A new configuration to improve the active loop technique for transistor large signal characterization in the Ka band

This article presents a new configuration to improve the conventional active loop technique with pre-matching. This reduces the power requirements of the loop amplifier when synthesizing high reflection coefficient for high power transistors. The active loop technique is very efficient in characterizing power transistors but the output power of the loop amplifier can be a strong limitation as it can exhibit non-linear behavior when high power is needed. The proposed new configuration improves the active loop capabilities as it allows a larger reflection coefficient to be synthesized with higher linearity of the loop amplifier. Theoretical results show the interest of the new active loop and experimental measurements in the Ka band validate the linear behavior improvement of the active loop for high reflection coefficients. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 589–593, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22220