Radio frequency module and communication device
A radio frequency module includes: a switch circuit including a transmit terminal, a receive terminal, a selection terminal, and a common terminal, the switch circuit being capable of switching between (A) a connection between the transmit terminal and the common terminal, (B) connections between the transmit terminal and the common terminal and between the selection terminal and the common terminal, (C) connections between the receive terminal and the common terminal and between the selection terminal and the common terminal, and (D) a connection between the receive terminal and the common terminal; a transmit/receive filter connected to the common terminal and to be used for a time division duplex system, a pass band of the transmit/receive filter being a transmit/receive band of Communication Band A; and a DTC connected to the selection terminal, the DTC changing its capacitance value according to connection switching of the switch circuit.
1. A radio frequency module comprising:
a switch circuit including a transmit terminal to which a radio frequency transmit signal is inputted, a receive terminal from which a radio frequency receive signal is outputted, a first selection terminal, and a first common terminal, the switch circuit being configured to switch between (1) a connection between the transmit terminal and the first common terminal, (2) connections between the transmit terminal and the first common terminal and between the first selection terminal and the first common terminal, (3) connections between the receive terminal and the first common terminal and between the first selection terminal and the first common terminal, and (4) a connection between the receive terminal and the first common terminal;
a first filter configured to be used for a time division duplex system, a pass band of the first filter being a transmit/receive band of a first communication band, the first filter being connected to the first common terminal; and
a variable impedance element connected to the first selection terminal, the variable impedance element changing an impedance thereof according to connection switching of the switch circuit.
2. The radio frequency module according to claim 1 , wherein the switch circuit and the variable impedance element are formed in one chip form.
3. The radio frequency module according to claim 1 , wherein the variable impedance element is a digital tunable capacitor (DTC).
4. The radio frequency module according to claim 2 , wherein the variable impedance element is a digital tunable capacitor (DTC).
5. The radio frequency module according to claim 1 , further comprising:
a transmit power amplifier including an input terminal and an output terminal, the output terminal being connected to the transmit terminal, the transmit power amplifier operating in one of a first transmit mode and a second transmit mode, the first transmit mode giving priority to power efficiency, the second transmit mode giving priority to magnitude of output power; and
a receive low noise amplifier including an input terminal and an output terminal, the input terminal being connected to the receive terminal.
6. The radio frequency module according to claim 2 , further comprising:
a transmit power amplifier including an input terminal and an output terminal, the output terminal being connected to the transmit terminal, the transmit power amplifier operating in one of a first transmit mode and a second transmit mode, the first transmit mode giving priority to power efficiency, the second transmit mode giving priority to magnitude of output power; and
a receive low noise amplifier including an input terminal and an output terminal, the input terminal being connected to the receive terminal.
7. The radio frequency module according to claim 3 , further comprising:
a transmit power amplifier including an input terminal and an output terminal, the output terminal being connected to the transmit terminal, the transmit power amplifier operating in one of a first transmit mode and a second transmit mode, the first transmit mode giving priority to power efficiency, the second transmit mode giving priority to magnitude of output power; and
a receive low noise amplifier including an input terminal and an output terminal, the input terminal being connected to the receive terminal.
8. The radio frequency module according to claim 5 , wherein in the switch circuit,
(1) when the transmit terminal is connected to the first common terminal, an impedance looking into the first filter from the first common terminal is matched to an optimum impedance of the first transmit mode,
(2) when the transmit terminal and the first selection terminal are connected to the first common terminal, the variable impedance element is set to a first impedance value, and the impedance looking into the first filter from the first common terminal is matched to an impedance of the second transmit mode, and
(3) when the receive terminal and the first selection terminal are connected to the first common terminal, the variable impedance element is set to a second impedance value, and the impedance looking into the first filter from the first common terminal is matched to an impedance looking into the receive low noise amplifier from the first common terminal.
9. The radio frequency module according to claim 8 , further comprising:
a second filter, wherein
the switch circuit further includes a second common terminal and a second selection terminal, the second selection terminal inputting or outputting a radio frequency signal of a second communication band,
the second filter is connected to the second common terminal and has a pass band that corresponds to the second communication band, and
in the switch circuit,
the variable impedance element is set to a third impedance value when a connection between the second common terminal and the second selection terminal is made at a same time as one of (1) the connection between the transmit terminal and the first common terminal, (2) the connections between the transmit terminal and the first common terminal and between the first selection terminal and the first common terminal, or (3) the connections between the receive terminal and the first common terminal and between the first selection terminal and the first common terminal.
10. A communication device comprising:
an RF signal processing circuit that performs processing on a radio frequency signal being transmitted or received by an antenna element;
a control unit that controls connection of the switch circuit; and
the radio frequency module according to claim 1 that transmits the radio frequency signal between the antenna element and the RF signal processing circuit.
11. A communication device comprising:
an RF signal processing circuit that performs processing on a radio frequency signal being transmitted or received by an antenna element;
a control unit that controls connection of the switch circuit; and
the radio frequency module according to claim 2 that transmits the radio frequency signal between the antenna element and the RF signal processing circuit.
12. A communication device comprising:
an RF signal processing circuit that performs processing on a radio frequency signal being transmitted or received by an antenna element;
a control unit that controls connection of the switch circuit; and
the radio frequency module according to claim 3 that transmits the radio frequency signal between the antenna element and the RF signal processing circuit.
13. A communication device comprising:
an RF signal processing circuit that performs processing on a radio frequency signal being transmitted or received by an antenna element;
a control unit that controls connection of the switch circuit; and
the radio frequency module according to claim 5 that transmits the radio frequency signal between the antenna element and the RF signal processing circuit.
14. A communication device comprising:
an RF signal processing circuit that performs processing on a radio frequency signal being transmitted or received by an antenna element;
a control unit that controls connection of the switch circuit; and
the radio frequency module according to claim 8 that transmits the radio frequency signal between the antenna element and the RF signal processing circuit.
15. A communication device comprising:
an RF signal processing circuit that performs processing on a radio frequency signal being transmitted or received by an antenna element;
a control unit that controls connection of the switch circuit; and
the radio frequency module according to claim 9 that transmits the radio frequency signal between the antenna element and the RF signal processing circuit.
16. The radio frequency module according to claim 1 , wherein the variable impedance element is connected in parallel to the first common terminal.
17. The radio frequency module according to claim 9 , wherein the variable impedance element is connected to a path connecting the first selection terminal and ground.
18. The radio frequency module according to claim 9 , wherein the variable impedance element is a digital tunable capacitor (DTC).
19. The radio frequency module according to claim 10 , further comprising a second switch circuit.
20. The radio frequency module according to claim 19 , wherein the control unit controls connection states of the second switch circuit.