According to an example embodiment of the inventive concept, a master unit for time division duplex includes a passive signal distributor for outputting, to a second node, a downlink signal input through a first node, and outputting, to the first node, an uplink signal input through a third node, and a signal transceiver for transmitting, to a remote unit, the downlink signal input from the second node, and outputting, to the third node, an uplink amplification signal received from the remote unit.

A radio frequency duplexer with a first directional coupler configured to divide an input reception signal into a first auxiliary reception signal and a second auxiliary reception signal, where the first auxiliary reception signal and the second auxiliary reception signal comprise signal components at a reception frequency, a first filter configured to filter the first auxiliary reception signal to obtain a third auxiliary reception signal, a second filter configured to filter the second auxiliary reception signal to obtain a fourth auxiliary reception signal, where pass bands of the first and the second filters comprise the reception frequency, a second directional coupler configured to combine the third auxiliary reception signal with the fourth auxiliary reception signal to obtain an output reception signal.

A radio frequency duplexer with a first directional coupler configured to divide an input reception signal into a first auxiliary reception signal and a second auxiliary reception signal, where the first auxiliary reception signal and the second auxiliary reception signal comprise signal components at a reception frequency, a first filter configured to filter the first auxiliary reception signal to obtain a third auxiliary reception signal, a second filter configured to filter the second auxiliary reception signal to obtain a fourth auxiliary reception signal, where pass bands of the first and the second filters comprise the reception frequency, a second directional coupler configured to combine the third auxiliary reception signal with the fourth auxiliary reception signal to obtain an output reception signal.

The present invention discloses a self-interference signal cancellation device. The device includes a first self-interference cancellation unit, configured to: obtain a first analog signal by coupling a transmit signal output by an analog transmit processing module; perform analog-to-digital conversion on the first analog signal, to obtain a first digital signal; perform interference reconstruction according to the first digital signal, to obtain a first digital interference cancellation signal; and cancel, according to the first digital interference cancellation signal, a self-interference signal included in a digital signal output by a first analog-to-digital conversion module, to obtain a first output signal, and output the first output signal to a digital receive processing module. In the present invention, after interference cancellation is performed by using the first digital interference cancellation signal and the digital signal output by the first analog-to-digital conversion module, a self-interference signal introduced during transmission can be canceled.

A radio-frequency module includes, for example, a low-band circuit configured to transfer a first transmit-signal group and a first receive-signal group in a low-band group, a middle-band circuit configured to transfer a second transmit-signal group and a second receive-signal group in a middle-band group, antenna connection terminals, a transmit-signal input terminal coupled to an output terminal of a power amplifier configured to amplify the first transmit-signal group, and a transmit-signal input terminal coupled to an output terminal of a power amplifier configured to amplify the second transmit-signal group. The low-band circuit includes duplexers, a switch, and a switch. The middle-band circuit includes duplexers, a switch, and a switch.

Systems, methods, and devices for reducing insertion loss and/or swapping transmitter (TX) and receiver (RX) frequencies in an electrical balance duplexer (EBD) used in a transceiver device for frequency division duplexing (FDD) applications are provided. Feed-forward receiver path from the antenna to a low noise amplifier (LNA) and a feed-forward path from the antenna to a power amplifier (PA) of the EBD may be used for reducing insertion loss of the RX and TX signals. In some embodiments, switches may be used to selectively alter operational modes for varied levels of isolation and/or swapping of TX and RX frequencies.

Systems, methods, and devices for reducing insertion loss and/or swapping transmitter (TX) and receiver (RX) frequencies in an electrical balance duplexer (EBD) used in a transceiver device for frequency division duplexing (FDD) applications are provided. Feed-forward receiver path from the antenna to a low noise amplifier (LNA) and a feed-forward path from the antenna to a power amplifier (PA) of the EBD may be used for reducing insertion loss of the RX and TX signals. In some embodiments, switches may be used to selectively alter operational modes for varied levels of isolation and/or swapping of TX and RX frequencies.

In a switching circuit, an inductance of an inductor of a shunt circuit is such that off capacitance of a second switching device that is in the off state when a first switching device is in the on state is used to define, in the shunt circuit, a series resonance circuit with a desired resonant frequency. Therefore, the frequency of an unnecessary signal to be attenuated is set to the resonant frequency of the series resonance circuit. Thus, the switching circuit achieves improved isolation characteristics with other circuits by attenuating the unnecessary signal.

In a switching circuit, an inductance of an inductor of a shunt circuit is such that off capacitance of a second switching device that is in the off state when a first switching device is in the on state is used to define, in the shunt circuit, a series resonance circuit with a desired resonant frequency. Therefore, the frequency of an unnecessary signal to be attenuated is set to the resonant frequency of the series resonance circuit. Thus, the switching circuit achieves improved isolation characteristics with other circuits by attenuating the unnecessary signal.

A front-end module includes: a switch module that performs CA for bands A and C and performs non-CA for band B, which is located between these two bands, and that has a common terminal and selection terminals; a duplexer that is connected to the selection terminal and allows band A to pass therethrough; a duplexer that is connected to the selection terminal and allows band C to pass therethrough; an impedance matching network that is connected to the selection terminal; and a reception filter that is connected to the impedance matching network and allows band B to pass therethrough. During CA for bands A and C, a first circuit, which includes the impedance matching network and the reception filter, forms an attenuation pole in the frequency band of band C in the transmission characteristic of a path connecting the duplexer, the common terminal, and the duplexer to each other.