KEYNOTE: The Unexpected Technology Race between Surface (SAW) and Bulk (BAW) Acoustic Wave Filters used in Today’s Cell Phones

Part of the Allure of Smartphones is they can be used anywhere in the world, reliably transmitting and receiving data at extremely high rates including real time video. Given the patchwork of allowable frequency bands across the world and the use of carrier aggregation to increase bandwidth, Smart phones have multiple filter bands. As an example, the IPhone16 PRO & PROMAX has 60 distinct radio frequency bands with some bands having multiple copies (for the diversity paths). Including the WiFi and GPS filters, there are close to 100 filters in the phone. Each filter represents a radio with Transmit and/or receive functionality. The challenge is not simply fitting more filters into a small physical area; these filters have to work with each other without interference due to spurious modes, intermodulation products, as well as having sufficient isolation. There are 2 technologies - Bulk (BAW) and Surface (SAW) mode devices -competing for the RF filter slots in Mobile phones. Above 1.5 GHz, high performance filters have been dominated by BAW devices. But, SAW technologies are catching up. Neither technologies have been staying still in this race. Quantum improvements have been made in both technologies since the 1990's. We can compare the relative merits of these 2 technologies using 7 or 8 key metrics. A brief overview of these metrics as applied to both technologies and their offshoots will be given. And lastly, some observations about the future and what to expect along with some of the latest breakthroughs in each respective technology. In the end, this race benefits the user in terms of longer battery life, fewer dropped calls and faster data rates (video).