A high-frequency circuit includes a power amplifier for a communication band A, and a power amplifier for a communication band B. Transmission in the communication band A, transmission in the communication band B, and reception in the communication band C can be simultaneously used. A frequency range of intermodulation distortion generated between a second harmonic wave of a transmission signal of the communication band A and a fundamental wave of a transmission signal of the communication band B, overlaps with at least part of a reception band of the communication band C. The power amplifier includes amplifying elements and an output trans including coils. One end of the coil is connected with an output of the amplifying element, the other end of the coil is connected with an output of the amplifying element, and one end of the coil is connected with an output terminal of the power amplifier.

An electronic device includes: an antenna, a PAM including a PA configured to amplify a transmitting signal and a protection circuit, a PMIC configured to supply voltage to the PA, and at least one processor is configured to: provide a first signal, to a NAND gate in the protection circuit, provide to a AND gate in the protection circuit, a second signal indicating a result of a logical operation between the first signal and a bias enable signal for the PA, provide to the AND gate, a third signal indicating whether the transmitting signal is input to the PAM, provide to a switching circuit, a fourth signal indicating a result of logical operation between the second signal and the third signal, identify whether to apply a bias voltage to the PA based on the fourth signal, and transmit the transmitting signal, to the external electronic device, via the antenna.

An acoustic wave device includes a piezoelectric substrate including a support substrate and a piezoelectric layer on the support substrate, the piezoelectric substrate including a first principal surface on the piezoelectric layer side, and a second principal surface on the support substrate side, an IDT electrode on the first principal surface, a support layer on the support substrate, a cover on the support layer, a through-via electrode provided through the support substrate and electrically connected to the IDT electrode, a first wiring electrode on the second principal surface of the piezoelectric substrate and electrically connected to the through-via electrode, and a protective film on the second principal surface to cover at least a portion of the first wiring electrode. The protective film is provided on an inner side of the support layer when viewed in a direction normal or substantially normal to the second principal surface.

An amplification subsystem for a communication system includes a downstream amplifier configured to transmit a downstream signal within a first frequency range, an upstream amplifier configured to transmit an upstream signal within a second frequency range, and a bidirectional amplifier configured to selectively transmit a mid-band signal in either of the upstream and downstream direction.

An electronic device and method thereof of are provided to prevent burnout due to overcurrent. An electronic device includes a power amplifier configured to amplify a transmission signal; a battery configured to provide a bias voltage to the at least one power amplifier; and an overcurrent protection circuit configured to prevent overcurrent from flowing through the power amplifier. The overcurrent protection circuit includes a configurer configured to configure a reference current value, based on the power amplifier; a measurer configured to measure a bias current value due to the bias voltage; a comparator configured to compare the measured bias current value with the reference current value; and a controller configured to recognize overcurrent flowing through the power amplifier and control provision of the bias voltage, based on a result of the comparison.

A radio frequency module includes: a module board that includes a first principal surface and a second principal surface on opposite sides of the module board; a power amplifier configured to amplify a transmission signal; a first circuit component; and a power amplifier (PA) control circuit configured to control the power amplifier. The power amplifier and the PA control circuit are stacked on the first principal surface, and the first circuit component is disposed on the second principal surface.

A radio frequency circuit includes a power amplifier configured to selectively amplify one of a first radio frequency signal and a second radio frequency signal that have different bandwidths, and when the first radio frequency signal is input to the power amplifier, a first bias signal is applied to the power amplifier, and when the second radio frequency signal is input to the power amplifier, a second bias signal different from the first bias signal is applied to the power amplifier.

A receiver front end having low noise amplifiers (LNAs) is disclosed herein. A cascode having a “common source” configured input FET and a “common gate” configured output FET can be turned on or off using the gate of the output FET. A first switch is provided that allows a connection to be either established or broken between the source terminal of the input FET of each LNA. A drain switch is provided between the drain terminals of input FETs to place the input FETs in parallel. This increases the g.sub.m of the input stage of the amplifier, thus improving the noise figure of the amplifier.

Disclosed is a radio frequency circuit, a method of transmitting and receiving radio frequency signals, and a wireless communication device. The radio frequency circuit includes a first radio frequency amplifier, a second radio frequency amplifier, a first channel switch, a first low noise amplifier, a second low noise amplifier, and a second channel switch; the first radio frequency amplifier and the second radio frequency amplifier are connected with a plurality of antennas through the first channel switch, respectively, and are connected with a plurality of SRS antennas through an SRS switch in the first channel switch; the first low noise amplifier and the second low noise amplifier are connected with the plurality of antennas through the first channel switch, respectively, and are connected with a receiver through the second channel switch, respectively; wherein, the first radio frequency amplifier or the second radio frequency amplifier transmits one channel of radio frequency transmission signals to realize one-channel transmission, and the first low noise amplifier and the second low noise amplifier simultaneously receive radio frequency reception signals to realize two-channel reception.

Aspects of this disclosure relate to acoustic wave filters with bulk acoustic wave resonators. An acoustic wave filter can include a first bulk acoustic wave resonator configured to excite an overtone mode as a main mode and a second bulk acoustic wave resonator having a fundamental mode as a main mode.