This paper presents a 3D topology for high miniaturization of the well-known hybrid branch-line coupler at the UHF band. A preliminary work already proposed the use of helical-microstrip TLs combined with a folded structure for this purpose. This extended work includes a compactness enhancement by loading the TL segments with capacitors. An study of loaded helical-microstrip TL is reported as well. The coupler prototypes have been simulated and fabricated by using a combination of Additive Manufacturing and copper electroplating. The performance results have been compared to the conventional model showing a good agreement. In order to place the designed devices within the state of the art a figure of merit that combines the compactness and the relative bandwidth has been proposed, showing very good results in terms of miniaturization.

In recent years there has been a growing interest in electronic design automation methodologies for the optimization-based design of radio frequency (RF) circuits and systems. While for simple circuits several successful methodologies have been proposed, these very same methodologies exhibit significant deficiencies when the complexity of the circuit is increased. The majority of the published methodologies that can tackle RF systems are either based on high-level system specification tools or use models to estimate the system performances. Hence, such approaches do not usually provide the desired accuracy for RF systems. In this paper, a methodology based on hierarchical multilevel bottom-up design approaches is presented, where multiobjective optimization algorithms are used to design an entire RF system from the passive component level up to the system level. Furthermore, each level of the hierarchy is simulated with the highest accuracy possible: electromagnetic simulation accuracy at device-level and electrical simulations at circuit/system-level.

A new design methodology for radiofrequency circuits is presented that includes electromagnetic (EM) simulation of the inductors into the optimization flow. This is achieved by previously generating the Pareto-optimal front (POF) of the inductors using EM simulation. Inductors are selected from the Pareto front and their S-parameter matrix is included in the circuit netlist that is simulated using an RF simulator. Generating the EM-simulated POF of inductors is computationally expensive, but once generated, it can be used for any circuit design. The methodology is illustrated both for a singleobjective and a multiobjective optimization of a low noise amplifier.

In this paper, a new methodology for the automated generation of the optimal performance trade-offs of integrated inductors is presented. The methodology combines a multiobjective optimization algorithm with electromagnetic simulation to get highly accurate results. A set of sized inductors is obtained showing the best performance trade-offs for a given technology. Unlike reported approaches for inductor synthesis, performance trade-offs are generated offline, i.e., before any specific inductance or quality factor are required. The tight efficiency versus accuracy trade-off of existing approaches is, in this way, avoided and performance evaluation via electromagnetic simulation becomes affordable.