AsicBoost was invented by Timo Hanke in collaboration with Sergio Lerner and is patent pending.
The method is based on an ingenious new way to process work items, both inside and outside of the Bitcoin mining ASIC. It involves a new design of the SHA 256 hash-engines inside the ASIC and an additional pre-processing step as part of the mining software outside the ASIC.
AsicBoost's hash-engine design is compatible with design philosophies such as “rolled cores” and “fully pipelined cores”. The performance gains are achieved on top of all other optimizations regarding timing, pipelining, path balancing, custom cell and full-custom designs.
For a technical description of the idea, invention and implementation see the whitepaper.