The present invention provides an apparatus and method for an envelope amplifier using adjustment of a switch current, in order to maximize the efficiency of the envelope amplifier at the entire sections of envelope output power. The apparatus and method can extend the battery lifetime of portable wireless devices such as smart phones or mobile phones or application devices such as notebook computers, which use a battery as a power supply.

Methods and systems for modulating an amplifier power supply to efficiently attain amplified RF output power with much lower power dissipation than existing amplifiers. In a cable television (CATV) network, a processor receives a signal to be amplified by an amplifier at a location remote from the processor. A bias point of the amplifier may be variably modulated based on peaks of an input signal to reduce amplifier dissipation.

In one embodiment a transmitter is disclosed. The transmitter comprises an envelope tracking amplifier circuit comprising a power amplifier; a radiofrequency path configured to couple a radiofrequency component of an input signal to an input of the power amplifier; an envelope path configured to modulate a supply voltage of the power amplifier with an envelope signal, the envelope path comprising an envelope shaping module configured to shape an envelope of the input signal using an envelope shaping function to obtain the envelope signal; and a delay block configured to vary the relative timing alignment of the radiofrequency path and the envelope path; storage for an indication of the envelope shaping function to be used by the envelope shaping module; and a processor operable to, iteratively search for a value of a first parameter of a generic envelope shaping function, by applying a test signal to the envelope tracking amplifier circuit and controlling the delay block over a sweep of the relative timing alignments between the radiofrequency path and the envelope path; determining an average measure of distortion of output of the envelope tracking amplifier circuit for the sweep of relative timing alignments; comparing the average measure of distortion of output of the envelope tracking amplifier circuit with an average measure of distortion of the output of the envelope tracking amplifier circuit for a previous iteration; and selecting for the envelope shaping function the value of the first parameter from the previous iteration if the average measure of distortion of the output of the envelope tracking amplifier circuit for the previous iteration is lower than the average measure of distortion of the output of the envelope tracking amplifier circuit determined; and storing an indication of the envelope shaping function with the selected value for the first parameter in the storage.

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.

A method of calibrating an envelope tracking system for a supply voltage for a power amplifier module within a radio frequency (RF) transmitter of a wireless communication unit is described. The method comprising, within at least one signal processing module of the wireless communication unit, applying a training signal comprising an envelope that varies with time to an input of the RF transmitter, receiving at least an indication of instantaneous output signal values for the power amplifier module in response to the training signal, calculating instantaneous gain values based at least partly on the received output power values, and adjusting a mapping function between an instantaneous envelope of a waveform signal to be amplified by the power amplifier module and the power amplifier module supply voltage to achieve a power amplifier module gain, for example that is monotonically increasing as a function of power amplifier output power.

A gain control circuit, having an attenuator including first to n-th (n>2) attenuator parts that attenuate an input signal respectively in accordance with first to n-th attenuation control signals to thereby generate an attenuated input signal, a signal amplifier configured to amplify the attenuated input signal, a detector circuit configured to conduct an envelope detection on the amplified attenuated input signal to thereby obtain an amplitude value, a comparator circuit configured to compare the amplitude value with a reference threshold value to thereby generate a comparison result signal, and an attenuator control circuit configured to generate the first to n-th attenuation control signals using the comparison result signal. The attenuation control signals indicate first to n-th attenuation amounts by which the first to n-th attenuator parts respectively attenuate the input signal, and first to n-th time periods during which the first to n-th attenuator parts respectively operate.

A power amplifier circuit including a power transistor, a variable impedance circuit, first and second envelope detecting circuits is provided. The power transistor receives an input signal and outputs an output signal. The variable impedance circuit includes an impedance control transistor and a first filter capacitor. An equivalent impedance of the variable impedance circuit varies with the input signal. The impedance control transistor is coupled to the power transistor and receives a control voltage. The first filter capacitor is coupled between the impedance control transistor and ground. Both the first and the second envelope detecting circuits detect the input signal to dynamically control the equivalent impedance of the variable impedance circuit.

Apparatus and methods for bypassing an inductor of a voltage converter are provided. In one embodiment, a voltage converter includes an inductor and a bypass circuit that selectively bypasses the inductor based on a state of a bypass control signal. The inductor includes including a first end electrically connected to a first node and a second end electrically connected to a second node. The bypass circuit includes a first p-type field effect transistor and a second p-type field effect transistor electrically connected in series between the first node and the second node. The first p-type field effect transistor includes a body electrically connected to a first voltage, and the second p-type field effect transistor includes a body electrically connected to a second voltage greater than the first voltage.

An amplifier circuit is provided for amplifying a radio frequency signal within one frame of a radio frequency signal by using multiple discrete voltages supplied from the tracker circuit. The amplifier circuit includes a power amplifier and an RC series circuit including a resistor and a capacitor that are connected in series between the ground and a voltage supply path between the tracker circuit and the power amplifier.

A power amplifier circuit includes a power amplifier unit and a broadband improvement unit. The power amplifier unit includes a signal input port, a signal output port, a power transistor, and a first inductor. The power transistor is configured to perform power amplification on radio frequency signals in a plurality of frequency bands. The broadband improvement unit adjusts a parallel resonance frequency of the power amplifier unit, to reduce envelope impedance of the power amplifier unit between a first target frequency and a second target frequency. The first target frequency is a maximum frequency difference between the plurality of frequency bands, and the second target frequency is a minimum frequency difference between the plurality of frequency bands.