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US 7,480,690 B2Granted
Arithmetic circuit with multiplexed addend inputs
AssigneeXilinx, Inc.
InventorsJames M. Simkins, Steven P. Young, Jennifer Wong, Bernard J. New, Alvin Y. Ching
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Abstract
Described are arithmetic circuits divided logically into a product generator and an adder. Multiplexing circuitry logically disposed between the product generator and the adder supports conventional functionality by providing partial products from the product generator to addend terminals of the adder. The multiplexing circuitry can also be controlled to direct a number of external added inputs to the adder. The additional addend inputs can include inputs and outputs cascaded from other arithmetic circuits.
Claims29
An integrated circuit having an arithmetic circuit comprising:
- a product generator having:
- a multiplier port for receiving a first operand;
- a multiplicand port for receiving a second operand;
- and
- a product port for providing a product of the first and second operands;
- multiplexing circuitry having:
- a first multiplexer input port connected to the product port for receiving the product;
- a second multiplexer input port connected to the multiplier port and the multiplicand port for bypassing the product generator to provide a bypass port of the product generator;
- a third multiplexer input port for receiving a cascade input from another product generator;
- and
- a multiplexer output port;
- and
- an adder having a first addend port connected to the multiplexer output port, a second addend port, and a sum port;
- the sum port connected to a fourth multiplexer input port of the multiplexing circuitry;
- the arithmetic circuit being configured as a comb stage.
12 more elements
Dependencies are inferred from the claim text.