High speed product term assignment for output enable, clock, inversion and set/reset in a programmable logic device
AssigneeXilinx, Inc.
InventorsSholeh Diba, Wei-Yi Ku
Life of this patent
Estimating the term…
Abstract
A macrocell for a programmable logic device includes private product term assignments to provide various functions including set and reset, output enable, clocking, and inversion. Each of these additional functions is provided by assigning one of the product terms associated with the macrocell to perform one of these functions locally. By means of additional logic circuitry these functions are achieved either singly or in combination for a particular macrocell, thus improving macrocell flexibility and in some cases conserving pins of the chip of which the programmable logic array is a part.
Claims12
A macrocell for a programmable logic device, the macrocell including a flip-flop having at least a data input terminal, a data output terminal, a set terminal, and a reset terminal, the macrocell comprising further:
- a first input terminal connected to receive a first product term;
- a second input terminal connected to receive a second product term;
- a third input terminal connected to receive a global set/reset signal;
- a fourth input terminal connected to receive the global set/reset signal;
- a first configurable switch connected between the first input terminal and the set terminal;
- a second configurable switch connected between the second input terminal and the reset terminal;
- a third configurable switch connected between the third input terminal and the set terminal;
- and
- a fourth configurable switch connected between the fourth input terminal and the reset terminal.
A method of operating a macrocell of a programmable logic device, the macrocell including a flip-flop having at least a data input terminal, a data output terminal, a set terminal, and a reset terminal, comprising the steps of:
- providing a selected one of a first product term signal and a global set signal to the set terminal;
- and
- providing a selected one of a second product term signal and a global reset signal to the reset terminal.
Dependencies are inferred from the claim text.