Accelerating MMIC, RF Module Design with ADS 2009 Update 1
Agilent’s Advanced Design System (ADS) 2009 Update 1 is a complete front-to-back solution for MMIC and RF module design. This includes a complete flow to manufacturing: Enhanced PDKs, Desktop LVS & DRC and Calibre LVS integration; full support for X-parameters*; enhanced integrated 3D EM analysis; and an easy-to-use Optimization Cockpit. This combination of capabilities enables designers to stay within a single design platform throughout their development cycle (design, simulation and manufacturing output), eliminating the time and expense integrating disparate point-tools.
Complete MMIC Manufacturing Design Flow
Agilent ADS accelerates design with capabilities such as a customized MMIC layout tool bar. Built on top of foundry-approved PDKs (currently available for TriQuint, Win Semiconductor and UMS), the tool bar allows one-click access to process-specific functions for layout creation and editing (see Figure 1). Example functions include automatic via insertion; the conversion of trace structures to transmission lines; and splitting, joining, stretching and tapping into transmission lines. Easy access to these capabilities improves productivity and also helps eliminate layout-versus-schematic errors early in the design process.
Figure 1 In MMIC design, the PDK-specific tool bar can be used to convert selected traces into transmission lines.
For improved synchronization, ADS 2009 Update 1 includes multiple options that go well beyond the typical “always on” tools that are often inflexible and may lead to design errors that are difficult to correct without damaging or discarding an entire design. One such capability is the continuously updated “Design Differences” window, which provides either a single or a dual representation of schematic and layout. In this mode, the designer can choose to place specific schematic components onto the layout or, at will, update the entire layout from the schematic.
Figure 2 Integration of Calibre LVS into the layout environment equivalency of a schematic and layout.
Once an initial MMIC design is complete, a full LVS check will ensure that the layout is electrically equivalent to the schematic prior to wafer fabrication. This is simplified by integration of tools such as Mentor Graphics™ Calibre LVS into the layout portion of ADS, as shown in Figure 2.
Many of today’s high-frequency designs are nonlinear (e.g. mixers and power amplifiers). The ability to model for nonlinear effects at the system level depends on behavioral models that accurately account for phenomena such as harmonics, frequency mixing and impedance mismatch. To meet this need, Agilent developed X-parameters, a new category of nonlinear network parameters for high-frequency design to accurately model nonlinear behavior. X-parameters help overcome a key challenge in RF design; nonlinear impedance differences, harmonic mixing and nonlinear reflection effects that occur when components are cascaded under large-signal operating conditions. X-parameters can be created from measurements made with a nonlinear vector network analyzer (NVNA) or the new X-parameter Generator in ADS 2009 Update 1. The resulting models enable design houses to provide virtual, simulated samples of power amplifiers (PA), front end-modules (FEM), transceivers and more to their customers before hardware samples are available while protecting the embedded intellectual property.
Figure 3 The Optimization Cockpit provides a unified interface for managing all setting and results.
The new Optimization Cockpit provides the designer with greater insight, real-time tuning and optimization control to help produce better designs faster. At a glance, one can identify which variables are constrained at the limits of their allowed ranges and adjust these limits. One can also observe the Pareto of which goals dominate the error function to provide guidance on setting the goal weightings. Error function trends can be monitored, providing guidance on when to choose a new optimization algorithm. The optimization is easily paused at any time (saving the state of component parameters), changes made, then continued from where it left off (see Figure 3).
Assessing EM effects
Figure 4 The perforated metal shield was created in EMPro and placed over a microstrip hair pin in ADS, enabling joint simulation of their combined interaction.
As high-frequency end-user devices become more compact, it becomes increasingly important to understand the EM effects of 3D components like interconnects, shielding, packages and on- and off-chip embedded passives. Integrated 3D EM in ADS enables the ability to co-simulate 3D components with 2D layouts to account for EM effects. ADS 2009 Update 1 includes swept simulation and optimization for its 3D FEM solver (EMDS G2). This, along with parameterized 3D components generated in EMPro, as shown in Figure 4, saves time compared to importing static simulation data and manually modifying 3D models in an isolated 3D EM point tool, producing the most accurate simulation results and uncovering interactions before fabrication.
Agilent ADS 2009 Update 1, a complete front-to-back solution for MMIC/RF module design, provides a single, integrated design flow enabling users to stay within a single design platform, eliminating the time and expense integrating disparate point-tools and accelerating the overall development cycle.
*X-parameters is a trademark of Agilent Technologies
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