The following technical publications are available for download. In addition, application notes can be found on our knowledge base page, and at muehlhaus.com. You may also find a large list of customer and Sonnet references on our Bibliography Page. 

Potentially Significant On-Wafer HF Measurement  Calibration Error

While significant effort has gone into the development of improved on-wafer de-embedding schemes, this article discusses and explores a previously unrecognized and possibly common on-wafer calibration error. This article addresses a specific case of a spiral inductor on silicon for which there was a significant difference between measurement data and analysis data and concludes that the problem is with the measurement. A new method of "synthetic calibration" is described that can be used with any EM analysis to quantify calibration error for any proposed set of calibration standards.

Copyright 2005 © by the Institute of Electrical and Electronic Engineers: this article appeared in IEEE Microwave Magazine, December 2005, pp. 94-100.

(Click to download PDF article)

Planar EM Analysis: A New Standard for High Frequency Applications

This article discusses few of the new features in Version 10 of the Sonnet® 3-D planar EM analysis software, including automatic generation of thick metal models for its exclusive conformal meshing, porting of Sonnet’s software to Linux, in addition to Windows and Unix, a new very powerful Cadence interface, a new very flexible interface to Eagleware and a new broadband SPICE model generator.

This paper, by Dr. James C. Rautio, was published in the November 2004 issue of Microwave Journal.  

(Click to download PDF article)

Testing Limits of Algorithms Associated with High Frequency Planar Electromagnetic Analysis

Rather than showing how “accurate” electromagnetic software is, this paper looks for error and failure modes with an eye to developing test cases to expose them and to quantify them. For example, interpolation can fail (i.e., take a long time, even though the result is still accurate) if there are a large number of box resonances. Large dynamic range analyses can fail if the noise floor is approached. Complete information on the test circuits is provided, however, don’t expect other vendors to rush to publish their results. These circuits really push some serious limits.

This paper, by Dr. James C. Rautio, was presented at the European Microwave Conference, October 2003, Munich by the president and founder of Sonnet Software, Dr. James C. Rautio. Users interested in this paper may also be interested in Sonnet Software's Benchmarking Page.

(Click to download PDF article)

Microstrip Conductor Loss Models for Electromagnetic Analysis

An Investigation of Microstrip Conductor Loss

Abstract: Conductor loss in microstrip is shown to exhibit much more complicated behavior than is generally recognized. This paper shows that conductor loss behavior can be divided into three distinct frequency bands. Furthermore, microstrip conductor loss in general does not vary with the normally expected square root of frequency, even at high frequency. Conductor loss is explored by means of numerical electromagnetic analysis based experiments and is verified by measurement.

This article by Dr. James C. Rautio appeared in the December 2000 issue of IEEE Microwave Magazine, pp.60-67, and is well worth your time for better understanding how and why microstrip circuit losses change with frequency. The ZIP file contains an MS Word file, together with Sonnet em Suite example files, which may be used with the free Sonnet Lite package. Click the tag below to download the ZIP file.

(click to download MTTmagMetalLoss1.zip, 613 KB)

Electromagnetic Analysis Speeds RFID Design

This article, by Dr. James C. Rautio, describes how to use Sonnet to design Radio Frequency IDentification (RFID) tags. In this extremely competitive and dynamic market, getting the best and most innovative products to market before the competition is absolutely critical to survival. This paper shows how to use Sonnet for a complete and accurate analysis of the reader-coil pair in minutes, allowing dozens of designs to be considered in a single day. 

This paper was first published in the February 2003 issue of Microwaves & RF magazine. The author, Dr. James C. Rautio, is the president and founder of Sonnet Software.

Planar Electromagnetic Analysis

This paper covers the history and speculates on the future of applied numerical electromagnetics for planar structures. Starting with Maxwell, the origin of numerical electromagnetics is discussed and an overview of the present state-of-the art is presented, covering both unshielded and shielded environment approaches. Detailed knowledge of EM theory is not required, theory and equations are not used at any time.

A Conformal Mesh for Efficient Planar Electromagnetic Analysis

A planar electromagnetic analysis can provide faster analysis by using larger subsections at the cost of reduced accuracy. However, even if both rectangular and triangular subsections are used, large subsections are not practical for complicated curving planar circuits. This paper describes the method introduced by Sonnet 9 for joining small subsections so that the large subsections so formed can follow the arbitrarily curving edges of a complicated circuit while still inherently including the high edge current. Using such conformal subsections, non-Manhattan geometries can be analyzed efficiently and accurately. This is especially important for continuously curving geometries (like circular spiral inductors), which cannot be efficiently meshed using rectangular and triangular subsections. These conformal subsections retain nearly all the accuracy of small subsection size while also realizing the speed of large subsections, even for complicated geometries.

Copyright 2004 © by the Institute of Electrical and Electronic Engineers: this article appeared in IEEE Transactions on Microwave Theory and Techniques, January 2004.

EM Approach Sets New Speed Records

This paper describes Sonnet's novel technique, called "Adaptive Band Syntheses" (ABS). The ABS technique combines minimal adaptive EM frequency simulation with a highly accurate proprietary interpolation technique to provide 200-400 data points.  Since the technique uses a minimal number of EM simulation samples, the data sweep requires significantly less time than conventional techniques and yields much higher data resolution.  For example, a 5th order microstrip bandpass filter may require only 4 or 5 frequency samples to yield a 300 point sweep from transition band to transition band.

This paper was first published in the May 2002 issue of Microwaves & RF magazine. The author, Dr. James C. Rautio, is the president and founder of Sonnet Software.

Rigorous Evaluation of Worst Case Total Crosstalk in the Time Domain Using Frequency Domain Scattering Parameters

This paper describes how to use frequency domain S-parameters to determine the maximum crosstalk in a digital interconnect. The approach starts with an electromagnetic analysis of the interconnect over a frequency range covering all significant spectral power in the expected input signal. Then a spreadsheet is used to evaluate the maximum possible crosstalk voltage in the time domain. The only assumption in this approach is that the subsection size used in the electromagnetic analysis is small with respect to wavelength. There are no other approximations or assumptions to break down.

For example, all effects of inductance, capacitance, resistance, transmission lines, loss, dispersion, non-parallel coupling, far spaced coupling, etc., are all completely included. This approach is especially useful for advanced designs when it is not known if previous approximations are adequate. Measured versus calculated data is included. An example of crosstalk between two 32 bit buses crossing over each other is provided.

The following download includes the paper, an Excel spreadsheet for calculating worst case crosstalk, and all the example files used in the paper.

(click to download crosstalk1.zip)

Short Paper: Free EM Simulator Analyzes Inductors on Silicon

See examples of how you can use our free Sonnet Lite planar EM simulator to analyze arbitrary spiral inductors on lossy silicon. This article by Sonnet president Dr. James C. Rautio appeared in the September 1999 issue of Microwaves & RF Magazine (p.165-172).

Short Paper: Tips and Tricks on Sonnet Lite

Get more out your free Sonnet Lite high frequency 3D planar EM software, with a few helpful hints and tips. This article by Dr. James C. Rautio appeared in the November 1999 issue of Microwave Product Digest. Dr. Rautio shows you how to obtain highly accurate results with Sonnet Lite, and introduces the combination of fast netlist analysis with accurate EM simulation to enable precise analysis of planar filters. This article provides great benefit to both Sonnet EM Suite customers and Sonnet Lite users.

(click to download mpdnov99.pdf, 572 KB)
(click to download example files used in this article: mpdnov99.zip)

An Electromagnetic Time-Harmonic Analysis of Shielded Microstrip Circuits

This paper summarizes the theory used by Sonnet's electromagnetic analysis engine. If you want to understand how Sonnet performs the EM simulation, this is the paper for you.

Copyright © 1987 by the Institute of Electrical and Electronic Engineers: this article appeared in IEEE Transactions on Microwave Theory and Techniques, MTT-35, Vol 8 August 1987.

(click to download PDF 494 KB)

Deembedding the Effect of Local Ground Plane in EM Analysis

In electromagnetic analysis of complex planar circuits, it may be necessary to use internal ports, e.g., in locations where surface mount devices might later be attached. These internal ports require a local ground plane for ground reference when access to the global ground reference is unavailable. Even if perfectly conducting, use of such a ground plane still introduces excess phase in the local ground currents. This paper describes how to remove the effect of a lossy or lossless local ground, even including multiple closely spaced ports.

Copyright 2005 © by the Institute of Electrical and Electronic Engineers: this article appeared in IEEE Transactions on Microwave Theory and Techniques, February 2005.

(click to download PDF)

Planar Electromagnetic Software - Personal Reflections

Dr. James C. Rautio, the President and founder of Sonnet Software takes a personal look back at the development of applied high frequency numerical electromagnetic analysis. This article was first published in the March 2005 issue of Microwave Journal as its Cover Feature.

(click to download PDF)

Unification of Double Delay and SOC Electromagnetic Deembedding

This paper describes a unifying theory, showing that double delay and SOC are each special cases of an extended SOC technique. Results related to the characteristic impedance as determined by this extended SOC deembedding are also presented.

Copyright© 2005 by the Institute of Electrical and Electronic Engineers: under submission to the IEEE Transactions on Microwave Theory and Techniques.

(click to download PDF)