Digit Pipelined Arithmetic for 3-D Massively Parallel Optoelectronic Circuits

A concept for a future integer arithmetic unit suitable for a realization with 3-D optoelectronic very large scale integrated (VLSI) circuits is presented. Due to the use of optical interconnections running vertically to the circuit's surface no pin limitation is given. This allows massively parallelism and a higher throughput performance than in all-electronic solutions. To exploit the potential of optical interconnections in VLSI systems efficiently well-adapted low-level algorithms and architectures have to be developed. This is demonstrated for a pipelined arithmetic unit using a redundant number representation. A transistor layout for the optoelectronic circuits is given as well as a specification for the necessary optical interconnection scheme linking the circuits with free-space optics. It is shown that the throughput can be increased by a factor of 10 to 50 compared to current all-electronic processors by considering state-of-the-art optical and optoelectronic technology. Furthermore we present results we gained by investigations on a first realized optoelectronic VLSI test chip.