Abstract: An apparatus comprises an amplifier having an input coupled to a radio frequency signal through a digital-to-analog circuit, an adaptive power supply having an output coupled to a bias voltage of the amplifier, wherein the output of the adaptive power supply is configured to have a shape similar to an envelope of the radio frequency signal and a feedback circuit comprising a sensing circuit and a mapping circuit, wherein the sensing circuit is configured to sense a current flowing from the adaptive power supply to the amplifier and sense the bias voltage of the amplifier, and wherein the mapping circuit is configured to sense the bias voltage of the amplifier, and wherein the mapping circuit is configured to generate a control signal for dynamically adjusting parameters of a low pass filter so as to stabilize the adaptive power supply.

Abstract: A method for implementing envelope tracking (ET), the method comprising switching from a receiver (Rx) radio frequency (RF) path to a supply sensing path during factory calibration, sensing the power amplifier (PA)'s supply voltage via the supply sensing path, comparing the PA's supply voltage to a corresponding reference supply voltage, determining the difference between the PA's supply voltage and the corresponding reference supply voltage, and updating one or more parameters used to perform a PA load pre-distortion during factory calibration, wherein the PA load pre-distortion is used to match the PA's supply voltage to the corresponding reference supply voltage.

Abstract: An apparatus for providing envelope tracking (ET), comprising: a power amplifier (PA) load variation pre-distortion, and an open loop ET modulator operatively coupled to the PA load variation pre-distortion, wherein the PA load variation pre-distortion is configured to determine a load variation at a PA supply voltage path based on an input signal received by a PA, and generate a pre-distortion compensation signal using the load variation, and wherein the open loop ET modulator is configured to generate a PA supply voltage on the PA supply voltage path using the pre-distortion compensation signal.

Abstract: Local oscillator (LO) in-phase/quadrature (IQ) imbalance correction data are generated for one or both of the transmitter and receiver of a radio-frequency (RF) communication device. An RF transmitter output signal is generated by the transmitter from a known test signal and transmitted to the receiver, where a baseband receiver signal is produced. A signal characteristic of the receiver baseband signal is measured in the presence of phase shifts introduced in the transmitter output signal. Joint LO IQ imbalance figures of merit are computed from the signal characteristic measurements, each characterizing signal processing artifacts in the receiver baseband signal caused by joint signal processing in the transmitter and the receiver under influence of transmitter LO IQ imbalance and receiver LO IQ imbalance.

Abstract: To generate amplitude modulation to phase modulation (AMPM) predistortion data that compensates for phase distortion in a power amplifier of a communication device, a test signal is amplified via the power amplifier. The amplified test signal is combined, by wave superposition, with a reference oscillator signal into a resultant signal. The resultant signal is an outcome of interference between the amplified test signal and the reference oscillator signal. The resultant signal power is measured using envelope information and, from the measurement, a predistortion phase shift is determined that when applied to the test signal maximizes the interference between the amplified test signal and the reference oscillator signal. AMPM predistortion data is generated to correspond with the predistortion phase shift.

Abstract: Aspects of the disclosure can provide a circuit to be used in a device. The circuit includes a first receiver circuit, a second receiver circuit and a processing circuit. The first receiver circuit is configured to receive a first signal from an antenna that captures a combination of a target signal transmitted from another device to the device and an output signal driven by a transmitter in the device. The second receiver circuit is configured to receive a second signal generated based on to the output signal. The processing circuit is configured to cancel from the first signal noise due to the output signal based on the second signal.

Abstract: A direct conversion transmitter has a mixer stage to up-convert an input signal to the frequency of a local oscillator (LO). A DC offset circuit is coupled to an input signal port to apply a set of DC offset signal values. A processor determines a set of optimal DC offset signal values by no more than three differential spectral measurements made at the transmitter output port with a test signal applied at the input port. Optimal DC offset signal values are those that, when applied to the input signal at the input port of the transmitter, minimize an LO leakage component of the transmit signal at the output signal port of the transmitter. The optimal DC offset values are stored in memory and retrieved and applied to information bearing signals provided as the input signal once those optimal DC offset values have been determined.

Abstract: Local oscillator (LO) in-phase/quadrature (IQ) imbalance correction data are generated for one or both of the transmitter and receiver of a radio-frequency (RF) communication device. An RF transmitter output signal is generated by the transmitter from a known test signal and transmitted to the receiver, where a baseband receiver signal is produced. A signal characteristic of the receiver baseband signal is measured in the presence of phase shifts introduced in the transmitter output signal. Joint LO IQ imbalance figures of merit are computed from the signal characteristic measurements, each characterizing signal processing artifacts in the receiver baseband signal caused by joint signal processing in the transmitter and the receiver under influence of transmitter LO IQ imbalance and receiver LO IQ imbalance.

Abstract: A direct conversion transmitter has a mixer stage to up-convert an input signal to the frequency of a local oscillator (LO). A DC offset circuit is coupled to an input signal port to apply a set of DC offset signal values. A processor determines a set of optimal DC offset signal values by no more than three differential spectral measurements made at the transmitter output port with a test signal applied at the input port. Optimal DC offset signal values are those that, when applied to the input signal at the input port of the transmitter, minimize an LO leakage component of the transmit signal at the output signal port of the transmitter. The optimal DC offset values are stored in memory and retrieved and applied to information bearing signals provided as the input signal once those optimal DC offset values have been determined.