Appeal 2007-1293
Application 10/745,124
FINDINGS OF FACT
RELATED TO ANTICIPATION BASED UPON LIEDER
9. Lieder teaches a telephone interface circuit with a polarity detector.
(Abstract.)
10. Lieder’s circuit includes three main elements, identified as three
stages ending at nodes A, B, and output respectively. (Paras. 0015-0020.)
11. The first stage includes a comparator, item 110, which has a feedback
resistor, item 103, connected to output, node A, to the inverting input of the
comparator. (Fig. 1.)
12. The output of the comparator, is the output of the first stage, and is
input to the second stage of the circuit.
13. The second stage is an RC filter consisting of series resistor, item 106,
and capacitor (to ground), item 130. (Para. 0016.)
14. The second stage RC filter is a low pass filter. (Para. 0016.)
15. Lieder specifically identifies that a low pass filter is a filter wherein
the values of the capacitor and resistor are “selected such that all signals
detected at or above a minimum frequency will be filtered out.”
16. The output of the RC filter is input to the third stage which comprises
a Schmitt trigger. (Para. 0017.)
ANALYSIS
RELATED TO ANTICIPATION BASED UPON LIEDER
Independent claim 1 recites “an RC delay circuit coupled to the comparator
output … wherein the RC delay circuit has an RC time constant sufficient to
prevent single event transients from adversely affecting the logic device output.”
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