Radio frequency circuit and mobile terminal

Abstract

The present invention provides a radio frequency circuit. In the circuit, a first directional coupler receives a second transmit signal, uses a part of the second transmit signal as a third transmit signal, directly sends the third transmit signal to a first port of a circulator, and obtains a first coupling signal from the second transmit signal; the circulator outputs the third transmit signal through a second port; an impedance tuner transmits the third transmit signal to an antenna port and transmits, to the second port of the circulator, a first input signal from the antenna port; the circulator inputs the first input signal to a second directional coupler through a third port; the second directional coupler obtains a second coupling signal from the first input signal; and a controller adjusts impedance of the impedance tuner according to the first coupling signal and the second coupling signal.

Description

technical field [0001] The present invention relates to the communication field, and more specifically, to a radio frequency circuit and a mobile terminal. Background technique [0002] In a frequency division duplex (Frequency Division Duplexing, FDD) system, the general duplex scheme can be as follows: Surface Acoustic Wave (SurfaceAcousticWave, SAW) / body The acoustic wave (BulkAcousticWave, BAW) process realizes the resonant filter. On the one hand, these two filters are used as the TX / RX bandpass filter of the radio frequency circuit, and on the other hand, they also provide TX-RX isolation. These two filters are at the antenna port Coupled together through an impedance matching circuit. However, the main disadvantage of the above-mentioned duplex scheme is that the TX / RX channel filtering and duplex functions are coupled together, and the operating frequency bands of the SAW / BAW resonant filter and the impedance matching circuit are both narrow-band, so the supported f...

AI Technical Summary

Problems solved by technology

However, the main disadvantage of the above-mentioned duplex scheme is that the TX / RX channel filtering and duplex functions are coupled together, and the operating frequency bands of the SAW / BAW resonant filter and the impedance matching circuit are both narrow-band, so the supported frequency range is small and the frequency band is fixed It cannot be tuned. If you need to support multi-mode and multi-frequency, you need multiple sets of the above-mentioned duplexers, which increases the cost, area and complexity of the radio frequency circuit, and another disadvantage of this solution is that it is not compatible with time division duplexing (TimeDivisionDuplexing, TDD) If the system needs to further support the TDD system, it is necessary to connect the TX / RX channel and the antenna (antenna, ANT) through a Transmitter-Receiver (TR) switch (Switch), which also increases the cost, area and complexity of the radio frequency circuit

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