The present disclosure relates generally to techniques for enhancing packing density of carry-chains implemented on an integrated circuit. In particular, a packed-carry chain may be implemented to redistribute and/or emulate the logic of a first number of arithmetic logic cells of a first and/or second carry-chain using a second number of arithmetic logic cells less than or equal to the first number. By fitting the first and second carry-chain into such a packed carry-chain, the area consumed to perform the arithmetic operations of the first and second carry-chain may be reduced. As a result, the integrated circuit may benefit from increased efficiencies, reduced latency, and reduced resource consumption (e.g., wiring, area, and power).

The present disclosure relates generally to techniques for enhancing packing density of carry-chains implemented on an integrated circuit. In particular, a packed-carry chain may be implemented to redistribute and/or emulate the logic of a first number of arithmetic logic cells of a first and/or second carry-chain using a second number of arithmetic logic cells less than or equal to the first number. By fitting the first and second carry-chain into such a packed carry-chain, the area consumed to perform the arithmetic operations of the first and second carry-chain may be reduced. As a result, the integrated circuit may benefit from increased efficiencies, reduced latency, and reduced resource consumption (e.g., wiring, area, and power).

An integrated circuit that includes very large adder circuitry is provided. The very large adder circuitry receives more than two inputs each of which has hundreds or thousands of bits. The very large adder circuitry includes multiple adder nodes arranged in a tree-like network. The adder nodes divide the input operands into segments, computes the sum for each segment, and computes the carry for each segment independently from the segment sums. The carries at each level in the tree are accumulated using population counters. After the last node in the tree, the segment sums can then be combined with the carries to determine the final sum output. An adder tree network implemented in this way asymptotically approaches the area and performance latency as an adder network that uses infinite speed ripple carry adders.

An integrated circuit that includes very large adder circuitry is provided. The very large adder circuitry receives more than two inputs each of which has hundreds or thousands of bits. The very large adder circuitry includes multiple adder nodes arranged in a tree-like network. The adder nodes divide the input operands into segments, computes the sum for each segment, and computes the carry for each segment independently from the segment sums. The carries at each level in the tree are accumulated using population counters. After the last node in the tree, the segment sums can then be combined with the carries to determine the final sum output. An adder tree network implemented in this way asymptotically approaches the area and performance latency as an adder network that uses infinite speed ripple carry adders.

An arithmetic circuit includes an input buffer latching each of a plurality of input signals, sequentially input, and sequentially outputting a plurality of first addition signals and a plurality of second addition signals based on the plurality of input signals; a first ripple carry adder (RCA) performing a first part of an accumulation operation on the first addition signals to generate a carry; a flip-flop; a second RCA performing a second part of the accumulation operation on the second addition signals and an output of the flop-flop; the first RCA latching the carry in the flip-flop after the accumulation operation is performed; and an output buffer latching an output signal of the first RCA and an output signal of the second RCA, and outputting a sum signal representing a sum of the plurality of input signals.

According to an embodiment, an arithmetic device includes a comparator, M cross switches, and M coefficient circuits. The comparator compares a first voltage generated at a first comparison terminal and a second voltage generated at a second comparison terminal. The M cross switches are provided corresponding to the M input signals. The M coefficient circuits are provided corresponding to the M coefficients, and each includes a first constant current source and a second constant current source. Each of the M cross switches performs switching between a straight state and a reverse state. In each of the M coefficient circuits, the first constant current source is connected between a positive output terminal of the corresponding coefficient circuit and a reference potential, and the second constant current source is connected between a negative output terminal of the corresponding coefficient circuit and the reference potential.

According to an embodiment, an arithmetic device includes a comparator, M cross switches, and M coefficient circuits. The comparator compares a first voltage generated at a first comparison terminal and a second voltage generated at a second comparison terminal. The M cross switches are provided corresponding to the M input signals. The M coefficient circuits are provided corresponding to the M coefficients, and each includes a first constant current source and a second constant current source. Each of the M cross switches performs switching between a straight state and a reverse state. In each of the M coefficient circuits, the first constant current source is connected between a positive output terminal of the corresponding coefficient circuit and a reference potential, and the second constant current source is connected between a negative output terminal of the corresponding coefficient circuit and the reference potential.

An integrated circuit that includes very large adder circuitry is provided. The very large adder circuitry receives more than two inputs each of which has hundreds or thousands of bits. The very large adder circuitry includes multiple adder nodes arranged in a tree-like network. The adder nodes divide the input operands into segments, computes the sum for each segment, and computes the carry for each segment independently from the segment sums. The carries at each level in the tree are accumulated using population counters. After the last node in the tree, the segment sums can then be combined with the carries to determine the final sum output. An adder tree network implemented in this way asymptotically approaches the area and performance latency as an adder network that uses infinite speed ripple carry adders.

An integrated circuit that includes very large adder circuitry is provided. The very large adder circuitry receives more than two inputs each of which has hundreds or thousands of bits. The very large adder circuitry includes multiple adder nodes arranged in a tree-like network. The adder nodes divide the input operands into segments, computes the sum for each segment, and computes the carry for each segment independently from the segment sums. The carries at each level in the tree are accumulated using population counters. After the last node in the tree, the segment sums can then be combined with the carries to determine the final sum output. An adder tree network implemented in this way asymptotically approaches the area and performance latency as an adder network that uses infinite speed ripple carry adders.

A compressor, an adder circuit, and an operation method thereof are provided. The compressor includes a first adder circuit and a second adder circuit. The first adder circuit receives a plurality of input values. The first adder circuit outputs a first inverted sum value (an inverted signal of a sum value) and a first inverted carry value (an inverted signal of a carry value). One of a plurality of input terminals of the second adder circuit is coupled to the first adder circuit to receive one of the first inverted sum value and the first inverted carry value. The second adder circuit outputs a second inverted sum value and a second inverted carry value.