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.<\/p>\n
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 \u201cGarbage In Garbage Out\u201d. 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\u2019t 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.<\/a>, looked into the circuit, we found that circuit can be done in 1\/4th<\/sup> of cost and 400% more precise for customer\u2019s application. Since we were able to reduce the cost on BOM by 1\/4th<\/sup> , 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.<\/p>\n 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.<\/p>\n If you feel you lack knowledge of circuit design, find a reputable company who has knowledge and experience in that field. Here at PNC<\/a>, 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.<\/p>\n Component selection and board layout will be discussed in detail in forth coming articles.<\/p>\n Thank you.<\/p>\n Sam Sangani Jr.<\/p>\n