AND NOW FOR SOMETHING COMPLETELY OUT OF THIS WORLD
PASADENA, California, March 2003—The James Webb Space telescope, next-generation successor to the Hubble, will be launched out to "L2", a solar orbit almost a million miles away from the earth, on a five-year mission to explore the origins of galactic formation in the early universe. Loaded with equipment to detect and decode the geometry of the universe, its age and perhaps even its ultimate fate, Webb telescope components must perform against the incredible challenges of the outer space environment.
After fierce competition, Rockwell Scientific is one of two companies left in the race to furnish the onboard electronic imagers and signal processing system for the Webb telescope. Each signal-processing chip designed by Rockwell Scientific includes an array of high-resolution analog-to-digital converters (ADCs) that were entirely designed using Tanner EDA's L-Edit Pro.
How do you design for for extra-terrestrial specifications? And what do you do when your deadline overlaps with a family trip to Paris? Just ask Lanny Lewyn, president and chief engineer of the Laguna Beach design firm bearing his name, about his part in with this tremendously difficult design effort.
"Our ADC takes the analog signal from the detector preamp and converts it to a 19-bit digital signal. There are 36 of our ADCs on each signal-processing chip, so there are severe power and area limitations. The power allocation for each ADC is only slightly more than a milliwatt. Each ADC must consume an area of less than 2 square millimeters. Signal-to-noise constraints are very demanding and operation is below liquid Nitrogen temperatures (40 degrees above absolute zero)!"
L-Edit Pro Makes It Possible
"L-Edit Pro was used to layout the entire ADC array. The tool is great! It saved us significant time and the expense of Unix-based EDA layout tools. Yet it was able to do everything we needed."
ADCs are vital to several fast-growing segments of the consumer ASIC market, including telecom and analog subsystems in complex SOC applications. This has created a huge demand for the fine art of mixed-signal design. With 20 years of IC design experience and a Ph.D. from the Stanford Center for Integrated Systems, Lanny has just what it takes to prevail in the design of very high performance linear systems.
"We started the electrical design of the ADC in April and were asked to do the layout in June. Both design and layout had ambitious schedule goals, and L-Edit Pro helped us achieve them. The layout had to be completed by the end of October. There was no time for a long ramp-up on the tool. Fortunately, the clear logic of the UI really makes sense. It saved us several weeks of laborious learning time. I had used L-Edit before for GDSII design checks, but it only took about a week to get up to speed using the tool for layout editing."
Scaling Nanospace for Outer Space
"Over the past decade, we have developed our own set of universal layout rules and modular cell approach for analog layout. These universal rules and special cell design approaches allow us to achieve low noise and very high density. The layout approaches, when combined with dimensionless schematic capture, let us port the design to several foundries and several process line-widths. Our present rule set should be compatible with dual-oxide-thickness processes down into the range including 0.1 microns and below."
"Our portable layout rules are specified in Gamma units using Tanner's highly flexible application setup. Our gates are drawn at 4 Gamma and the complete 166-rule set defines all the remaining layers, independent of foundry or process. One of the most important aspects of using this layout approach is that once the ADC has been debugged in a given technology, very few polygons change when migrating to the next. This approach allowed our HDSL telecom ADC to migrate from TSMC 1.0, to 0.8 and finally 0.6 uM without changing one polygon. Of course, the pad cells had to be over-sized in the beginning. With this approach you can keep getting it right the first time."
"The ADC L-Edit Pro layout in Gamma units was ported to the UMC 0.25 uM analog process from our GDSII stream file using Dracula® software. The CAD porting step worked perfectly!"
Design Anytime, Anywhere
"This layout design was actually completed in the Latin Quarter of Paris. My wife and I had purchased the tickets for this trip in March, with each of our children coming from a different city-there was no way I could miss it. I brought L-Edit along on a portable PC with a 13" screen. I was astonished that it was so easy to pan and zoom from one end of the layout to the other. Even with the small screen of the portable, it was easy to keep track of the large design. I never felt at anytime that I was in need of a huge plotter. L-Edit Pro's portability represents a significant competitive advantage as it gives the potential to transition easily from one platform to another."
James Webb "Next Generation" Space Telescope for NASA
If the Rockwell Scientific Company imager and signal processor are selected for theJames Webb Space Telescope, the highest possible resolution images from outer space will be passing through ADCs laid out with L-Edit Pro. Testing and final chip trials are scheduled for the summer of 2003. Webb's revolutionary infrared-sensing cameras and spectrometers could bear the mark "made with L-Edit Pro"-stay tuned.
For
additional information, please contact:
Lanny Lewyn
President Lewyn Consulting Inc.
Laguna Beach, CA