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Circuit Design for Reliability Part 2
Reliability of the circuit depends on many factors, starting from topology of the circuit, selection of the appropriate components and final board layout. Each phase has several theories and principles to be considered during the development phase and they will be discussed here.
Topology of the circuit is the most critical step in circuit design. In my 25 years of experience, I came across so many engineers who rely on text book circuit, circuit on the internet and reference design kit from manufacturers. There is nothing wrong with copying the circuit from these sources if you are not violating the intellectual rights of the author of the circuit. However there are unlimited risks using these circuits blindly in your applications because the circuit, that the author has published, might be appropriate for his particular application and your application(s) might be completely different than his. The same risk applied to other sources too. As an example, a circuit published by author for peak detector has general purpose amplifier or instrumentation amplifier does work very well with signal level and frequency of his applications, like input bias current, rail-to-rail swing, input offset voltage, gain-bandwidth product, noise figures etc. If your sensor is sensitive to extra loading due to bias current, the output of the sensor becomes garbage. And fundamental rule we have to remember is “Garbage In Garbage Out”. If you feed the circuit garbage, you cannot expect gold at output. In my recent experience, one of my customers wasted over six months and spent over $36,000 to figure out why the circuit, he took as a reference from internet, didn’t work for him. Finally we got an opportunity to review that circuit. In short there was a fundamental problem of gain roll-off due to higher frequency of the sensor signal, inaccurate board layout causing ground bounce due to unwanted current loops. When we, PNC Inc., looked into the circuit, we found that circuit can be done in 1/4th of cost and 400% more precise for customer’s application. Since we were able to reduce the cost on BOM by 1/4th , this customer was able to manufacturer his product at much more competitive price in the market. So for long run, it turned out to be a high margin profitable product for them.
In conclusion I would like innovators/engineers to know that: be careful when you borrow the circuit from any unauthorized source. Make sure you know the in & out working principle of the circuit. Do circuit analysis based on your application requirements. Once you know the requirements and the working principle of the circuit, you will be able to reduce the cost as well as elevate accuracy of the circuit if you are knowledgeable enough to tweak the topology of the circuit.
If you feel you lack knowledge of circuit design, find a reputable company who has knowledge and experience in that field. Here at PNC, we have been doing circuit design from concept to final product for over 25 years. We have been helping small innovators, OEM, CM to fortune 500 and other organizations around the world.
Component selection and board layout will be discussed in detail in forth coming articles.
Thank you.
Sam Sangani Jr.
PNC INC. PCB Design and Layout Services
Written by Sam Sangani
Sam Sangani is the President & CEO of PNC Inc., a Nutley, NJ based Printed Circuit Board manufacturer. Sam graduated from L. D. Engineering College with a BS Degree in Mechanical Engineering. He also continued his education and graduated from Steven’s Institute of Technology where he acquired a Master’s degree in Computer Science.
After completion of his BS, Sam worked as a QC Manager, for Xerox, Romania and London. He was responsible for the Quality Control of Cable and Wire Harness imports from Romania. After completing his Master’s Degree, he worked as a Senior Programmer with IBM, Tucson, Arizona. Sam was responsible for leading the Mainframe System Programming Team.
In 1997, Sam acquired PNC INC., a Nutley, NJ based PC Board fabrication Shop. From 1997-2013, Sam has made tremendous improvements and changes within PNC INC., as he added many new Products and Technologies in PNC’s portfolio. With his proven track record and leadership, PNC has never had an unprofitable year and has continued its growth yearly since 1997.
His current responsibilities are Strategic Planning, Corporate Management, New Business Ventures, Sales & Marketing, Trade Shows, Professional Services and leading productive teams to achieve peak potential. He has also utilized Lean Management techniques which have built a foundation for PNC’s high-paced growth. Sam also enjoys real-estate investing, web design & SEO, trading stocks, options, futures and Forex markets.
