Improved Analog Layout Productivity using Template-Driven Modgen Reuse Methodology

For a full custom analog layout development, device level pattern planning, placement and routing of the matched structure is an important phase. Matched devices are extensively used in analog designs, such as differential amplifiers and current mirrors. The matching performance achieved is crucial ingredient to ensure the specifications. According to the criticality of the matching performance, different matching techniques are required depending upon the number of devices. Quality matched structure primarily requires compact layout and gradient cancellation. For gradient cancellation, structures require pattern visualization and pattern visualization is becoming complex for devices mapped in more than 4-6 rows. In already implemented semi-custom designs, a placed and routed pattern might be present more than once. Designer can save these patterns as “template” and re-use these patterns to generate the similar style matched placement pattern quickly, instead of starting from scratch. Also, patterns are user configurable, stored in pattern database and can be loaded for reusability. In core analog blocks, approximately 40-60% devices required to be matched. These devices are preferably matched in common centroid techniques. In this work, layout re-use methodology, different visualization techniques and Module Generator (Modgen) topology editor interfaces have been discussed for quick matched pattern planning, placement and routing. By reusing templates layout design time is greatly reduced.