Appeal No. 1997-2297 Page 12
Application No. 08/337,636
times, i.e., a ratio of 1:5 for A:B, that of drive transistor
2p. As acknowledged by appellants (brief, page 10) "[i]f the
E and F values from Koker and the values of McClure, col. 1,
lines 56-66 were combined, ((F/A / E/B)) would be
'approximately 3 to 5'." We agree. We find that upon
providing the transistor 2n of Koker with the conventional
three to five scaling between the pull-up and pull-down
transistors 2p, 2n of the Schmitt trigger as disclosed by
McClure, would meet the claim limitation "wherein a ratio of
the first input gate size divided by said first gate size to a
second input gate size of a pull-up device of said buffer
divided by said second gate size is at least five" i.e., ((F/A
/ E/B))$ 5. We are unpersuaded by appellants assertion
(brief, page 10) that the teachings of McClure cannot be
applied to Koker because "McClure teaches away from using such
'heavily ratioed' drive transistors. See, for example, col.
1, line 56 to col. 2, line 68. In fact, it appears that the
entire motivation of McClure is to avoid such situations." In
Koker, the gate size of the transistors N1pa and N2pa of the
Schmitt trigger are three times the gate size of transistors
P1pa and P2pa. Although McClure is directed to providing
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