Automatic routing flow development for layout design of mixed-signal power management IC

Abstract

Modern power management integrated circuits (PMIC) development follows an analog mixed-signal (AMS) design architecture. Automation of AMS integrated circuit (IC) design has become a critical requirement to meet industry demands. Analog layout design automation still has considerable room for improvement to achieve higher levels of automation capability. Routing automation is a key step in layout design automation. Although analog routing automation is not very popular in practice, several initiatives have been undertaken over the past three decades to enhance routing automation capabilities in analog layout design tools. The latest Cadence Virtuoso Studio has introduced an integrated auto-router solution capable of automated AMS routing.

This thesis aims to explore the possibility of using the Virtuoso automated chip assembly integrated router to route AMS interconnects of PMIC layout designs and to identify good layout design practices that can enhance the quality of auto-router-generated layouts. Router behavior is first studied using simple layout test cases. Two case studies are also presented to evaluate the performance of the integrated auto-router compared to manually routed layout designs. Qualitative and quantitative analyses are conducted based on parasitic extraction, resistance mapping, area, and the neatness of the layouts.

It is identified that layout preparation and router configuration have a significant impact on the performance and quality of the integrated auto-router. The router can be used as a tool to assist a PMIC layout designer in quickly generating block-level signal interconnects, yet the generated layout requires manual intervention to address design rule violations. The integrated auto-router is not capable of matching the compactness of manual routing achieved by experienced PMIC layout designers for an AMS block. However, layout design best practices and custom auto-routing channel creation used in auto-routing flow helped to achieve relatively compact AMS block routing results.