Digital polar transmitter

A digital polar transmitter, comprising:

• a baseband processor configured to receive an input signal and to convert the input signal into a baseband amplitude component and a baseband phase component;
• a phase modulator in communication with the baseband processor, wherein the phase modulator is configured to modulate an RF carrier signal based on the phase component and to generate a phase-modulated RF carrier signal;
• a power amplifier in communication with the baseband processor and the phase modulator, wherein the power amplifier is configured to amplify the phase-modulated RF carrier signal based on the baseband amplitude component and to generate an amplified RF signal;
• and
• a digital feedback loop in communication with the power amplifier and the baseband processor, wherein the digital feedback loop is configured to detect the amplified RF signal and to provide a digital amplitude feedback signal and a digital phase feedback signal to the baseband processor;
• the baseband processor comprising
• a phase predictor configured to operate during a closed-loop calibration period and to provide a closed-loop phase correction signal based on predicted changes in the phase of the amplified RF signal,
• a phase correction lookup table configured to store a plurality of phase pre-distortion values and to provide an open-loop phase correction signal based on at least one of the plurality of phase pre-distortion values,
• a phase interpolator configured to operate during the closed-loop calibration period and to generate the plurality of phase pre-distortion values, and
• a phase synchronizer configured to operate during the closed-loop calibration period and during an open-loop operation period, wherein the phase synchronizer is further configured to pre-distort the baseband phase signal based on the closed-loop phase correction signal during the closed-loop calibration period and to pre-distort the baseband phase signal based on the open-loop phase correction signal during the open-loop operation period.

A digital polar transmitter, comprising:

• a baseband processor configured to receive an input signal and to convert the input signal into a baseband amplitude component and a baseband phase component;
• a phase modulator in communication with the baseband processor, wherein the phase modulator is configured to modulate an RF carrier signal based on the phase component and to generate a phase-modulated RF carrier signal;
• a power amplifier in communication with the baseband processor and the phase modulator, wherein the power amplifier is configured to amplify the phase-modulated RF carrier signal based on the baseband amplitude component and to generate an amplified RF signal;
• and
• a digital feedback loop in communication with the power amplifier and the baseband processor, wherein the digital feedback loop is configured to detect the amplified RF signal and to provide a digital amplitude feedback signal and a digital phase feedback signal to the baseband processor;
• the baseband processor comprising
• an amplitude predictor configured to operate during a closed-loop calibration period and to provide a closed-loop amplitude correction signal based on predicted changes in the amplitude of the amplified RF signal,
• an amplitude correction lookup table configured to store a plurality of amplitude pre-distortion values and to provide an open-loop amplitude correction signal based on at least one of the plurality of amplitude pre-distortion values,
• an amplitude interpolator configured to operate during the closed-loop calibration period and to generate the plurality of amplitude pre-distortion values, and
• an amplitude synchronizer configured to operate during the closed-loop calibration period and during an open-loop operation period, wherein the amplitude synchronizer is further configured to pre-distort the baseband amplitude signal based on the closed-loop amplitude correction signal during the closed-loop calibration period and to pre-distort the baseband amplitude signal based on the open-loop amplitude correction signal during the open-loop operation period.