A selectable low noise amplifier (LNA) system comprising, a plurality of LNAs having a plurality of LNA characteristics and at least one selection switch network coupled to the plurality of LNAs to select at least one of the plurality of LNAs.

Aspects of this disclosure relate to a cascode circuit electrically coupled between an amplifier configured to amplify a radio frequency (RF) signal and different loads. The cascode circuit can function as a switch to selectively provide an output from the amplifier to a number of different loads. In certain embodiments, the cascode circuit can be electrically coupled between different stages of a multi-stage power amplifier. For instance, the amplifier can be a first stage of the multi-stage power amplifier and the different loads can include different power amplifier transistors of a second stage of the multi-stage amplifier. The cascode circuit can be implemented by bipolar transistors according to certain embodiments.

A power amplifier die includes a semiconductor substrate, a power amplifier implemented on the semiconductor substrate, a radio-frequency input configured to receive a radio-frequency input signal having a radio-frequency component and a DC bias component, a bias circuit implemented on the semiconductor substrate, the bias circuit coupled to the power amplifier, and a bias tee circuit implemented on the semiconductor substrate, the bias tee circuit configured to receive the radio-frequency input signal and pass at least a portion of the DC component to the bias circuit and at least a portion of the radio-frequency component to the power amplifier.

An input signal amplification system comprises at least two different means of amplifying input signals in order to obtain amplified signals. It also comprises at least one means of summing amplified signals, and dynamic means of activating or deactivating one or more of the amplifying means based on input signals.

In a semiconductor device, received signals of different frequency bands are input selectively to low noise amplifiers. A plurality of primary inductors are coupled between differential output nodes of the respective low noise amplifiers. A secondary inductor is provided commonly for the primary inductors, and magnetically coupled to the primary inductors. A demodulator converts a received signal transmitted from one of the primary inductors to the secondary inductor by electromagnetic induction, into a signal of a low frequency.

Devices and methods for improving reliability of scalable periphery amplifiers is described. Amplifier segments of the scalable periphery architecture can be rotated to distribute wear. Further, extra amplifier segments can be implemented on amplifier dies to extend the overall lifetime of amplifiers.

A power amplifier (PA) system includes an amplifying transistor having a base, a collector, and an emitter. The PA system further includes a radio-frequency (RF) input configured to receive an RF input signal having an RF component and a DC bias component, a bias circuit coupled to the base of the amplifying transistor, and a bias tee circuit configured to receive the RF input signal and pass at least a portion of the DC component to the bias circuit and at least a portion of the RF component to the base of the amplifying transistor.

A surface acoustic wave (SAW) filter that receives an aggregate circuit and outputs two or more sub-signals on outputs each of a different frequency band. The sub-signals are amplified by low noise amplifiers and, in one implementation, the amplified sub-signals can be summed. The outputs are connected via a switched passive network so that portions of the sub-signals on the outputs that are not in the selected frequency band are at least partially terminated.

An RF front end circuit is described. The RF front end circuit comprises a plurality of amplifiers defining multiple amplification branches. A plurality of input nodes are provided which are associated with one or more amplification branches. A plurality of output matching networks are provided which are associated with one or more amplication branches. The amplifiers are selectively controllable such that one or more amplifiers associated with one or more active input nodes are activated while other amplifiers associated with the one or more active input nodes are deactived.

In a semiconductor device, received signals of different frequency bands are input selectively to low noise amplifiers. A plurality of primary inductors are coupled between differential output nodes of the respective low noise amplifiers. A secondary inductor is provided commonly for the primary inductors, and magnetically coupled to the primary inductors. A demodulator converts a received signal transmitted from one of the primary inductors to the secondary inductor by electromagnetic induction, into a signal of a low frequency.