Electronic Design


Author Expands Idea For Design
I tested the circuit using the AD9832 DDS device along with the AD8400-50 digital potentiometer \["Digital potentiometers Vary Amplitude In DDS Devices," May 29, p. 108\]. By programming the pot with a value of 20 decimal, the AD8400 was set to have a resistance of 3.9 Ω, the specified value for the RSET in the datasheet. With this pot value and with a master clock of 25 MHz, the spurious-free dynamic range is typically 61.3 dB when a 1-MHz output signal is generated. By loading the pot with 200 decimal, the resistance is increased to 39 Ω. This reduces the full-scale current and, therefore, the maximum analog output voltage of the AD9832 by a factor of 10. With this maximum analog output voltage and under the same test conditions as above, the SFDR of the AD9832 doesn't alter. In conclusion, while many DDS devices don't have an amplitude-modulation facility on board, digital pots permit easy implementation in the analog domain. Additionally, the DDS devices mentioned in the Idea for Design idea don't degrade in performance when the full-scale current is reduced from the maximum value listed in the datasheet to a value which is ten times less.
Mary McCarthy
Applications Engineer
Analog Devices, Ireland

What's There Without The Degree?
I read your article \["The Thinning Engineering Talent Pool Sparks A Lively Debate,"March 6, p. 158\] with some laughter. It's amusing that engineering schools believe that only with higher degrees do talented designers come forth. From my observation of many years as a practicing design engineer, those with MS and PhD degrees looked good on paper, but in general lacked the ability to be new thinkers. All their years at school, they had been told how to think, that only one correct answer exists. So, how do these students with schooled blinders evolve into creative thinkers, and more importantly doers? Well, it has often taken more than a few knocks on the head from the practicing engineers to bring them down into the reality of getting the job done, and on schedule. Many don't make it, and they retreat back to the schools to hide.

My own experience with graduate school was mixed. The chairman of the EE department told me that because I had been out of school for about 10 years, working as an engineer, I would not be able to compete with current BS graduates, as my math skills would be rusty and I was no longer competitive. I asked him when he had ever functioned as an engineer and was told never. It became clear that he had no idea how the practicing engineering world operated, nor the rules of the game.

How can the engineering faculty meet such appraisal standards in the performance of their jobs as educators? The best measure I have found in assessing prospective engineers during interviews is to find out what they did on their own during middle and high school. Those who actively went about solving problems, because they wanted something different or just for the challenge, were players that I wanted to hire. They had "learned" how to be critical problem solvers and doers long before college. More importantly, they had learned how to see both the big and small picture at the same time. College provides the refinement of the inherent skills. The talent, however, remains native to the student. It isn't imparted by the school to the student.

Why the lack of skilled programmers graduating given all the students in the program? Well, the number driven to live and breathe programming has stayed the same. There's just so many who have the talent. The rest can only be technicians. Those few can cause the rest of us to follow along. This is true whether it's analog/digital/RF engineering or programming.

So where does this leave us? The engineering world needs to reach much farther back into the schools and provide exposure, as well as opportunity for growing minds. Our schools play everything so safe that no one gets to work with the real thing. The bottom line is: if you want talent, you must invest in the younger generation.
Fred Husher
Staff Design Engineer
Beckman Coulter
Accountants Aren't Accountable

I feel that your article \["Engineers Vs. Bean Counters: The Struggle Continues," March 6, p. 164\] must be an attempt at comedy, as many of the stories you recount are of mad or bad management and aren't down to accountants at all. I will answer your points in the order that you raised them.

  1. A spreadsheet does all the adding up required. If it takes an engineer half a day to complete an expense report, then that person has been away a long time, or is having trouble remembering what he or she spent. Accountants only pay the bills. They aren't responsible for ensuring that what is claimed is correct. Managers should approve. If you allow everyone free access to your bank account then I'm surprised.
  2. Accountants don't fire people. Management does.
  3. A call-logging system would have achieved the same controls, so why didn't management look at alternatives?
  4. Didn't you complete a budget showing the level of expected business, and the subsequent level of overhead recovery that followed from these projections? The new division was killed by lack of management, not by the accountant.

Finally, you accept that costs should be monitored, but feel that engineers cannot be trusted to accurately and honestly record their actions. This neatly takes us back to point one, allowing your engineers to claim whatever they like from your bank account.
Michael Woodisse
Financial Director
Grant Instruments

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