Apparatus and methods for reconfigurable directional couplers in an RF transceiver with selectable phase shifters

A directional coupler for a power signal, the directional coupler comprising:

• a transmission path that includes an input port and an output port with a first selectable phase shifter interposed therebetween;
• a coupled path that includes a coupled output port and an isolation port that has a second selectable phase shifter interposed therebetween;
• a first capacitive coupling element that couples the input port on the transmission path to the coupled port on the coupling path;
• a second capacitive coupling element that couples the output port on the transmission path to the isolation port on the coupled path, the isolation port on the coupled path configured to receive a first signal from the transmission path and second capacitive coupling element and to receive a second signal from the first capacitive coupling element and the coupled path;
• and
• a processor that adjusts the first and second selectable phase shifters based upon variations of the power signal to achieve a desired phase shift of the first and second signals received by the isolation port, and to achieve a desired directivity of the coupler.

A wireless device for a power signal comprising:

• an antenna;
• a transceiver;
• a power amplifier that amplifies signals between the transceiver and the antenna;
• a coupler that receives the amplified signal from the power amplifier, the coupler having an input port that receives the signal from the power amplifier, an output port that provides a signal to the antenna and that is connected to the input port via a first selectable phase shifter, a coupled port that is connected to the input port via a first capacitive coupling element and provides a coupled signal to a sensor, and an isolation port that is connected to the coupled port via a second selectable phase shifter and is further connected to the output port via a second capacitive coupling element;
• and
• a processor that adjusts the first and second selectable phase shifters based upon variations of the power signal to achieve a desired phase shift of the first and second signals received by the isolation port, and to achieve a desired directivity of the coupler.