Distortion and aliasing reduction for digital to analog conversion
View Patent ↗Distortion and aliasing reduction for digital to analog conversion. Synthesis of one or more distortion terms made based on a digital signal (e.g., one or more digital codewords) is performed in accordance with digital to analog conversion. The one or more distortion terms may correspond to aliased higher-order harmonics, distortion, nonlinearities, clipping, etc. Such distortion terms may be known a priori, such as based upon particular characteristics of a given device, operational history, etc. Alternatively, such distortion terms may be determined based upon operation of a device and/or based upon an analog signal generated from the analog to conversion process. For example, frequency selective measurements made based on an analog signal generated from the digital to analog conversion may be used for determination of and/or adaptation of the one or more distortion terms. One or more DACs may be employed within various architectures operative to perform digital to analog conversion.
1. An apparatus comprising:
a modulator configured to process digital data to generate at least one codeword.
a digital to analog converter (DAC) configured to process the at least one codeword to generate a first analog signal;
a synthesizer configured to process the at least one codeword to generate at least one distortion term corresponding to a frequency band of the first analog signal;
at least one stop band configured to filter the first analog signal to generate a filtered, first analog signal; and
an adapter configured to modify the at least one distortion term based on at least one frequency selective measurement corresponding to the first analog signal, the filtered, first analog signal or at least one additional signal derived there from; and
a combiner configured to combining the filtered, first analog signal and a second analog signal to reduce distortion within the filtered, first analog signal, wherein the second analog signal is based on the at least one distortion term corresponding to a frequency band of the first analog signal.
2. The apparatus of claim 1 further comprising:
the DAC is a first DAC that is configured to operate at a first frequency; and
a second DAC configured to operate at a second frequency to process a modified version of the at least one distortion term to generate the second analog signal or at least one additional signal.
3. The apparatus of claim 1 further comprising:
an amplifier configured to process the first analog signal before providing the first analog signal to the stop band filter.
4. The apparatus of claim 1 further comprising:
the adapter configured to perform adaptation of at least one of filtering, gain, phase, or delay adjustment of the at least one distortion term.
5. The apparatus of claim 1 further comprising:
a communication device that is operative within at least one of a satellite communication system, a wireless communication system, a wired communication system, or a fiber-optic communication system.
6. An apparatus comprising:
a digital to analog converter (DAC) configured to process at least one codeword to generate a first analog signal;
a synthesizer configured to process the at least one codeword to generate at least one distortion term corresponding to a frequency band of the first analog signal;
a stop band configured to filter the first analog signal to generate a filtered, first analog signal; and
a combiner configured to combine the filtered, first analog signal and a second analog signal to reduce distortion within the filtered, first analog signal, wherein the second analog signal is based on the at least one distortion term corresponding to a frequency band of the first analog signal.
7. The apparatus of claim 6 further comprising:
the DAC is a first DAC that is configured to operate at a first frequency; and
a second DAC configured to operate at a second frequency to process the at least one distortion term to generate the second analog signal or at least one additional signal.
8. The apparatus of claim 6 further comprising:
a modulator configured to process digital data to generate the at least one codeword.
9. The apparatus of claim 6 further comprising:
an amplifier configured to process the first analog signal before providing the first analog signal to the stop band filter.
10. The apparatus of claim 6 further comprising:
an adapter configured to modify the at least one distortion term based on at least one frequency selective measurement corresponding to the first analog signal, the filtered, first analog signal or at least one additional signal derived there from.
11. The apparatus of claim 6 further comprising an adapter configured to:
modify the at least one distortion term based on at least one frequency selective measurement corresponding to the first analog signal, the filtered, first analog signal or at least one additional signal derived there from; and
perform adaptation of at least one of filtering, gain, phase, or delay adjustment of the at least one distortion term.
12. The apparatus of claim 6 further comprising:
an adapter configured to modify the at least one distortion term based on at least one frequency selective measurement corresponding to the first analog signal, the filtered, first analog signal or at least one additional signal derived there from;
a coupler configured to output at least a portion of a combined signal output from the combiner;
a frequency selective filter configured to select a spectral band component of at least a portion of the combined signal;
a power detector configured to measure power of the spectral band component; and
a controller configured to direct operation of the adapter based on the measured power of the spectral band component.
13. The apparatus of claim 6 further comprising:
a communication device that is operative within at least one of a satellite communication system, a wireless communication system, a wired communication system, or a fiber-optic communication system.
14. A method for execution by a communication device, the method comprising:
operating a digital to analog converter (DAC) of the communication device to process at least one codeword to generate a first analog signal;
processing the at least one codeword to generate at least one distortion term corresponding to a frequency band of the first analog signal;
stop band filtering the first analog signal to generate a filtered, first analog signal; and
combining the filtered, first analog signal and a second analog signal to reduce distortion within the filtered, first analog signal, wherein the second analog signal is based on the at least one distortion term corresponding to a frequency band of the first analog signal.
15. The method of claim 14 further comprising:
operating the DAC, which is a first DAC, at a first frequency; and
operating a second DAC at a second frequency to process the at least one distortion term to generate the second analog signal or at least one additional signal.
16. The method of claim 14 further comprising:
operating a modulator to process digital data to generate the at least one codeword.
17. The method of claim 14 further comprising:
amplifying the first analog signal before performing the stop band filtering thereto.
18. The method of claim 14 further comprising:
modifying the at least one distortion term based on at least one frequency selective measurement corresponding to the first analog signal, the filtered, first analog signal or at least one additional signal derived there from; and
performing adaptation of at least one of filtering, gain, phase, or delay adjustment of the at least one distortion term.
19. The method of claim 14 further comprising:
modifying the at least one distortion term based on at least one frequency selective measurement corresponding to the first analog signal, the filtered, first analog signal or at least one additional signal derived there from;
coupling to output at least a portion of a combined signal output from the combining of the filtered, first analog signal and the second analog signal;
frequency selective filtering to select a spectral band component of at least a portion of the combined signal;
measuring power of the spectral band component; and
directing operation of the modifying the at least one distortion term based on the measured power of the spectral band component.
20. The method of claim 14 , wherein the communication device is operative within at least one of a satellite communication system, a wireless communication system, a wired communication system, or a fiber-optic communication system.