Appeal No. 1997-3166
Application No. 08/509,638
37 CFR 1.196(b): Claim 21 is rejected under 35 U.S.C. § 103(a) as unpatentable over Oldham.
Oldham discloses a memory cell comprising a flip-flop circuit with first and second inverters;
see Fig. 1 and column 1, line 65 through column 2, line 20. The first inverter has a first driver transistor
T1 and a first load transistor T2. The second inverter has a second driver transistor T3 and a second
load transistor T4. The circuit includes a first word transistor T5 and a second word transistor T6. At
least for the reason that first and second load transistors T2, T4 are distinct and separate physical
structures, the “gate area” of the first is different from the “gate area” of the second. In addition,
columns 3 through 5 of the written description detail forming the gate insulating layer of one load
transistor differently from the other, succinctly set forth by Oldham in Claims 1 and 5 as the “means for
selectively altering charge state.”
According to appellants, Claim 21 distinguishes over Oldham because “[t]here is neither
teaching nor suggestion” of the Claim 21 limitation that “‘a channel of said first load transistor is longer
than a channel of said second load transistor.’” (Brief, page 5.) However, the reference details the
following with respect to first and second load transistors T2, T4:
In order to insure that the memory cell (in connection with supply voltage U )
cc
flips into a predetermined position corresponding to a continuously stored digital
information, the field effect transistors T2 and T4 are designed with different channel
resistances. For this purpose, dimensions of their source-drain channels are embodied
differently. If, for example, the transistor T2 has a channel width W which, with respect
to its channel length L, is in a ratio of 20:4, while the quotient of channel width to
channel length in the case of transistor T4, for example, is 15:4, then the channel
resistance of T2, because of the larger channel width, is lower than that of T4.
- 8 -
Page: Previous 1 2 3 4 5 6 7 8 9 10 11 12 Next
Last modified: November 3, 2007