초록 ▼

A linearizer for a non-linear transmitter includes a tap delay line that provides samples of an input signal at selected times. At least one Volterra tap is coupled to the tape delay line. The Volterra tap includes a lookup table representation of a polynomial. An adaptive controller is coupled to t

A linearizer for a non-linear transmitter includes a tap delay line that provides samples of an input signal at selected times. At least one Volterra tap is coupled to the tape delay line. The Volterra tap includes a lookup table representation of a polynomial. An adaptive controller is coupled to the Volterra tap for modifying values in the lookup table.

대표청구항 ▼

The invention claimed is: 1. A linearizer for a non-linear transmitter, the linearizer comprising: a tap delay line that provides samples of an input signal at selected times; multiple Volterra taps coupled to the tap delay line, wherein each Volterra tap includes a lookup table representation of a

The invention claimed is: 1. A linearizer for a non-linear transmitter, the linearizer comprising: a tap delay line that provides samples of an input signal at selected times; multiple Volterra taps coupled to the tap delay line, wherein each Volterra tap includes a lookup table representation of a polynomial; and an adaptive controller coupled to the Volterra tap for modifying values in the lookup table, wherein outputs from the Volterra taps are added together at a summer to provide a predistorted version of the input sample for provision to the non-linear transmitter. 2. The linearizer of claim 1 wherein the tap delay line comprises an array of Z−n delay elements with tap-spacing of N samples, where n is a discrete time index and Z−n designates a propagation delay of n discrete samples. 3. The linearizer of claim 1 wherein the tap delay line comprises elements distributed across the Volterra tap inputs and outputs. 4. The linearizer of claim 1 wherein the lookup tables comprise uniform sets of dual-port RAMs. 5. The linearizer of claim 4 wherein the dual-port RAMs provide for modification and accumulation of processing elements to implement Volterra terms. 6. The linearizer of claim 1 and further comprising an error module coupled to an output of the non-linear transmitter and a delay compensated input signal for providing an error signal to the adaptive controller. 7. The linearizer of claim 6 and further comprising a causality delay module for shifting of the location of the present tap by a desired number of samples back in time and virtually creating non-causal inverse models which work on past, present and future input samples. 8. The linearizer of claim 6 wherein the adaptive controller provides a sample-by-sample lookup table value optimization. 9. The linearizer of claim 8 wherein the adaptive controller modifies a lookup table Volterra tap location value by reading its current value, modifying it with a processed error, and writing the new value to the same lookup table location. 10. The linearizer of claim 9 wherein a lookup table location values is modified in accordance with: yiKyiK−+μi.errinorm where Yk−Ii is the existing LUT contents of tap i at the discrete time instant n; the real-valued parameter μi is the “adaptation step” which may be different for each tap; and errinorm is a version of a complex-valued error signal which is phase- and magnitude-normalized differently for each tap. 11. The linearizer of claim 1 wherein the tap-delay line includes a history of the evolution of the input such that different polynomials may be applied across time. 12. A linearizer for a non-linear transmitter, the linearizer comprising: a tap delay line that provides samples of an input signal at selected times; multiple Volterra taps coupled to the tap delay line, wherein each Volterra tap includes a lookup table representation of a polynomial; and an adaptive controller coupled to the Volterra tap for modifying values in the lookup table, wherein main X-terms can be created by connecting Volterra tap inputs to different outputs from the tap-delay line. 13. A linearizer for a non-linear transmitter, the linearizer comprising: a tap delay line that provides samples of an input signal at selected times; multiple Volterra taps coupled to the tap delay line, wherein the Volterra tap includes a lookup table representation of a polynomial; and an adaptive controller for each Volterra tap coupled to the Volterra taps for modifying values in the lookup tables; and wherein at least two Volterra taps are used for a sample to provide main X-terms for the sample. 14. The linearizer of claim 13 and further comprising creating secondary X-terms by adding one or more single input lookup tables for performing power functions. 15. The linearizer of claim 13 wherein outputs from the Volterra taps are added together at one or more summers to provide a predistorted version of the input sample for provision to the non-linear transmitter. 16. The linearizer of claim 15 wherein the tap delay line comprises delay elements arranged a tap delay line matrix or distributed across Volterra tap inputs, outputs and summers. 17. The linearizer of claim 15 and further comprising an error module coupled to an output of the non-linear transmitter and a delay compensated input signal for providing an error signal to the adaptive controllers. 18. The linearizer of claim 17 and further comprising a causality delay module for shifting of the location of the present tap by a desired number of samples back in time and virtually creating non-causal inverse models which work on past, present and future input samples. 19. A method of providing a predistorted input signal to a non-linear transmitter, the method comprising: providing temporal samples of an input signal; solving a Volterra series polynomial by use of a lookup table for each of multiple Volterra taps that receive a sample of the input signal; and modifying values in the lookup tables as a function of an error signal generated from a comparison of a transmitted output signal and the solved Volterra series polynomial, wherein outputs from the Volterra taps are added together at a summer to provide a predistorted version of the input sample for provision to the non-linear transmitter. 20. The method of claim 19 and further comprising modifying a lookup table Volterra tap location value by reading its current value, modifying it with a processed error, and writing the new value to the same lookup table location.