S.L. Ulyanov

Bio: S.L. Ulyanov is an academic researcher from Russian Academy of Sciences. The author has contributed to research in topics: Harmonic balance & Phase noise. The author has an hindex of 6, co-authored 43 publications receiving 117 citations. Previous affiliations of S.L. Ulyanov include National Research University – Higher School of Economics.

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.

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.

Smoothed form of nonlinear phase macromodel for oscillators

Abstract: This paper proposes an improvement to the well-known oscillator nonlinear phase macromodel based on Floquet theory. A smoothed form of the nonlinear phase macromodel is derived by eliminating highly oscillatory terms in the macromodel, resulting in a significant speed-up in transient simulation. For an LC oscillator under sinusoidal excitation the new macromodel is equivalent to the Adler model. Numerical experiments confirm a considerable decrease of computational efforts. It is further shown that the new macromodel allows one to perform phase noise analysis of locked oscillators under arbitrary periodic injection.

The enchancing of efficiency of the harmonic balance analysis by adaptation of preconditioner to circuit nonlinearity

Abstract: Krylov subspace techniques in harmonic balance simulations become increasingly ineffective when applied to strongly nonlinear circuits. This limitation is particularly important in the simulation if the circu it has components being operated in a very nonlinear region. Ev en if the circuit contains only a few very nonlinear components, Krylov methods using standard preconditioners can become ineffective. To overcome this problem, we present two adaptive preconditioners that dynamically exploit the properties of the harmonic balance Jacobian. With these techniques we have been able to retain the advantages of Krylov methods even for strongly nonlinear circuits. Some numerical experiments illustrating the techniques are presented.

A Linear-Centric Modeling Approach to Harmonic Balance Analysis

Abstract: In this paper, we propose a new harmonic balance simulation methodology based on a linear-centric modeling approach. A linear circuit representation of the nonlinear devices and associated parasitics is used along with corresponding time and frequency domain inputs to solve for the nonlinear steady-state response via successive chord (SC) iterations. For our circuit examples, this approach is shown to be up to 60/spl times/ more run-time efficient than traditional Newton-Raphson (N-R) based iterative methods, while providing the same level of accuracy. This SC-based approach converges as reliably as the N-R approaches, including for circuit problems which cause alternative relaxation-based harmonic balance approaches to fail. The efficacy of this linear-centric methodology further improves with increasing model complexity, the inclusion of interconnect parasitics and other analyses that are otherwise difficult with traditional nonlinear models.