This changed dramatically in the second decade of the new millennium with the launch of Smartphones having multiple frequency bands and carrier aggregation (CA). Today, one of the most expensive components in a Smartphone are the RF Radio Front End modules (or RFFE). The most expensive components inside the RFFE module are the 30 to 50 filters collectively (per module). Filters define the cost. Filters define the size. And Filters define the performance of these modules. All 3 of these orthogonal demands from the customer can be solved with better filters. Currently, there are two competing technologies for high performance filters. In the mid band (1.4 to 2.7 GHz), both Guided Wave Surface Acoustic Wave Devices (GWSAW, but often referred to as Piezo on Insulator or POI) and Free-Standing Bulk-Wave Devices or FBAR. The ‘new frontier’ for acoustic filters are radio bands above 4 GHz. Here, we are seeing new kinds of acoustic filters including the new and innovative XBAR devices. This is essentially a Lamb Mode device where the fundamental frequency of the A1 mode is a function of the piezo thickness. Not to be outdone, FBAR folks are working on their own innovative technologies for ultra-high frequency applications. One of the more promising technologies is the RSBAR, where the piezo layer is divided into two layers with opposite polarity. This suppresses the fundamental mode while favoring the 2nd harmonic, thus doubling the frequency. RSBARs have relatively thicker electrodes than a standard FBAR and avoid the thickness scaling laws that reduce electrode thickness for higher frequencies.

At the same time that there is a future for further innovation, there is also the reality that filter technology is becoming commoditized. Filters that used to sell for $5, now sell for pennies. Navigating our way through both the challenges of innovation and the horrors of commoditization will be the theme of my talk.