A structured ASIC has some arrays of prefabricated yet configurable logic blocks (CLBs) with/without a regular routing fabric. In this paper, we propose a standard cell like via-configurable logic block (VCLB). We design a 0.18um standard cell library based on our VCLB and establish a design flow using as many commercial tools as possible. We also propose a method to evaluate the viability of a structured ASIC fabric. Our structured ASIC fabric with programmable metals for routing achieves a delay of 2.7 times, an area of 3 times, and a power of 1.5 times that attained by the designs using a commercial cell library.

A structured application-specific integrated circuit (ASIC) has prefabricated yet configurable logic block arrays. We investigate some important via-configurable logic block (VCLB) design issues. We particularly focus on creating a VCLB layout that enables a standard cell like design. We propose the VCLB composability concept which enables us to use multiple VCLB instances to realize a complex logic gate. We devise four new VCLBs and construct several cell libraries based on these VCLBs. We develop a design flow mostly using industrial design tools and propose a method to evaluate VCLB viability. The experimental results show that a medium-grained VCLB that realizes a rich set of logic functions attains the best performance.Index Terms-Regular fabric, standard cell, structured application-specific integrated circuits (ASICs), via-configurable logic block.