Duplexer

A duplexer comprising:

• a transmission-side terminal for inputting a transmission signal;
• a reception-side terminal for outputting a received signal;
• a common terminal for inputting the transmission signal from the transmission-side terminal and outputting the received signal to the reception-side terminal;
• a transmission-side circuit unit connected between the transmission-side terminal and the common terminal;
• and
• a reception-side circuit unit connected between the common terminal and the reception-side terminal;
• wherein:
• the transmission-side circuit unit includes:
• a first transmission-side filter provided in a subsequent stage of the transmission-side terminal to allow passage of a predetermined transmission-band component in the transmission signal;
• a second transmission-side filter provided in a stage subsequent to the first transmission-side filter to allow passage of the transmission-band component in the transmission signal;
• and
• a transmission-side directional propagation circuit connected between the first transmission-side filter and the second transmission-side filter to propagate, in a specific direction, a signal input from one transmission-side terminal and output the signal from the other transmission-side terminal, and
• the reception-side circuit unit includes:
• a first reception-side filter provided in a subsequent stage of the common terminal to allow passage of a predetermined reception-band component in the received signal;
• a second reception-side filter provided in a stage subsequent to the first reception-side filter to allow passage of the reception-band component in the received signal;
• and
• a reception-side directional propagation circuit connected between the first reception-side filter and the second reception-side filter to propagate, in a specific direction, a signal input from one reception-side terminal and output the signal from the other reception-side terminal;
• wherein:
• the transmission-side directional propagation circuit includes:
• a transmission-band circulator;
• and
• an out-of-transmission-band filter for blocking the transmission-band component in the transmission signal, the transmission-side circulator including:
• a transmission-side first terminal for inputting the transmission signal from the first transmission-side filter and propagating the transmission signal to a transmission-side third terminal;
• a transmission-side second terminal for outputting, to the second transmission-side filter, the transmission-band component in the transmission signal;
• and
• a transmission-side third terminal for outputting, to one terminal of the out-of-transmission-band filter, a component other than that of the transmission band in the transmission signal, and propagating the transmission-band component to the transmission-side second terminal;
• and
• the reception-side directional propagation circuit includes:
• a reception-band circulator;
• and
• an out-of-reception-band filter for blocking the reception-band component in the received signal, the reception-band circulator including:
• a reception-side first terminal for inputting the received signal from the first reception-side filter and propagating the received signal to a reception-side third terminal;
• a reception-side second terminal for outputting, to the second reception-side filter, the reception-band component in the received signal;
• and
• a reception-side third terminal for outputting, to one terminal of the out-of-reception-band filter, a component other than that of the reception band in the received signal, and propagating the reception-band component to the reception-side second terminal.