Nexxim Circuit Design Analyses

Nexxim® is the Ansys state-of-the-art circuit simulator for RF, analog, and mixed-signal designs. Nexxim combines transistor-level simulation accuracy, high execution speed, and robust capability to handle circuits with thousands of active and passive elements. Nexxim simulates in all three domains — DC, time, and frequency — on the same set of device models.

• In addition to the classic variable sweeps of temperature, voltage, and current, Nexxim allows you to perform sweeps of any model or parameter in a circuit.
• Circuit designs can be simulated using a variety of time domain and frequency domain solvers, including system-level analysis with combinations of electrical and behavioral components.

Nexxim Time Domain analyses include DC analysis, transient analysis, statistical eye analysis with VerifEye and QuickEye, and IBIS-AMI analysis. Support is available for HSPICE simulation when that system is installed. The focus of the time-domain solvers is on signal integrity issues.

• DC analysis calculates the circuit’s DC operating point and is the basis for other analyses.
• Transient analysis calculates the time-domain behavior of the circuit. Nexxim transient analysis incorporates a new, Ansys-proprietary variable time-step integration formula and advanced error estimation and control. The analysis can include S-parameter input data files for accurate analysis in the time domain.

Circuit time domain analyses can yield time-voltage plots, eye diagrams, and tabular data arrays of the time domain simulation results. Information on Circuit design reports is included in the analysis documentation.

Nexxim Frequency Domain analyses include harmonic balance, oscillator analysis, envelope analysis, time-varying noise analysis, and linear network analysis.

• Harmonic balance analysis calculates the frequency-domain responses of the circuit. Nexxim harmonic balance performs single-tone and multi-tone analysis that combines Krylov subspace methods with Ansys-proprietary preconditioning algorithms to achieve fast convergence.
• Small-signal analyses (AC, linear network, DC noise) are based on the DC solution. The Nexxim proprietary linear system solver is optimized for circuit simulation, and produces accurate answers without compromising speed. Nexxim also supports small-signal frequency analysis based on harmonic balance.

Frequency domain analyses can generate spectral plots, constellation diagrams, and Smith charts. Information on Circuit design reports is included in the analysis documentation.