Using top-down CAD tools for mixed analog/digital ASICs : a practical design case

A mixed analog/digital ASIC from a real satellite application (a radiation detector front-end) hasbeen designed, simulated and processed according to a hierarchical top-down design methodology. CAD tools(commercial and academic) have been used as much as possible. The top-down methodology is discussed andillustrated by going through the different steps of the ASIC design. At each level the different choices and tradeoffs are briefly discussed and practical difficulties of top-down design are pointed out. One of the most importantproblems in top-down mixed-signal ASIC design-modeling and verification-is highlighted and discussed indetail.