An electronic device may include wireless circuitry with a baseband processor, a transceiver circuit, a front-end module, and an antenna. The front-end module may include amplifier circuitry such as a low noise amplifier for amplifying received radio-frequency signals. The low noise amplifier is operable in a non-carrier-aggregation (NCA) mode and a carrier aggregation (CA) mode. The low noise amplifier may include a first input stage, a second input stage, a complementary degeneration transformer, and an input impedance compensation circuit. During the NCA mode, the first input stage is turned on while the second input stage is turned off, the degeneration transformer is controlled to provide maximum inductance, and the compensation circuit is turned on to provide input matching. During the CA mode, the first and second input stages are turned on, the degeneration transformer is adjusted to provide less inductance, and the compensation circuit is turned off.

A clamping circuit that may be used to provide efficient and effective voltage clamping in an RF front end. The clamping circuit comprises two series coupled signal path switches and a bypass switch coupled in parallel with the series coupled signal path switches. A diode is coupled from a point between the series coupled signal path switches to a reference potential. In addition, an output selection switch within an RF front end has integrated voltage clamping to more effectively clamp the output voltage from the RF front end. Additional output clamping circuits can be used at various places along a direct gain signal path, along an attenuated gain path and along a bypass path.

An amplification circuit includes: a power supply terminal that is connected to a power supply; a transistor that has a source terminal, a drain terminal, and a gate terminal to which a high-frequency signal is input; a transistor that has a source terminal that is connected to the drain terminal, a drain terminal that outputs a high-frequency signal, and a gate terminal that is grounded; a capacitor that is serially disposed on a second path that connects the gate terminal and the power supply terminal to each other; and a switch that is serially disposed on a first path or the second path. The drain terminal and the gate terminal are connected to each other via the switch and the capacitor.

Transconductor circuits with programmable tradeoff between bandwidth and flicker noise are disclosed. An example circuit includes an input port, an output port, a plurality of transistors, and a switch arrangement that includes a plurality of switches, configured to change coupling between the input port, the output port, and the transistors to place the transconductor circuit in a first or a second mode of operation. An input capacitance of the transconductor circuit operating in the first mode is larger than when the transconductor circuit is operating in the second mode. In the first mode, having a larger input capacitance results in a decreased flicker noise because the amount of flicker noise is inversely proportional to the input capacitance. In the second mode, having a smaller input capacitance leads to an increased flicker noise but that is acceptable for wide-bandwidth applications because wide-bandwidth signals may be less sensitive to flicker noise.

Transconductor circuits with programmable tradeoff between bandwidth and flicker noise are disclosed. An example circuit includes an input port, an output port, a plurality of transistors, and a switch arrangement that includes a plurality of switches, configured to change coupling between the input port, the output port, and the transistors to place the transconductor circuit in a first or a second mode of operation. An input capacitance of the transconductor circuit operating in the first mode is larger than when the transconductor circuit is operating in the second mode. In the first mode, having a larger input capacitance results in a decreased flicker noise because the amount of flicker noise is inversely proportional to the input capacitance. In the second mode, having a smaller input capacitance leads to an increased flicker noise but that is acceptable for wide-bandwidth applications because wide-bandwidth signals may be less sensitive to flicker noise.

Techniques and apparatus for output common-mode control of dynamic amplifiers, as well as analog-to-digital converters (ADCs) and other circuits implemented with such dynamic amplifiers. One example amplifier circuit includes a dynamic amplifier and a current source. The dynamic amplifier generally includes differential inputs, differential outputs, transconductance elements coupled to the differential inputs, a first set of capacitive elements coupled to the differential outputs, and a control input for controlling a time length of amplification for the dynamic amplifier. The current source is configured to generate an output current such that portions of the output current are selectively applied to the differential outputs of the dynamic amplifier during at least a portion of the time length of amplification.

A high-frequency signal transmission-reception circuit includes a plurality of band pass filter groups each including a plurality of band pass filter pairs; a first switch including a plurality of band pass filter-side terminal groups each including a plurality of band pass filter-side terminals, and an antenna-side terminal group; a plurality of couplers configured to output respective signal strengths of high-frequency signals transmitted on a plurality of transmission paths; and a second switch including an input terminal group electrically connected to the plurality of couplers, and an output terminal configured to output a detection signal output from one of the plurality of couplers. The first switch electrically connects one band pass filter-side terminal in one band pass filter-side terminal group and one antenna-side terminal, and also electrically connects one band pass filter-side terminal in another band pass filter-side terminal group and another antenna-side terminal.

Apparatus and methods for biasing of low noise amplifiers (LNAs) are provided herein. In certain embodiments, an LNA includes at least one transistor that amplifies a radio frequency (RF) input signal, and a bias circuit including a current bias circuit that generates a bias current based on a reference current and a voltage bias circuit that generates at least one input bias voltage for the at least one transistor based on the bias current. The current bias circuit includes a first bias transistor that receives the reference current, a second bias transistor that generates the bias current, and an amplifier that controls a first bias voltage of the first bias transistor to match a second bias voltage of the second bias transistor.

Reconfigurable output baluns for wideband push-pull amplifiers are disclosed. In certain embodiments, a mobile device includes a transceiver that generates a first radio frequency signal of a first frequency band and a second radio frequency signal of a second frequency band, and a front-end system including a push-pull power amplifier that selectively amplifies one of the first radio frequency signal or the second radio frequency signal based on a band control signal. The push-pull power amplifier includes an input balun, an output balun, and a pair of amplifiers coupled between the input balun and the output balun. The band control signal is operable to control an impedance of the output balun.

Aspects of the disclosure relate to devices, wireless communication apparatuses, methods, and circuitry implementing a low noise amplifier (LNA) with phase-shifting circuitry to achieve a continuous phase at the output of the LNA. One aspect is an amplifier including a high gain active path comprising active circuitry, and a low gain path comprising passive circuitry and phase-shifting circuitry. In one or more aspects, the phase-shifting circuitry is configured to shift a phase of an input signal within the low gain path such that the phase of an output signal outputted from the low gain path approximately matches a phase of an output signal outputted from the high gain active path. In at least one aspect, a gain of the high gain active path is higher than a gain of the low gain passive path.