Postdistortion amplifier with predistorted postdistortion

A method for predistorting an error signal in a postdistortion amplifier that receives a digital input signal and produces a linearized amplified signal based on the digital input signal, wherein the method comprises steps of:

• maintaining a predistorted error signal model;
• producing a digital error signal based on the digital input signal;
• and
• producing a digital predistorted error signal based on the received digital error signal and by reference to the predistorted error signal model.

A postdistortion amplifier comprising:

• a main signal path that receives a digital input signal and produces an amplified signal in response to receiving the digital input signal;
• a postdistortion correction circuit that is coupled to the main signal path, wherein the postdistortion correction circuit receives at least a portion of the digital input signal, maintains a characterization of the main signal path, produces a digital error signal based on the at least a portion of the digital input signal and the characterization of the main signal path, predistorts the digital error signal based on a predistorted error signal model to produce a digital predistorted error signal, and produces an amplified error signal based on the predistorted error signal, wherein the predistortion of the error signal at least partially cancels distortion introduced by the postdistortion correction circuit to the amplified error signal;
• and
• a signal combiner coupled to the main signal path and to the postdistortion correction circuit that receives the amplified signal from the main signal path, receives the amplified error signal from the postdistortion correction circuit, and combines the amplified signal with the amplified error signal to produce a postdistortion amplifier output signal.

A wireless communication device comprising:

• an information source that sources information to a processor;
• a processor that receives the information from the information source, produces a digital input signal based on the received information, and couples the digital input signal to a postdistortion amplifier;
• a postdistortion amplifier that receives the digital input signal from the processor and produces a linearized amplified signal based on the digital input signal, the postdistortion amplifier comprising:
• a main signal path that receives the digital input signal and produces an amplified signal in response to receiving the digital input signal;
• a postdistortion correction circuit that is coupled to the main signal path, wherein the postdistortion correction circuit receives at least a portion of the digital input signal, maintains a characterization of the main signal path, maintains a predistorted error signal model, produces a digital error signal based on the at least a portion of the digital input signal and the characterization of the main signal path, predistorts the digital error signal based on the predistorted error signal model to produce a digital predistorted error signal, and produces an amplified error signal based on the predistorted error signal, wherein the predistortion of the error signal at least partially cancels distortion introduced by the postdistortion correction circuit to the amplified error signal;
• and
• a signal combiner coupled to the main signal path and to the postdistortion correction circuit that receives the amplified signal from the main signal path, receives the amplified error signal from the postdistortion correction circuit, and combines the amplified signal with the amplified error signal to produce a linearized amplified signal.