ADAPTIVE DIGITAL PREDISTORTION FOR POLAR TRANSMITTER
First Claim
1. A method comprising:
- receiving an input polar transmit signal including an input amplitude signal and an input phase signal;
generating a predistorted polar transmit signal by predistorting the input polar transmit signal using at least one predistortion parameter selected from a lookup table;
generating a phase-and-amplitude modulated radio-frequency transmit signal corresponding to the predistorted polar signal;
providing a copy of the generated radio-frequency signal to a polar receiver having an injection lock oscillator (ILO);
operating the ILO of the polar receiver to generate in response to the copied, generated radio-frequency signal, a sampled polar signal including a sampled amplitude signal and a sampled phase signal;
comparing the sampled polar signal to the input polar transmit signal; and
updating the lookup table in response to the comparison.
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Accused Products
Abstract
A predistortion circuit receives an input polar signal to be transmitted, including an input amplitude signal and an input phase signal. The input polar signal is predistorted using at least one predistortion parameter selected from a lookup table. A phase-and-amplitude modulated radio-frequency signal is generated corresponding to the predistorted polar signal. A copy of the generated radio-frequency signal is provided to a polar receiver. The polar receiver is operated to generate, from the copy of the radio-frequency signal and without information relating to the generated transmit signal, a feedback polar signal including a feedback amplitude signal and a feedback phase signal. The feedback polar signal is compared to the input polar signal, the lookup table is updated in response to the comparison.
33 Citations
20 Claims
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1. A method comprising:
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receiving an input polar transmit signal including an input amplitude signal and an input phase signal; generating a predistorted polar transmit signal by predistorting the input polar transmit signal using at least one predistortion parameter selected from a lookup table; generating a phase-and-amplitude modulated radio-frequency transmit signal corresponding to the predistorted polar signal; providing a copy of the generated radio-frequency signal to a polar receiver having an injection lock oscillator (ILO); operating the ILO of the polar receiver to generate in response to the copied, generated radio-frequency signal, a sampled polar signal including a sampled amplitude signal and a sampled phase signal; comparing the sampled polar signal to the input polar transmit signal; and updating the lookup table in response to the comparison. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A circuit comprising:
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a lookup table having at least one address input and a data output, the address input being connected to a polar signal input, the lookup table being operative to store a plurality of predistortion parameters; predistortion logic having at least a first predistortion input connected to the polar signal input and a second predistortion input connected to the data output of the lookup table, the predistortion logic further having a predistortion output; a polar transmitter having an input connected to the predistortion output, the polar transmitter having an RF output; a polar receiver having an RF input coupled to the RF output of the polar transmitter, the polar receiver having a sampled polar signal output; and an adaptation circuit having a first input connected to the sampled polar signal output of the polar receiver and a second input connected to the polar signal input, the adaptation circuit being operative to modify the stored predistortion parameters based on a comparison of the sampled polar signal output with the polar signal input. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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Specification