Appeal No. 97-2993 Page 4
Application No. 08/363,133
OPINION
It is the examiner’s contention that Smith discloses the
subject matter of instant claim 1 but for the low pass filter
section. Smith employs sample and hold circuits but the
examiner relies on a recitation at column 6, line 16 of Smith,
to wit, “A S/H circuit performs roughly as a low-pass filter,”
as a suggestion that a low pass filter section can be used in
place of the disclosed S/H circuits. Then, the examiner cites
Sedra for a showing that filters may make use of inductors and
capacitors so that, if one were to substitute a low pass filter
for the S/H circuits of Smith, then that filter would be made
of inductors and capacitors.
We disagree. At best, the cited portion of Smith can
only be held to be a suggestion that, under the right
circumstances, such as the particular arrangement of Smith, a
S/H circuit might act like a low-pass filter. Clearly,
however, a S/H circuit is not, inherently, a low-pass filter
and we find no reason why the skilled artisan would have
removed the active S/H circuit disclosed by Smith and
substituted therefor a passive low-pass filter, as claimed.
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