Digital multi-band predistortion linearizer with nonlinear 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 concurrent multi-band linearized transmitter comprising:
a concurrent digital multi-band predistortion block, having a plurality of outputs, each for producing a predistorted signal corresponding to a single frequency channel of the multi-band linearized transmitter; and
a signal observation feedback loop including an analyzing and modeling stage directly connected to each said plurality of outputs of said digital multi-band predistortion block for receiving the respective predistorted signals and for using said received predistorted signals in controlling said digital multi-band predistortion block.
2. The concurrent multi-band linearized transmitter of claim 1 , wherein said concurrent digital multi-band predistortion block further comprises: a plurality of digital baseband signal predistorter blocks, each baseband signal predistorter block having a plurality of first inputs and a single output, the plurality of first inputs corresponding in number to the multiple bands of the multi-band transmitter and each first input corresponding to a single frequency channel.
3. The concurrent multi-band linearized transmitter of claim 2 , wherein each said single output of each said plurality of digital baseband signal predistorter blocks is connected to one of a plurality of second inputs of a concurrent multi-band transmitter block.
4. The concurrent multi-band linearized transmitter of claim 2 , wherein said analyzing and modeling stage further comprises: a plurality of outputs connected to, and for updating the parameters of, said digital multi-band signal predistorter blocks; and a plurality of inputs connected to said outputs of said signal observation feedback loop.
5. The concurrent multi-band linearized transmitter of claim 1 , wherein said analyzing and modeling stage is further connected to receive an output signal from said concurrent multi-band transmitter to perform time alignment of complex baseband signals from sampling said output of said concurrent multi-band transmitter and perform reconstruction of the complex baseband signals from sampling said output of the said concurrent multi-band transmitter; and compute parameters for said digital baseband signal predistorter block.
6. The concurrent multi-band linearized transmitter of claim 1 , wherein said signal observation feedback loop further includes a down converter to down-convert samples of the RF signals at an output of a concurrent multi-band transmitter and extract from said down-converted samples a baseband equivalent for all frequency channels.
7. The concurrent multi-band linearized transmitter of claim 1 , wherein said signal observation feedback loop further comprises a plurality of channels each channel including an RF filter, a signal down conversion block; and an analog-to-digital converter (ADC).
8. The concurrent multi-band linearized transmitter of claim 1 , wherein said signal observation feedback loop further comprises: a single subsampling-based receiver to down-convert samples output from a concurrent multi-band transmitter.
9. The concurrent multi-band linearized transmitter of claim 8 , wherein said single subsampling-based receiver includes an RF filter; a track and hold (T&H) block; and an analog-to-digital converter (ADC).
10. The concurrent multi-band linearized transmitter of claim 1 , further including a concurrent multi-band transmitter block connected to the plurality an of outputs of the multi-band predistortion block.
11. The concurrent multi-band linearized transmitter of claim 10 , wherein the signal observation feedback loop samples signals from the concurrent multi-band transmitter block, the feedback loop including:
a subsampling-based receiver to down-convert samples of all frequency bands at a same time output from the concurrent multi-band transmitter block; and
an analyzing and modeling stage using said down-converted samples to control said digital multi-band predistortion block.
12. The concurrent multi-band linearized transmitter of claim 1 , wherein the signal observation feedback loop sampling signals from the concurrent multi-band transmitter block, the feedback loop including:
a subsampling-based receiver to down-convert samples of all frequency bands at a same time output from the concurrent multi-band transmitter block; and
an analyzing and modeling stage using said down-converted samples to control said digital multi-band predistortion block.