A multiplexer (100) includes a first filter (FLT1) that passes a signal in a first frequency band, a second filter (FLT2) that passes a signal in a second frequency band lower than the first frequency band, and a third filter (FLT3) that passes a signal in a third frequency band. The third frequency band is a frequency band higher than the first frequency band, or a frequency band lower than the second frequency band. The first filter includes a first inductor (L11) that forms a first attenuation pole on a low-frequency side of the first frequency band. The second filter includes a second inductor (L23) that forms a second attenuation pole on a high-frequency side of the second frequency band. At least a portion of a component constituting the third filter is disposed between the first inductor and the second inductor.

A radio frequency circuit is capable of sending a transmit signal of a first communication band and a transmit signal of a second communication band simultaneously and includes a transmit input terminal, a power amplifier capable of amplifying a transmit signal of the first communication band, and a filter connected between the transmit input terminal and an input terminal of the power amplifier. In the filter, a pass band is a band including a transmit band of the first communication band, and an attenuation band is a band including a transmit band of the second communication band.

A multiplexer (100) includes a first filter (FLT1) that passes a signal in a first frequency band, a second filter (FLT2) that passes a signal in a second frequency band lower than the first frequency band, and a third filter (FLT3) that passes a signal in a third frequency band. The third frequency band is a frequency band higher than the first frequency band, or a frequency band lower than the second frequency band. The first filter includes a first inductor (L11) that forms a first attenuation pole on a low-frequency side of the first frequency band. The second filter includes a second inductor (L23) that forms a second attenuation pole on a high-frequency side of the second frequency band. At least a portion of a component constituting the third filter is disposed between the first inductor and the second inductor.

A transmission frontend includes a modulator configured to generate a modulated signal. A first selectable path is electrically coupled to the modulator and is configured to generate a first signal having a first power level. A second selectable path is electrically coupled to the modulator and is configured to generate a second signal having a second power level. The first power level is greater than the second power level. A transformer is electrically coupled to each of the first selectable path and the second selectable path. An antenna is electrically coupled to the transformer.

The circuit includes a transformer having a first primary coil coupled to a first power amplifier (PA), a second primary coil coupled to a second PA, and a secondary coil. The secondary coil supplies a current to an antenna based on a first direction of a first phase of a first amplified constant-envelope signal in the first primary coil with respect to a second phase of a second amplified constant-envelope signal in the second primary coil. A first load impedance is associated with the first PA and a second load impedance is associated with the second PA. The first load impedance and the second load impedance receive currents from the first PA and second PA, respectively, based on a second direction of the first phase of the first amplified constant-envelope signal with respect to the second phase of the second amplified constant-envelope signal.

The circuit includes a transformer having a first primary coil coupled to a first power amplifier (PA), a second primary coil coupled to a second PA, and a secondary coil. The secondary coil supplies a current to an antenna based on a first direction of a first phase of a first amplified constant-envelope signal in the first primary coil with respect to a second phase of a second amplified constant-envelope signal in the second primary coil. A first load impedance is associated with the first PA and a second load impedance is associated with the second PA. The first load impedance and the second load impedance receive currents from the first PA and second PA, respectively, based on a second direction of the first phase of the first amplified constant-envelope signal with respect to the second phase of the second amplified constant-envelope signal.

A transmission frontend includes a modulator configured to generate a modulated signal. A first selectable path is electrically coupled to the modulator and is configured to generate a first signal having a first power level. A second selectable path is electrically coupled to the modulator and is configured to generate a second signal having a second power level. The first power level is greater than the second power level. A transformer is electrically coupled to each of the first selectable path and the second selectable path. An antenna is electrically coupled to the transformer.

The power combiner circuit includes a transformer having a first primary coil coupled to a first power amplifier (PA), a second primary coil coupled to a second PA, and a secondary coil. The secondary coil supplies a current to an antenna based on a first direction of a first phase of a first amplified constant-envelope signal in the first primary coil with respect to a second phase of a second amplified constant-envelope signal in the second primary coil. A first load impedance is associated with the first PA and a second load impedance is associated with the second PA. The first load impedance and the second load impedance receive currents from the first PA and second PA, respectively, based on a second direction of the first phase of the first amplified constant-envelope signal with respect to the second phase of the second amplified constant-envelope signal.