Low noise wideband digital predistortion amplifier

A method of predistorting a digital input signal for a non-linear amplifier, the method comprising:

• generating a digital correction signal based at least upon the digital input signal and an output signal from the non-linear amplifier;
• converting the digital input signal to at least one analog input signal;
• separately converting the digital correction signal to create an analog correction signal;
• and
• combining the at least one analog input signal and the analog correction signal to create an analog predistorted input signal.

A method for converting a digital input signal to an analog input signal for input to a power amplifier, the method comprising:

• separating the input signal into a plurality of digital subband signals;
• processing the digital subband signals to generate digital precompensated subband signals;
• converting the digital precompensated subband signals to analog form using subband-specific digital to analog converters to generate analog precompensated subband signals;
• and
• combining the analog precompensated subband signals.

A system for converting a digital input signal to an analog input signal for an analog amplifier, the circuit comprising:

• a first circuit configured to separate the digital input signal into a plurality of digital subband input signals;
• a plurality of digital to analog converters, wherein each of the plurality of digital to analog converters is configured to convert one of the digital subband input signals to an analog subband input signal;
• and
• a second circuit configured to combine the analog subband input signals to form the analog input signal.

A circuit for predistorting a digital input signal for input to a non-linear analog amplifier, the circuit comprising:

• a first circuit configured to separate the digital input signal into a plurality of digital subband input signals;
• a first plurality of digital to analog converters, wherein each of the first plurality of digital to analog converters is configured to convert one of the digital subband input signals to an analog subband input signal;
• a second circuit configured to create a digital error correction signal based at least upon an output signal from the non-linear amplifier and the digital input signal;
• and
• a second set of at least one digital to analog converters, the second set of converters configured to convert the digital error correction signal to an analog error correction signal, wherein none of the converters in the second set are included in the first plurality,
• wherein the analog subband input signals and the analog error correction signal are combined to form an analog input signal to the analog amplifier.

A system for predistorting a digital input signal to compensate for nonlinearities in an amplification process, the system comprising:

• a first circuit which adaptively processes the digital input signal to compensate for at least one type of distortion introduced by the amplification process, to thereby generate a predistorted digital input signal;
• a second circuit which substantially removes the digital input signal from the predistorted digital input signal to generate a digital correction signal;
• a digital to analog converter which converts the digital correction signal to analog form to generate an analog correction signal;
• and
• a third circuit which combines the analog correction signal with at least one analog signal representing the digital input signal, to thereby generate an analog predistorted input signal.