Apple has purchased Silicon Valley-based wireless chip developer Passif Semiconductor, reports technology writer Jessica Lessin. The company, which Apple has reportedly been after for several years, specializes in low-power communication chips that could be used to improve battery life in wearable devices such as Appleās rumored iWatch. Passif develops communication chips that use very little power. Its technology, which includes a radio that works with a low-energy version of Bluetooth called Bluetooth LE, is promising for health-monitoring and fitness devices that need extra-long battery life. (Apple, of course, is working on one of those.)Apple has confirmed the acquisition, with Apple spokeswoman Am