Appeal No. 2002-0397
Application 08/925,968
modification would completely change Nelson. That is, the
rejection requires doing more than replacing a fixed resistor
with an active element FET acting as a resistor in a one-to-one
swap; it requires replacing the voltage divider structure in
Nelson (an RC impedance in series and an RC impedance in shunt)
with a single FET. The examiner's rejection does not address
this difference in structures or show that these structures were
known to be equivalent. Furthermore, we agree with appellant's
arguments that the claimed structure is different because a
parasitic capacitor is not present in the RC attentuator of
Nelson and an FET operates differently than the RC attenuator in
Nelson because of the "pumping" effect of this parasitic
capacitor. The examiner's rejection ignores the structural and
operational differences stated in these arguments. The examiner
states that "any resulting effect of the claimed structure will
of course be present once the obvious modification of Nelson's
Fig. 5 is made" (emphasis omitted) (EA7), which we interpret to
mean that if the RC voltage divider attenuator 14 of Nelson is
replaced with a biased FET, the parasitic capacitor and its
function would be inherent. This idea of modifying a reference
for one reason (replacing one kind of resistor with another kind
of resistor) and then stating that other claimed structure and
functions (parasitic capacitor and "pumping") would be inherent
is indicative of hindsight based on appellant's disclosure. Such
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