A linearization circuit reduces intermodulation distortion in an amplifier that includes a first stage and a second stage. The linearization circuit receives a first signal that includes a first frequency and a second frequency and generates a difference signal having a frequency approximately equal to the difference of the first frequency and the second frequency, generates an envelope signal based at least in part on a power level of the first signal, and adjusts a magnitude of the difference signal based on the envelope signal. When the amplifier receives the first signal at an input terminal, the first stage receives the adjusted signal, and the second stage does not receive the adjusted signal, intermodulation between the adjusted signal and the first signal cancels at least a portion of the intermodulation between the first frequency and the second frequency from the output of the amplifier.

A linearization circuit that reduces intermodulation distortion in an amplifier output receives a first signal that includes a first frequency and a second frequency and generates a difference signal having a frequency approximately equal to the difference of the first frequency and the second frequency. The linearization circuit generates an envelope signal based at least in part on a power level of the first signal and adjusts a magnitude of the difference signal based on the envelope signal. When the amplifier receives the first signal at an input terminal and the adjusted signal at a second terminal, intermodulation between the adjusted signal and the first signal cancels at least a portion of the intermodulation products that result from the intermodulation of the first frequency and the second frequency.

Provided is a power supply for envelope tracking, comprising: a first driving unit for finally providing a first current based on a preset and variably-set first high-frequency threshold or threshold interval; a second driving unit for finally providing a second current based on a preset and variably-set second low-frequency threshold or threshold interval; a third driving unit for providing a third current based on a delayed signal; and a superimposing unit for superimposing the first current, the second current, and the third current to to provide a supply voltage of a radio-frequency power amplifier. A new power supply for envelope tracking is provided, which is capable of more efficiently providing a supply voltage of the radio frequency power amplifier by superimposing a first current to a third current.

A transmission unit includes a first transistor that amplifies power of a first signal and outputs a second signal, a power supply circuit that supplies to the first transistor a power supply voltage that changes in accordance with an amplitude level of the first signal, and an attenuator that attenuates the first signal in such a manner that an amount of attenuation of the first signal increases with a decrease in the power supply voltage when the power supply voltage is less than a first level.

An envelope tracking (ET) power management circuit is provided. The ET power management circuit includes an amplifier circuit(s) configured to output a radio frequency (RF) signal at a defined power level corresponding to a direct current, an alternating current, and an ET modulated voltage received by the amplifier circuit(s). The ET power management circuit can operate in a high-power ET mode when the defined power level exceeds a defined power level threshold and the RF signal is modulated to include no more than a defined number of resource blocks. The ET power management includes two ET tracker circuitries each generating a respective ET modulated voltage and two charge pump circuitries each generating a respective current. In the high-power ET mode, both charge pump circuitries are activated to each provide a reduced current to the amplifier circuit, thus helping to reduce a footprint and cost of the ET power management circuit.

A wide-bandwidth envelope tracking (ET) circuit is provided. In examples discussed herein, the wide-bandwidth ET circuit is configured to enable a differential amplifier circuit(s) to amplify a radio frequency (RF) signal(s) modulated at a wide-bandwidth (e.g., up to 160 MHz) without increasing power dissipation. Specifically, the wide-bandwidth ET circuit employs a pair of tracker circuits to concurrently provide ET modulated voltages and currents (e.g., direct current and/or alternating current) to the differential amplifier circuit(s) for amplifying the RF signal(s). For example, each of the tracker circuits can be configured to provide one-half () of the total current required by the differential amplifier circuit(s). Accordingly, the tracker circuits can be implemented with smaller output stages. As a result, the tracker circuits can supply the ET modulated voltages at a higher slew rate and reduced output impedance, thus helping to improve power dissipation in the wide-bandwidth ET circuit.

An envelope tracking (ET) amplifier circuit is provided. In examples discussed herein, an amplifier circuit(s) is configured to amplify a radio frequency (RF) signal based on an ET modulated voltage. A tracker circuit is configured to generate the ET modulated voltage based on a number of target voltage amplitudes derived from a time-variant signal envelope of the RF signal. However, the tracker circuit can cause the ET modulated voltage to deviate from the target voltage amplitudes due to various impedance variations. In this regard, a voltage memory digital pre-distortion (mDPD) circuit digitally pre-distorts the target voltage amplitudes based on the time-variant signal envelope such that the ET modulated voltage can closely track the target voltage amplitudes. As such, it is possible to mitigate ET modulated voltage deviation, thus helping to improve overall linearity performance of the ET amplifier circuit.

Embodiments disclosed herein relate to a bias circuit that uses Schottky diodes. Typically, a bias circuit will include a number of transistors used to generate a bias voltage or a bias current for a power amplifier. Many wireless devices include power amplifiers to facilitate processing signals for transmission and/or received signals. By substituting the bias circuit design with a design that utilizes Schottky diodes, the required battery voltage of the bias circuit may be reduced enabling the use of lower voltage power supplies.

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.

Apparatus and methods for programmable low dropout (LDO) regulators for radio frequency (RF) electronics are provided herein. In certain configurations, an LDO regulator for generating a programmable output voltage includes a regulation field-effect transistor (FET) having a drain electrically connected to the LDO regulator's output, an error amplifier that controls a gate of the regulation FET, a feedback circuit that provides a feedback signal to an inverting input of the error amplifier, an output capacitor electrically connected to the LDO regulator's output, and an alternative discharge circuit. When the output voltage of the LDO regulator is programmed from a high voltage level to a low voltage level, the alternative discharge circuit activates to discharge the output capacitor to improve the LDO regulator's transient response.