Appeal No. 2002-0397
Application 08/925,968
R1 and C1 is Z1 and the impedance of R2 and C2 is Z2. The
attenuation factor ATT = Z2/(Z1 + Z2) (col. 1 eqn. (1)), which is
recognized as the voltage division expression. The attenuation
factor ATT is frequency independent if C1R1 = C2R2 (col. 1,
lines 44-47). However, it is often difficult to satisfy this
relationship by manual adjustment. Nelson detects any incorrect
frequency response at the output of the attenuator and
electrically compensates for it (col. 2, lines 35-42). Nelson
performs the claimed function of transforming "binary signals
that vary between first and second preselected voltage levels" to
"binary signals that vary between the first preselected voltage
level and a third preselected voltage level." The output shown
in Fig. 2B is attenuated from the input in Fig. 2A, where it is
assumed that the lower (first) voltage level could be zero volts.
However, Nelson does not perform the function using the structure
and function of the claimed invention. Manifestly, there can be
many patentable ways to perform the same function.
The examiner undertakes to perform a wholesale rebuilding of
Nelson by taking Official Notice of the equivalence of resistors
and biased FETs and then by adding in a gate resistor. There is
certainly no suggestion for this modification in Nelson; indeed,
since Nelson is an RC attenuator, structured as a voltage
divider, and since the rejection appears to require replacing the
RC attenuator 14 (not just one resistor) with an FET, the
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