The present disclosure relates generally to techniques for enhancing adders implemented on an integrated circuit. In particular, arithmetic performed by an adder implemented to receive operands having a first precision is restructured so that a set of sub-adders performs the arithmetic on a respective segment of the operands. More specifically, the adder is restructured, and a decoder determines a generate signal and a propagate signal for each of the sub-adders and routes the generate signal and the propagate signal to a prefix network. The prefix network determines respective carry bit(s), which carries into and/or select a sum at a subsequent sub-adder.

The present disclosure relates generally to techniques for enhancing adders implemented on an integrated circuit. In particular, arithmetic performed by an adder implemented to receive operands having a first precision is restructured so that a set of sub-adders performs the arithmetic on a respective segment of the operands. More specifically, the adder is restructured, and a decoder determines a generate signal and a propagate signal for each of the sub-adders and routes the generate signal and the propagate signal to a prefix network. The prefix network determines respective carry bit(s), which carries into and/or select a sum at a subsequent sub-adder.

A device including: a first adder having first adder inputs and first adder outputs; a first register having first register inputs and first register outputs, the first register inputs coupled to the first adder outputs; a second register having second register inputs and second register outputs, the second register inputs coupled to the first adder outputs; and a second adder having second adder inputs and second adder outputs and configured to receive register output signals from the first register outputs and the second register outputs. Wherein, the first adder is configured to calculate a first sum of a first input value and a second input value, and the first register is configured to store the first sum, and the first adder is configured to calculate a second sum of a third input value and a fourth input value, and the second register is configured to store the second sum.

Approaches for logic compaction include inputting an optimization directive that specifies one of area optimization or speed optimization to a synthesis tool executing on a computer processor. The synthesis tool identifies a multiplier and/or an adder specified in a circuit design and synthesizing the multiplier into logic having LUT-to-LUT connections between LUTs on separate slices of a programmable integrated circuit (IC) in response to the optimization directive specifying speed optimization. The synthesis tool synthesizes the multiplier and/or adder into logic having LUT-carry connections between LUTs and carry logic within a single slice of the programmable IC in response to the optimization directive specifying area optimization. The method includes implementing a circuit on the programmable IC from the logic having LUT-carry connections in response to the optimization directive specifying area optimization.

Approaches for logic compaction include inputting an optimization directive that specifies one of area optimization or speed optimization to a synthesis tool executing on a computer processor. The synthesis tool identifies a multiplier and/or an adder specified in a circuit design and synthesizing the multiplier into logic having LUT-to-LUT connections between LUTs on separate slices of a programmable integrated circuit (IC) in response to the optimization directive specifying speed optimization. The synthesis tool synthesizes the multiplier and/or adder into logic having LUT-carry connections between LUTs and carry logic within a single slice of the programmable IC in response to the optimization directive specifying area optimization. The method includes implementing a circuit on the programmable IC from the logic having LUT-carry connections in response to the optimization directive specifying area optimization.

In some aspects of the present disclosure, an adder tree circuit is disclosed. In some aspects, the adder tree circuit includes a plurality of full adders (FAs) including: a first subgroup of FAs, wherein each FA of the first subgroup includes a first number of transistors; and a second subgroup of FAs, wherein each FA of the second subgroup includes a second number of transistors, the first number being greater than the second number; wherein each FA of the first subgroup receives a first input from a first one of the second subgroup of FAs and a second input from a second one of the second subgroup of FAs, and each FA provides a first output to a third one of the second subgroup of FAs and a second output to a fourth one of the second subgroup of FAs.

In some aspects of the present disclosure, an adder tree circuit is disclosed. In some aspects, the adder tree circuit includes a plurality of full adders (FAs) including: a first subgroup of FAs, wherein each FA of the first subgroup includes a first number of transistors; and a second subgroup of FAs, wherein each FA of the second subgroup includes a second number of transistors, the first number being greater than the second number; wherein each FA of the first subgroup receives a first input from a first one of the second subgroup of FAs and a second input from a second one of the second subgroup of FAs, and each FA provides a first output to a third one of the second subgroup of FAs and a second output to a fourth one of the second subgroup of FAs.

An adder is implemented in a field programmable gate array (FPGA). The adder has a first ripple carry adder block, for least significant bits of the adder. The adder has a plurality of carry skip adder blocks of differing block sizes. Each block size relates to bit-width of input to a block. The carry skip adder blocks of differing block sizes are for a plurality of bits of the adder. The adder has a second ripple carry adder block, for most significant bits of the adder.

The present invention discloses a computing array based on 1T1R device, operation circuits and operating methods thereof. The computing array has 1T1R arrays and a peripheral circuit; the 1T1R array is configured to achieve operation and storage of an operation result, and the peripheral circuit is configured to transmit data and control signals to control operation and storage processes of the 1T1R arrays; the operation circuits are respectively configured to implement a 1-bit full adder, a multi-bit step-by-step carry adder and optimization design thereof, a 2-bit data selector, a multi-bit carry select adder and a multi-bit pre-calculation adder; and in the operating method corresponding to the operation circuit, initialized resistance states of the 1T1R devices, word line input signals, bit line input signals and source line input signals are controlled to complete corresponding operation and storage processes.

An adder includes a primary carry bit generation circuit and a summing circuit. The primary carry bit generation circuit is configured to generate first carry bits for a first number of pairs of bits from first and second operands, and to generate second carry bits for a second number of pairs of bits from the first and second operands. The second number of pairs being different than the first number of pairs. The summing circuit is configured to generate first sums by adding bits of pairs from the first and second number of pairs and the first and second carry bits. The summing circuit is configured to generate second sums by adding bits of other pairs of the bits from first and second operands than the pairs in the first and second number of pairs and additional carry bits generated when adding the bits of the other pairs.