Franco Mastri

A general SPICE model for arbitrary linear dispersive multiport components described by frequency-domain data

The paper introduces a general and efficient approach to dispersive multiport component modeling for use in conjunction with SPICE-like time-domain transient analysis programs. The model computes at any time instant the port currents making use of the time-dependent exciting voltages and of frequency-domain data generated once for all by electromagnetic or circuit analysis.

Efficient Krylov-subspace simulation of autonomous RF/microwave circuits driven by digitally modulated carriers

Presents a new approach to the simulation of self-oscillating nonlinear circuits excited by modulated RF/microwave carriers and/or dc sources. The analysis is reduced to the solution of a sequence of coupled harmonic-balance systems. A Krylov-subspace method explicitly developed for autonomous circuits and the suppression of any time-domain integration provide a dramatic speed increase with respect to conventional envelope-oriented techniques.

Modulation-oriented harmonic balance based on Krylov-subspace methods

The paper introduces a new approach to the circuit-level analysis of nonlinear RF/microwave (sub)systems driven by digitally modulated carriers. The circuit is simulated by a sequence of modified harmonic-balance analyses based on a Krylov-subspace method driven by an inexact Newton loop. In this way, problems with many million nodal unknowns may be efficiently tackled at the workstation level.

Efficient circuit-level analysis of large microwave systems by Krylov-subspace harmonic balance

The paper proposes a rigorous harmonic balance technique for the circuit-level simulation of complex microwave systems consisting of many interconnected functional blocks. The voltages at the interface ports between building blocks are used as auxiliary unknowns, and are determined simultaneously with the block stale variables by a Krylov-subspace inexact Newton iteration. This provides exact results and allows large savings of both memory and CPU time.

A Krylov-subspace technique for the global stability analysis of large nonlinear microwave circuits

The paper discusses a new approach to the global stability analysis of large nonlinear microwave circuits for which Nyquists analysis is not usable owing to the size of the characteristic equation. Making use of a Krylov method for autonomous circuits, a state lying on the bifurcated branch close enough to the bifurcation may be efficiently located. The bifurcated branch may then be found by ordinary continuation.

Generalized distributed nonlinear device modeling for Krylov-subspace based microwave circuit analysis

The paper introduces a new approach to the description of microwave devices by distributed models of complex topology. Each model is treated as a nonlinear subcircuit arbitrarily described on a nodal basis and interacting with the rest of the network through a number of external ports. A suitable formulation of the model equations allows harmonic-balance analysis to be carried out in a most efficient way by Krylov-subspace methods.

Scattering-Matrix Based Inexact-Newton Harmonic Balance with Incomplete Preconditioning

In harmonic-balance (HB) analysis based on Krylov-subspace methods, an effective exploitation of the available computer resources may be achieved by incomplete factorization of the preconditioner, after artificially generating a suitable sparsity pattern in the Jacobian matrix. The algorithm works best in conjunction with a new formulation of the HB errors based on the linear subnetwork scattering parameters. Important reductions of both memory occupation and CPU time may be obtained in this way, without compromising the power-handling capabilities of the analysis algorithm.

Transient Analysis of Microwave Oscillators by Krylov-Subspace Harmonic Balance

Transient analysis in microwave oscillators includes problems of primary importance such as oscillation buildup at bias turnon and frequency settling in VCOs. Until now this class of problems has been tackled by two families of algorithms, i.e., either rigorous but computationally inefficient time-domain methods, or fast but approximate envelope-oriented techniques. The paper shows that an excellent trade-off retaining the advantages of both the above without significant shortcomings, may be achieved by Krylov-subspace based inexact-Newton harmonic-balance (INHB) analysis.

Computation of near‐carrier phase noise in large RF/microwave front ends

The analysis of complex front ends containing many nonlinear devices and supporting signal waveforms with many spectral components can be handled efficiently by the harmonic-balance technique based on Krylov-subspace methods. This letter extends this approach to the computation of PM and AM noise of the down-converted carrier at the front-end output.xa0© 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 26: 24–30, 2000.

Simulation of Autonomous Nonlinear Microwave Circuits by Krylov-Subspace Methods

The paper discusses a novel approach to autonomous nonlinear microwave circuit simulation by the harmonic-balance (HB) technique coupled with Krylov-subspace methods. A new formulation of the nonlinear solving system for autonomous circuits is introduced. This consists of the ordinary HB system for the forced case, with the addition of one equation used to fix the arbitrary phase of the autonomous regime. In this way, the iterative solution schemes already available for the forced case can be substantially reused in the autonomous case, with a negligible over-head due to the additional equation. Further equations may be added to impose additional contraints, e.g., to hold constant the magnitude of a selected harmonic in order to suppress the degenerate solution.