How to design a high-performance scope: One team’s approach

The life of a designer can be a difficult and arduous one, often punctuated by great successes, disappointing failures and a continual onslaught of obstacles to overcome. This reality remains the same regardless of whether the designer is designing a next-generation cell phone or attempting to develop the industry’s best measurement instrument. That’s exactly what a select group of designers from Agilent Technologies discovered when it set out to develop the world’s highest performance oscilloscope. The design team succeeded in that goal, but along the way it also discovered some valuable lessons that could prove useful for any designer or design team looking for success on their next project.

The Project Details
When Agilent first embarked on its oscilloscope development project over 4 years ago, its goal was clear: to develop an instrument that would leapfrog the competition in terms of bandwidth and deliver almost triple the signal integrity of any other scope on the market. The result was the industry’s first 33-GHz oscilloscope, dubbed the Infiniium 90000 X-Series (Figure 1) and with it a number of industry firsts including:
-    33 GHz of true analog bandwidth
-    the lowest noise floor (2.25 mV at 50 mV/div. 33 GHz)
-    the lowest jitter measurement floor (150 fs), and
-    the flattest frequency response.


    
Figure 1. The Infiniium 90000 X-Series oscilloscope has true analog bandwidth to 33 GHz. The InfiniiMax III, the world’s highest speed and highest performing probe system, was specifically developed for use with the 90000 X-Series.

The design team also developed the industry’s first and only 30-GHz oscilloscope probing system for the 90000 X-Series.

Key Project Lessons
Achieving these two developments required an integrated team effort, investment in new technology and use of best-in-class tools. In particular, throughout the oscilloscope and probe system development process, three key factors stood out as critical to the team’s overall success:

Synergy is essential
The difficulty of the oscilloscope and probe system development task required that designers from different organizations within the company come together. This meant bringing together teams specializing in wide-bandwidth semiconductors, high-performance ceramic micro-circuitry and high-speed analog-to-digital converters. The organizational complexity alone was a major challenge.

As Dan Thomasson, head of Agilent Technologies’ High-Frequency Technology Center in Santa Rosa, CA, explains, “This was the first time where we said, ‘Let’s do everything imaginable for the oscilloscopes in this process.’ It wasn’t a serial approach where components were produced and handed off; it was an integrated approach where everything was designed from a systems standpoint.”

Bringing so many different organizations together created a number of pressing issues and questions. For starters: When you come to a fork in the road, who decides which way you go? How do you manage checkpoints, progress reports and decision flow when the program is not all under the control of one solid-line manager? And on a more practical level, how do you enable geographically-disperse teams to work together? In this case, the teams were a thousand miles apart, in California and Colorado.

The job fell to the team’s overall project manager Brad Doerr to create an environment of open communication. According to Brad, it required implementation of “basic organization and a philosophical approach that drove transparency, trust and extreme communication. “

To avoid problems associated with hearsay, guessing and undermining, he asked people to make their statements face-to-face. This helped breakdown any gaps in communication and eliminated misunderstandings and confusion. It also helped rally the engineers together as one team driven by a single quest: to make the world’s best, most successful oscilloscope. The challenges and complexity of that task, while still large, became surmountable once everyone was aligned behind that vision and that quest.

It helped, too, that team members were occasionally able to close the thousand-mile gap between them and meet in person, both in and out of the office. Further team motivation came from visits with key customers. Having an inside look at what the oscilloscope could mean to customers and hearing details on what they would like to see became a major coalescing activity.

Take educated risks
Developing a breakthrough oscilloscope required the Agilent team to take a number of educated risks when it came to new technology. One of the key early decisions the team faced was whether to make ICs out of indium phosphide (InP), a promising but unproven material. While the team knew it was very high performance, some argued that it couldn’t be made reliable and manufacturable.

Despite these concerns, the team decided to take the risk. There were setbacks, but the strong synergy of the team enabled it to quickly regroup as each obstacle appeared. It identified issues that had to be resolved and then set out to solve them (Figure 2).


Figure 2. An indium phosphide (InP) heterojunction bipolar transistor wafer containing all 
six 90000 X-Series IC designs.

Another technology that proved well worth the risk for the team was Quick Film, a technology developed by Agilent over the course of 16 years (Figure 3). Quick Film is constructed by screen printing gold and dielectric pastes on a ceramic substrate. It can then be made into unique three-dimensional structures, giving it superb wide-bandwidth performance.


Figure 3. Quick Film technology with five indium phosphide ICs, 
the heart of the 90000 X-Series oscilloscope.

Agilent researchers realized long before existing technologies reached their limits, that new materials and techniques would eventually be needed. So they worked on Quick Film in whatever spare time they had, with management’s understanding and trust that one day that work would prove valuable. With the 90000 X-Series oscilloscope, the technology finally proved its worth, acting as the scope’s microcircuit technology.

Another crucial decision came when the production prototypes were done and all that remained were a few additional routine tests. A clock-coupling issue was discovered inside the Quick Film packaging that contained five indium phosphide die. Quick thinking by one of the team’s engineers came up with a last-minute, high-risk solution. Again management took the educated risk and adopted the solution. It was clever and it worked.