A digital envelop tracker for a power amplifier. The digital envelop tracker includes a supply filter for filtering a supply voltage to a power amplifier, a level selection circuitry configured to determine a level of supply voltage based on an instantaneous power of an input data stream, schedule a series of switching events based on the determined level of supply voltage, and generate a level select signal based on the scheduled series of switching events, and a switch for connecting one of supply voltages to the supply filter based on the level select signal. The level selection circuitry schedules a primary switching event of the switch based on the determined level of supply voltage and secondary switching events of the switch delayed with respect to the primary switching event based on the determined level of supply voltage to generate a filter response of the supply filter with smaller peaking.

In one embodiment, a dual-mode power amplifier that can operate in different modes includes: a first pair of metal oxide semiconductor field effect transistors (MOSFETs) to receive and pass a constant envelope signal; a second pair of MOSFETs to receive and pass a variable envelope signal, where first terminals of the first pair of MOSFETs are coupled to first terminals of the second pair of MOSFETs, and second terminals of the first pair of MOSFETs are coupled to. second terminals of the second pair of MOSFETs; and a shared MOSFET stack coupled to the first pair of MOSFETs and the second pair of MOSFETs.

An apparatus and method for calibrating an envelope tracking (ET) lookup table (LUT) are provided. An ET power management apparatus includes a power amplifier configured to amplify a radio frequency (RF) signal from a time-variant input power to a time-variant output power linearly related to the time-variant input power. A calibration circuit is employed to receive a time-variant output power feedback nonlinearly related to the time-variant input power, determine a linear relationship between the time-variant input power and the time-variant output power based on the time-variant output power feedback, and calibrate the ET LUT based on the determined linear relationship. As a result, it is possible to improve accuracy of the ET LUT to thereby improve operating efficiency and linearity of the power amplifier.

A wideband envelope modulator comprises a direct current (DC)-to-DC switching converter connected in series with a linear amplitude modulator (LAM). The DC-DC switching converter includes a pulse-width modulator that generates a PWM signal with modulated pulse widths representing a time varying magnitude of an input envelope signal or a pulse-density modulator that generates a PDM signal with a modulated pulse density representing the time varying magnitude of the input envelope signal, a field-effect transistor (FET) driver stage that generates a differential PWM or PDM drive signal, a high-power output switching stage that is driven by the PWM or PDM drive signal, and an output energy storage network including a low-pass filter (LPF) of order greater than two that filters a switching voltage produced at an output switching node of the high-power output switching stage.

An envelope tracking (ET) integrated circuit (ETIC) supporting multiple types of power amplifiers. The ETIC includes a pair of tracker circuits configured to generate a pair of low-frequency currents at a pair of output nodes, respectively. The ETIC also includes a pair of ET voltage circuits configured to generate a pair of ET voltages at the output nodes, respectively. In various embodiments disclosed herein, the ETIC can be configured to generate the low-frequency currents independent of what type of power amplifier is coupled to the output nodes. Concurrently, the ETIC can also generate the ET voltages in accordance with the type of power amplifier coupled to the output nodes. As such, it is possible to support multiple types of power amplifiers based on a single ETIC, thus helping to reduce footprint, power consumption, and heat dissipation in an electronic device employing the ETIC and the multiple types of power amplifiers.

A tracking power supply includes a power conversion subsystem and one or more tracking subsystems. The power conversion subsystem is configured to generate N power rails, where N is an integer greater than one. Each tracking subsystem includes a switching network and a controller. The switching network is electrically coupled between each of the N power rails and a tracking power rail of the tracking power supply. The controller is configured to control operation of the switching network according to a tracking signal associated with a load powered by the tracking power supply, such that a voltage at the tracking power rail is one of two or more values, as determined at least partially based on the tracking signal. The controller is further configured to adjust voltage of at least one of the N power rails.

A wideband transmission circuit is provided. The wideband transmission circuit includes a power amplifier circuit(s) and an envelope tracking (ET) integrated circuit (ETIC). The ETIC is configured to generate a modulated voltage based on a modulated target voltage. The power amplifier circuit(s) amplifies a radio frequency (RF) signal(s) based on the modulated voltage and provides the amplified RF signal(s) to a coupled RF front-end circuit. In embodiments disclosed herein, the ETIC is configured to cause the modulated target voltage to be equalized by a real equalization filter to thereby compensate for a complex voltage distortion filter resulting from a coupling between the power amplifier circuit(s) and the RF front-end circuit. As a result, it is possible to reduce undesired instantaneous excessive compression and/or spectrum regrowth resulting from the complex voltage distortion filter to thereby improve efficiency and linearity of the power amplifier circuit(s).

Envelope tracking (ET) voltage correction in a transmission circuit is provided. The transmission circuit includes a transceiver circuit and a power amplifier circuit(s). The transceiver circuit generates a radio frequency (RF) signal(s) from a time-variant modulation vector and the power amplifier circuit(s) amplifies the RF signal(s) based on a modulated voltage and provides the amplified RF signal(s) to a coupled RF front-end circuit. Herein, the transceiver circuit is configured to apply a complex filter(s) to the time-variant modulation vector and/or the RF signal(s) to compensate for a voltage distortion filter created across a modulation bandwidth of the RF signal(s) by coupling the power amplifier circuit with the RF front-end circuit. As a result, it is possible to reduce undesired instantaneous excessive compression and/or spectrum regrowth resulting from the voltage distortion filter to thereby improve efficiency and linearity of the power amplifier circuit(s) across the modulation bandwidth of the RF signal(s).

Voltage ripple suppression in a transmission circuit is disclosed. The transmission circuit includes a power amplifier circuit coupled to an envelope tracking integrated circuit (ETIC) via a conductive path. Notably, the ETIC and the conductive path can present a large source impedance to the power amplifier circuit, which can cause a ripple in the modulated voltage received by the power amplifier circuit. In a conventional approach, the large source impedance may be isolated by a large decoupling capacitor at the expense of increased voltage switching time and battery current drain. In contrast, the ETIC disclosed herein can determine and apply a correction term to the modulated voltage generated by the ETIC to thereby suppress the ripple without requiring the large decoupling capacitor. By eliminating the large decoupling capacitor, the transmission circuit can thus achieve fast voltage switching with lower battery current drain.

An apparatus for detecting difference in operating characteristics of a main circuit by using a replica circuit is presented. In one exemplary case, a sensed difference in operating characteristics of the two circuits is used to drive a tuning control loop to minimize the sensed difference. In another exemplary case, several replica circuits of the main circuit are used, where each is isolated from one or more operating variables that affect the operating characteristic of the main circuit. Each replica circuit can be used for sensing a different operating characteristic, or, two replica circuits can be combined to sense a same operating characteristic.