Research in the Microelectromagnetic Device Group

The University of Texas at Austin

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Electromagnetic Behavior of IC Packaging, Interconnect, and Transmission Line Devices

The "intrinsic" speed/frequency performance of electronic circuits and ICs has increased dramatically in the last fifteen years. For instance, a variety of state-of-the-art integrated circuits operate at clock rates of well over 100 MHz, with digital edge transition times well under 1 nsec. Similarly, today you can buy for approximately $100 (actually, I think its even less now!) a MMIC (monolithic millimeter / microwave integrated circuit) amp with 10 dB of gain and about 1 dB noise figure which operates at 94 GHz; ten years ago such performance at even 5 GHz probably cost at least ten times more. But can these improvements continue unabated? Even if intrinsic performance continues to improve, will extrinsic effects limit system performance? What connection (pardon the pun) is there between how the "components" are packaged and system performance? What electromagnetic effects must we understand and model to design high speed/frequency systems?

Our current DARPA sponsored project on mixed signal packaging:

• Interconnect Series Impedance Calculator .
• SIMIAN: A program for calculating the series impedance of two-dimensional multi-conductor interconnects and transmission lines using the Surface Ribbon Method.
  • Users Manual .
  • Links to the computer code (password required; inquire via e-mail).
• Short paper on our interconnect modeling. This work includes:
  1. Electromagnetics-based Interconnect Parameter Extraction from Geometry .
  2. Effective Internal Impedance .
  3. Conformal Mapping .
  4. Current Ribbon Technique for Frequency Dependent Interconnect Modeling .
• Summary of a paper on the electromagnetic basis of the effective internal impedance .
• Interconnect Series Impedance Determination Using a Surface Ribbon Method .
  • Slide show on the 2-D ribbon method (15 slides,300K total)
  • Minimum ribbons for very efficient modeling of microstrips including finite resistance ground planes
• Extraction of Series Impedance of Three Dimensional Discontinuities .
  • Slide show on 3-D extraction (13 slides, 260K total)
• Interconnect Modeling Code (you'll need a password to get to this; contact me via e-mail to get one)
  • SIMIAN .
• Compact equivalent circuit models for the skin effect .
• Application of compact equivalent circuits to time domain modeling .

• A short paper on a highly accurate, analytical model for microstrip lines on semiconductor (e.g., silicon) substrates (pdf file, 42K).
  • Here's an example of how a semiconducting substrate can interact with metal "ground" lines to affect the series inductance and resistance of an interconnect line.
  • And here's a calculator for the characteristic impedance and propagation constant of these "MIS microstrip lines".
• A short paper on compact circuit models of the skin effect.
• A short paper on microstrip lines on silicon "pillars".
• Experimental measurements on sub-micron microstrip-like transmission lines .

• Slides from our 1993 MTT-S poster on measurements and modeling of conductor loss in CPW.
• A short paper on modeling Schottky-contacted coplanar waveguide on epitaxial semiconducting substrates. This device can be used as either a phase shifter or a delay line.
• A short paper on the behavior of CPW using a "V-groove" ground plane.

• ARPA MCM CAD Project ; a summary of one of our past projects in this area: