It is provided a method for providing feedback to pre-distorters in branches of a MISO system such that the pre-distortion cancels distortions caused by the signal path and the combiner combining the signals from the branches into which input signals are input. The method includes generating uncorrelated noises and mixing them with the input signals, evaluating the output of the combiner based on the input signals and the noises in order to determine a respective contribution of each input signal to the output of the combiner, and accordingly determining an appropriate pre-distortion. The signal path may apply a non-linear and/or dynamic function on the signal.

Methods of managing heat generated by amplifiers are disclosed. A metal pillar, a plurality of resistors, and a transistor array are formed over a silicon substrate. The plurality of resistors provide emitter-ballasting for the amplifier. A footprint defined by a periphery of the metal pillar is adjacent to a footprint defined by a periphery of the transistor array and overlaps a footprint defined by a periphery of the plurality of resistors so that heat generated during operation of the amplifier is transferred through the silicon substrate to the metal pillar.

A signal amplifier device is provided to ensure the continuity of the gain of an amplifier. The signal amplifier device includes a main path and a sub path connected in parallel to the main path. A main path first amplifier circuit amplifies an input signal on the main path. A main path second amplifier circuit includes a common-gate transistor connected in series with an output of the main path first amplifier circuit without sharing a DC current. On the main sub path, the sub path amplifier circuit amplifies the input signal by using a gain lower than the maximum gain in the main path.

A power amplifying apparatus includes a first bias circuit configured to generate a first bias current, a first amplification circuit, configured to receive the first bias current, amplify a signal input to the first amplification circuit through a first node, and output a first amplified signal to a second node, a second bias circuit, configured to generate a second bias current which has a magnitude different from a magnitude of the first bias current, and a second amplification circuit, connected in parallel with the first amplification, configured to receive the second bias current, amplify the signal input through the first node, and output a second amplified signal to the second node. The second amplification circuit is configured to output the second amplified signal with a third-harmonic component that has a phase offsetting a third-order intermodulation distortion (IM3) component included in the first amplified signal, based on the second bias current.

A power amplifying apparatus includes a first bias circuit that generates a first bias current having a first magnitude, a first amplification circuit connected between a first node and a second node, and that receives the first bias current, amplifies a signal input through the first node, and outputs a first amplified signal to the second node, a second bias circuit that generates a second bias current having a second magnitude that is different from the first magnitude of the first bias current, and a second amplification circuit connected in parallel with the first amplification circuit between the first node and the second node, and that receives the second bias current, amplifies the signal input through the first node, and outputs a second amplified signal to the second node, wherein the second amplification circuit may have a size that is different from a size of the first amplification circuit.

A power amplifier circuit amplifies a radio-frequency signal in a transmit frequency band. The power amplifier circuit includes an amplifier, a bias circuit, and an impedance circuit. The amplifier amplifies power of a radio-frequency signal and outputs an amplified signal. The impedance circuit is connected between a signal input terminal of the amplifier and a bias-current output terminal of the bias circuit and has frequency characteristics in which attenuation is obtained in the transmit frequency band. The impedance circuit includes first and second impedance circuits. The first impedance circuit is connected to the signal input terminal. The second impedance circuit is connected between the first impedance circuit and the bias-current output terminal.

A matching network is a matching network of a power amplifier circuit that outputs a signal obtained by a differential amplifier amplifying power of a high-frequency signal. The matching network includes an input-side winding connected between differential outputs of the differential amplifier; an output-side winding that is coupled to the input-side winding via an electromagnetic field and whose one end is connected to a reference potential; a first LC series resonant circuit including a capacitive element and an inductive element connected in series with each other, and being connected in parallel with the input-side winding; and a second LC series resonant circuit including a capacitive element and an inductive element connected in series with each other, and being connected in parallel with the output-side winding.

An apparatus includes a first plurality of low noise amplifiers (LNAs) and a cascaded switch configured to route outputs of the first plurality of LNAs to a second plurality of LNAs.

Apparatus and methods for envelope tracking systems are provided. In certain configurations, an envelope tracking system includes a digital filter that generates a filtered envelope signal based on a digital envelope signal representing an envelope of a radio frequency signal, a buck converter controllable by the filtered envelope signal and including an output electrically connected to a power amplifier supply voltage, a digital-to-analog converter module including an output electrically connected to the output of the buck converter and that provides an output current, and a digital shaping and delay circuit configured to generate a shaped envelope signal based on shaping the filtered envelope signal. The shaped envelope signal controls a magnitude of the output current, and the digital shaping and delay circuit controls a delay of the shaped envelope signal to align the output of the digital-to-analog converter module and the output of the buck converter.

Power amplifier circuitry includes an amplifier stage, a non-linear compensation network, and non-linear compensation control circuitry. The amplifier stage includes an input and an output, and is configured to receive an input signal at the input and provide an amplified output signal at the output. The non-linear compensation network is coupled between the input and the output of the amplifier stage. The non-linear compensation control circuitry is coupled to the non-linear compensation network and one or more of the input and the output of the amplifier stage. The non-linear compensation control circuitry is configured to adjust a capacitance of the non-linear compensation network to cancel a parasitic capacitance associated with the amplifier stage and thus reduce AM-PM distortion.