Fast LUT predistorter for power amplifier
First Claim
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1. A fast look up table (LUT) predistortion apparatus comprising:
- a predistortion means for predistorting an input complex digital signal based on an LUT implementation and outputting a predistorted complex signal; and
a power amplifier for amplifying the predistorted signal and outputting an amplified complex signal,wherein the predistortion means includes;
a selection unit for receiving the input complex digital signal, generating an access point and a quantized signal based on the input complex digital signal;
a memory unit for storing values of the input complex digital signal corresponding to the accessing point from the selection unit and outputting a stored signal;
a multiplexer for generating a multiplexed signal by selecting one of the stored signal and the input digital complex signal;
a address generator for generating an access point according to the quantized signal from the selection unit;
a LUT for storing complex gain values according to the access point from the address generator and outputting stored complex gain value;
a multiplier for multiplying the multiplexed signal from the multiplexer and stored complex gain value from the LUT;
a delayer for receiving the multiplexed signal, and generating a delayed signal by delaying the multiplexed signal to match a feedback signal from the power amplifier;
a adaptation unit for calculating an error signal by comparing the delayed signal and the feedback signal and updating the complex gain values of the LUT; and
a control unit for controlling the selection unit and multiplexer by state of the error signal from the adaptation unit.
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Abstract
A fast LUT predistortion apparatus and method for compensating nonlinear distortion of the high power amplifier HPA is disclosed. The apparatus includes a predistortion unit for predistorting an input complex digital signal based on a look up table LUT implementation and outputting a predistorted complex signal; and a power amplifier for amplifying the predistorted signal and outputting an amplified complex signal.
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8 Claims
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1. A fast look up table (LUT) predistortion apparatus comprising:
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a predistortion means for predistorting an input complex digital signal based on an LUT implementation and outputting a predistorted complex signal; and a power amplifier for amplifying the predistorted signal and outputting an amplified complex signal, wherein the predistortion means includes; a selection unit for receiving the input complex digital signal, generating an access point and a quantized signal based on the input complex digital signal; a memory unit for storing values of the input complex digital signal corresponding to the accessing point from the selection unit and outputting a stored signal; a multiplexer for generating a multiplexed signal by selecting one of the stored signal and the input digital complex signal; a address generator for generating an access point according to the quantized signal from the selection unit; a LUT for storing complex gain values according to the access point from the address generator and outputting stored complex gain value; a multiplier for multiplying the multiplexed signal from the multiplexer and stored complex gain value from the LUT; a delayer for receiving the multiplexed signal, and generating a delayed signal by delaying the multiplexed signal to match a feedback signal from the power amplifier; a adaptation unit for calculating an error signal by comparing the delayed signal and the feedback signal and updating the complex gain values of the LUT; and a control unit for controlling the selection unit and multiplexer by state of the error signal from the adaptation unit. - View Dependent Claims (2, 3, 4)
where vi shows the input complex signal to multiplier, va represents the feedback signal from output of power amplifier and K depicts the gain of power amplifier.
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5. A fast look up table (LUT) predistortion method comprising:
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an acquisition step for selecting LUT access points and performing a predistortion and updating operation with the selected access points; and a tracking step for performing the predistortion and updating operation with an input complex digital signal wherein the acquisition step includes a reset step for performing the predistortion and updating operation without the input complex digital signal and generating accessing points to a memory unit in a predefined order; and an error severe step for performing the predistortion and updating operation with the input complex signal and generating accessing points to the memory unit based on values of the input complex digital signal. - View Dependent Claims (6, 7, 8)
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Specification