CAD Sessions

Abstract: Traditionally thermal analysis tools have been disconnected from the RF design tools resulting in a completely manual data entry process to get the data into the thermal analysis tool. As a consequence, the thermal analysis tools are typically used only at the final design verification stage in the flow, if at all. To improve this cumbersome area in the design flow, AWR has partnered with CapeSym to integrate AWR’s Microwave Office® RF design environment with CapeSym’s SYMMIC thermal analysis software. With this integrated toolset, the RF Design Engineer now has the ability to quickly perform thermal analysis early in the design flow to provide insight into design optimization due to thermal considerations, instead of late in the flow where finding problems is most costly, or worse doing a thermal IR scan on hardware only to find a thermal problem.
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Combining Differential/Integral Methods and Time/Frequency Domain Analysis to Solve Complex Antenna Problems

Abstract: The accurate and efficient electromagnetic simulation of antenna elements poses a substantial challenge due to the wide variation present in antenna topologies and operating specifications as well as the environments they are installed in for end use. This presentation provides an overview of several of the most robust numerical techniques currently employed by commercial simulation packages, including transient, finite element and integral equation based methods. The details of each algorithm are discussed, and their relative strengths and weaknesses are compared. Several antenna examples are presented to demonstrate where each solver technology is most applicable, as well as scenarios in which they can be used in combination.
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Advances in Linear and Non-Linear Modeling for Improved Microwave Design

Abstract: This talk will present two areas of improvement to linear and non-linear modeling. The first area concerns best-practice application examples of electromagnetic (EM) analysis combined with accurate broad-band parasitic models for improved board-based designs using surface mount components. The focus is on co-simulation – which combines circuit and EM simulation – of surface mount capacitors in shunt configurations. This is an important topic especially for microwave power amplifier designers, who commonly use shunt-mounted capacitors in impedance matching networks that require very precise impedance transformations. The accuracy of the simulations is important at the fundamental design frequency as well as at several harmonics.
The second area that will be covered in this talk is behavioral modeling using X-parameters. X-parameters comprise a parameter set that describes the amplitude and phase relationship between different frequency spectra for waves incident and reflected from a multi-port. The availability of measurement instrumentation and design simulation software to support this technology now makes X-parameters a viable option for “black-box” nonlinear device modeling. Examples to be shown in this talk will include a surface mount driver amplifier, represented as a substrate-scalable X-parameter model that has been independently validated against measured load-pull data.
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CAD tools for Multi-Radio Design

Abstract: Advances in technology have enabled the possibilities to integrate multi-band and multi-mode radios into single packaged chips covering the diversity of communication standards from 2G GSM, 3G UMTS, to 4G LTE and LTE-advanced as well as WLAN, BT, and GPS impart unique challenges on the RF CAD due to the high complexity and integration of such chips. This requires simulation of the package as a whole to include electromagnetic coupling, interference, and radiation. The focus will be on the challenges and requirements as well as the latest trends on multi-radio CAD. A thorough discussion of advanced techniques for receivers and transmitters modeling of multi-radio SoC or SiP will be presented.
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Spiral Inductor Model Extraction and Utilization - A Survey of the Field

Abstract: Equivalent circuit model extraction of spiral inductors is an active area of research. Uses of equivalent circuit extraction range from simply providing insight to a designer, to allowing for automated design optimization. Over the years, many equivalent circuit topologies have been proposed for modeling spiral inductors. A cursory review of such topologies will be provided. A few of the methods used to extract these models will be discussed. Finally, utilization of these models will be demonstrated. Most equivalent circuit topologies include a series inductor meant to represent the main inductance of a spiral. The series metal loss is modeled with a resistor and the turn - to - turn capacitance is represented with a capacitor. All three components can be replaced or augmented with more complex sub-circuits to allow for more physically accurate models. For example, the RL pair included in the series branch of the equivalent circuit in Figure 1b models skin-effect losses. The substrate around the spiral is often modeled with capacitors (bulk capacitance) and resistors (substrate loss) connected to ground.

A design engineer may be interested in a particular property of a spiral inductor. As such, he/she may perform a full-wave electromagnetic analysis on a proposed spiral design and perform an equivalent model extraction. The modeled values can then be used to modify the design of the spiral to achieve the desired performance. Alternatively, this approach can be automated to allow a software optimizer to manage the design process. Model extraction itself can be performed using analytical, numerical, or physical (heuristic) approaches. Analytical methods suffer from extreme sensitivity to noise. Numerical methods are computationally intensive and can often result in non-physical models. Heuristic approaches suffer from inaccuracy. Hybrid methods involving all three have been shown to be effective.

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