Swap MUX to relieve logic device input line stress
AssigneeAltera Corporation
InventorsMichael Hutton, Vaughn T. Betz
Life of this patent
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Abstract
Disclosed is a method an apparatus for selectively providing additional inputs into a logic block, such as a LAB of a PLD, carrying out a logic function requiring a relatively high number of inputs. A PLD in accordance with the present invention includes at least first and second LABs. A plurality of signal lines are capable of driving the second LAB and a plurality of output lines are driven by the first LAB. The PLD also includes a swap multiplexer (MUX) having a first selectable input capable of being driven by the output lines and a second selectable input capable of being driven by the signal lines. An output of the swap MUX is capable of driving the first LAB.
Claims21
A programmable logic device (PLD) including:
- at least first and second logic array blocks (LABs);
- a plurality of first signal lines capable of driving the second LAB;
- a plurality of output lines driven by the first LAB;
- and
- a first swap multiplexer (MUX) having a first selectable input capable of being driven directly by at least one of the plurality of output lines and a second selectable input capable of being directly driven at least one of the plurality of the first signal lines, and an output capable of driving the at least first LAB.
A programmable logic device (PLD) including:
- at least first and second logic array blocks (LABs), the first LAB including a first plurality of logic elements (LEs) and the second LAB including a second plurality of LEs;
- a plurality of first signal lines capable of driving at least one of the second plurality of LEs;
- a plurality of output lines driven by at least one of the first plurality of LEs;
- and
- a first swap multiplexer (MUX) having a first selectable input capable of being driven directly by at least one of the plurality of output lines and a second selectable input capable of being directly driven by at least one of the plurality of first signal lines, and an output capable of driving at least one of the first plurality of LEs.
A method of driving logic array blocks (LABs) in a programmable logic device (PLD) including:
- providing at least first and second LABs in the PLD;
- driving the second LAB with at least one of a first plurality of signal lines;
- driving at least one of a plurality of output lines with the first LAB;
- directly driving a first selectable input of a first swap multiplexer (MUX) with at least one of the plurality of output lines;
- directly driving a second selectable input of the first swap MUX with at least one of the plurality of first signal lines;
- and
- driving at least the first LAB with an output of the first swap MUX.
Dependencies are inferred from the claim text.