Please tell us what do you do professionally and what other activities you have.

I am an Electronics Engineer, specialized in low noise analog circuitry design and mixed-signal design. My job is the design and development of high-end equipment for the scientific and research market. At the same time I am an Adjunct Faculty and I teach digital design and programming. I also like biking, charcoal drawing, and I play classical guitar.

How did you get into electronics/ engineering and when did you start?

I had an uncle who owned a small repair shop, where he would fix anything from TV-sets and radios to steam-irons. I started to visit his shop when I was about 9 years old. Electricity fascinated me and I paid attention to his explanations trying to understand how things work. Later on he gave me things to do, like restoring the bobbin of a burned transformer, sorting resistors, and other small jobs. Then I started to go with him at his clients, or I was his third hand in his shop when needed. Time passed and I learned about electricity in school and then I went to university to study electrical engineering and electronics. I started to know more than my uncle did and I remember, while I was in university, I explained to him how operational amplifiers work, while his mind was still in the vacuum tube world. When I wrote my PHD thesis I dedicated it to my uncle, for opening my eyes to the world of electronics.

What are your favorite hardware tools that you use?

I use a good oscilloscope, with built in FFT, storage, and USB communication for screen capture. I also use precision current sources, like the trusted and never old Keithley 263. I design low noise equipment so I need a good spectrum analyzer. I also need low-noise differential voltage preamplifiers. For very special low-noise applications I designed my own battery powered low-noise differential preamplifier, with a signal to noise ratio of 140 dB and gain up to 40000 at a bandwidth of 1 MHz.

What are your favorite software tools that you use?

I do a lot of modeling to make sure the circuits I design will work as expected. When I design a circuit, I like to calculate everything to avoid surprises later on. For that I use Mathcad. I like it, because it has a whiteboard like interface so that I can document my design as well, besides writing my own models. I can put there thoughts, ideas for improvement, calculate variations, and so on. The fact that Mathcad can work with units is a plus, as it naturally invites one to use the dimensional analysis method for calculation verification.

I also use Multisim for SPICE simulation and to verify my calculations. Using both software tools it gives me great confidence in my design when the results match between the two.

What is the hardest/trickiest bug you have ever fixed?

Well, in time, there were many bugs to be found. It is difficult to rank them. One that I remember now was an error amplifier in an analog feedback system that had low gain. Moreover, the gain was different from unit to unit. Because of the low gain, the precision of the feedback loop was affected. The system behavior was unpredictable. What was the bug?

The error amplifier was a PI type, so it had a surface mount capacitor in its feedback. The problem was that the board manufacturer did not clean the board properly. Because of that, the capacitor had a stray resistor in parallel, made with the residuum left by the manufacturing process. The stray resistor had a sufficiently low resistance to change the error amplifier gain and, of course, it was different from board to board. I showed the board manufacturer that, if the capacitor is removed and the board cleaned underneath, then the capacitor soldered back, the error amplifier gain is restored.

What is on your bookshelf?

I believe in a balanced lifestyle. This includes reading. On my bookshelf there are professional books, fictional literature books, hobby books, etc. Among the professional books there is “Analysis and Design of Analog Integrated Circuits” by Paul R. Gray, Paul J. Hurst and Stephen H. Lewis. Also, “The SPICE Book” by Andrei Vladimirescu and “The Scientist and Engineer’s Guide to Digital Signal Processing” by Steven W. Smith. Another great book I have is “High Speed Digital Design: A Handbook of Black Magic” by Howard Johnson and Martin Graham.

In fiction you will find “Ender’s Game” by Orson Scott Card. In the hobby section, I like charcoal drawing, so I have “The New Drawing on the Right Side of the Brain” by Betty Edwards. I play classical guitar so I have guitar books like Matteo Carcassi’s classical guitar method.

Do you have any tricks up your sleeve?

I have a few rules when it comes to designing circuits:

Mother Nature always wants to challenge you. So, calculate everything and expect the unexpected.

Kirchhoff’s Laws are always true. This means that, if the sum of voltage drops on a loop does not equal zero, there is another component in that loop that has a voltage drop and you are not aware of it. By the same token, if the sum of currents in a node is not zero, it means that there is another signal path coming out of that node which is hidden from you.

Signals are always differential. Never treat your ground as an absolute zero volt trace, because it never is.

Zero does not exist in analog or mixed signal design. There is no such thing as zero voltage, zero current, zero ohms, zero inductance or zero capacitance. Depending on your design specs, one of these so called “zeros” will quickly show you that it has a non-zero value. As such, I always think in dB. For example, I know I will never have zero noise in a system, but if my noise to signal ratio is -100 dB, great. If it is -120 dB, awesome. If it is -140 dB, super. Knowing that you cannot achieve that zero, makes you think twice when planning your PCB layout.

If you do not provide a return path for your signal, it will find one for you, and it may not be one that you like.

I always follow the current path when analyzing a circuit. In a low noise signal environment one needs to be aware of the signal return and design the ground planes accordingly. When I plan my component placement on a PCB I always imagine the current path between components and I draw the current flow to and from the driver component, on large sheets, to visually see any possible problems.

What has been your favorite project?

Some years ago I was hired by a company in the hard drive business to design a test fixture to measure the imperfections of the disk surface. Of course, the company already had test equipment for this measurement and its factories had hundreds of them deployed for production testing. The problem was that the measurement was perceived slow. It was made on the idea of data acquisition and post processing. It took time to acquire many points of data on a disk track, store them, then analyze them, and then moving to the next track. Knowing that I was specialized in low noise analog design and mixed-signal design, the company asked me to design an analog test fixture that would give an instantaneous result for the track under test, right after a few disk spins. I loved that project. It worked great and it proved that, in a world in which everything moves towards digital design, there are some applications where the analog signal processing cannot be replaced.

Do you have any note-worthy engineering experiences?

I think my patents are note-worthy projects. Also, one accomplishment that stands out is a current meter with a proved 10 fA resolution. As you know, 10 fA is a really small current, the passing of a few tens of electrons every millisecond. Any leakage in the input stage can affect the measurement. Component noise, induced noise, as well as humidity can be really annoying when performing measurements at this level. I did this with a careful PCB architecture, good components and special component mounting. The meter went into production and, along the years, it proved to be stable and well received by customers.

What are you currently working on?

I am working on a new meter with more measurement capabilities and on a new current source with excellent signal-to-noise specs.

In your opinion, what is the future of analog/mixed-signal design and analog circuits in general?

I am convinced that analog circuits are here to stay. Analog design and mixed-signal design will continue to evolve with new components and techniques. This is especially true, knowing that we live in an analog world and the human sensors are analog. I have an article about this in my blog, “It’s an Analog World by Design”:http://masteringelectronicsdesign.com/it-s-an-analog-world-by-design/. Many believe that the future is digital. That is correct from a signal processing point of view and digital communications. The advances in digital processing and digital communications today are spectacular with error free data transmission. Still, we need to convert the analog signal into digital and restore it after digital processing to accommodate our human analog sensors. This is done with analog and mixed-signal circuits.

Besides the interface with the Mother Nature we also need high efficiency switching power supplies and DC to DC converters. Those are analog circuits and there is a constant research for new components to increase the efficiency of these circuits as well as their switching frequency. There are some other areas where the analog circuits are invaluable, like control loops in low noise applications, filtering, etc.

You said that you also teach, besides your engineering full-time job. How did you start teaching and what do you teach?

Years ago a former professor of mine asked me if I would like to teach at his university. He had a digital design class and was looking for an associate faculty to help him with course delivery and seminars. I accepted it as a part time job and found out that I enjoyed teaching very much. Along the years I taught at different institutions and now I teach at Mt. San Jacinto College in California. I teach classes in digital design, PHP, C++ and ASP.NET. Together with Glenn Stevenson, the CSIS Department Chair, we work on expanding the engineering curriculum to also include analog design and different levels of certification in electronics.

Why did you start your own blog MasteringElectronicsDesign.com?

I constantly go online to search for datasheets, application notes and the latest technology that would help in my new product development. Many times I noticed people asking questions about analog design and I saw good answers but, unfortunately, many not so good or confusing answers as well. So, I thought I could do a better job by writing about different topics in analog design. After I launched MasteringElectronicsDesign.com I was surprised that I had many visits in the first month. Since then, the website grew and now I am in correspondence with electronics enthusiasts, engineers, professors, students from all around the world. I find out about their projects, and plans, some of them amazing. It is a great experience, which I would have never had without this blog.