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Agilent EEsof EDA RF Board Design Flow |  |
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RF Board Design ChallengesDesigning RF printed circuit boards today to address the market demand for smaller size, higher performance, lower cost and increased wireless functionality presents a daunting challenge for RF design engineers. Complex multilayer RF boards integrating different technologies like RF and MultiChip (MCM) modules, die-in-board, SMT devices and packaged IC’s are employed to address size and functionality. To optimize volumetric space saving, passive and active devices are embedded and stacked in 3D. Time to market pressures demand minimal design spins while cost pressures demand design-for-manufacturing (DFM) to optimize production yields. In the past, experienced RF design engineers could rely on bench work to tweak their designs; however, today’s multilayer RF boards with embedded and miniature components make this physically impossible, while time-to-market requirements do not allow time consuming tweaking to be competitive. Today, you can rely on Agilent EEsof EDA’s integrated and accurate RF design solutions to quickly evaluate and refine designs before committing to expensive hardware benchwork. Next Section | Flow Chart | Top of Page RF Board Design Flow Chart
Previous Section | Next Section | Flow Chart | Top of Page Starting at the system level The complexities of system design are greater today than ever before. If you are working with recent and emerging wireless standards such as WLAN, UWB, 3GPP, WiMAX and LTE, you can reduce design turns and get to market faster with a complete system that satisfies the needs of RF/analog and baseband applications. Wireless communications system designs must be partitioned into their baseband and RF portions. For the baseband portion, ADS offers an extensive digital baseband library for use with Agilent EEsof EDA’s Ptolemy simulator. ADS Ptolemy is the only commercially available timed synchronous data flow simulator. It is used at the behavioral level to simulate baseband circuits as well as analog and RF circuits, allowing RF pcb engineers to see the effects of circuit-level blocks have on system-level results, for a true mixed signal analysis. For the RF portion, ADS provides you more behavioral models than any other EDA vendor – more than 1800 models in all. ADS design and model libraries are preconfigured for simulation and contain the most complete set of measurements available. Most of the models and libraries are co-developed with Agilent instrument divisions and share the same golden standard algorithms. Many RF engineers are often not familiar with the emerging wireless standards they need to verify their RF design against. The ADS design and model libraries contain pre-configured schematics, data displays, and test benches to help you verify your designs against measurements defined in the wireless standards specifications. Testing and verifying your designs during each stage of development greatly speeds the design process. When additional measurements are required, our Connected Solutions interface to measurement equipment fills the gap with signal generation, sharing, and analysis via instrument-software links. Using the various built-in wireless system test benches you can easily setup a system-circuit co-simulation to verify your analog circuit design against the wireless standards specifications.
UWB Transmitter Test Bench Example In this example, an UWB Transmitter test bench is loaded from the wireless library. You can drop in and tune your RF transistor level amplifier. The results of the specification tests are visualized in the datadisplay. Previous Section | Next Section | Flow Chart | Top of Page Connection to measurement equipment Verification of your communication design using today’s complex communications signal formats is a challenge. Designs can be analyzed early in simulation, and they can be verified later, after all of the hardware returns from fabrication - but mostly you don’t have the luxury of waiting for all of the hardware. You need an intermediate level of verification to cut overall design time and reduce risk. Agilent’s Connected Solutions enables you to perform verification very early in the prototyping cycle for applications ranging from emerging wireless communications products to aerospace/defense by integrating ADS with Agilent test instruments such as signal generators and signal analyzers to enable new design and verification capabilities. This unique combination allows you to share signals, measurements, algorithms, and data seamlessly between the virtual software and physical hardware domains. Designers use this linkage to simulate and evaluate design trade-offs and what-ifs and then turn the simulated signal into an RF test signal on the test bench for hardware test. Conversely, you can take the measured output signal from the DUT and bring it into ADS for additional analysis in the simulation environment.
Connected Solutions enables RF and Mixed-Signal System Integration Testing using ADS Connected Solutions links to digital, analog and RF Test Equipment. Previous Section | Next Section | Flow Chart | Top of Page Schematic design and simulation using the ADS integrated design environment ADS offers the most complete set of simulation technologies available today, from enhanced frequency-domain simulation for conventional RF pcb design, to time-domain and advanced EM simulations. ADS simulation technology enables you to plot, optimize, and visualize circuit performance results. Integrated sensitivity analysis and Design of Experiments (DOE) capabilities enable you not only to flag a yield problem, but to quickly identify and optimize it.
Agilent EEsof EDA's broad range simulation technology offering Designing circuits for different functional blocks often requires an array of simulation techniques. At the end, you want to analyze your complete design including results of different functional blocks or circuit elements. Take a typical LNA board as example. The complete multilayer pcb board can be simulated with our electromagnetic simulator Momentum. In this way, all magnetic coupling between traces, vias and ground planes are modeled as well as other high frequency effects like conductor and substrate losses. The non linear behavior like IP3 of the LNA circuit can be simulated with our Harmonic Balance simulator. Finally, you want to simulate and optimize the complete circuit including the board electromagnetic effects. This can be done by setting up an EM and circuit co-simulation. Agilent EEsof EDA pioneered the co-simulation design concept years ago. It is recognized by many users as an inevitable part of their design flow enabling them to design faster and achieve more accurate simulation results. ADS allows co-simulation by virtually every simulator.
Previous Section | Next Section | Flow Chart | Top of Page Design guides offer you expert help Most design tools don’t include application specific design help. Because ease-of-design is so important, Agilent EEsof EDA has more than a dozen industry experts using their experience and best practices to create application-oriented ADS Design Guides. DesignGuides make your job of circuit design easier, faster, and more consistent with wizards, pre-configured set-ups and data displays, and step-by-step instructions. Complete design applications such as amplifiers, filters, mixers, microstrip circuits, RF systems, Bluetooth, and ultra-wideband designs, to name just a few, give you easy access to the power of ADS without taking time to learn from scratch.
Design guides are created by industry experts. They provide you step by step instructions to make your design and simulation setup a matter of seconds. In this example a design guide template is loaded to simulate load-pull, contour lines and output spectrum. Previous Section | Next Section | Flow Chart | Top of Page Genesys filter sysnthesis tools The Genesys filter synthesis tools are world renowned for their ease of use and extensive capabilities. With the acquisition of Eagleware, the complete set of filter synthesis tools is now available for ADS RF board users as well. Filters designed with Genesys can easily be transferred to the ADS design environment for further integration. Previous Section | Next Section | Flow Chart | Top of Page Integrated RF data processing and data display capabilities If your simulation results do not allow you to see at a glance how your design is performing, you are loosing productivity. The strong and RF focused data analysis and display technology in ADS enables you to view and process your results in the many ways you may want to see them. You can use design review templates as an integrated part of your design flow process. Many customers develop their own data display templates to see the processed data in a specific format. These templates can easily be shared with other designers or complete design groups. In this way, your design review templates become an integral part of your complete documented design flow. All the information is stored together with the project. A perfect example of IP re-usage.
"Using the many built-in templates and RF specific functions, you can quickly build up a set of data display templates and use those as an inherent part of your design process." Previous Section | Next Section | Flow Chart | Top of Page High quality models for accuracy Accurate models are a prerequisite for any successful design flow. Without good models, you cannot make adequate progress or have confidence in your simulation results. Accurate models are available for a wide range of microstrip, stripline and multilayer pcb interconnects as well as packaged devices like resistors, capacitors, inductors, transistors, etc. These models enable you to quickly and easily include details of the board layout at both the circuit and RF subsystem levels in schematic as well directly in layout. ADS includes models for every RF and microwave design application:
Several options enable you to develop customized models that meet your specific device and product requirements:
Previous Section | Next Section | Flow Chart | Top of Page Momentum for 3D Planar EM Analysis Not so long ago, RF pcb designers could get their RF pcb designed without using EM tools. Nowadays, board complexity has gone up so much in terms of layers and interconnect structures as well as operating frequencies, that EM simulation has become an inevitable part of the standard RF pcb design flow. Momentum, our 3D planar Method Of Moments electromagnetic (EM) simulator for passive circuit analysis is fully integrated with the ADS environment. You don’t have to transfer files, rely on interfaces or learn a different tool again, instead you run Momentum directly on your layout saving you significant design time and reducing risk Momentum models the electromagnetic behavior of simple microstrip structures up to the most complex multi-layer geometries with hundreds of vias. Momentum generates accurate EM models you can use directly in the ADS circuit and system simulators using the EM co-simulation concept. In this way your circuit and/or system design can be tuned or optimized with the highest predictability by taking the EM effects of your board in account during your design phase. Momentum offers multi-core 64-bit support with advanced meshing and solver techniques that enable simulation of complex boards. Unlike other EM simulators that mesh with traditional square "Manhattan" meshing, Momentum meshes using a polygonal mesh which offers superior accuracy particularly for curved objects. To handle your ever increasing complex boards, Momentum does support 64-bit and takes advantage of multi-core processor technology as well as parallel distributed computing. In this way your computer power gets optimally used.
Current visualization of a high order Low Pass Filter simulated with momentum μW giving the highest accuracy by using a #D polygonal mesh setup.
Using Momentum RF optimized to simulate complex board structure a resonance and coupling between two signal paths was identified. Previous Section | Next Section | Flow Chart | Top of Page EMDS-for-ADS for Full 3D EM Analysis Some design challenges like wirebonds to substrates or non homogeneous dielectrics cannot be solved by a 3D planar simulator. To support a complete board design flow, ADS now has an integrated, full 3D Finite Element Method (FEM) simulator. In the past, many engineers had to export their layout back and forward to a standalone full 3D EM tool. This resulted in loosing a lot of time translating a layout structure into another drawing environment, redefining the layer stack and dielectric properties, assigning port numbers and reconnecting a S-parameter black box for co-simulation with active elements. With the integration of EMDS-for-ADS, you can now directly send your ADS layout to a full 3D simulator without risking any translation error or going back and forward between two different tools. EMDS-for-ADS uses the established momentum use model for simulating directly from layout as well as simulation from schematic via the layout look-a-like components to perform an EM co-simulation.
EMDS-for-ADS is a Finite Element Method (FEM) electromagnetic simulator enabling the simulation of board structures with bondwires and finite dielectrics. It enables you to simulate directly from layout as well as simulation from schematic via the layout look-a-like component. Agilent's EMDS-for-ADS can also be used standalone as a full-wave 3D EM software platform, with its own complete 3D drawing and visualization environment for non-planar structures such as connectors, packages, machined parts and antennas. Previous Section | Next Section | Flow Chart | Top of Page Direct layout import from Cadence Allegro The Cadence Allegro pcb interface allows you to select Allegro nets by name or by identifying them directly in layout and have them transferred straight into the ADS layout environment. The ADS layout layer stack and momentum substrate information are automatically set during the transfer process. In this way you can transfer and integrate parts of a Cadence pcb layout directly into ADS and take advantage of the extensive set of RF design and simulation capabilities. The direct layout import from Allegro guides you through the process of selecting traces and layers. This interface has cut typical transfer time literally to minutes. Once you have your selected Allegro layout in ADS you have full flexibility to integrate it further in your layout of analyze the circuit using the extensive set of simulators.
Previous Section | Next Section | Flow Chart | Top of Page Antenna Modeling Design System (AMDS) Whenever you have designed your RF board using ADS it has to be integrated in a housing. In the case of wireless appliances, designers face the challenge of fitting multi-band antennas together with the RF board into ever smaller and more stylish packaging that appeals to fashion conscious customers, while complying with regulatory, operator and end-user demands for radiation safety and performance quality. ADS users can export their RF board layout to AMDS. AMDS is the only 3D full wave electromagnetic antenna design and simulation tool specifically developed to enable antenna and industrial designers to overcome this challenge. AMDS provides the capability to simulate antenna structures and their placement within the appliance, in conjunction with the presence of the real-world proximity effects of the human head and hand. This capability is critical to determining parameters such as detuning and sensitivity. The result is an integrated RF board design with antennas and housing that meets or exceeds regulatory and end-user performance requirements, while minimizing the risks of downstream failures in prototype testing.
S11 parameters simulated in AMDS showing the influence of the various components in a mobile phone Previous Section | Next Section | Flow Chart | Top of Page Statistical Design ADS provides you a solution to the challenge of designing products for efficient production. For low volume production, the statistical design ensures product robustness and reliability. In high volume production applications it will help you eliminate manufacturing process and component variations surprises, maximize yield and reduce costs. ADS provides a complete set of statistical design options including Optimization, Sensitivity Analysis, Yield, Yield Optimization (also known as Design Centering), Design of Experiments (DOE), and Yield Sensitivity Histograms.
Statistical analysis of an oscillator whereby 21 different measured transistors were used as well the tolerance of all discrete components was taken in account Previous Section | Next Section | Flow Chart | Top of Page Layout and physical design The ADS integrated layout is the cornerstone of a comprehensive design environment for RF circuit boards. Compared to other pcb tools, it is fast and easy to create your layout. Either by auto-generating a layout from schematic via design synchronization, or by manually placing the layout components and packaged parts directly in layout, ADS offers you multiple modes of design synchronization to match your methodology and enable you to experiment. Special attention is given to speed up the creation of your layout by simplifying many RF specific layout functions such as the creation of clearances, Boolean operations, trace routing and via stitching, just to name a few.
The ADS layout environment provides RF designers the best in class tools for RF layout. Previous Section | Next Section | Flow Chart | Top of Page Physical Connectivity Engine (PCE) When it comes to high-frequency design, traditional LVS tools often limit your interconnect options to simple traces. Agilent’s Physical Connectivity Engine enables you to use any custom shape to build interconnects. The engine runs in the background and extracts interconnect information from traces, paths, vias, and custom polygons, in real time, enabling you to perform a number of interconnect checks without launching a separate utility. The Physical Connectivity Engine also enables you to verify real-time-connectivity graphically on your layout, providing a true representation of interconnects. The Physical Connectivity Engine can also be used to check an imported layout on missing interconnects due to small gaps or other layout inefficiencies. Better interconnect representations reduce design uncertainty before prototyping, so you can be confident that what you design in schematic is what your represent in layout.
The Physical Connectivity Engine extracts real time interconnect information from traces, vias, polygons, etc. Together with the 3D EM viewer, it increases your productivity when designing a board. Previous Section | Next Section | Flow Chart | Top of Page Layout versus Schematic (LVS) Whenever you place components from schematic to layout or vice versa, you must be sure both representations match. ADS offers you a complete set of LVS options such as:
An LVS can be run at any time during the design process; its reporting and auto-zoom functionality enables you to quickly find and correct problems. Previous Section | Next Section | Flow Chart | Top of Page Output to manufacturing You can quickly and efficiently transfer your designs to manufacturing with a number of industry-standard database output formats, such as Gerber, ODB++, DXF, IGES, GDSII. A pick and place file as well as a Bill Of Material (BOM) can be fully customized to your company or supplier preferred format. The ADS layout translators use the industries most advanced and reliable translator algorithms. To achieve the highest confidence that your design is exported correctly, ADS has an integrated output verification tool. This output verification tool will analyze your exported layout for any difference compared to the original layout database. The differences are visualized in the new pre-production environment to enable you to make the necessary correction if needed. In this way you can export your layout with the highest possible confidence, and thus avoiding any corrupt export. The pre-production environment also enables viewing and editing of your design when importing a gerber, dxf, GDSII, or iges file.
The pre-production viewer/editor enables visual inspection of imported and exported layout formats. Previous Section | Next Section | Flow Chart | Top of Page Design Flow Integration - partners for complete success Instead of RF being black magic in your pcb, RF & mixed-signals can now be dealt with and absorbed into your main pcb flow from Cadence, Mentor or Zuken. The integration of the ADS RF board designer removes your boundaries to the RF design domain. In this way, your pcb product designers are free to deliver any amount of RF value from concept to production within your native design flow. Our expanding list of partners goes well beyond standard relationships and is part of an ongoing effort to provide best-in-class tools and technology that work the way you work best in an integrated environment.
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