If you’ve ever had a case of a hot hand from holding your smartphone or cell phone then you know that these small systems have thermal challenges as much as any large system. In fact, those challenges may be greater since there are limited options to cool such devices. Rob Rovetta, VP of Products, Quantance Inc, wrote an interesting editorial on this topic that’s well worth a read. In his editorial he notes such alarming facts as:
Thermal images of a high-speed USB data card with the plastic case removed, measured at room temperature and operating at peak transmit power shows a PA case temperature of greater than 91 degrees celsius (196 degrees fahrenheit).
and
Similar measurement for a smart phone, also with the plastic case removed, measured at room temperature, and operating at peak transmit power show a PA temperature to be greater than 86 degrees celsius (189 degrees fahrenheit). Clearly, the PAs used in today’s data cards and smartphones are one of the hottest items in the device and thus a primary cause for consumer complaints about heat. It is also worth noting that the operational specification for these PAs states the maximum case temperature should be limited to 90 degrees celsius, so even under fairly benign conditions, the PA is already being pushed to its thermal limit.
Rob offers some suggestions to get at the root issue in his editorial.
Quantance is in the business of creating low power RF technologies, but, Rob’s views are still valuable. As designers, we owe it to users to create the most thermally safe products that we can. Rob’s editorial gives food for thought in this area. Have a read by clicking to, “Reality Check: The heat is on; increasingly higher speeds introduce thermal challenges in mobile data devices“