Ex parte Freeman

Board of Patent Appeals and Interferences

Oct 31, 2001

08906676 (B.P.A.I. Oct. 31, 2001)

1
The opinion in support of the decision being entered today was
not written for publication and is not binding precedent of
the Board.
Paper No. 15
UNITED STATES PATENT AND TRADEMARK OFFICE
__________
BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
__________
Ex parte RICHARD A. FREEMAN
__________
Appeal No. 2000-0717
Application 08/906,676
___________
ON BRIEF
___________
Before KRASS, RUGGIERO, and BLANKENSHIP, Administrative Patent
Judges.
KRASS, Administrative Patent Judge.
DECISION ON APPEAL
This is a decision on appeal from the final rejection of
claims 1-20, all of the pending claims.
The invention is directed to a phase locked loop filter
having a tuned filter. Reference is made to representative
independent claim 1, reproduced as follows:
1. A high frequency signal source comprising:

Appeal No. 20000-0717
Application 08/906,676
2
a voltage controlled oscillator for providing a high
frequency source signal;
a divider coupled to the voltage controlled oscillator
and receiving the source signal, the divider providing a
divided high frequency signal; and
a phase locked filter including:
a first signal splitter having a source input, a first
output, and a second output the source input being coupled to
the divider to receive the divided high frequency signal;
a band pass filter having a signal input, a signal
output, and a control input, the signal input being coupled to
the first output, the band pass filter having a frequency
response in accordance with a control signal at the control
input;
a second signal splitter having a filter input, a third
output, and a fourth output, the filter input being coupled to
the signal output; and
a phase control circuit having a first phase input, a
second phase input, and a phase output, the first phase input
being coupled to the second output, the second phase input
being coupled to the third output, the phase output being
coupled to the control input.
The examiner relies on the following references:
Rogers, Jr. 4,316,108 Feb. 16,
1982
Claims 1-20 stand rejected under 35 U.S.C. 103 as
unpatentable over Rogers.
Reference is made to the brief and answer for the
Appeal No. 20000-0717
Application 08/906,676
3
respective positions of appellant and the examiner.
OPINION
We REVERSE.
The initial burden of establishing a prima facie case of
obviousness with regard to the claimed subject matter rests
with the examiner.
The examiner maintains, with regard to instant claims 1-8
and 10-20, that the tracking filter shown in Figure 2 of
Rogers discloses the instant claimed subject matter but for an
integrator (low pass filter) placed after the phase
comparator, and a frequency divider placed after the input
signal source for reducing the frequency of the input signal
source.
However, the examiner still contends that the claimed
subject matter would have been obvious, within the meaning of
35 U.S.C. 103, because it was “notoriously well known” to use
a low pass filter for cleaning high frequency noise and to use
a frequency divider as a means for reducing frequency.
Therefore, concludes the examiner, it would have been obvious
Appeal No. 20000-0717
Application 08/906,676
4
to place a low pass filter after phase comparator 32 of Rogers
to remove noise and to place a frequency divider before the
tracking filter of Rogers to reduce the frequency of the input
signal to a predetermined frequency matched to the operating
frequency of the tunable band pass filter 30.
Appellant does not deny that low pass filters for
removing noise and frequency dividers for reducing the
frequency of signals were known and we agree that such
elements were known at the time of the instant invention.
However, merely because such elements and their functions were
known would not have provided a suggestion to skilled artisans
to have provided these elements in the specific combination of
elements claimed by appellant.
The examiner asserts the use of these elements to be “a
matter of a design expedient for an engineer dependent upon a
particular environment and the applications in which the
tracking filter circuit of Roger [sic, Rogers], Jr. is to be
used” [answer-page 5].
Appeal No. 20000-0717
Application 08/906,676
5
However, since Rogers is not concerned with high
frequency signal sources or VHF synthesizers or a high
frequency synthesizer, as is the instant invention, where the
use of dividers for generating signals from a single VCO
presents a noise problem, Rogers would appear to have had no
need for the dividers and low pass filters which the examiner
so cavalierly proclaims would have been a “design expedient.”
If Rogers suggested that the source signal frequency needed to
be reduced or if Rogers suggested, or indicated, in any
manner, that there was a need for filtering the output of the
phase comparator 32 or that there was a problem with noise
regarding the signal output by the phase comparator, then we
would agree with the examiner that the skilled artisan would
have known to employ a divider and/or a low pass filter,
respectively, at the appropriate points in the circuit to
alleviate these problems. But, in fact, Rogers does not
indicate that there is a problem with high frequencies at the
source input or that there is a noise problem with the signal
output from the phase comparator. In fact, appellant has
argued that because Rogers teaches the use of a real-time
Appeal No. 20000-0717
Application 08/906,676
6
tracking filter in the intermediate frequency (IF) stage of a
frequency modulation (FM) receiver, the use of a divider would
be “counter-productive” [brief-page 8] since Rogers’ tracking
filter involves the rapid tracking of continuously frequency-
varying input signals, the frequency variation being
independent of the system in which the filter is used.
The examiner’s response, unconvincing to us, is to merely
contend that Rogers does not employ a frequency divider
because the frequency of the input signal from source 30 is
matched
with the operating frequency of the tunable band pass filter
30 and so the use of a frequency divider for matching the
input
frequency to the operating frequency of the tunable band pass
filter is considered to be a matter of design expedient for an
engineer.
Taking independent claim 1 as exemplary, and applying
Rogers’ disclosure, at Figure 2, thereto, we find that Rogers
does, indeed, disclose a phase locked filter comprising a
Appeal No. 20000-0717
Application 08/906,676
7
first signal splitter 29 which has an input from a source and
a first and second output. A bandpass filter 30 has a signal
input, a signal output and a control input, wherein the signal
input is coupled to the first output of the first signal
splitter and the response of the band pass filter is in
accordance with a control signal (provided by phase comparator
32 and control amplifier 33). A second signal splitter 31 has
a filter input and a third output, wherein the filter input is
coupled to the signal output of the bandpass filter. However,
we do not find the “fourth output,” as required by the instant
claim. Rogers also discloses a phase control circuit 32 having
a first phase input, a second phase input and a phase output,
wherein the first phase input is coupled to the second output
(of the first signal splitter 29), the second phase input is
coupled to the third output (of the second signal splitter 31)
and the phase output is coupled to the control input (to
bandpass filter 30).
Independent claims 10 and 18 do not require the “fourth
output” of independent claim 1. However, each of the
Appeal No. 20000-0717
Application 08/906,676
8
independent claims does require a high frequency source and a
divider for receiving the high frequency source signal. Since
we find no such teaching or suggestion of a high frequency
source signal and a divider connected thereto in Rogers, and
the examiner has not convinced us of the obviousness of
providing such a high frequency source and divider in Rogers,
we will not sustain the rejection of claims 1-20 under 35
U.S.C. 103.
The examiner’s decision is reversed.
REVERSED
ERROL A. KRASS )
Administrative Patent Judge )
)
)
) BOARD OF PATENT
JOSEPH F. RUGGIERO )
Administrative Patent Judge ) APPEALS AND
)
) INTERFERENCES
)
HOWARD B. BLANKENSHIP )
Administrative Patent Judge )
Appeal No. 20000-0717
Application 08/906,676
9
EAK:pgg
Rockwell Collins Inc.
Attention Kyle Eppele MS 124 323
400 Collins Rd. N.E.
Cedar Rapids, IA 52498