Appeal No. 2003-0258
Application 09/684,138
The portion of the specification relied upon by the examiner is
as follows:
The amplifier output stage 22 is Class A. PMOS pass
transistor 12 is a large device and has a large gate
capacitance. The emitter follower 28 can turn off
transistor 12 very quickly because of the beta
multiplication of its base current.
Contrary to the examiner’s argument, this portion of the
appellant’s specification does not associate emitter followers
and class A output stages as one and the same. What the
specification discloses is that emitter follower 28 is a
component of class A output stage 22 (page 4, lines 7-8;
figure 1).
The examiner further argues (answer, pages 4-5):
Additionally one of ordinary skill in the art at the
time of the invention would readily appreciate that the
generically shown and described rail-to-rail buffer 18
utilized in [Rincon-Mora’s] figure 1 would by necessity
constitute a class A amplifier. Class A amplifiers due
to their linearity are perhaps the only possible design
choice for an analog amplifier such as a buffer or
error amplifier since any other classification of
amplifier would by their very design distort the
processed signal in an unacceptable manner. Thus
although Rincon-Mora may not explicitly state that the
buffer 18 is a class A amplifier, it is implicitly
understood by those of ordinary skill in the art at the
time of the invention that by necessity buffer 18 is
constituted as a class A amplifier.
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