Resynthesis method for significant delay reduction

Abstract

Integrated circuit chips (IC's) require proper placement of many cells (groups of circuit components) and complex routing of wires to connect the cells. Designing of the IC's require meeting real-world constraints one of which is the performance of the IC, or the period of time required by the integrated circuit to produce the output signals from the time the input signals are available. Typically, the performance of an integrated circuit is determined by the slowest path of the signals, called the critical path. The critical path is usually only a small portion of the IC. The present invention discloses a method and apparatus for transforming the circuits comprising the critical path, thereby increasing the performance of the entire IC. The transformation is performed by segmenting, or blocking, the cells which make up the critical path. Then, each block is transformed, or replaced, with a resynthesized circuit to which both the digital 0 and digital 1 values are provided. The critical path is defined by the fact that the delay at each block is accumulated because each block has to wait for the output signal of the preceding block to use as its input signal. After the resynthesis of the blocks, none of the blocks need to wait for the output signal of its preceding block because each of the resynthesized blocks has the output for all possible inputs values (0 and 1). Thus, the signal delay at each block is not accumulated; rather, the only accumulated delay is the delay of the multiplexors used to select the correct output. The result is a dramatically reduced critical path delay.