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GaN-based power devices offer game-changing potential in power-conversion electronics

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David Kim
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re: GaN-based power devices offer game-changing potential in power-conversion electronics
David Kim   10/20/2011 4:02:03 PM
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Are you qualified for and interested in this position? Or do you have anyone to recommend for this? East coast position. Please return this email with your resume. locations. David Kim Lincoln Johnson Group Division of WebJobBank Inc. Greenwich, CT (203) 661-6363 newjobs@mindspring.com Principal/Sr. Scientist-GaN on Si -Director level As part of our new endeavor in the power electronics market we are in search of a Senior or Principal level Scientist who is a GaN on Si expert to lead the activities for our new development group. This role includes process development activities as well as building and testing characterization devices. Responsibilities * Provide technical leadership for process development of leading-edge GaN on Si epitaxial stacks for power electronics and LED applications. * Define and coordinate fabrication and testing of GaN on Si power electronics devices and LEDs using external device fabrication and characterization / testing resources.

sensatech
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re: GaN-based power devices offer game-changing potential in power-conversion electronics
sensatech   1/29/2009 7:09:14 AM
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We need small,sot23?, devices for high volumes automotive applicatons. Please keep me informed.

green_power
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re: GaN-based power devices offer game-changing potential in power-conversion electronics
green_power   1/13/2009 9:54:15 PM
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While GaN devices offer distinct advantages over silicon, this paper is misleading in how they materialize in DC-DC power conversion from 12 to 1.2V. The main distinction between GaN and silicon is that the critical field for breakdown is roughly 10X higher. However, the mobility is actually lower compared to silicon. The higher breakdown capability translates to a much smaller drift resistance in a GaN hemt, which dominates overall resistance for large breakdown voltages. If the voltage is 30V or less, this difference is not that significant. Thus although you would see an initial benefit of a GaN buck converter compared to a trench MOS solution, there is no reason to expect further improvements as the benefits become incremental. On this note, the high frequency efficiency quoted at higher than 10Mhz operation is wildly optimistic at 100A operation. For example, the author quotes 95% efficiency at 50Mhz by 2014. Even if you had completetly lossless active devices, inductor core and board resistive parasitic loss would limit peak efficiency to below than 90%. It would be useful to see a comparison of the 12V GaN solution to the traditional MOS solution from a cost perspective. What is the cost of ownership for the touted efficiency gains? Also it would be informative to compare the environmental impact of MOS vs GaN processing. Which technology has the lowest carbon footprint overall in 12V applications?

green_is_now
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re: GaN-based power devices offer game-changing potential in power-conversion electronics
green_is_now   1/8/2009 7:37:33 PM
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Did anybody do same frequency comparison with just the devices swapped out? The graphs did not show the switching loss increase with frequency in terms of efficiency. I understand this goes down by an order of magnitude, but does it become so trivial to push things to 50 Mhz?. Even if so does it not pay to have a drop in design phase until the 60Mhz designs are really on the ground. Do switching losses get set or measured at any specific points? 1%,0.1%,0.01%. Or against conduction losses? It would be interesting to see the efficiency graph get worse as the switching frequency starts to get prohibitivly high for given materials Gate drive capacitance for Si, GaN at their relative frequencies. Also of interest is how much conduction losses are contributing compared to switching. In terms of the GaN vs Si. the knee in the curve would show the switching losses. Your graphs did not show this effect other than giving limits to upper operating frequencies. How much savings in "down stream losses" are their in comparison to the switching losses if they are not shown. Both for silicon and its frequency knee and GaN frequency Knee further over and this relative to the down stream savings. In other words you have chosen to keep efficiency constant and lower material cost. This may be the best analysis method as cost is king. However, if it was done on a constant frequency basis and allow the lower frequency operations higher efficiency to be measured relative to this how would this compare with the down stream efficiencies you are eluding to? Are these mostly capacitive, or both inductive and capacitive reductions? Showing the efficiency gains at lower frequencies as a "drop in" upgrade in efficiency right now with existing designs is worth doing also and to show against the down stream losses in terms of standard designs in use in 2008. This would show a output increase and lower operating temperatures, improving reliability and operating efficiencies now. Lower operating costs of power use achieved.

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