Ex parte Gotoh

Board of Patent Appeals and Interferences

Mar 5, 1999

08261613 (B.P.A.I. Mar. 5, 1999)

Application for patent filed June 17, 1994.1
1
THIS OPINION WAS NOT WRITTEN FOR PUBLICATION
The opinion in support of the decision being entered today (1) was not written for
publication in a law journal and (2) is not binding precedent of the Board.
Paper No. 13
UNITED STATES PATENT AND TRADEMARK OFFICE
__________
BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
__________
Ex parte KIMIKO GOTOH
__________
Appeal No. 96-3440
Application 08/261,6131
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ON BRIEF
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Before JERRY SMITH, CARMICHAEL, and RUGGIERO, Administrative
Patent Judges.
CARMICHAEL, Administrative Patent Judge.
DECISION ON APPEAL
This is an appeal from the final rejection of Claims 2
and 7-9. Claim 1 was canceled. The Examiner’s Answer
indicates that the other remaining claims, Claims 3-6 and 10,
are directed to allowable subject matter.
Claim 7 reads as follows:
A low-voltage output driving circuit comprising:
Appeal No. 96-3440
Application 08/261,613
2
a buffer stage comprising an input for connection to a
control circuit and an output;
a pull-up transistor connected between the output and a
power supply voltage source, said pull-up transistor having a
control terminal for rendering said pull-up transistor
conductive when activated;
a gate circuit having an input and an output, the input
of said gate circuit being connected to the control circuit
and the output of said gate circuit being connected to the
control terminal of said pull-up transistor; and
a clamping transistor connected to the output and to the
control terminal of said pull-up transistor at a node located
in the connection between said gate circuit and said pull-up
transistor, said clamping transistor having a control terminal
for connection to the power supply voltage source and having
respective input and output terminals, the input terminal of
said clamping transistor being connected to the node between
said gate circuit and the control terminal of said pull-up
transistor and the output terminal of said clamping transistor
being connected to the output of said buffer stage;
said clamping transistor when conductive maintaining the
control terminal of said pull-up transistor at the output
level of said buffer stage when the output level is higher
than the level of the power supply voltage.
The examiner’s Answer cites admitted prior art and the
following prior art reference:
Tarng 5,280,200 Jan. 18, 1994
OPINION
The claims stand rejected under 35 U.S.C. § 103 as
unpatentable over admitted prior art in view of Tarng.
Appeal No. 96-3440
Application 08/261,613
3
The claimed invention is an improvement over the admitted
prior art driving circuit shown in Figure 5 of the
application. The improvement is the addition of a clamping
transistor which maintains the control terminal of a pull-up
transistor at the output level of a buffer stage when the
output level is higher than the level of the power supply
voltage.
According to the examiner, the improvement was suggested
by Tarng, who shows a clamping transistor MONC in Figure 10A.
In response, appellant argues:
The purpose of the recited “clamping
transistor” is to maintain the control terminal of
the “pull-up transistor” at the output level of the
buffer stage when the output level is higher than
the level of the power supply voltage V . Althoughcc
Tarng shows that a “voltage clamping circuit” per se
is generally known, the context in which the
“voltage clamping circuit” is disclosed in Tarng
significantly differs from the purpose of the
defined “clamping transistor” comprising a component
of the “driving circuit” as defined in Claims 2-10
on appeal. Thus, Tarng describes the “voltage
clamping circuit” as illustrated in Figure 7 of the
drawings thereof which includes parallel branches of
serially connected CMOS transistors MCNO and MCPO in
a first branch and MONC and MOPC in a second branch.
It is not at all apparent from the Examiner’s brief
comments as to how he proposes to incorporate the
voltage clamping circuit as disclosed in Figure 7 of
Tarng into the conventional driving circuit
illustrated in Figure 5 of the drawings of this
Appeal No. 96-3440
Application 08/261,613
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application on appeal. Appeal Brief at 10, lines
10-27.
We agree with appellant. The mere fact that the prior
art may be modified in the manner suggested by the examiner
does not make the modification obvious unless the prior art
suggested the desirability of the modification. In re Fritch,
972 F.2d 1260, 1266 n.14, 23 USPQ2d 1780, 1783-84 n.14 (Fed.
Cir. 1992).
First, Tarng employs a clamping transistor for reasons
that appear inapplicable to the admitted prior art driver
circuit. Column 1, lines 15-42. Second, even if there were
motivation to combine the teachings of Tarng with the admitted
prior art, we are left to speculate why the skilled artisan
would employ Tarng’s clamping transistor in the recited
position and with the recited function. The only reason we
can discern is improper hindsight reconstruction of
appellant’s claimed invention.
Appeal No. 96-3440
Application 08/261,613
5
Because we are unable to identify how the prior art
suggested the desirability of the modification as required by
In re Fritch, the rejection will not be sustained.
CONCLUSION
The rejection of Claims 2 and 7-9 is not sustained.

REVERSED
JERRY SMITH )
Administrative Patent Judge )
)
)
)
) BOARD OF PATENT
JAMES T. CARMICHAEL )
Administrative Patent Judge ) APPEALS AND
)
) INTERFERENCES
)
)
JOSEPH F. RUGGIERO )
Appeal No. 96-3440
Application 08/261,613
6
Administrative Patent Judge )
JTC/kis
William E. Hiller
TEXAS INSTRUMENTS INCORPORATED
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