Bulk acoustic wave (BAW) is suddenly rising in the 5th generation mobile communication era. Previous surface acoustic wave (SAW) filter had limits in dealing with 5th gen. communication bandwidth. Companies are trying to obtain BAW filter technology in order to take place in 5G smartphone market.

Samsung Electronics is reviewing whether to apply BAW filter expansion via next generation band pass filter. It is much more expensive than the currently used SAW filter but more effective for 5G, which is expected to be used in 28㎓ or higher ultrahigh frequency range.

Band Pass Filter is the main part in filtering out needed frequency range out of many. It is located on the back of smartphone RF part and functions as filter for frequency. Either only the filter is put in or is made into duplex form by putting many pieced together.

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<SAW filter structure >

Up to 2G, 3G 4G, the SAW filter that created comb shaped electrode via photo lithography process on piezoelectric polymer (piezoelectric element) board was commonly used. It produces well and function under 1.5㎓ low frequency range is excellent price. its limit is that it cannot shrink the size because it creates electrode off of surface. Also it cannot function properly in the 2㎓ or higher frequency range.

BAW filter is similar to SAW filter in theory because it uses resonating piezoelectric in a certain frequency. Unlike the SAW filter that sends signals horizontally, the electrode is placed in upper and bottom part of piezoelectric making it a sandwich form, sending signals vertically.

It has better frequency filtering, module receiving, and requires less power when transmitting than using SAW. Because it adjust according to the thickness and not surface, it can be easily miniaturized but at the same time costly.

Current commercial frequency range is saturated with smartphones, wearable devices, Internet of Things (IoT) and other new technologies. Next generation mobile communication technology 5G is not set for the global standard. Yet, for faster communication, ultrahigh frequency ranges such as 28㎓, 38㎓, 70㎓ are being debated for usage.

Industry related official said, “Functions and structure-wise, BAW is better than SAW in many ways. The problem is the patent issue and cost-effectiveness satisfaction. If the complicated process is innovated and the price is lowered, than there is higher chance to be selected as the next generation band pass filter.”

Staff Reporter Park, Jungeun | jepark@etnews.com