Pole-zero identification refers to the obtaining of the poles and zeros of a linear (or linearized) system described by its frequency response. This is usually done using optimization techniques (such as least squares, maximum likelihood estimation, or vector fitting) that fit a given frequency response of the linear system to a transfer function defined as the ratio of two polynomials. This kind of linear system identification in the frequency domain has numerous applications in a wide variety of engineering fields (such as mechanical systems, power systems and Electromagnetic Compatibility). In the microwave domain, rational approximation is increasingly used to obtain black-box models of complex passive structures for model order reduction and efficient transient simulation. In this paper we will focus on a different application of pole-zero identification. We will review the different ways in which pole-zero identification can be applied to nonlinear circuit design (for power amplifier stability analysis and beyond). We will give a comprehensive view on recent approaches through illustrative application examples. Other uses of rational approximation techniques are beyond the scope of this paper.

(NSA) mota bat dira. NSA tradizionalek ez bezala, PNS-ek informazioa pultsu diskretuetan oinarrituta prozesatzen dute, errendimendu altuagoa eta eraginkortasun energetiko nabarmenagoa lortuz. Hala ere, gaur egungo hardware plataforma gehienek ez dute aprobetxatzen PNS-en gertaera bidezko izaera eta horrek sare handiak eta konplexuak prozesatzea oztopatu dezake. Arazo horiei aurre egiteko, artikulu honetan Ate-matrize programagarrietan (FPGA) oinarritutako hardware azelerazio plataforma berria (SNNorlax) aurkezten da, sarearen tamaina eta sinapsi konexioak konfiguratzeko maila altua duena.

Understanding the nature of potential instabilities is indispensable for the stabilization of power amplifiers (PAs). Pole-zero identification is one of the techniques that can be used to determine the stability of a design in large-signal operations. In this work, the possible presence of poles at the fundamental frequency linked to the long-term memory parameters of the transistor’s model (self-heating and traps) is presented and discussed. This article shows how their effect on the identified frequency responses around the fundamental frequency may compromise the stability analysis results and the assessment of stability margins. The low observability of the poles at the fundamental frequency highlights the importance of an accurate identification of real poles in low-frequency bands. A specific algorithm for the automatic frequency domain identification of non-resonant frequency responses and a procedure for detecting and reducing overfitting of real poles is proposed in this article. The benefits of the proposed methodology to correctly detect and analyze real poles at low frequencies is demonstrated through Monte-Carlo (MC) sensitivity analyses of two different amplifier designs.

SiliconBurmuin is aimed at creating a multi-disciplinary neurocomputing community in the Basque Country, bringing together technology and scientific research centres and industry companies. This community will: (1) identify key biological structures and mechanisms that play a major role in vision across species, and (2) transform this knowledge into novel mathematical formalisms, neuromorphic designs and algorithms to solve industry challenges and enable new experiments of interest in neuroscience and clinical research. To achieve the latter objective in a time-effective manner, SiliconBurmuin will draw strong connections with the ongoing Horizon Europe Nim-bleAI project, with which it shares coordination. This is expected to allow reinforcement of ideas, knowledge and technology via a common prototyping platform where to implement IP from both projects. In addition to describing the research objectives and direction of SiliconBurmuin, this paper posits that co-coordination and co-funding of aligned projects at EU and regional levels might well be a catalyst for raising regional self-awareness of own potential and develop it to help fulfill global challenges, such as semiconductor sovereignty.

This article proposes an efficient method for the calculation of the stabilization parameters in RF power amplifiers operating in periodic large-signal regimes. Stabilization is achieved by applying the principles of linear control theory for periodic linear time-varying (PLTV) systems. A numerical method is proposed to obtain the harmonic transfer function that represents the system linearized around the large-signal steady state. Then, a feedback analysis is performed to calculate the closed-loop poles of the PLTV system. The proposed approach is demonstrated with two examples. First, a three-stage amplifier that exhibits a low-frequency oscillation for increasing values of input power is correctly stabilized. Next, the stabilization of an unstable design that exhibits an odd-mode parametric oscillation is presented. The results of the proposed technique are compared to those obtained with the conventional parametric stability simulation. These examples serve to illustrate the capability and efficiency of the proposed approach.

Low-frequency resonances with low stability margins affect video bandwidth characteristics of power amplifiers. In this paper, a nonconnectorized measurement technique is presented to obtain the low-frequency critical poles at internal nodes of a hybrid amplifier. The experimental setup uses a high-impedance probe connected to a vector network analyzer to obtain a fully calibrated closed-loop frequency response that is identified to get the poles of the device at low frequency. Compared to previous connectorized solutions, the approach avoids the ad hoc insertion of extra RF connectors to access the low-frequency dynamics of the amplifier. In addition, it simplifies the characterization at multiple internal nodes, which is worthwhile for an efficient detection and fixing of critical low-frequency dynamics in multistage power amplifiers. The technique is first applied to dc steady-state regimes and compared to the connectorized approach on a single-stage amplifier. Next, it is applied to a three-stage amplifier to show its potential to detect the origin of the undesired dynamics and the most effective way to increase stability margin. Finally, the technique has been extended to the large-signal case to increase its usefulness for the design and diagnosis of high-power amplifiers.

Determining the origin and nature of the possible instabilities is key for an effective elimination of the unstable dynamics in multistage power amplifier design. In this work, a novel technique is proposed to provide a quantitative metrics that serves to locate and categorize the sensitive sections of the amplifier at which the unstable dynamics can be controlled and eliminated. The technique is based on an automatic Multiple-Input Multiple-Output (MIMO) frequency identification performed at different observation ports, followed by a residue analysis of critical poles. A three-stage amplifier exhibiting two common types of instabilities has been used to illustrate the complete approach.