Digital predistortion for amplifiers

A method for predistorting a digital signal prior to amplification comprising:

• computing a look-up table using power values of digital input signal samples as look-up values wherein the look-up table is a function of pre-measured calibration data;
• applying the look-up table to digital input signals for producing the predistorted signal;
• and
• changing all the look-up values in response to a change in only one parameter, wherein the change in the one parameter is a measure of a change in amplification.

A method for predistorting a digital signal prior to amplification comprising:

• computing a look-up table using power values of digital input signal samples as look-up values wherein the look-up table is a function of pre-measured calibration data;
• applying the look-up table to digital input signals for producing the predistorted signal;
• and
• changing all the look-up values in response to a change in only a pair of parameters, wherein the change in the pair of parameters is a measure of a change in amplification.

A method for linearizing an amplifier to produce an amplified output signal comprising:

• predistorting a signal prior to amplification comprising:
• computing a look-up table using power values of digital input signal samples as look-up values wherein the look-up table is a function of pre-measured calibration data;
• wherein the step of computing the look-up table further comprises:
• determining a set of input power values;
• obtaining the pre-measured calibration data including an output power data value and phase data value of the amplifier corresponding to each of the input power values;
• deriving a set of calibration power values using the output power data values;
• deriving amplitude predistortion calibration values using the calibration power values and the input power values;
• determining phase predistortion calibration values from the phase data values;
• interpolating the calibration power values and corresponding amplitude predistortion calibration values to provide amplitude predistortion values;
• interpolating the calibration power values and corresponding phase predistortion calibration values to provide phase predistortion values;
• and
• wherein the look-up table is computed from the amplitude predistortion values and the phase predistortion values;
• and
• applying the look-up table to digital input signals for producing the predistorted signal;
• wherein the amplitude predistortion values and the phase predistortion values are polar values, the method further comprising:
• translating the amplitude predistortion values and the phase predistortion values from polar values to Cartesian values.

A method for linearizing an amplifier to produce an amplified output signal comprising:

• computing a look-up table including;
• determining a set of input power values;
• obtaining an output power value and phase value of the amplifier corresponding to each of the input power values;
• deriving a set of calibration power values using the output power values;
• deriving amplitude predistortion calibration values using the calibration power values and the input power values;
• determining phase predistortion calibration values from the phase values;
• interpolating the calibration power values and corresponding amplitude predistortion calibration values to provide amplitude predistortion values;
• interpolating the calibration power values and corresponding phase predistortion calibration values to provide phase predistortion values;
• and
• wherein the look-up table is computed from the amplitude predistortion values and the phase predistortion values;
• and
• applying the look-up table to a digital input signal for producing a predistorted signal;
• amplifying the predistorted signal;
• producing an output signal which is linearly related to the digital input signal;
• and
• translating the amplitude predistortion values and the phase predistortion values from polar values to Cartesian values.

A method for linearizing an amplifier to produce an amplified output signal from a set of carrier frequencies, the method comprising:

• linearly combining a set of digital baseband signals corresponding to the set of carrier frequencies to produce an extended digital baseband signal;
• wherein the step of linearly combining the set of digital baseband signals further comprises:
• complex mixing individual digital baseband signals of the set of digital baseband signals with trigonometric signals to produce complex mixed signals;
• and
• adding the complex mixed signals to produce the extended digital baseband signal;
• deriving look-up values from the power values of the extended digital baseband signal for applying to a look-up table to obtain predistortion values, wherein the look-up table is a function of pre-measured calibration data;
• producing one or more predistorted signals by complex mixing the predistortion values with a selected one of the extended digital baseband signal and the set of digital baseband signals;
• and
• producing the amplified output signal which is linearly related to the set of digital baseband signals.

A semiconductor device comprising:

• a memory for storing a look-up table wherein the look-up table is a function of pre-measured calibration data, and wherein the look-up table uses power values of digital input signal samples as look-up values;
• a complex mixer for applying the look-up table to digital input signals for producing a predistorted signal;
• wherein the complex mixer further comprises:
• a plurality of multipliers;
• an amplifier for receiving and amplifying the predistorted signal;
• and
• wherein an amplified output signal is produced which is linearly related to the digital input signals.

A semiconductor device comprising:

• a memory for storing a look-up table wherein the look-up table is a function of pre-measured calibration data, and wherein the look-up table uses power values of digital input signal samples as look-up values;
• a complex mixer for applying the look-up table to digital input signals for producing a predistorted signal;
• an amplifier for receiving and amplifying the predistorted signal;
• and
• wherein an amplified output signal is produced which is linearly related to the digital input signals;
• and
• wherein the look-up values are adapted in response to changes in amplification using a pair of constants.