Appeal No. 1997-2297 Page 10
Application No. 08/337,636
Turning next to the rejection of claims 3-5, 7, 8, and
10-21 under 35 U.S.C. § 103 as unpatentable over Koker
considered with McClure, we turn first to independent claims
12 and 21. The examiner (answer, pages 7 and 8) relies upon
McClure for a teaching of a Schmitt trigger circuit where the
pull-down driver has a gate size five times greater than the
pull-up driver. We find however, that the examiner's
reference to McClure (col. 1, lines 61-65) is referring to the
difference in gate sizes between the pull-up and pull-down
transistors of the Schmitt trigger and not the gate sizes of
the inverter 3, 13, etc., of the buffer circuit.
We note that each of independent claims 12 and 21 recite
a similar limitation as claim 1, i.e., in claim 12 "said
buffer has a first input gate size of a pull-down device of
said buffer that is at least five times greater than said gate
sizes of said first and second MOS transistors" and claim 21
"said CMOS inverter has a first input gate size of a pull-down
device that is about ten times greater than said gate sizes of
said first and second PMOS transistors." As McClure is silent
as to the relative scaling of the transistors in the buffer
circuit inverters 3, 13, etc., to the scaling of the drive
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