Pre-distortion architecture for compensating non-linear effects
AssigneeAndrew Corporation
InventorRajiv Chandrasekaran
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Abstract
An input signal is pre-distorted to reduce distortion resulting from subsequent signal amplification. Frequency-dependent pre-distortion is preferably implemented in combination with frequency-independent pre-distortion, where the frequency-dependent pre-distortion is generated by expanding the derivative of a product of a pre-distortion function and the input signal and then relaxing constraints on the pre-distortion function and/or on frequency-dependent filtering associated with the frequency-dependent pre-distortion. In one implementation, four different frequency-dependent pre-distortion signals are generated for the expansion using up to four different pre-distortion functions and up to four different frequency-dependent filters.
Claims26
A method for reducing distortion in an output signal by applying pre-distortion to an input signal to generate a pre-distorted signal, such that, when the pre-distorted signal is applied to a non-linear system to generate the output signal, the pre-distortion reduces the distortion in the output signal, wherein the pre-distorted signal is generated by:
- (a) generating a first frequency-dependent pre-distortion signal corresponding to a product of (i) a derivative of a first pre-distortion function and (ii) the input signal;
- (b) generating a second frequency-dependent pre-distortion signal corresponding to a product of (i) a derivative of a second pre-distortion function and (ii) the input signal;
- (c) generating a third frequency-dependent pre-distortion signal corresponding to a product of (i) a third pre-distortion function and (ii) a derivative of the input signal;
- (d) generating a fourth frequency-dependent pre-distortion signal corresponding to a product of (i) a fourth pre-distortion function and (ii) the derivative of the input signal;
- and
- (e) generating the pre-distorted signal based on a combination of the first, second, third, and fourth frequency-dependent pre-distortion signals.
Apparatus for reducing distortion in an output signal by applying pre-distortion to an input signal to generate a pre-distorted signal, such that, when the pre-distorted signal is applied to a non-linear system to generate the output signal, the pre-distortion reduces the distortion in the output signal, wherein apparatus comprises:
- a first signal path configured to generate a first frequency-dependent pre-distortion signal corresponding to a product of (i) a derivative of a first pre-distortion function and (ii) the input signal;
- a second signal path configured to generate a second frequency-dependent pre-distortion signal corresponding to a product of (i) a derivative of a second pre-distortion function and (ii) the input signal;
- a third signal path configured to generate a third frequency-dependent pre-distortion signal corresponding to a product of (i) a third pre-distortion function and (ii) a derivative of the input signal;
- a fourth signal path configured to generate a fourth frequency-dependent pre-distortion signal corresponding to a product of (i) a fourth pre-distortion function and (ii) the derivative of the input signal;
- and
- a summer configured to generate the pre-distorted signal based on the first, second, third, and fourth frequency-dependent pre-distortion signals.
Dependencies are inferred from the claim text.