SPECIAL UNIVERSITY ORAL EXAMINATION

Mixed Circuit and Device Simulation for Modeling,
Analyzing, and Designing RF Devices

Francis M. Rotella

Integrated Circuits Laboratory
Department of Electrical Engineering,
Stanford University

CIS Extension Auditorium
Friday, June 5, 1998
12:45 - 1:45 pm

Refreshments: 12:30 pm

Abstract

Wireless and mobile communications have grown significantly over the last decade. Projected growth is expected to continue along similar trends as new markets, especially in Asia and Africa, are opened. In order to meet the demands of these new markets, next generation technology is required on continually shorter time schedules. For new technology development, TCAD tools, such as PISCES, have provided invaluable information to a design engineer; hence, it is important that such tools are developed and utilized in the RF domain in order to meet the demands of the new wireless and communication markets.

This talk will discuss the use of PISCES (aka Medici from Avant! and Atlas from Silvaco) in RF device simulation. It begins with a discussion of two additions to PISCES in order to meet the challenges of RF simulation: circuit elements (i.e. parasitic components and matching networks) and large signal steady state simulation (i.e. harmonic balance). The coupling of circuit and device simulation is discussed and specific improvements to PISCES are explained. Harmonic balance simulation is only described, but references to previous works are included.

With the improvements to PISCES, an RF LDMOS (laterally diffused MOSFET) device is modeled and analyzed for performance. A brief review of the device operation is provided and the key modeling regions for the device are discussed. Upon developing a model, it is verified using measured IV and CV characteristics. The model is used in an RF distortion simulation which is shown to match experimental results. With a proven RF model, the device's RF performance is studied and the effect of parasitic components are analyzed. With confidence in a valid RF model, design decisions can be addressed and studied before committing to silicon. Thus a shorter development cycle results.

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