Progress for Behavioral Challenges: A Summary of Time-domain Behavioral Modeling of RF and Microwave Subsystems

The quest for the best compromise between the requirements for battery preservation and system operation linearity in the radio frequency (RF) and microwave front end has been a constant push for research on behavioral modeling of active devices since the early days of satellite communications [1] and has accelerated with the growth of modern mobile communication infrastructures. This focus has resulted today in a vast amount of behavioral model options, especially for the RF power amplifier (PA), in which it is not always simple for a designer to find his or her way as discussed in [2]-[5]. Using the term "behavioral model," we define these models as those derived from the observation of the electrical variables at the block ports (with very little insight on the internal composition of the block) and dedicated to the modeling of baseband/bandpass subsystems. Unlike transistor-level compact modeling, where there are well-established initiatives for model standardization driven by foundries and computer-aided design vendor companies [6], [7], there is, unfortunately, no such comparable effort yet at the subsystem level [8]. This article offers a concise summary of the recent progress on time-domain behavioral modeling with a particular focus on the continuous-time (CT) modeling theory [9].