Automatic optimization of linearity for envelope feedback RF amplifier linearization
AssigneeTelefonaktiebolaget LM Ericsson
InventorLars Sundstorm
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Abstract
An amplifier configuration and method of amplifying a signal are provided for automatic optimization of linearity of power amplifier input/output characteristics. The amplifier configuration utilizes a feedback loop that includes detecting envelopes of signals that are input and output from a power amplifier. The amplifier configuration includes an offset parameter determined in a second feedback loop that adapts to values for optimizing the linearity of the power amplifier output when input signal amplitudes are within a predetermined range of small signal values, thereby producing a substantially reduced distortion and thus linearized output over the entire input signal amplitude range.
Claims36
A method of amplifying an input signal, comprising:
- generating an error signal based on an input signal envelope and an output signal envelope;
- determining an amplification level as a function of the error signal and an offset amount;
- amplifying the input signal based on the amplification level;
- and
- adjusting the offset amount only when an amplitude of the input signal is within a range having an upper limit defined by a predetermined small signal threshold value.
An amplifier apparatus, comprising:
- a power amplifier having an input signal path and an output node, the power amplifier configured to produce an output signal on the output node in response to receiving an input signal on the input signal path;
- a feedback loop configured to produce a feedback signal in response to the input signal and the output signal, wherein the feedback signal is a function of the input signal, the output signal and an offset signal and wherein the feedback signal in conjunction with the input signal controls an output level of the power amplifier;
- an offset signal circuit that generates the offset signal;
- and
- wherein the offset signal circuit is configured to output a constant predetermined offset signal value when the amplitude of the input signal is above a predetermined small signal threshold level, and to output an adaptive offset signal when the amplitude of the input signal is at or below the predetermined small signal threshold level.
An amplifier apparatus for amplifying an input signal, comprising:
- means for generating an error signal based on an input signal envelope and an output signal envelope;
- means for determining an amplification level as a function of the error signal and an offset amount;
- means for amplifying the input signal based on the amplification level;
- and
- means for adjusting the offset amount only when an amplitude of the input signal is within a range having an upper limit defined by a predetermined small signal threshold value.
Dependencies are inferred from the claim text.