B.J. Mulvaney

Bio: B.J. Mulvaney is an academic researcher from Freescale Semiconductor. The author has contributed to research in topics: Harmonic balance & Nonlinear system. The author has an hindex of 7, co-authored 24 publications receiving 130 citations.

Simulation of high-Q oscillators

Abstract: We present a new technique, based on a continuation method, for oscillator analysis using harmonic balance. With the use of Krylov subspace iterative linear solvers, harmonic balance has become a very powerful method for the analysis of general nonlinear circuits in the frequency domain. However, application of the harmonic balance method to the oscillator problem has been difficult due to the very small region of convergence. The main contribution of the paper is a robust and efficient continuation method that overcomes this problem.

Iterative solution of linear systems in harmonic balance analysis

Abstract: Harmonic balance (HB) is a steady-state simulation technique of primary interest for RF and microwave circuits. Krylov subspace methods promise efficient solution of the large linear systems that arise in HB simulators. This paper deals with an experimental investigation of GMRES and QMR, two leading Krylov subspace methods as applied to the HB problem. The problem of coordinating the linear solver's accuracy with the error at the nonlinear level is also discussed.

Timing verification of an integrated circuit

Abstract: This disclosure describes a design tool that verifies timing of an integrated circuit design by partitioning the integrated circuit design's gate-level netlist into target cell partition netlists and performs transistor-level circuit simulation on each target cell partition netlist. The design tool performs a back tracing procedure on each target sequential cell to define the target cell partition netlists. The design tool then identifies timing modes that enable valid logical paths through the target cell partition netlists from source sequential cells to the target sequential cells. In turn, the design tool performs transistor-level circuit simulation (e.g., SPICE simulations) on each target cell partition netlist to check for timing violations based upon the timing modes. In one embodiment, the design tool includes clock tree delay information, power supply variations, or routing parasitic information in the simulations to achieve improved timing analysis accuracy compared with traditional static timing analysis or timing optimization.

Injection locking conditions under small periodic excitations

Abstract: Injection locking of oscillators subject to small periodic excitations is derived from existence conditions of the solution of the small signal harmonic balance degenerate system. The resulting expression for the locking range can be applied to any oscillator circuit with arbitrary periodic injection waveform, and can be easily implemented into a circuit simulator. The application of the general expression to some special cases is considered, and comparison with known results is given. Theoretical results are confirmed by SPICE simulations.

Analysis of oscillator injection locking by harmonic balance method

Abstract: A new approach to analyze injection locking mode of oscillators under small external excitation is proposed. The proposed approach exploits existence conditions of the solution of HB linear system with degenerate matrix. The method allows one to obtain the locking range for an arbitrary oscillator circuit with an arbitrary periodic injection waveform. The approach can be easily implemented into a circuit simulator. Examples are given to confirm the correctness of the new approach.

Fast Entropy Minimization Based Autofocusing Technique for ISAR Imaging

Abstract: Autofocusing technology is an essential step of Inverse Synthetic Aperture Radar (ISAR) imaging, whose performance has great influence on the quality of the radar image As far as the existed autofocusing methods are concerned, the methods based on minimum entropy criterion are robust and have been widely applied in both Synthetic Aperture Radar (SAR) and ISAR imaging However, the Minimum Entropy based Autofocusing (MEA) methods usually suffer from heavy computation burden because of the complex formula of image entropy and the optimal search of the phase error In this paper, a novel fast MEA method based on the Newton method is proposed Moreover, the Simplified Newton (SN) method and the Modified Newton (MN) method are also introduced to the implement of MEA, and provide high computation efficiency Mathematical analysis and experimental results based on real measured data of two airplanes have validated the high computation efficiency of the proposed methods Compared to the widely applied MEA method for ISAR imaging, the proposed methods can improve the computation efficiency by 10 to 20 times

Modelling and discretization of circuit problems

Abstract: Publisher Summary This chapter discusses the modeling aspect of differential-algebraic equations (DAEs). In computational engineering, the network modeling approach forms the basis for computer-aided analysis of time-dependent processes in multibody dynamics, process simulation, or circuit design. Its principle is to connect compact elements via ideal nodes, and to apply some kind of conservation rules for setting up equations. The mathematical model, a set of so-called network equations, is generated automatically by combining network topology with characteristic equations describing the physical behavior of network elements under some simplifying assumptions. Interconnects and semiconductor devices (i.e., transistors) are modeled by multi-terminal elements (multi-ports), for which the branch currents entering any terminal and the branch voltages across any pair of terminals are well-defined quantities. Interconnects and semiconductor devices (i.e., transistors) are modeled by multiterminal elements (multi-ports), for which the branch currents entering any terminal and the branch voltages across any pair of terminals are well-defined quantities.

Method and system for modeling time-varying systems and non-linear systems

Abstract: A method and system for generating reduced models of systems having time-varying elements, non-linear elements or both is provided. The system to be modeled is described utilizing differential equations (100). The differential equations of the system are then linearized (110) and the frequency domain representations of the linearized differential equations are obtained (120). A finite dimensional representation of the frequency domain representations is generated (130) and is reduced by Krylov subspace projection (140). The reduced finite dimensional representation is solved (150) to obtain the reduced model of the system.

Fundamentals of Fast Simulation Algorithms for RF Circuits

Abstract: Designers of RF circuits such as power amplifiers, mixers, and filters make extensive use of simulation tools which perform periodic steady-state analysis and its extensions, but until the mid 1990s, the computational costs of these simulation tools restricted designers from simulating the behavior of complete RF subsystems. The introduction of fast matrix-implicit iterative algorithms completely changed this situation, and extensions of these fast methods are providing tools which can perform periodic, quasi-periodic, and periodic noise analysis of circuits with thousands of devices. Even though there are a number of research groups continuing to develop extensions of matrix-implicit methods, there is still no compact characterization which introduces the novice researcher to the fundamental issues. In this paper, we examine the basic periodic steady-state problem and provide both examples and linear algebra abstractions to demonstrate connections between seemingly dissimilar methods and to try to provide a more general framework for fast methods than the standard time-versus-frequency domain characterization of finite-difference, basis-collocation, and shooting methods