A communication circuit, including a first supply modulator configured to provide a first supply voltage; a first power amplifier configured to generate a first output signal by amplifying a first input signal corresponding to a first operation frequency band; a second power amplifier configured to generate a second output signal by amplifying a second input signal corresponding to a second operation frequency band; and a switching circuit configured to selectively provide the first supply voltage from the first supply modulator to the second power amplifier based on a first switching signal according to an operation mode.

An ultrasound circuit comprising a multi-stage trans-impedance amplifier (TIA) is described. The TIA is coupled to an ultrasonic transducer to amplify an electrical signal generated by the ultrasonic transducer in response to receiving an ultrasound signal. The TIA may include multiple stages, at least two of which operate with different supply voltages. The TIA may be followed by further processing circuitry configured to filter, amplify, and digitize the signal produced by the TIA.

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; and a first circuit component. The power amplifier includes: a first amplifying element; a second amplifying element; and an output transformer that includes a primary coil and a secondary coil. An end of the primary coil is connected to an output terminal of the first amplifying element, another end of the primary coil is connected to an output terminal of the second amplifying element, an end of the secondary coil is connected to an output terminal of the power amplifier, the first amplifying element and the second amplifying element are disposed on the first principal surface, and the first circuit component is disposed on the second principal surface.

A circuit including an amplifier having an input and an output. The circuit also includes a current-to-voltage amplifier having an input. The circuit further includes a current mirror coupled between the output of the amplifier and the input of the current-to-voltage amplifier. The current mirror is configured to chop current flowing through the first current mirror.

A circuit including an amplifier having an input and an output. The circuit also includes a current-to-voltage amplifier having an input. The circuit further includes a current mirror coupled between the output of the amplifier and the input of the current-to-voltage amplifier. The current mirror is configured to chop current flowing through the first current mirror.

A circuit including an amplifier having an input and an output. The circuit also includes a current-to-voltage amplifier having an input. The circuit further includes a current mirror coupled between the output of the amplifier and the input of the current-to-voltage amplifier. The current mirror is configured to chop current flowing through the first current mirror.

An apparatus and a method are provided for, in an electronic device which generates a reference signal having a reference frequency, mixes the reference signal to an input signal for transmission, and amplifies power, outputting a control signal for turning off amplifying the power, if a frequency of a signal acquired at an arbitrary point after generating the reference signal or mixing the signals before amplifying the power is out of a designated frequency band, thus preventing burnout of a power amplifier.

A power amplifier circuit includes a first amplifier that amplifies a first signal, and a second amplifier arranged subsequent to the first amplifier. The second amplifier amplifies a second signal that is based on an output signal of the first amplifier. The first amplifier performs class inverse-F operation, and the second amplifier performs class F operation.

Doherty power amplifiers with coupled line combiners are provided herein. In certain embodiments, a power amplifier system includes a carrier amplifier having a carrier output that provides a first radio frequency signal, a peaking amplifier having a peaking output that provides a second radio frequency signal, and a coupled line combiner including a first conductor line connected to the peaking output, a second conductor line electromagnetically coupled to the first conductor line, a third conductor line connected to the carrier output, and a fourth conductor line electromagnetically coupled to the third conductor line and in series with the second conductor line. The power amplifier system further includes an inductor in series with the fourth conductor line and the second conductor line and operable to provide a radio frequency output signal to an output terminal.

A power amplifier circuit includes a first amplifier that amplifies a first signal, and a second amplifier arranged subsequent to the first amplifier. The second amplifier amplifies a second signal that is based on an output signal of the first amplifier. The first amplifier performs class inverse-F operation, and the second amplifier performs class F operation.