Digital multi-band predistortion linearizer with non-linear subsampling algorithm in the feedback loop
A concurrent multi-band linearized transmitter (CMLT) has a concurrent digital multi-band predistortion block (CDMPB) and a concurrent multi-band transmitter (CMT) connected to the CDMPB. The CDMPB can have a plurality of digital baseband signal predistorter blocks (DBSPBs), an analyzing and modeling (A&M) stage, and a signal observation feedback loop. Each DBSPB can have a plurality of inputs, each corresponding to a single frequency band of the multi-band input signal, and its output corresponding to a single frequency band; each output connect corresponding to an input of the CMLT. The A&M stage can have a plurality of outputs connected to and updating the parameters of the DBSPBs, and a plurality of inputs connected to either both outputs of the signal observation loop or the output of the subsampling loop and to outputs of the DBSPBs. The A&M stage can perform signals' time alignment, reconstruction of signals and compute parameters of DBSPBs.
1 . A linearized transmitter comprising:
a digital predistorter block in a transmit signal path effecting signal distortion to output a plurality of distinct concurrent predistorted signals, each of the distinct concurrent predistorted signals being a function of a single input signal;
a transmitter block connected in the transmit signal path for combining said plurality of distinct concurrent predistorted signals for transmission by a power amplifier block;
a signal observation feedback receiver block coupled in a signal observation feedback path configured with a down converting subsampling operation to generate a plurality of concurrent and distinct feedback signals; and
an analyzing and modelling block configured to use the concurrent and distinct feedback signals for synthesizing predistorter coefficients for the digital predistorter block.
2 . The linearized transmitter of claim 1 , wherein said analyzing and modeling block is further configured to align delays and phases of the concurrent and distinct feedback signals.
3 . The linearized transmitter of claim 1 , wherein said down converting subsampling operation simultaneously and concurrently down converts all bands of an observed multiband signal.
4 . The linearized transmitter of claim 1 , wherein the subsampling operation is over multiple frequency segments.
5 . The linearized transmitter of claim 2 , wherein the signal distortion is performed in parallel on at least two signals.
6 . The linearized transmitter of claim 1 , said transmitter having hardware impairments, nonlinearities, harmonic distortions, memory effects and intermodulation distortion.
7 . The linearized transmitter of claim 1 , said input signal being a multiband signal and wherein the concurrent predistorted signals being a representation of at least two distinct band signals.
8 . The linearized transmitter of claim 1 , said digital predistorter block configured to compensate for hardware impairments, distortion and nonlinearities of said transmitter.
9 . The linearized transmitter of claim 1 , said digital predistorter block configured to compensate for memory effects of said transmitter.
10 . The linearized transmitter of claim 1 , said digital predistorter block configured to compensate for intermodulation and harmonic distortion.
11 . The linearized transmitter of claim 1 , said digital predistorter block configured to compensate for in-band intermodulation distortion and cross-band intermodulation.
12 . The linearized transmitter of claim 1 , said digital predistorter block including a predistortion model, said model being selected to compensate for intermodulation and cross-modulation products.
13 . The linearized transmitter of claim 12 , wherein the synthesized predistorter coefficients are for said compensation of said intermodulation and said cross-modulation products.
14 . A method for linearizing a transmitter, the method comprising:
effecting predistortion, in parallel, of signal components; applied to a digital predistorter block in a transmit signal path, to output a plurality of distinct concurrent predistorted signals, each of the distinct concurrent predistorted signals being a function of the signal components;
combining said plurality of distinct concurrent predistorted signals to form a multiband signal to be transmitted by a power amplifier block;
subsampling, in a signal observation feedback path to generate a plurality of concurrent and distinct feedback signals; and
using the concurrent and distinct feedback signals for synthesizing predistorter coefficients for the digital predistorter block.
15 . The linearized transmitter of claim 14 , said digital predistorter block compensating for hardware impairments, distortions and nonlinearities of said transmitter.
16 . The linearized transmitter of claim 14 , said digital predistorter block compensating for memory effects of said transmitter.
17 . The linearized transmitter of claim 14 , said digital predistorter block compensating for intermodulation and cross modulation products.
18 . The linearized transmitter of claim 14 , said digital predistorter block compensating for in-band intermodulation distortion and cross-band intermodulation distortion.
19 . The linearized transmitter of claim 14 , said digital predistorter block including a predistortion model, said model being selected to compensate for intermodulation and cross-modulation products.
20 . The linearized transmitter of claim 19 , wherein the synthesized predistorter coefficients are for said compensation of said intermodulation and said cross-modulation products.
21 . A method for a concurrent multiband receiver, the method comprising:
receiving a multiband signal; and
generating from the multiband signal, in at least one down converting subsampling operation, concurrent and distinct signals, each corresponding to respective distinct bands, the subsampling frequency being selected to preclude, aliasing between the concurrent and distinct signals.
22 . A transmitter comprising:
a concurrent digital multiband predistortion block configured to effect concurrent predistortion of respective band signals of a multiband signal to compensate for nonlinearities in the transmitter;
a power amplifier block configured to amplify a predistorted multiband signal to provide an amplified multiband signal; and
a signal observation feedback loop configured with a concurrent sampling block for concurrently sampling respective band signals corresponding to respective bands of the amplified multiband signal to produce concurrent feedback signals, the sampling being at a subsampling frequency lower than twice the highest signal frequency applied to the sampling block.
23 . The transmitter of claim 22 , wherein the feedback loop is further configured to effect concurrent frequency down conversion of the respective bands of the amplified multiband signal prior to the sampling block.
24 . The transmitter of claim 22 , the subsampling frequency being selected to preclude aliasing between distinct ones of the concurrent feedback signals.
25 . The transmitter of claim 24 , wherein the aliasing includes at least one of the harmonics and intermodulation of the concurrent feedback signals.
26 . A method for linearizing a transmitter comprising:
configuring a concurrent digital multiband predistortion block to effect concurrent predistortion of respective band signals of a multiband signal to compensate for nonlinearities in the transmitter;
amplifying a predistorted multiband signal in a power amplifier block to provide an amplified multiband signal; and
concurrently sampling, in a concurrent sampling block of a feedback loop, respective band signals corresponding to respective bands of the amplified multiband signal to produce concurrent feedback signals, the sampling being at a subsampling frequency lower than twice the highest signal frequency applied to the sampling block.
27 . The method of claim 26 , wherein the feedback loop is further configured to effect concurrent frequency down conversion of the respective band signals corresponding to the respective bands of the amplified multiband signal prior to the sampling block.