Vendors target oscilloscope sweet spot

When choosing oscilloscopes in the 1- to 4-GHz range, engineers have an expanding variety of price, performance, and usability options as the market acquires a new competitor.

Rick Nelson, Editor-in-Chief -- EDN, September 9, 2010

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The market for 1- and 2-GHz oscilloscopes is so attractive that a new competitor, the Rohde & Schwarz test-and-measurement division, introduced models in that range in June. At a press conference announcing the instruments, Michael Vohrer, who was then chief executive officer and has since retired, said that the time-domain initiative represents an attempt of the privately held company to push into new markets and expand market share in its traditional markets for frequency-domain-analysis equipment. Vohrer placed the scope market at $1 billion and added that, with a highly diversified customer base, it represents lower volatility than do other segments.

Market-share niche

Roland Steffen, head of the R&S test-and-measurement division, says that initial models in the new R&S RTO-oscilloscope line offer top bandwidths of 1 and 2 GHz. The company is not ignoring lower bandwidths, however, and introduced complementary RTM models with 500-MHz bandwidths. The RTO and RTM models combine to serve the 500-MHz to 2-GHz bandwidth range that is enjoying the largest share of market volume.

Prathima Bommakanti, senior research analyst for test and measurement at Frost & Sullivan, concurs with the perceived importance of that market niche. “Big giants, including Tektronix and Agilent, view the 500-MHz to 2-GHz range as a ‘definite-demand’ market,” she says, referring to the bandwidth ranges that the new R&S scopes serve. Bommakanti’s research indicates that there is constant demand for 500-MHz to 2-GHz scopes selling for $8000 to $20,000.


The new oscilloscopes don’t represent Rohde & Schwarz’s first corporate excursion into the time domain. Five years ago, the company acquired low-end scope-maker Hameg. Hameg will continue to supply instruments costing roughly €4000 and less through distributors, and the Rohde & Schwarz test-and-measurement division will serve the market for scopes operating at 500 MHz and more and selling for €4000 or more through its direct sales force.

Josef Wolf, head of the spectrum and network analyzers, EMC (electromagnetic-compatibility) tests, and oscilloscopes subdivision at R&S, commented during the June press conference on the development effort that went into the new scopes. That effort focused on the high-level integration of analog, mixed-signal, and digital subsystems. A key goal was a low-noise analog front end, which the company achieved through the use of a single-core SiGe (silicon-germanium), 10-GHz ADC with an ENOB (effective number of bits) better than seven. A 90-nm ASIC with 15 million gates provides hardware implementation of digital-signal-processing functions, enabling the analysis of 1 million waveforms/sec.

The 2-GHz top-of-the-line RTO models employ a purely digital trigger system that eliminates the alignment errors that can occur with software-compensation schemes with separate analog triggers. The company specifies the RTO models’ trigger jitter in femtoseconds rather than picoseconds. In addition, the digital trigger eliminates rearm times associated with analog triggers, which can mask events of interest that occur shortly after an analog trigger. The RTO provides as much as 20 times less blind time than competitive models to help identify intermittent problems, according to Wolf.

The market will decide how much share the new R&S scopes will gain with their price, performance, and features, and Bommakanti at Frost says that a clearer picture will emerge in 2011. Nevertheless, she expects the instruments to be competitive. “Market participants opined that they are seeing Rohde & Schwarz already competing vigorously in this market,” she explains. “From our perspective, having researched the general-purpose-test-equipment market for a number of years, we believe R&S can leverage its brand reputation based on quality in the overall test-and-measurement-equipment market. Oscilloscopes were just the missing pieces of their product line.” According to Steffen at R&S, the company’s first efforts in oscilloscope marketing will be to target its customers for frequency-domain equipment who also need oscilloscopes in these bandwidths; the company will then look beyond its customer base.

Serial-data options

Meanwhile, the company’s competitors are not standing still. They have their own ideas of the price, performance, and feature combinations that they believe make their scopes with comparable bandwidths competitive. “In terms of performance, oscilloscopes can no longer be quantified by bandwidth alone,” says Joseph Ting, product manager for high-frequency instruments at Yokogawa Corp of America. “Many other common measures of oscilloscope performance include noise/accuracy, frequency-response curve, waveform-acquisition rate, memory depth, memory handling, real-time- and postacquisition-analysis capabilities, and responsiveness under load.” Yokogawa offers scopes having bandwidths as high as 1.5 GHz, including the DLM6000 series digitaland mixed-signal oscilloscopes. They can perform waveform characterization, include tools for detecting glitches and anomalies, incorporate signal-enhancement and noise-reduction technologies, and come with a range of options for serial-bus analysis and power measurement. Models offer four channels plus 16- or 32-bit logic inputs and feature 500-MHz, 1-GHz, or 1.5-GHz bandwidths.


Scopes need adaptability

The many serial-bus options available for scopes such as LeCroy’s WaveRunner suggest that the instruments must be adaptable for a variety of applications, and serial-bus options aren’t the only areas in which the scopes exhibit flexibility. “An oscilloscope in the 1- to 4-GHz class would still be qualified as a general-purpose testing tool that should have the capability to adapt to a wide range of applications,” says Driver. LeCroy’s scopes in this range include an integrated switchable 50Ω and 1-MΩ front-end termination. The 1-MΩ option allows you to use simple passive probes for applications that require a basic understanding of a signal without concern for noise or timing accuracy. In contrast, the 50Ω path can serve in applications that require the most accurate signal shape, including cabled systems and those employing single-ended FET probes or active differential probes.


According to Woodward, Agilent is the only vendor to support both traditional hardware triggering and software-based triggering, which the company calls InfiniiScan. Hardware-based triggering enables a wide range of predefined trigger conditions from which users can select. The hardware triggering embraces analog, digital, and protocol triggers to catch even the rarest of events. “Software-based triggering enables the user to graphically define a trigger,” Woodward says. “The scope then compares each acquisition to the trigger specification and displays only the acquisitions that match the trigger specification.” You can also cascade hardware and software triggers to create multistage triggers.

Digital or logic triggering is helpful in systems for which you want to verify performance across many data points but have few concerns about signal integrity, according to Chris Loberg, senior technical-marketing manager at Tektronix. “The digital trigger can speed up verification without tying up time worrying about analog-signal characteristics that may not be important due to a lower clock speed or logic type,” he says. Analog event-based triggering is critical, however, for performing signal-integrity checks or for drilling deeper into signal performance during debugging. When you combine analog triggering with a high waveform-display rate, such as the one that Tektronix’s DPX (digital-phosphor technology) provides, the debugging capability improves dramatically, Loberg adds.

Woodward echoes Driver’s emphasis on the importance of flexible probing options. “Scopes need to connect to target systems,” he says, and customers must choose the right probes and be able to later add probes. Agilent’s Infiniium scopes work with a range of single-ended, differential, high-voltage, and current probes. “We’ve developed this probing arsenal over a number of years by working with key customers and helping them solve their probing challenges,” he explains. “During just the last year, Agilent introduced more than 27 probes.”

Usability is key


Ting at Yokogawa agrees. “User interface is very important not only for engineers’ productivity, but also for their mental health. An intuitive interface, menu tree, and optimized keystrokes for each operation all make for an improved user experience.” He notes that usability often depends on familiarity. Each vendor implements user-interface methods unique to its instruments. Yokogawa oscilloscopes, for example, all employ a jog shuttle, which comprises an inner dial with detents and an outer dial with a spring-loaded ring. “Users who are familiar with our interface are reluctant to change to other vendors [and vice versa],” Ting says.

Woodward at Agilent attributes the usability features of its Infiniium scopes to the company’s continual refinement of the instruments, which it bases on input from a large installed base. In response to Agilent’s queries about usability, customers respond, “Please don’t change it,” according to Woodward. Agilent scopes ranging from the Infiniium models to the real-time-bandwidth-champion, 32-GHz model employ the same software architecture.

LeCroy’s Driver also touts usability. “We have pioneered a lot of user-interface techniques,” he says, including a touchscreen, multiple grids for independently viewing waveforms, and the ability to draw a box on the screen to zoom in on a waveform. “When a user interface does what customers expect it to do, they spend more time debugging instead of climbing the learning curve,” he adds. Like Woodward, Driver cites a consistent architecture across product lines: “When a customer picks up a 400-MHz LeCroy oscilloscope or a 30-GHz LeCroy oscilloscope, the user interface is the same.”

Usability, however, can be a tough sell. “The usability is equally important [as other features] but unfortunately subjective,” says Driver. The decision to purchase a scope in this class typically begins with a banner-specification comparison, then a price comparison, and a usability evaluation, he explains. Ting notes that usability can be a key deciding factor, but it would be difficult to quantify it to an actual cost value.

Tektronix’s Loberg also emphasizes usability and an effective user interface in today’s fast-paced lab environment. “Engineers need familiar, intuitive instruments that save them from having to spend time adapting to the instrument’s operation,” he says. “Many are jumping from a workstation-based environment to the lab and want to solve problems or verify performance quickly.”

Although you cannot reduce usability to a banner spec, such as bandwidth or number of channels, Tektronix has made an effort to quantify usability, at least as it relates to performing a set of tasks, according to Loberg. The company commissioned Hansa Research to conduct a study asking users, given a test circuit, to set up a Tektronix MSO4000 series oscilloscope and competing oscilloscopes to monitor for glitches and runts, set up a trigger and capture a runt, and search the waveform to locate all instances of the runt (Reference 2). The study found 53% improvement in debugging time with the use of the Tektronix scope.

The banner specs themselves are also open to misinterpretation. “A common mistake is to specify a bandwidth that is not sufficient to see all of the signal content,” explains Driver, who notes that customers often ask for bandwidth equal to the bit rate of the signal under test. “A common rule for specifying bandwidth is to have a bandwidth equal to or greater than five times the primary frequency or … the fifth harmonic,” he says.

Ting echoes that advice, saying that an oscilloscope that can acquire signals up to the fifth-order harmonics can generally reconstruct a pulse signal with sufficient accuracy. He also cautions that some users may overlook the fact that the oscilloscope’s sample-rate specification is only a maximum. Both memory depth and observation time restrict the actual sample rate.

Specs, future markets

Driver advises engineers to consider future needs when evaluating banner specs. If the current budget situation prevents the purchase of a higher-bandwidth oscilloscope, he suggests the purchase of an upgradable product. Woodward at Agilent has similar advice, noting that Agilent customers can buy a 1-GHz model now and upgrade to 2.5 or 4 GHz as their needs grow. Similarly, they can easily upgrade to add 16 digital channels, he says.

Once you determine specs such as the bandwidth you need and can afford, it’s relatively easy to compare them on a data sheet. Other specs, although quantifiable, are open to misinterpretation. “Users should be aware that waveform capture/update rate is directly related to their ability to detect intermittent anomalies that cannot be perfectly isolated by triggers,” says Yokogawa’s Ting.

Woodward cites an example regarding waveform-capture rate, which can vary depending on scope settings. “The Infiniium 9000 delivers 250,000 waveforms per second in segmented-memory mode and up to 3000 waveforms per second with shallow memory,” he says. “With 1M point of memory turned on, the scope still delivers more than 600 waveforms per second.”

Frost’s Bommakanti predicts steady, low-single-digit growth for scopes in the 2-GHz range. Revenue growth should be slower for midrange scopes than that for high-performance scopes, but unit shipments of lower-bandwidth models will continue to experience higher unit shipments. Expect vendors to continue to fine-tune performance to capture their fair share of the market.

You can reach Editor-in-Chief Rick Nelson at 1-781-869-7970 and richard.nelson@cancom.com.

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References

Rowe, Martin, “Agilent introduces 32- GHz oscilloscope,” Test & Measurement World, April 27, 2010. Nelson, Rick, “Testing embedded data buses and analog signals,” EDN, June 24, 2010, pg 36.

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For More Information
Agilent Technologies	Frost & Sullivan	Hansa GCR
LeCroy	Rohde & Schwarz	Tektronix
Yokogawa Corp of America