Knowledge Center
Knowledge Center

Radio Frequency Silicon On Insulator (RF-SOI)

RF SOI is the RF version of silicon-on-insulator (SOI) technology.


RF SOI is a specialized process used to make select RF chips, such as switch devices and antenna tuners, for smartphones and other products. RF SOI is the RF version of silicon-on-insulator (SOI) technology, which is different than fully-depleted SOI (FD-SOI) for digital chips.

There are several dynamics at play with RF SOI. In simple terms, the number of frequency bands has increased in wireless networks. So OEMs must add more RF components, such as RF switches based on RF SOI, in smartphones to deal with the complexity of these bands as well as other issues.

Chips using RF SOI processes are targeted for various applications, but the big market is RF front-end modules in cell phones. In total, Gartner forecasts that worldwide mobile phone shipments will reach 1.9 billion units in 2018, up 1.6% over 2017. In 2019, smartphone sales are on pace to grow at 5%, according to Gartner.

RF SOI chips are used in RF switches, one of the RF components integrated into a smartphone’s RF front-end module, which handles the transmit/receive functions. The front-end module consists of a number of components, including power amplifiers, antenna tuners, low-noise amplifiers (LNAs), filters, and RF switches. Switch chips and tuners are based on RF SOI. RF switches route signals from one component to another, and tuners help the antenna adjust to any frequency band.

Fig. 2: Another RF front-end module. Source: STMicroelectronics

“Each new generation of handsets, for example, requires support for more and more bands and standards and each requires filters that are switched in and out of the circuit by RF SOI components. RF SOI is also used in WiFi for receive and switch functions, and in antenna tuners to improve reception,” said Marco Racanelli, senior vice president and general manager of the RF/High Performance Analog Business Unit at TowerJazz in 2018. “The increased number of antennas is also contributing to this trend, with diversity antennas now more common. And MIMO (multiple-in-multiple-out) antennas are being adopted, each requiring additional RF switches to help direct traffic.”

Fig. 4: RF SOI substrate Source: Soitec


Related Entities