AGO Circuit Optimization Software Trial Chris Ambri Apr. 08, 2015
AGO – AnExplorer • It is a circuit optimizer that works within Cadence Environment – Designers will find the tool a natural fit to their familiar toolset – Open Tool from a Menu in a Cadence Schematic – No need to transfer out of Cadence to Minitab and Crystal Ball – Maintains highest accuracy as optimization is done with Spectre simulation and device models. – Downside – Takes more simulation time because optimization is being done with Spectre using full device models. • Sophisticated Algorithms Reduce the Number of Simulations
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Experience with Tool to Date • Tried a very simple circuit to understand mechanics of software. • Optimized a more sophisticated circuit to be used in a real product. – – – – –
The tool did feel like an extension to existing Cadence tool set. Found the menus to be intuitive Found the documentation to be helpful Did run into problems and had a helpful response within 24 hours. Negative – since the technical people are in India, communication is done mostly by email with a roughly 12 hour delay; can’t easily pick up the phone and work through a problem real time.
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Basic AgO AnExplorer Flow
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Example: n3v Inref Circuit
Specify Variables to be Optimized and Range of Variables. It is important to specify an accurate range for variables for efficient optimization (picking the range blindly will result in extremely long optimization time if the optimizer converges at all).
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Optimization Example Cont’d 1. 2. 3. 4.
Specify number of threads Specify Stop Criteria Specify Corners to use for Centering Define Models (consist of Proc, Voltage, and Temperature)
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Optimization Example Cont’d
1. Specify a analysis name (user defined) 2. Specify the ADEL Cadence Test Bench to use 3. Specify the type of simulation (either AC,DC,TRAN) or Monte Carlo
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Optimization Example Cont’d
4. Specify the Optimization Criteria. Each one of these corresponds to a Defined equation in the ADEL test bench.
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Global Optimization
The Optimizer produces a list of suggestion points that meets the Performance Objectives. This list was produced within about 35 hours. The designer can choose the particular Optimization Point that works best. There may be more than one set of inputs that produces an output that meets specification. One may be superior to the others.
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Centering • Centering can then be run over more Corners • Monte Carlo should then be run to show proper margin with Capability Indexes. • This particular Optimization took about 35 hours to fully complete, although, Optima started to be produced within about 8 hours. • The optimization point chosen from AgO was very close to a point we had achieved by other means, however, it took a couple of weeks to arrive at this point manually. The AgO tool produced this in 35 hours of computer run time.
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Conclusion • The AgO tool was intuitive to use, and works well within the environment to which IC Design Engineers are accustomed. • This would result in more Design Engineers using the Optimizer. • This will result in saved time, and better quality circuits. However, the optimizer does not take the place of good IC design engineering – good circuit architecture, decent initial starting points and ranges, and smart interpretation of the results is essential. • Recommendation is to purchase 1-2 licenses for 6 months to a year and encourage use of the Optimizer. The broader use by the design community will result in either the tool being embraced, or rejected as useful to Medtronic. • Only the GUI portion of the tool was explored. The command line option has other features not available in the GUI. Expanded use will further allow all features to be analyzed. • Last Cadence has a optimizer which warrants further study prior to commitment to AgO as we may already have an optimizer that works well for us. There is not much experience in using the Cadence built in optimizer. This may be just a matter of training on this tool.
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