An RF amplifier includes a harmonic filter with a plurality of shunt filter legs. The harmonic filter provides a suppressing frequency range for a harmonic frequency of a carrier frequency in a range of carrier frequencies. Each of the shunt filter legs includes capacitor, inductor, and a node coupled between the capacitor and inductor. Each node of the shunt filter leg is coupled to at least one other node of another shunt filter leg of the filter with a resistive element. The harmonic filter includes a first shunt filter leg that has a resonant frequency between the center frequency and (1/1.220) times the center frequency and a second shunt filter leg that has a resonant frequency between the center frequency and 1.220 times the center frequency.

An RF amplifier includes a harmonic filter with a plurality of shunt filter legs. The harmonic filter provides a suppressing frequency range for a harmonic frequency of a carrier frequency in a range of carrier frequencies. Each of the shunt filter legs includes capacitor, inductor, and a node coupled between the capacitor and inductor. Each node of the shunt filter leg is coupled to at least one other node of another shunt filter leg of the filter with a resistive element. The harmonic filter includes a first shunt filter leg that has a resonant frequency between the center frequency and (1/1.220) times the center frequency and a second shunt filter leg that has a resonant frequency between the center frequency and 1.220 times the center frequency.

A polar transmitter includes an amplitude path comprising an amplitude signal that corresponds to an amplitude of a vector sum of an in-phase input signal and a quadrature input signal; a phase path comprising a phase modulator configured to phase-modulate a phase signal that corresponds to the phase of the vector sum of the in-phase input signal and the quadrature input signal; a digital power amplifier (DPA) configured to amplify the phase-modulated (PM) input signal based on the amplitude signal; a tunable matching network coupled to an output of the DPA and configured to adjust a load impedance of the DPA; and a controller configured to adjust the matching network based on a look-up table with respect to amplitude and frequency information, where the look-up table indicates a plurality of optimal operation modes of the matching network for specific combinations of amplitude and frequency information.

An amplifier includes an input node, an output node, a transistor and a transformer. The input node is configured to receive a first signal. The output node is configured to output an amplified first signal. The transistor includes a first terminal, a second terminal and a third terminal. The first terminal is coupled to the input node and a first supply voltage source. The second terminal is coupled to a second supply voltage source and the output node. The third terminal is coupled to a reference node. The transformer is coupled to the first terminal and the third terminal. The transistor is configured to operate in a sub-threshold region and a near-triode region.

Provided is a power amplification circuit that includes: a first transistor that has an emitter to which a first radio frequency signal is supplied, a base to which a first DC control current or DC control voltage is supplied and a collector that outputs a first output signal that corresponds to the first radio frequency signal; a first amplifier that amplifies the first output signal and outputs a first amplified signal; and a first control circuit that supplies the first DC control current or DC control voltage to the base of the first transistor in order to control output of the first output signal.

A packaged RF amplifier device includes a transistor and an output circuit. The transistor includes a control terminal and first and second current carrying terminals. The output circuit is coupled between the first current carrying terminal and an output lead. The output circuit includes first and second inductive elements coupled in series. The first inductive element, which may be a first bondwire array or an integrated inductance, is coupled between the first current carrying terminal and a node. The second inductive element, which includes a second bondwire array, is coupled between the node and the output lead. The device also includes a shunt circuit with a shunt capacitor and a third bondwire array coupled between the first current carrying terminal and the shunt capacitor. The first and second inductive elements and the third bondwire array are configured to have a desired mutual inductance.

A cascode power cell for a power amplifier circuit includes a radio frequency signal input node, a radio frequency signal output node, and a plurality of sub-cells each including a first transistor having a collector coupled to the radio frequency signal output node, each of the plurality of sub-cells further including a second transistor having a collector coupled to an emitter of the first transistor at a connection node, and a base coupled to the radio frequency signal input node, the connection nodes for each of the plurality of sub-cells being electrically isolated from one another.

Provided is a power amplification circuit that includes: an amplifier that amplifies an input signal and outputs an amplified signal; a first bias circuit that supplies a first bias current or voltage to the amplifier; a second bias circuit that supplies a second bias current or voltage to the amplifier; a first control circuit that controls the first bias current or voltage; and a second control circuit that controls the second bias current or voltage. The current supplying capacity of the first bias circuit is different from the current supplying capacity of the second bias circuit.

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.

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.