Miscellaneous active electrical nonlinear devices – circuits – and – Gating – Converging with plural inputs and single output
Reexamination Certificate
2001-09-05
2002-12-03
Cunningham, Terry D. (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Gating
Converging with plural inputs and single output
C327S403000
Reexamination Certificate
active
06489830
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to digital logic circuits and more specifically to an apparatus and method for implementing a multiplexer.
BACKGROUND OF THE INVENTION
Multiplexers are used extensively in many applications such as computers and telecommunications. For example, multiplexers comprise the primary portion of the register file in a field-programmable-gate-array (FPGA) implementation of a microprocessor. The problem sometimes arises, however, that the multiplexer function does not map efficiently onto four-input look-up tables, which are the basic logical building block of many FPGAs. Specifically, some FPGA synthesis tools use additional logic available in the majority of FPGAs to fit, for example, a four-to-one multiplexer into two four-input look-up tables. Unfortunately, use of this additional logic makes it unavailable for other uses and complicates the process of placement and routing. It is thus apparent that there is a need in the art for an improved multiplexer implementation.
SUMMARY OF THE INVENTION
An apparatus and associated method are provided for implementing a multiplexer. The multiplexing function is divided into two stages, the first of which outputs either a selection result or a selection signal. The selection result corresponds to one of a first set of data inputs to the first stage. The second stage selects one of a second set of data inputs to the second stage in response to the selection signal.
REFERENCES:
patent: 4926423 (1990-05-01), Zukowski
patent: 6118300 (2000-09-01), Wittig et al.
patent: 6124736 (2000-09-01), Yamashita et al.
Yamashita, S. : Performance-Driven Functional Decomposition And Circuit Minimization, Last Modified: Wed, Oct. 14, 1998, pp. 1-2.
Croft Thomas M.
Cunningham Terry D.
Hewlett--Packard Company
Nguyen Long
LandOfFree
Apparatus and method for implementing a multiplexer does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus and method for implementing a multiplexer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus and method for implementing a multiplexer will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2988793