Digital multi-band predistortion linearizer with non-linear subsampling algorithm in the feedback loop
A concurrent multi-band linearized transmitter (CMLT) has a concurrent d a 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 signal predistorter block including digital baseband signal predistorters effecting predistortion of concurrent input signals to output concurrent predistorted signals;
a power amplifier block connected to amplify the predistorted signals; and
an analyzing and modelling stage receiving first feedback signals taken from an output of the power amplifier, and second feedback signals taken concurrently from the concurrent predistorted signals and using the first feedback and the second feedback signals in the analyzing and modelling stage to model a nonlinearity in the power amplifier, wherein the digital baseband signal predistorters are updated by the analyzing and modelling stage.
2. The linearized transmitter of claim 1 , wherein said concurrent digital multi-band predistortion block further comprises:
a plurality of the digital baseband signal predistorters each corresponding to a respective channel; and a signal observation feedback loop for generating said first feedback signals.
3. The linearized transmitter of claim 2 , wherein said plurality of digital baseband signal predistorters further comprises:
a plurality of inputs, each input corresponding to a single frequency channel; and
a plurality of outputs, each output corresponding to a single frequency channel, and each output connected to an input of a concurrent multi-band transmitter.
4. The linearized transmitter of claim 2 , wherein said analyzing and modeling stage further comprises:
a plurality of outputs connected to update the parameters of said digital baseband signal predistorters; and
a plurality of inputs connected to both: (a) outputs of said signal observation feedback loop comprising said first feed back signals, and (b) to outputs of said digital signal predistorter block.
5. The linearized transmitter of claim 2 , wherein said analyzing and modeling stage is further adapted to:
perform time alignment of complex baseband signals from sampling said first feedback signals; and
perform reconstruction of the complex baseband signals from said sampling.
6. The linearized transmitter of claim 2 ,
said first feed back signals corresponding to a baseband equivalent for all frequency channels and wherein the baseband equivalent signals being extracted from down-converted samples of RF signals output from said power amplifier block.
7. The linearized transmitter of claim 2 , wherein said signal observation feedback loop further comprises a plurality of channels, each channel comprising:
an RF filter;
a signal down conversion block; and
an analog-to-digital converter (ADC).
8. The linearized transmitter of claim 2 , wherein said signal observation feedback loop further comprises:
a single subsampling-based receiver to down-convert samples output from said power amplifier block.
9. The linearized transmitter of claim 8 , wherein said single subsampling-based receiver further comprises:
an RF filter; a track and hold (T&H) block; and an analog-to-digital converter (ADC).
10. A method for linearizing a transmitter, said method comprising:
effecting predistortion of concurrent input signals to output concurrent predistorted signals using a digital signal predistorter block including digital baseband signal predistorters;
amplifying the predistorted signals using a power amplifier block;
receiving in an analyzing and modelling stage first feedback signals taken from an output of the power amplifier, and second feedback signals taken concurrently from the concurrent predistorted signals; and
using the first feedback and the second feedback signals in the analyzing and modeling stage to model a nonlinearity in the power amplifier, wherein the digital baseband signal predistorters are updated by the analyzing and modelling stage.