A circuit includes a power amplifier configured to amplify a first signal in a first channel and a second signal in a second channel under a condition that the first signal and the second signal are simultaneously transmitted. An envelope tracking mode is applied to the power amplifier under a condition that a frequency gap between the first channel and the second channel is less than a first threshold width, and an average power tracking mode is applied to the power amplifier under a condition that the frequency gap is at least the first threshold width.

A wideband envelope tracking power amplifier includes a plurality of low dropout voltage regulators (LDOs) including at least a first LDO and a second LDO. The wideband envelope tracking power amplifier also includes a single-input-multi-output (SIMO) voltage supply to output a plurality of voltage signals at different voltage levels, the voltage levels including a highest voltage level and one or more voltage levels lower than the highest voltage level. The SIMO voltage supply connects a first of the plurality of voltage signals at a first voltage level to the first LDO to form at least a portion of an envelope tracking voltage level signal, and connects a second of the plurality of voltage signals at a second voltage level less than or equal to the first voltage level to the second LDO to form at least another portion of the envelope tracking voltage level signal.

Described herein are power amplifier (PA) architectures that improve PA performance (e.g., efficiency, linearity, etc.) over an extended range of the operating power levels of the PA. These architectures can be implemented on a single chip to provide a single-chip standalone PA solution. This improvement comes with little additional complexity, little additional current consumption, and/or little additional chip area. The architectures utilize a dynamic biasing technique using positive envelope feedback based at least in part on an instantaneous envelope signal at an output of a power amplifier.

An envelope tracking device includes circuitry that senses a current of an input state of the envelope tracking device. The circuitry also senses an output voltage of the envelope tracking device, and turns on at least one of a first and a second output switches to generate an output current based on at least one of the sensed current and the sensed voltage.

Improvement in linearity is achieved at low costs in a power amplifier module employing an envelope tracking system. The power amplifier module includes a first power amplifier circuit that amplifies a radio frequency signal and that outputs a first amplified signal, a second power amplifier circuit that amplifies the first amplified signal on the basis of a source voltage varying depending on amplitude of the radio frequency signal and that outputs a second amplified signal, and a matching circuit that includes first and second capacitors connected in series between the first and second power amplifier circuit and an inductor connected between a node between the first and second capacitors and a ground and that decreases a gain of the first power amplifier circuit as the source voltage of the second power amplifier circuit increases.

Provided is a power amplification module that includes: an amplification transistor that has a constant power supply voltage supplied to a collector thereof, a bias current supplied to a base thereof and that amplifies an input signal input to the base thereof and outputs an amplified signal from the collector thereof; a first current source that outputs a first current that corresponds to a level control voltage that is for controlling a signal level of the amplified signal; and a bias transistor that has the first current supplied to a collector thereof, a bias control voltage connected to a base thereof and that outputs the bias current from an emitter thereof.

A high power class D amplifier/modulator for use in Radio Frequency ranges that is capable of digital modulation schemes at high efficiencies is disclosed. The new amplifier design features an envelope tracker unit that uses digital pulse-width modulation (PWM) generation to create analog I and Q phase high voltage signal components and sign bits. The I and Q phase signal components and sign bits are fed into an Fs/4 modulator stage to produce an analog output that is an high power RF signal modulated by the analog input signal.

Provided is a receiver including an oscillator (OSC) configured to generate an oscillation signal based on a radio signal, a clocked envelope detector (ED) configured to detect an envelope of the oscillation signal and hold a peak value of the envelope during a time interval, and an analog-to-digital converter (ADC) configured to convert the peak value of the envelope into a digital signal.

Provided herein are apparatus and methods for power enhancement of self-biased distributed amplifiers with gate bias networks. By sampling output power a gate bias network with a filter network can adjust gate bias so as to improve the P1 dB compression point and the Psat saturation power level of a self-biased distributed amplifier. Advantageously the filter network can be derived using passive components thereby making it an easy to implement and cost effective approach to improve linearity and output power.

The disclosed system and method provide for a CATV power amplifier in which power dissipation may be reduced by dynamically adjusting the amplifier bias such that the bias is high only when high peak output signals need to be produced. By combining a bias control signal and an RF data signal into a single signal produced by a single DA converter, the disclosed examples require fewer DA converters and a need to synchronize DA converters to produce each of the signals individually is eliminated. A low frequency signal may be added to the RF band to find an optimum compromise between positive and negative peak excursions produced by the amplifier such that an overall reduction in bias may be achieved.