESIGNING power amplifiers for wireless transmitters requires accurate knowledge of the transistors that drive those amplifiers. Fortunately , effective impedance-tuning systems are available for analyzing power transistors under different load conditions, One of these, a harmonic active load-pull system (HALPS), operates from 800 to 3000 MHz in its fundamental-frequency mode. It is capable of tuning impedances at sec ond-and third-harmonic frequencies with Gamma = 1 at the on-wafer devi ce-under-test (DUT) reference plane, Through analysis and appropriate tuning of the harmonic impedances with this system, the gain and effic iency of power-transistor chips can be improved by 5 to 15 percent.