Appeal No. 96-2722
Application 08/281,168
page 7) states that it is well known that FET’s include MOS’s, and that it would have been obvious to
substitute different device technologies (i.e., IGFET’s, JFET’s, MOSFET’s, BJT’s, etc.). The
examiner offers Sedra & Smith to show that a FET can indeed be a MOS transistor. Appellants argue
(Brief, page 11) that there is no motivation for replacing the FET with a MOS, and that Sedra & Smith
actually teach a bipolar transistor and not a MOS (Reply Brief, page 5).
We agree with the examiner that it would have been obvious to employ various different device
technologies, and that the resulting connections would have been within the ordinary level of skill in the
art. This is buttressed by appellants' admission in their specification at pages 40 to 41 that while MOS
transistors are used in the start-up circuit of the preferred embodiment, the start-up circuit "may include
other insulated gate transistors which provide effects similar to those of the preferred embodiments"
(specification, pages 40 to 41).
We also agree with the examiner that Sedra & Smith’s Figure 5.9(b) at page 308 shows a
MOSFET. We conclude that it was well-known in the art at the time of applicants’ invention that
surface FET’s include MOSFET’s and other insulated gate FET’s, that MOSFET’s are a type of FET,
and that field effect transistors (FET’s) fall into two general classes: metal-oxide semiconductor (MOS)
FET’s, and thin-film FET’s. See SEVIN, JR., Field-Effect Transistors, pp. 24 and 123, McGraw-Hill
Book Company (1965); and RICHMAN, MOS Field-Effect Transistors and Integrated Circuits, pp. vii
7
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