Tunable directional coupler for RF front-end applications

A tunable directional coupler for radio frequency (RF) front-ends of handheld mobile devices is presented. The coupler is implemented in a 0.13 μm bulk RF-CMOS technology with all elements monolithically integrated on a single die. A digitally-tuned termination network at the isolated port of the coupler is realised solely with RF-switch transistors using the channel resistance of a metal-oxide-se...