Finisar Corporation

Finisar adopted PADS shortly after its introduction. Now, twenty years later, PADS has grown to anticipate users’ needs, and still delivers the performance for Finisar’s extremely-high-speed fiber-optic systems and network test systems.

“We have a seat of Allegro, but PADS…this is our tool. Everyone here is proficient with PADS.”

Finisar and PADS go way back

Finisar designs and manufactures state-of-the-art fiber-optic subsystems and network test systems with very fast bit rates that will challenge any printed circuit design and layout tool. Denis Lefebvre is a member of Finisar’s design team. He was an “early adopter” class of PADS customer, starting with PADS Version 2.0. Although Denis was yet to arrive at Finisar, they adopted PADS around the same time. And, it’s been the standard tool for the more than 20 years since. “PADS is a lot more technology for the price than anything available,” explains Lefebvre.

One of PADS’ benefits shines when training a new employee on PADS: learning is quick. “It’s easy to learn. There are, of course, some ‘hidden’ features that you probably would not know about without training, but it’s easy for us to train our new people.”

PADS has kept Finisar at the razor-edge of technology as well, with enhancements that are easy-to-learn and adopt. “When I look at what I can do with PADS today versus the early 90s, well, it’s night and day. The product has evolved right in step with the technology,” says Lefebvre.

Typical project workflow

At Finisar, a project begins with the design engineer preparing the schematic. Once a working schematic is complete, the engineer and the PCB designer meet and define the rules set.

“I think we take advantage of more of the PADS feature set than most users,” says Lefebvre.  “We’ve been ‘training’ the engineers and now have a very cooperative design workflow with them. They define rules by classes of nets, for example, a ‘50 net’. That’s just one of the features we take full advantage of.”

Armed with the set of rules, the PCB design team begins designing the board.

Denis finds the autorouter to be very efficient and makes regular use of its capabilities. “One way I use the autorouter is to set the top and bottom trace and then let the autorouter route the traces on the layers between. If you give it boundaries, it works very well.”

On one board, he had to move an entire DDR memory array 2.5 mm. He estimated it would have taken him about two-and-a-half weeks to move the parts by hand. “With the autorouter, it took me less than 8 hours, even with a little tweaking. It was actually a fun job,” he says, smiling.

PADS handles their tough jobs

PADS is capable of handling complex jobs that require specialized techniques as well. Recently, Lefebvre designed a test board to house 50 laser drivers. The bit rate was 10 Gbps in addition to the complexity and density of the board. Among the specialized layout techniques he applied were stitching vias and co-planar wave guides.

Once the design was in place, he used PADS to duplicate the routing for each of the remaining 49 laser drivers. He also laid-out a single high-current power supply and re-used its design for the other 49 drivers. He estimates they “saved easily two full days” compared to having to layout each of the driver circuits.

All in all, the laser driver project taxed PADS capabilities both as a PCB layout tool and also as a change handling automation tool.

“The laser driver board took me two-and-a half-months…ten weeks to design. Without the automation it affords in both layout and project management, it would have easily taken 14 weeks.”

Staying with PADS?

With up to 40% reduction in design time you would think that PADS has a firm hold at Finisar. But, every competent manager keeps an eye on technology. “We evaluate other tools all the time,” says Lefebvre. Then he shows his frequent smile again. “But PADS always wins.”

“PADS is a lot more technology for the price than anything available.”