Devices and methods related to radio-frequency (RF) filters on silicon-on-insulator (SOI) substrate. In some embodiments, an RF device can include a silicon die such as an SOI die including a first side and a second side. The silicon die can further include a plurality of vias, with each via configured to provide an electrical connection between the first side and the second side of the silicon die. The RF device can further include at least one RF flip chip mounted on the first side of the silicon die. The silicon die can include, for example, an RF circuit such as a switch circuit, and the RF flip chip can include, for example, a filter such as a surface acoustic wave (SAW) filter.