TestBench: September 2009

Marc Vanden Bossche, Founder and CEO of NMDG explains the company’s focus on nonlinear characterization and behavior of high frequency electronic components, how the Belgium based company evolved and the company’s development of key partnerships, both commercial and with academia.

MWJ: Please explain the origins of NMDG as a Belgian company on the world stage.

Vanden Bossche: The history of NMDG dates back to the early ’90s when I realized the impact that network analyzers had on the evolution of high frequency systems and how the quest for mobility was starting to drive high frequency components and systems in a direction that requires new measurement approaches. Indeed, the percentage of components living on the edge of linearity and working in a nonlinear mode of operation were on the increase, while simple test signals were not good enough to design and test systems properly.

Therefore, during my PhD, funded by Hewlett Packard (HP) – now Agilent Technologies – I investigated the basic principles from characterization to behavioural modelling of nonlinear high-frequency components that would be required for the next generation of network analyzers. I convinced HP to start and fund a research group at the ELEC department of Vrije Universiteit Brussel to work out these principles towards developing a prototype instrument. I was lucky to get a very good, small team together that had complimentary skills, from theoretical insight to practical realization. Hence, HP NMDG was born, as part of HP.

MWJ: Where does the NMDG name originate?

Vanden Bossche: I am often asked that. It is related to the fact that we were a small Group, reporting to HP NMD in Santa Rosa, the division that developed the network analyzers. Then we gave the name “NMDG” a meaning: Network Measurement (characterization) and Description (modelling) Group. When NMDG was created as a totally separate company in June 2003, we decided to maintain the well-established ‘NMDG’ name.

MWJ: How important was the research grant that you received from the Flemish government and how did the company progress from there?

Vanden Bossche: After its creation NMDG submitted a substantial project proposal to the Institute for the Promotion of Innovation by Science and Technology in Flanders. This institute promotes innovation in Flanders by funding research and development work. The project was approved and enabled NMDG to develop some new key technologies for nonlinear characterization and modelling. Additionally the required software architecture and framework could be designed as a foundation for NMDG’s flagship – the Integrated Component Characterization Environment (ICE).

This is a pseudo real-time (event-driven) measurement, modelling platform, which is device-centric. It is aimed at the accurate measurement of the voltage-current behaviour of devices under realistic stimuli. It can connect and combine different types of receivers, ranging from high-frequency oscilloscopes and network analyzers to vector signal analyzers, while supporting different stimuli, going from CW, modulation stimuli to passive and active tuners.

The research grant offered important leverage towards attracting venture capital into NMDG. Both VINNOF, the Flemish Innovation Fund, and BI3 Fund, the seed capital provider from the Vrije Universiteit Brussel (the root of NMDG) participate in the company.

MWJ: NMDG offers software and hardware products for R&D and test engineers. It has become established in a relatively short time. How has this been achieved?

Vanden Bossche: The nonlinear market is just developing. It is clear that the need for new tools to deal with nonlinearities exists and is growing but the concepts and solutions offered are still perceived as being quite new. A few companies, both large and small, are trying to position themselves in this emerging market. Thanks to the very good team and its evangelistic past efforts, I can say that as ‘HP/Agilent NMDG’ a worldwide reputation with regard to large-signal network analyzer technology was already established.

Now as an independent company, NMDG is also establishing, step by step, a commercial reputation. Using our expertise and by listening to and working closely with customers, NMDG is evolving its measurement and modelling platform for the benefit of the high-frequency designers and testers.

MWJ: As well as software and hardware NMDG offers Services. Please outline what is offered.

Vanden Bossche: Products to characterize and model the nonlinear behaviour of components are challenging. Up until now, I have not seen one standard instrument that directly meets the needs of the customer. Recognising that fact, NMDG’s products are always offered with customization services and, in addition, we offer complementary training and consultancy.

Importantly, before techniques end up in our products, NMDG uses and matures them during its service operation in order to produce practical tools. Of course, the products themselves are also extensively used during service operations.

Customers can send components and systems with nonlinear behaviour, such as diodes, transistors, amplifiers and multipliers/dividers, to us and NMDG will fully characterize the nonlinear behaviour of the components under realistic test conditions. This data helps customers to better understand the performance and behaviour of these devices.

This is in contrast with, for example, classic sources and load-pull, where one sees only final performance factors and it can be very difficult to understand the origin of the results.

Additionally these measurements enable the verification and tuning of large-signal models and ensure proper prediction capability under realistic circumstances and NMDG can also couple these measurements into simulation tools. This eliminates all uncertainty about instrument/component interaction, which occurs with current instrument links in simulators. Up to now, the main focus has been on the ADS environment from Agilent Technologies.

On top of the characterization, NMDG generates nonlinear behavioural models. Depending on the model approach, different aspects of the behaviour can be taken into account. Lately NMDG has introduced S-functions, which were originally developed at Agilent Technologies by former HP/Agilent NMDG colleague Jan Verspecht and published as describing functions.

MWJ: Outline NMDG’s contribution to the development of Large-Signal Network Analyser Technology.

Vanden Bossche: It is not up to me to judge the contribution or impact that HP/Agilent NMDG and the present NMDG, is having on large-signal network analyzer technology. Hewlett Packard began active research and development in this area and contacts with research institutes and academia were established. Additionally a Pan-European Initiative of HP enabled the donation of some early-stage large-signal network analyzers in Europe, which sparked additional research work in the nonlinear area. All this, combined with scientific enthusiasm from different groups, created certain dynamism. This expanded further thanks to the efforts from ARFTG, establishing and supporting the NVNA users meetings. In fact, one can say, “l’ histoire se repete”, considering the origin of ARFTG and their efforts on regular network analyzers.

As a result and due to the growing need for ‘nonlinear tools’, commercial activities grew.

MWJ: Currently, the main focus of your work is on the nonlinear behaviour of high frequency electrical components. Can you expand on the company’s activities?

Vanden Bossche: Indeed, NMDG is focusing on products, characterization and modelling services, consulting and training to assist RF and HF engineers in the design, test and production of components and systems that demonstrate nonlinear behaviour in one way or another. The company is focusing on the large-signal behaviour of components.

This also encompasses activities around Electrostatic Discharge (ESD), where there is a growing interest in measuring and visualizing the behaviour of ESD protection circuits in combination with the normal mode of operation of the devices that they protect. The frequencies of these signals are now moving up the GHz range and require proper calibration techniques. Here NMDG can capitalise on its high-frequency calibration expertise.

Presently NMDG is not involved with RF and HF passive components, neither with noise behaviour of both linear and nonlinear components.

MWJ: Extension Kits are a key company offering. Explain their development and applications.

Vanden Bossche: When NMDG started in 2003, the company worked with Maury Microwave to develop the ‘nonlinear market’, based on a sampler-based ‘MT4463’instrument., A prototype was developed at Agilent Technologies and further developed into a product by NMDG. Maury Microwave was responsible for the distribution and sales as it complemented their tuning products and solutions.

The sampler-based system is the Rolls-Royce of large-signal network analyzers, due to its extended capability and future growth potential. In my opinion, it is an ideal instrument for research institutes and corporate R&D. But it was not able to replace the well-established oscilloscopes or network analyzers. Additionally the cost of ownership of the MT4463 is quite high.

As time progressed, NMDG wanted to reduce the entrance barrier into the industrial market by providing a subset of capabilities for existing receivers. As such extension kits were developed for network analyzers and high-frequency oscilloscopes. The ICE platform is the core of the offering in combination with the required additional calibration hardware. Through plug-ins, connection can be made to different types of receivers and stimuli, originating from different manufacturers.

MWJ: As you have mentioned, much of NMDG’s progression has been through partnerships with other test and measurement companies. Why have you taken this approach?

Vanden Bossche: An important reason is that working with established companies to market hardware products that require a certain investment, eliminates the normal and healthy suspicion of customers towards warranty guarantees, support over a reasonable time period etc.

MWJ: Some of the T&M companies you have partnered with have been competitors with one another. How do you balance these relationships?

Vanden Bossche: NMDG has always been an independent company. As I mentioned, in its early days, it was natural to work with Maury Microwave, channel partner of Agilent Technologies. That relationship allowed NMDG to continue to work based on prototypes and software developed at Agilent Technologies.

However, it would be bad business practice for NMDG to continue to be dependent on third parties for its technology and products. After attracting the necessary investments to fund the R&D work, the company has been working towards independence while informing and respecting fully its partner relationships.

Explaining the capabilities of the new measurement and modelling platform ‘ICE’ to different possible interested parties in late 2007 and early 2008, Rohde & Schwarz showed interest and invited NMDG to demonstrate ICE on their ZVA and ZVT network analyzers during IMS 2008. Step by step, this relationship evolved while new dynamics were established in the marketplace.

Meanwhile NMDG started to work closely with Focus Microwaves. In a very short time this collaboration resulted in a real-time harmonic load-pull system, combining the R&S network analyzer, the Focus harmonic tuner (MPT), the Focus VIProbing product and the NMDG extension kit, including ICE.

NMDG is still a fully independent company and offers its ICE characterization and modelling platform on different types of receivers and stimuli, including tuners, from different manufacturers.

Of course, due to a close relationship with Rohde & Schwarz and Focus Microwaves it is possible to realize a much closer integration and to perform extensive quality control such that it becomes ‘one solution’ for the customer. In contrast, connecting to receivers and stimuli from other manufacturers is usually realised as a consulting project in combination with the extension kit.

Finally, it is the customer who decides what combination of instruments he or she wants to use and what makes most sense.

MWJ: You also have partnerships with academic and research institutes. What specific work has been undertaken?

Vanden Bossche: The evolution of large-signal network analyzer technology would not have been possible without the research work undertaken by different academic and research institutes. Also significant is the ARFTG initiative to create the NVNA forum, which developed synergy and a discussion platform bringing ‘demand and offering’ together.

Although, the concepts of large-signal network analyzer technology date from the early ’90s, there is still a lot of education and promotion to be done. I see an important role for academic and research institutes to educate high-frequency engineers in these matters, beyond S-parameter education.

Also, there is still an enormous amount of work to be done related to behavioural modelling for nonlinear devices. What is very crucial here is the validity and applicability of the modelling techniques. For sure, we are talking about ‘nonlinear components’.

Additionally there is still a lot of work to be done in order to gain further insight into absolute calibration formalism, techniques, propagation of errors etc. For these reasons, NMDG is maintaining contacts with different research institutes and academia so that we remain aware of the scientific progress and, in time, can turn these techniques into products that will benefit our customers.

MWJ: Are there any ongoing projects you can tell me about?

Vanden Bossche: NMDG continuously evolves its products based on customer needs, which are presently driving the extension of behavioural modelling techniques, namely the S-functions for different applications.

To accommodate the growing need for more complex and higher frequency signals, the basic measurement capabilities of the extension kit need to be extended. Another important aspect is the openness of the characterization and the modelling platform. Due to the fact that nonlinear measurements require ‘realistic stimuli’, which very much depend on the application, NMDG wants to provide a platform that enables the customer to stay in full control of the stimuli and flexibly perform different types of experiment designs.

MWJ: What are the advantages and disadvantages of being a European headquartered company operating in a global market?

Vanden Bossche: I have not experienced any disadvantages. On the contrary, different initiatives are taken at the European level to position companies in the global market. If one is willing to perform the necessary paperwork there are distinct advantages. For example there is the EU’s 7th Framework Programme that facilitates and supports the establishment of consortia that can work on longer term topics than would be possible for a company to do so alone.

For example, NMDG participated in the European Network of Excellence, known as ‘TARGET’. This European funded network brought research institutes and academics together, covering aspects from active semiconductor process technology up to complete amplifier systems. This was a very active network, sharing and working out new ideas, benefiting amplifier characterization, analysis, modelling and simulation. During customer visits outside Europe, I heard that some were envious of such initiatives.

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