Ansoft Designer was introduced to the RF/microwave industry when “The New World of Communications Design Software” appeared as a cover feature in Microwave Journal back in March 2001 (see Figure 1). Ansoft, now a division of ANSYS Inc., had developed a new design environment from the ground up, to integrate what had been separate circuit, system and planar EM simulation products. The product addressed high frequency design by offering a hierarchical approach to simulating complex distributed networks directly within the context of a circuit (including nonlinear devices, i.e. transistors and diodes) and/or system-level (behavioral models) analysis.

Figure 1 March 2001 Microwave Journal cover featuring Ansoft Designer.

Ansoft Designer incorporated a number of innovations into the design environment’s user-interface, providing circuit designers with unprecedented access to the company’s core competency in electromagnetic simulation. The so-called “Solver-on-Demand” feature allowed engineers to characterize passive interconnects in situ using the software’s planar EM solver. Direct access of the planar solver to a parameterized physical design within the circuit simulation would change the role of an EM simulator from verification tool to a full-fledged design optimization tool.

The roadmap for Ansoft Designer called for developing dynamic links to Ansoft’s other 3D electromagnetic simulation products (HFSS and SIwave) and replacing the circuit simulation technology (Serenade) with a new high-capacity circuit simulator developed by Ansoft called Nexxim, which was introduced in 2004. Combining the capabilities of HFSS and SIwave with Nexxim through the Ansoft Designer environment, Ansoft envisioned a solution for three specific application areas that required a set of tools capable of solving larger problems without sacrificing accuracy. The targeted applications included high-performance RF/microwave, Signal Integrity and RFIC designs that, due to the size and complexity of the passive structures, high transistor count and spectral density could not be addressed with existing simulation tools or had to be partitioned to reduce the problem size.

With the recent release of Ansoft Designer/Nexxim version 5.0, the company is expanding the product’s focus beyond the needs of the most demanding, high-performance circuits in order to address a wider range of design problems. While the majority of high speed/frequency electronics require the functionality offered by the integration of circuit, system and EM simulators, many design problems do not. For instance, a planar antenna designer typically only needs an EM simulator, layout tool, optional schematic capture (depending if the design is based on a library of parts), design environment with plot generation and linear (and maybe transient) analyses. Unless the antenna is to be integrated with a power amplifier, the antenna designer will likely have no need for system-level or harmonic balance circuit simulation.

To address applications such as this, the product is now available in different suites with functionality bundled into sub-sets for specific design types, reducing potential gaps between tool capability and designer requirements. The three RF product suites are DesignerRF, DesignerRF Circuit and DesignerRF PlanarEM. The two product suites targeting signal integrity designs are DesignerSI and DesignerSI Circuit.

The DesignerRF product suite is tailored to the needs of engineers who design radio frequency integrated circuits (RFIC), monolithic microwave integrated circuits (MMIC), wireless transmission, system-on-chip (SoC), and other RF and microwave devices. Designers can choose between the full set of functions available with DesignerRF or targeted functionality with DesignerRF Circuit (no planar EM capability; see Figure 2) or DesignerRF PlanarEM (no system or nonlinear circuit analyses; see Figure 3). This bundling allows companies with limited budgets to acquire just the necessary functionality for their particular product development needs. New enhancements for RF and microwave design include:

  • System simulator integrated in circuit design with baseband and envelope simulation of advanced communication systems
  • Filter synthesis tool that generates ideal and physical filters for circuit and EM tools
  • Library expansion through downloadable vendor libraries as well as physical library expansion along with the latest active industry models
  • EM improvements with design hierarchy, post-processing variables, thick conductor Q enhancements and parametric snapshot improvements with dynamic links

Figure 2 DesignerRF Circuit with schematic, netlist and layout design views: linear, transient (time-domain) and nonlinear (frequency-domain) intermodulation simulations.

Figure 3 Designer PlanarEM showing field plots (of MMIC with radiating on-chip inductors) and linear frequency response hairpin filter.

The DesignerSI product suite is ideal for engineers designing high-speed electronic interfaces including XAUI™, XFI, Serial ATA, PCI Express™, HDMI™, DDR, DDR2 and DDR3. Engineers using DesignerSI can leverage its optimization algorithms, design of experiments, tuning and post-processing capabilities for key signal-integrity metrics, such as time-domain reflectometry (TDR), bit-error-rate (BER), timing analysis and eye diagrams (see Figure 4). All SI analyses can dynamically link to rigorous electromagnetic extraction. New signal integrity analysis features include:

  • IBIS-AMI simulation: fully supports the latest IBIS standard, enabling fast behavioral modeling of electronic systems with silicon vendor-supplied driver and receiver models
  • QuickEye™ and VerifEye™ enhancements: separate rise/fall step responses, step response parallel processing, improved BER noise floor and enhanced jitter algorithms
  • Design of experiments: large data handling, statistical eye plotting and text array variable support
  • Reporter improvements: statistical eye, mixed mode reporting and network data explorer enhancements
  • Model enhancements: S and W elements wizard, MATLAB™ models, S model caching and multi-source components

Figure 4 DesignerSI showing HDMI (category 2) cable compliance eye diagram test, bit error rate contours, and cable attenuation vs. length and frequency.

By focusing on the most challenging of high frequency design problems, Ansoft has developed a suite of products with impressive accuracy, capacity and speed. The performance of these combined products has made the Ansoft solution very widely used in the signal integrity community and niche RFIC applications. Since their initial release, the Ansoft Designer/Nexxim products have addressed these high-performance markets with regular, timely feature developments and product releases. With the new reconfigured product suites, the company is able to offer portions of this functionality which may be better aligned with the varied needs of the broader RF/microwave design community.

Ansoft Corp.
Pittsburgh, PA
(412) 261-3200