Specialized programmable logic region with low-power mode
AssigneeAltera Corporation
InventorsChiao Kai Hwang, Gregory Starr, Martin Langhammer
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Abstract
In a specialized functional region of a programmable logic device, in which certain components may not be used, those components can be placed in a low-power mode so that they do not switch. For example, in an adder which is not being used but is receiving inputs, the current path for the adding circuitry is interrupted, while the output is forced low. If the adder is a carry/look-ahead adder, the GENERATE and PROPAGATE signals normally used in subsequent stages to predict the value of the carry signal are forced to constant values even if the inputs to the adder are changing.
Claims40
A specialized functional region for a programmable logic device, said specialized functional region comprising:
- functional circuitry that performs at least one specialized function, said functional circuitry comprises an arithmetic circuit including:
- at least one functional circuit input, and
- at least one functional circuit element that consumes power when said functional circuit input changes state;
- and
- at least one control element having a control input and being responsive to a low-power mode selection signal on said control input for at least reducing consumption of power by said functional circuit element when said functional circuit input changes state.
Dependencies are inferred from the claim text.