Simulation of coupled oscillators using nonlinear phase macromodels and model order reduction

Oscillators are used in many integrated RF circuits. Since their behavior is highly nonlinear, full system simulation can be expensive. Furthermore, the behavior of an oscillator can be (un)intendedly perturbed by that of other components and oscillators. We present a method to build nonlinear phase macromodels of voltage controlled oscillators and show how these can be used to predict the behavior of oscillators under perturbation. Model order reduction techniques are used to decrease simulation times. Numerical results for realistic design illustrate the proposed approach

Model order reduction for multi-terminal circuits

Analysis of effects due to parasitics is of vital importance during the design of large-scale integrated circuits, since it gives insight into how circuit performance is affected by undesired parasitic effects. Due to the increasing amount of interconnect and metal layers, parasitic extraction and simulation may become very time consuming or even unfeasible. Developments are presented, for reducing systems describing R and RC netlists resulting from parasitic extraction. The methods exploit tools from graph theory to improve sparsity preservation especially for circuits with multi-terminals. Circuit synthesis is applied after model reduction, and the resulting reduced netlists are tested with industrial circuit simulators. With the novel RC reduction method SparseMA, experiments show reduction of 95% in the number of elements and 68x speed-up in simulation time

A framework for synthesis of reduced order models

A framework for model reduction and synthesis is presented, which enables the re-use of reduced order models in circuit simulation. Especially when model reduction exploits structure preservation, we show that using the model as a current-driven element is possible, and allows for synthesis without controlled sources. Two synthesis techniques are considered: (1) by means of realizing the reduced transfer function into a netlist and (2) by unstamping the reduced system matrices into a circuit representation. The presented framework serves as a basis for reduction of large parasitic R/RC/RCL network

Simulation of mutually coupled oscillators using nonlinear phase macromodels

Design of integrated RF circuits requires detailed insight in the behavior of the used components. Unintended coupling and perturbation effects need to be accounted for before production, but full simulation of these effects can be expensive or infeasible. In this paper we present a method to build nonlinear phase macromodels of voltage controlled oscillators. These models can be used to accurately predict the behavior of individual and mutually coupled oscillators under perturbation at a lower cost than full circuit simulations. The approach is illustrated by numerical experiments with realistic designs

Spectral collocation solutions to multiparameter Mathieu's system

Our main aim is the accurate computation of a large number of specified eigenvalues and eigenvectors of Mathieu's system as a multiparameter eigenvalue problem (MEP). The reduced wave equation, for small deflections, is solved directly without approximations introduced by the classical Mathieu functions. We show how for moderate values of the cut-off collocation parameter the QR algorithm and the Arnoldi method may be applied successfully, while for larger values the Jacobi-Davidson method is the method of choice with respect to convergence, accuracy and memory usage

Simulation of mutually coupled oscillators using nonlinear phase macromodels

Design of integrated RF circuits requires detailed insight in the behavior of the used components. Unintended coupling and perturbation effects need to be accounted for before production, but full simulation of these effects can be expensive or infeasible. In this paper we present a method to build nonlinear phase macromodels of voltage controlled oscillators. These models can be used to accurately predict the behavior of individual and mutually coupled oscillators under perturbation at a lower cost than full circuit simulations. The approach is illustrated by numerical experiments with realistic designs

O-MOORE-NICE!: new methodologies and algorithms for design and simulation of analog integrated circuits

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Counter-narratives against hardships among Syrian refugee youth and parents

The conventional literature and popular media describe the challenges of (Syrian) refugees in terms of their being victims who need to deal with the traumatic events they experienced before and during their flight. Their lack of seeking professional psychosocial help to improve their mental wellbeing is often explained by migrants’ supposed fear of stigmatization. Using in-depth interviews with 10 Syrian refugees in the Netherlands, we show that their main struggle concerns their identity fragmentation as a result of both their displacement and the stereotypical discourses of Muslim/Syrian people as victims or terrorists. In this article, we explore how Syrian refugee youths use strategic forgetting and remembering of both positive and negative memories to reconstruct their (collective) identity. Our finding that Syrian refugee youths use counter-narratives of being strong and competent to deal with their experience of identity fragmentation offers an alternative explanation for refugees not seeking professional help in dealing with their hardships