Directional coupler, radio communication device, and control method

A radio communication device comprising a directional coupler, wherein

• the directional coupler includes:
• a primary line that transmits signals from a first terminal to a second terminal,
• a secondary line that gets coupled with the primary line and draws some of the signals into a third terminal,
• a first switching unit that switches connection destination of the third terminal between one end of the secondary line and other end thereof,
• a first impedance regulating unit that is installed in between the one end of the secondary line and ground, and that changes impedance according to frequency of the signals,
• a second impedance regulating unit that is installed in between the other end of the secondary line and the ground, and that changes impedance according to the frequency of the signals, and
• a resonance circuit that is installed in between the first switching unit and the third terminal, and that changes impedance of the third terminal according to the frequency of the signals, wherein the resonance circuit includes:
• a coupling planarization unit that is electrically connected in series in between the first switching unit and the third terminal, wherein the coupling planarization unit performs such adjustment that frequency dependence of coupling characteristic between the first terminal and the third terminal is planarized in a predetermined band, and
• a matching regulator unit that is electrically connected in parallel with the coupling planarization unit and in between the first switching unit and the third terminal.

A control method for a directional coupler, the control method comprising:

• a primary line that transmits signals from a first terminal to a second terminal,
• a secondary line that gets coupled with the primary line and draws some of the signals into a third terminal,
• a first switching unit that switches connection destination of the third terminal between one end of the secondary line and other end thereof,
• a first impedance regulating unit that is installed in between the one end of the secondary line and ground, and that changes impedance according to frequency of the signals,
• a second impedance regulating unit that is installed in between the other end of the secondary line and the ground, and that changes impedance according to the frequency of the signals, and
• a resonance circuit that is installed in between the first switching unit and the third terminal, and that changes impedance of the third terminal according to the frequency of the signals, wherein the resonance circuit includes:
• a coupling planarization unit that is electrically connected in series in between the first switching unit and the third terminal, wherein the coupling planarization unit performs such adjustment that frequency dependence of coupling characteristic between the first terminal and the third terminal is planarized in a predetermined band, and
• a matching regulator unit that is electrically connected in parallel with the coupling planarization unit and in between the first switching unit and the third terminal,
• wherein the control method regulates the first impedance regulating unit, the second impedance regulating unit, and the resonance circuit according to the frequency of the signals.