Appeal No. 2000-0312
Application No. 08/610,007
teachings of Masuda, the examiner is of the opinion (answer,
page 4) that:
Those having ordinary skill in the art would recognize
that the DC offset circuit of Masuda also can be used
to compensate for DC offset voltage on the input
signal 10 by connecting the non-inverting terminal and
the inverting terminals of the amplifiers (22, 28) to
predetermined reference voltages. Thus, compensating
DC offset voltage on the input signal of the Masuda
circuit is a routine design expedient for an engineer
depending upon the particular environment and the
applications in which the Masuda circuit is to be
used.
The examiner’s contentions to the contrary notwithstanding,
Masuda never indicates that there is a dc offset voltage on the
input signal 10. In Masuda, either a dc offset voltage (i.e., a
reference voltage at ground potential) or an input signal 10 is
provided as an input to amplifier 22 via two-position switch 14.
The input to amplifier 22 never simultaneously receives both the
reference voltage and the input signal. Accordingly, we agree
with the appellants’ argument (reply brief, page 3) that “it
would be impossible with this circuit configuration to
‘compensate for variations in a dc offset component of an analog
input signal’ as required by Applicants’ claimed invention.” We
also agree with appellants’ arguments (reply brief, page 4) that
“in the Masuda reference, the dc offset voltage being
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