Appeal No. 2002-0397
Application 08/925,968
Nelson and the subject matter of claim 1 "is that appellant uses
a continuously-on biased FET instead of the discrete resistor
shown by [Nelson]" (EA3). The examiner reasons (EA3-4):
[T]he replacement of a discrete resistor with a
continuously-on biased FET is notoriously well-known in the
art (official notice is taken) and there is obvious
motivation to make such a replacement, i.e., to save chip
real estate, since discrete resistors take up more space
than integrated FETs acting as resistance element. The
resistor recited in the claim also fails to distinguish
patentably over Nelson because it is also old and well-known
in the art to add such a series resistor between the gate
bias voltage and the gate of the FET for the purpose of
controlling the on level of the FET (and thereby controlling
the resistance value of the FET), which is an old and
well-known concept to those having ordinary skill in the
art.
The examiner cites Carroll, Figs. 1 and 2, Townley, Figs. 3-6,
and Ohmi, Fig. 9 as showing the equivalence between a discrete
resistor and a continuously biased FET (EA5).
Appellant argues that the claimed biased transistor includes
a parasitic capacitance and, therefore, is not structurally
similar to an RC attenuator circuit using discrete resistors
(Br6-7). It is argued that while a transistor, continuously
biased ON, may provide impedance between its input and output
terminals, e.g., resistance, unlike a discrete resistor, the
transistor comprises a parasitic capacitance that cooperates with
a resistive element coupled to the transistor's enable terminal
to increase ("pump") the voltage applied to the enable terminal
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