Correct-by-construction layout-centric retargeting of large analog designs

Abstract

Aggressive design cycles in the semiconductor industry demand a design-reuse principle for analog circuits. The strong impact of layout intricacies on analog circuit performance necessitates design reuse with special focus on layout aspects. This paper presents a computer-aided design tool and the methodology for a layoutcentric reuse of large analog intellectual-property blocks. From an existing layout representation, an analog circuit is retargeted to different processes and performances; the corresponding correct-byconstruction layouts are generated automatically and have performances comparable to manually crafted layouts. The tool and the methodology are validated on large analog intellectual-property blocks. While manual re-design and re-layout is known to take weeks to months, our reuse tool-suite achieves comparable performance in hours.

Fast analog layout prototyping for nanometer design migration

“…Most of the layout migration algorithms are based on layout compaction [4], [5], [7], [8], [9], since it closely resembles the source layout [15]. It automatically constructs a symbolic structural template to preserve layout topology, design rules, symmetry and matching information from an existing layout.…”

Classification of analog synthesis tools based on their architecture selection mechanisms

“…Since linear programs are only encountered in some special cases (e.g., for filter optimization [41] or layout retargeting [42]), the main focus of analog CAD tools is on nonlinear programs. Several algorithms have been successfully applied for analog designs, like gradient-based approaches (e.g., JiffyTune [43]), methods of feasible directions (e.g., DELIGHT.SPICE [38,44]), and SQP for op amps [45], analog filters [46], LNAs [17], and general analog cells including statistical analysis (e.g., iEDISON2 [47], WICKED [48]).…”

Template-driven parasitic-aware optimization of analog integrated circuit layouts

“…Layout retargeting refers to the generation of a target layout from an existing layout [3]. In this method, a set of constraints corresponding to technology design rules, layout symmetry etc.…”

“…Layout retargeting can be formulated as a one-dimensional compaction problem [3]. If x R and x L are the right and left ends of a layout, the problem in horizontal direction is given as:…”

“…Here, we explain our algorithm with the horizontal constraint graph. If all the horizontal constraints are feasible, then the longest path algorithm can be employed directly to solve the compaction problem [3]. Upon its completion, the longest path algorithm finds the x-positions of the left and right edges of all layout rectangles.…”