Appeal No. 1998-1107 Page 2
Application No. 08/536,768
an input signal is aliased into the base signal. Once aliased
therein, the noise cannot be removed by conventional
filtering.
The invention uses a low pass filter stage to filter
noise at frequencies above the base signal of an input signal.
By filtering the noise before the decimation process, the
noise does not get aliased into the base signal during
decimation.
Claim 6, which is representative for our purposes,
follows:
6. A method for digitally filtering a bit
stream signal of one bit wide comprising the steps
of:
a) delaying said bitstream signal in a
plurality of serially connected delay stages;
b) summing together the true or complement of
a selected group of said delay stages to form a
summed signal, said group being greater than two;
and,
c) integrating said summed signal in a
plurality of integration stages to form a filtered
output signal.
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