Design and implementation of a standard cell based programmable logic core

As process geometries shrink, the nonrecurring engineering (NRE) cost is increasing; the ability to make post-fabrication changes to system-on-chip (SoC) is becoming more and more attractive. This ability can be realized by embedding a PLC (programmable logic core) into a SoC. However, the design of PLC is a complex and daunting process; there are many issues to be addressed such as architecture, performance and flexibility. Most of these issues are related to design methodology. In this paper, a novel design method based on standard cells is proposed. With this method, not only bi-directional routing resources in the PLC fabric can be maintained which largely saves the area, but the semi-custom design approach can be adopted which greatly enhances design efficiency. In order to verify this method, a proof-of-concept PLC prototype has been designed and fabricated. Meanwhile, relevant CAD tools have also been presented. The experimental results prove this design methodology. This paper also discusses the performance and the area of PLC designed with this method.