Appeal No. 1999-1935
Application No. 08/754,270
Claims 1-10 stand rejected under 35 U.S.C. § 103. As evidence of obviousness,
the examiner offers two, alternative, combinations of prior art, the first being Nishio in view
of Miyakoshi and Ahamed, the second being APA in view of Nishio and Ahamed.
Reference is made to the brief and answer for the respective positions of
appellants and the examiner.
OPINION
With regard to the first rejection, the examiner cites Nishio as disclosing a signal
processed by sigma delta modulation wherein Figure 10 shows a switch for selecting
between an idling signal and the sigma delta modulated signal and coupling one of the
signals to an output terminal. The examiner notes column 10, lines 31-41, of the reference
for the teaching of using, as the idling signal, a signal of a period of one half of the
sampling frequency fs of the sigma delta modulation, resulting in a signal spectrum formed
of only a component of ½ of the sampling frequency fs, making it possible to suppress
noise.
The examiner recognizes that Nishio lacks a teaching of the claimed finite impulse
response filter but contends that filtering of a DAC output is “fundamental to the circuit and
actual non-existence of such a low pass filter would be outside the norm” [answer-page 4].
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