A radio frequency circuit includes: a first power amplifier capable of amplifying a first radio frequency signal and a second radio frequency signal each having a different frequency; and a second power amplifier capable of amplifying the second radio frequency signal. In a case where the first radio frequency signal and the second radio frequency signal are simultaneously transmitted, (i) under a condition that a sum of a bandwidth of the first radio frequency signal and a bandwidth of the second radio frequency signal is broader than or equal to a predetermined bandwidth, the first radio frequency signal is amplified by the first power amplifier, and the second radio frequency signal is amplified by the second power amplifier, and (ii) under a condition that the sum is narrower than the predetermined bandwidth, the first radio frequency signal and the second radio frequency signal are amplified by the first power amplifier.

A radio frequency module includes: a module board including first and second principal surfaces; first and second power amplifiers on the first principal surface; external-connection terminals on the second principal surface; and first and second via conductors connecting the first and second principal surfaces. The first and second via conductors are spaced apart in the module board, one end of the first via conductor is connected to a first ground electrode of the first power amplifier, the other end of the first via conductor is connected to a first external-connection terminal, one end of the second via conductor is connected to a second ground electrode of the second power amplifier, the other end of the second via conductor is connected to a second external-connection terminal, and the first and second via conductors each penetrate through the module board in a direction normal to the first and second principal surfaces.

A bi-directional buffer for applications using in an I2C or SMBUS or other bus systems. The bi-directional buffer has an input terminal to receive an input voltage signal and an output terminal for providing an output voltage signal, and the output voltage signal follows the input voltage signal. The output voltage signal is regulated to have a first bias voltage greater than the input voltage signal by a first operational amplifier, or to have a second bias voltage greater than the input voltage signal by a second operational amplifier, the second bias voltage is smaller than the first bias voltage.

A radio frequency (RF) summer circuit having a characteristic impedance Zo comprises first and second ports coupled by first and second resistances, respectively, to a junction. The circuit further comprises a series combination of a third resistance and a switch movable between open and closed positions and an amplifier having input and output terminals and operable in an off state and an on state wherein the series combination is coupled across the input and output terminals of the amplifier between the junction and a third port. The first resistance, second resistance, and the third resistance are all substantially equal to Z.sub.0/3. Further, when the switch is moved to the closed position and the amplifier is switched to the off state a passive mode of operation is implemented and when the switch is moved to the open position and the amplifier is switched to the on state an active mode of operation is implemented. The RF summer circuit develops a summed signal at the third port equal to a sum of signals at the first and second ports modified by one of first and second gain values.

A radio frequency (RF) summer circuit having a characteristic impedance Zo comprises first and second ports coupled by first and second resistances, respectively, to a junction. The circuit further comprises a series combination of a third resistance and a switch movable between open and closed positions and an amplifier having input and output terminals and operable in an off state and an on state wherein the series combination is coupled across the input and output terminals of the amplifier between the junction and a third port. The first resistance, second resistance, and the third resistance are all substantially equal to Z.sub.0/3. Further, when the switch is moved to the closed position and the amplifier is switched to the off state a passive mode of operation is implemented and when the switch is moved to the open position and the amplifier is switched to the on state an active mode of operation is implemented. The RF summer circuit develops a summed signal at the third port equal to a sum of signals at the first and second ports modified by one of first and second gain values.

Aspects of the disclosure include a wireless device comprising a module input to receive an input signal, a module output to provide an amplified output signal, a low-noise amplifier including an input amplification stage coupled to the input, and a plurality of output amplification stages switchably coupled to the input amplification stage, and a plurality of impedance-matching circuits, each impedance-matching circuit of the plurality of impedance-matching circuits having an input coupled to a respective output amplification stage and an output coupled to the module output.

Circuits and methods for improving the noise figure (NF) of an amplifier, particularly an LNA, in high-gain modes while improving the IIP3 of the amplifier in low-gain modes. The source of an amplifier common-source FET is coupled to circuit ground thorough a degeneration circuit comprising a two-port inductor and a bypass switch coupled in parallel with the inductor. A switched feedback circuit is coupled between the gate of the common-source FET and a feedback node in the amplifier output signal path. During a low gain mode, the inductor is entirely bypassed and the enabled feedback circuit lowers the input impedance of the common-source FET and reduces the gain of the amplifier circuit, essentially eliminating the need for a degeneration inductor. During a high gain mode, the source of the common-source FET is coupled to circuit ground through the inductor and the feedback circuit is disabled. Other gain modes are supported.

Circuits and methods for improving the noise figure (NF) of an amplifier, particularly an LNA, in high-gain modes while improving the IIP3 of the amplifier in low-gain modes. The source of an amplifier common-source FET is coupled to circuit ground thorough a degeneration circuit comprising a two-port inductor and a bypass switch coupled in parallel with the inductor. A switched feedback circuit is coupled between the gate of the common-source FET and a feedback node in the amplifier output signal path. During a low gain mode, the inductor is entirely bypassed and the enabled feedback circuit lowers the input impedance of the common-source FET and reduces the gain of the amplifier circuit, essentially eliminating the need for a degeneration inductor. During a high gain mode, the source of the common-source FET is coupled to circuit ground through the inductor and the feedback circuit is disabled. Other gain modes are supported.

An apparatus for turning off a cascode amplifier having a common-gate transistor and a common-source transistor is disclosed that includes the cascode amplifier, a feedback circuit, and a bias circuit. The feedback circuit is configured to receive a drain-voltage from the drain of the common-source transistor when the common-source transistor is switched to a first OFF state and produce a first feedback signal. The drain-voltage is equal to a source voltage of the common-gate transistor and the drain-voltage increases in response to switching the common-source transistor to the first OFF state. The bias circuit is configured to receive the first feedback signal and produce a bias-voltage. A first gate-voltage is produced from the bias-voltage. The cascode amplifier is configured to receive the first gate-voltage and a second gate-voltage. The common-gate transistor is configured to switch to a second OFF state in response to receiving the second gate-voltage.

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