Flexible adder circuits with fast carry chain circuitry

摘要

Configurable adder circuitry is provided on an integrated circuit that includes redundant circuitry. The integrated circuit may contain nonvolatile memory and logic circuitry that produces a redundancy control signal. During manufacturing, the integrated circuitry may be tested. If a defect is identified on the integrated circuit, the redundancy control signal may be used in switching redundant circuitry into place bypassing the defect. The integrated circuit may contain an array of logic regions. Each logic region may contain adders and multiplexer circuitry for selectively combining the multiplexers to form larger adders. The multiplexer circuitry in each logic region may be controlled by propagate signals from the adders and by static redundancy control signals.