Thesis
Modeling of FETs with abnormal gate geometries for radiation hardening
Washington State University
Master of Science (MS), Washington State University
2004
Handle:
https://hdl.handle.net/2376/225
Abstract
A new accurate modeling technique is described that provides a SPICE model, based on the SPICE model of a standard rectangular FET, for any FET with an abnormal gate geometry, such as an annular FET. The new model uses conformal mapping to map an abnormal geometry onto a rectangular geometry. Conformal mapping has been used as a tool for this type of problem in previous research, but the new method presented splits the problem into mapping of multiple regions defined by the equal-potential lines on the rectangular gate being inverse mapped onto the given gate geometry. The length of the equal potential lines are used to define the length of the channel in a region of the gate and the spacing of equal potential lines is used along with space-charge conservation to find how the output resistance is altered by the geometry. This method for finding accurate DC models of a FET with any gate geometry was then automated making it fast and easy to use. To get correct small-signal models, as well, the necessary changes to a BSIM3 SPICE model are described taking into account the effect of geometry on the small-signal capacitance values. The modeling of the DC behavior is shown to be accurate to better than 10% for drain current values and 11% for output resistance. Capacitance measurements agree with theory to better than 8%. The models are proven to be accurate for annular FETs and for another radiation hardened FET, which is called a horseshoe FET. Other radiation hardened FETs are also described. These FETs include gate around source and gate around transistor FETs. The DC and small-signal models for these FETs were shown accurate to within 20% using a simplified modeling technique. The methods used to model these different types of FETs with abnormal gate geometries are very powerful allowing the modeling of transistors of any gate geometry with high accuracy, whether for radiation hardening or another purpose.
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Details
- Title
- Modeling of FETs with abnormal gate geometries for radiation hardening
- Creators
- Corbin Leigh Champion
- Contributors
- George S. La Rue (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Electrical Engineering and Computer Science, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900525373001842
- Language
- English
- Resource Type
- Thesis