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46 The PCB Design Magazine • September 2016 but there is very minimal change with input voltage and load current, especially above 0.2A DC load. There are many other parameters we may want to test. In the frequency domain we could check the gain-phase plot to assess the stability margin of the converter. In the time domain we can measure the output ripple, high-frequency burst noise and transient response. And finally we could tie all that data back to simulations to see how good correlation we get. We will ad- dress some of those items in future columns, and also things that don't make sense to check on evaluation boards. So next time when you evaluate an evalua- tion board, be prepared to know what to expect. Double checking the test data always helps to avoid wrong and potentially misleading con- clusions. PCBDESIGN References 1. Quietpower column, Do not measure PDN noise across capacitors! 2. LM20143 data sheet 3. AN-1691 LM20143 evaluation board 4. DesignCon East 2011 paper, DC and AC Bias Dependence of Capacitors Including Tem- perature Dependence Dr. Istvan Novak is a distinguished engineer at Oracle, working on signal and power integrity designs of mid-range servers and new technology developments. With 25 patents to his name, Novak is co-author of "Frequency-Domain Characteriza- tion of Power Distribution Networks." To contact Istvan, click here. EVALUATING EVALUATION BOARDS Figure 7: Variation of impedance surface as a function of input voltage. Left plot: 3.5V;middle plot: 4.5V; right plot: 5.5V DC input voltage. For sake of simplicity, axis labels and titles are not shown, but are the same as in Figure 2. KnowMade, partner of Yole Développement, pro- poses a new patent landscape analysis titled Micro- battery, dedicated to the microbatteries IP world and taking into account more than 300 patent applicants. CEA is still the main patent holder around the world. But according to KnowMade analysis, Cym- bet, Polyplus Battery, Infinite Power Solutions and Panasonic have the strongest patent portfolios with a real IP blocking potential. KnowMade has developed a unique understand- ing of patent and scientific information that enables the patent analysis company to accurately analyze IP and research findings. Today, it is crucial to under- stand the global patent landscape in order to antici- pate changes, harvest business opportunities, miti- gate risks and make strategic decisions to strengthen one's market position and maximize return on one's IP portfolio. KnowMade—Microbattery

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