Systems and methods for providing baseband-derived predistortion to increase efficiency of transmitters

A transmitter incorporating baseband-derived predistortion, the transmitter comprising:

• a main signal path that receives a baseband analog input signal and generates a main signal in response thereto;
• an intermediate frequency (IF) filter in said main signal path for removing unwanted signal components from said main signal;
• a power amplifier having non-linearity;
• a predistortion module for processing said baseband analog input signal to generate a predistortion signal that models an inverse of said non-linearity of said power amplifier;
• and
• a combiner located between said filter and said power amplifier, for combining said predistortion signal with said main signal to generate a combined signal, and for providing said combined signal to said power amplifier.

A method of applying baseband-derived predistortion to a power amplifier having non-linearity, the method comprising:

• digitally deriving from an input signal a predistortion signal that models an inverse of said non-linearity of said power amplifier;
• generating a main signal from said input signal;
• filtering at an intermediate frequency (IF) to remove unwanted signal components from said main signal;
• and
• combining said predistortion signal with said main signal after said filtering step to generate a combined signal for driving said power amplifier.

A transmitter comprising:

• a digital portion configured to receive a baseband digital input signal and to generate an analog main signal and an analog predistortion signal in response thereto;
• an intermediate frequency (IF) filter configured to produce a filtered analog main signal by removing out-of-band signal components from the analog main signal;
• a combiner configured to produce a combined signal by combining the filtered analog main signal and the analog predistortion signal;
• and
• an amplifier having a non-linear response, the amplifier configured to receive and to amplify the combined signal comprising the predistortion signal that is operative to canceling undesirable signal components from a transmitted RF signal.

A transmitter comprising:

• a digital baseband filter system configured to receive a baseband digital input signal and to generate a filtered digital main signal in response thereto;
• a first digital-to-analog converter system configured to receive the filtered digital main signal and to generate a baseband analog main signal in response thereto;
• a predistortion signal generator system configured to receive the baseband digital input signal and to generate a baseband digital predistortion signal in response thereto;
• a second digital-to-analog converter system configured to receive the digital predistortion signal and to generate a baseband analog predistortion signal in response thereto;
• a radio frequency (RF) modulator system configured to receive the baseband analog main signal and the baseband analog predistortion signal to generate an RF main signal and an RF predistortion signal in response thereto;
• a combiner configured to combine the RF main signal and the RF predistortion signal to generate an RF transmit signal in response thereto;
• and
• an amplifier having a non-linear response, the amplifier configured to receive and to amplify the RF transmit signal comprising the RF predistortion signal that is operative to canceling undesirable signal components from a transmitted RF signal.