A radio-frequency (RF) amplifier circuit facilites carrier-aggregation (CA) operation in a wireless communication network. A first amplifier subcircuit is coupled to an input node, and a second amplifier subcircuit is coupled to the input node. An amplifier subcircuit selector is to selectively enable operation of the first amplifier subcircuit, the second amplifier subcircuit, or the first and the second amplifier subcircuits together, in response to a selection indication. A reactive coupling network is arranged to selectively adjust the input impedance at the input node in response to the selection indication to reduce the input impedance variation.

Amplifier having input power protection. In some embodiments, an amplifier circuit can include an input node and an output node, and an amplifier implemented between the input node and the output node. The amplifier circuit can further include a bias circuit configured to provide a bias signal to the amplifier. The amplifier circuit can further include a protection circuit configured to generate a detected voltage representative of a peak of a radio-frequency signal present at the input node. The protection circuit can be further configured to enable a protection mode when the detected voltage is greater than a first threshold value and to disable the protection mode when the detected voltage is less than a second threshold value that is less than the first threshold value.

A protection circuit is provided. The protection circuit protects a power amplifier that includes a power transistor configured to receive a power voltage, and a bias circuit configured to supply a bias current to the power transistor. The protection circuit includes: a first transistor, connected between a terminal of the bias circuit and a ground, and configured to sink a first current from the terminal of the bias circuit; and a second transistor, comprising a first terminal connected to the power voltage, a second terminal connected to a control terminal of the first transistor, and a control terminal connected to a reference voltage.

A protection circuit is provided. The protection circuit protects a power amplifier that includes a power transistor configured to receive a power voltage, and a bias circuit configured to supply a bias current to the power transistor. The protection circuit includes: a first transistor, connected between a terminal of the bias circuit and a ground, and configured to sink a first current from the terminal of the bias circuit; and a second transistor, comprising a first terminal connected to the power voltage, a second terminal connected to a control terminal of the first transistor, and a control terminal connected to a reference voltage.

Certain aspects of the present disclosure are generally directed to circuitry and techniques for current sensing. For example, certain aspects provide a circuit for signal amplification including a first amplifier, a second amplifier, and a third amplifier. The circuit also includes a first capacitive element coupled between a first output of the first amplifier and a first input of the third amplifier, a second capacitive element coupled between a second output of the first amplifier and a second input of the third amplifier, a third capacitive element coupled between a first output of the second amplifier and the first input of the third amplifier, and a fourth capacitive element coupled between a second output of the second amplifier and the second input of the third amplifier.

A second member is joined in surface contact with a first surface of a first member including a semiconductor region made from an elemental semiconductor. The second member includes a radio-frequency amplifier circuit made from a compound semiconductor. A conductive protrusion projects from the second member toward a side opposite to the first member. The first member includes a temperature measurement element that detects a temperature.

A power amplifier comprising a first member and a second member including a compound semiconductor region joined to a first face of the first member including a semiconductor region. The second member includes an amplifier circuit including a compound semiconductor element, and multiple clamp diodes connected in multiple stages and between an output port of the amplifier circuit and ground. The first member includes a switch, connected between an extension point, which is a middle point of the multiple clamp diodes and the ground, a temperature sensor, and a switch control circuit which performs on-off control of the switch based on a result of measurement by the temperature sensor. The extension point is connected to the switch via a path including an inter-member connection wire on an interlayer insulating film from the first face of the first member to a surface of the second member.

A power amplifier comprising a first member and a second member including a compound semiconductor region joined to a first face of the first member including a semiconductor region. The second member includes an amplifier circuit including a compound semiconductor element, and multiple clamp diodes connected in multiple stages and between an output port of the amplifier circuit and ground. The first member includes a switch, connected between an extension point, which is a middle point of the multiple clamp diodes and the ground, a temperature sensor, and a switch control circuit which performs on-off control of the switch based on a result of measurement by the temperature sensor. The extension point is connected to the switch via a path including an inter-member connection wire on an interlayer insulating film from the first face of the first member to a surface of the second member.

This application relates to circuitry for monitoring for instability of an amplifier. The amplifier (100) has a first signal path between an amplifier input (IN.sub.N) and an amplifier output (V.sub.OUT) and a feedback path from the output to form a feedback loop with at least part of the first signal path. A comparator (212) has a first input configured to receive a first signal (IN.sub.N) derived from a first amplifier node which is part of said feedback loop and a second input configured to receive a second signal (IN.sub.P) derived from a second amplifier node which varies with the signal at the amplifier input but does not form part of said feedback loop. The comparator is configured to compare the first signal to the second signal and generate a comparison signal (COMP), wherein in the event of amplifier instability the comparison signal comprises a characteristic indicative of amplifier instability.

This application relates to circuitry for monitoring for instability of an amplifier. The amplifier (100) has a first signal path between an amplifier input (IN.sub.N) and an amplifier output (V.sub.OUT) and a feedback path from the output to form a feedback loop with at least part of the first signal path. A comparator (212) has a first input configured to receive a first signal (IN.sub.N) derived from a first amplifier node which is part of said feedback loop and a second input configured to receive a second signal (IN.sub.P) derived from a second amplifier node which varies with the signal at the amplifier input but does not form part of said feedback loop. The comparator is configured to compare the first signal to the second signal and generate a comparison signal (COMP), wherein in the event of amplifier instability the comparison signal comprises a characteristic indicative of amplifier instability.