Appeal No. 97-1694
Application 08/351,064
line 63 to col. 2, line 17), although the examiner does not
rely on this teaching.
IBM indicates the use of "CMOS-driven transmission lines"
(page 393). It is known that CMOS drivers are of the
push-pull type. Also, as shown in IBM figure 4, "at the
extremes of the operating region, only one of the two
transistors is conducting and it is in the square law region"
(page 395). Since only one termination transistor is active
to source or sink current, the driver must be a push-pull type
that sources or sinks current for the high and low logic
states. Appellants do not contest that push-pull output bus
driver circuits having resistor terminations were well known
and, indeed, this is admitted to be prior art in appellants'
figure 3. IBM discloses a terminal device comprising
diode-connected PMOS and NMOS transistors, i.e., "a simple
CMOS inverter wired short circuit common drain to common gate"
(page 394), which form a "termination device," as recited in
claims 40, 41, and 55. The PMOS transistor is a "first
non-linear element being connected between a termination
voltage line and said bus in a forward direction," as recited
in claims 40 and 41, and has a "rise characteristic" and is a
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