Adaptive second harmonic active load for pulsed-IV/RF class-B operation

To provide a proper load impedance termination under class-B operation, for pulsed-IV biasing and pulsed-RF (pulsed-IV/RF) excitations, an adaptive harmonic active load is presented. Pulsed-IV/RF measurement is the technique of choice for characterization and modeling of RF devices as it guarantees that the transistor is not afflicted by low-frequency memory effects. It is also a promising technique to assist with the design of efficient pulsed power-amplifiers for TDMA or radar applications. In this work the multi-harmonic active load-pull technique used for CW excitations is extended to pulsed-IV pulsed RF excitations. The harmonic load was implemented with an active load and a large signal network analyzer (LSNA) both under computer control for adaptive tuning. The technique is demonstrated on both a GaN HEMT and a 65 nm NMOS transistor operating in class-B to quantify the impact of memory effects in pulsed-IV/pulsed-RF operation compared to CW operation.