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 synthesizer to process a first signal to generate a plurality of distortion terms;
a plurality of narrowband filters to receive, respectively, the plurality of distortion terms and to generate a plurality of narrowband filtered distortion terms, wherein:
a first of the plurality of narrowband filters to receive a first of the plurality of distortion terms and to generate a first of the plurality of narrowband filtered distortion terms; and
a second of the plurality of narrowband filters to receive a second of the plurality of distortion terms and to generate a second of the plurality of narrowband filtered distortion terms; and
a first combiner to combine the plurality of narrowband filtered distortion terms to generate a combined signal for use to reduce distortion associated with the first signal or another signal generated there from;
a second combiner to combine the combined signal and the first signal to generate a second signal; and
a digital to analog converter (DAC) to process the second signal to generate an analog signal; and wherein:
at least one of the plurality of distortion terms to undergo adjustment of at least one of filtering, gain, phase, and delay adjustment before undergoing combination by the combiner.
2. The apparatus of claim 1 , further comprising:
a plurality of adapters to process, respectively, the plurality of narrowband filtered distortion terms, before undergoing combination by the combiner, based on at least one frequency selective measurement corresponding to the analog signal, wherein:
a first of the plurality of adapters to process the first of the plurality of narrowband filtered distortion terms; and
a second of the plurality of adapters to process the second of the plurality of narrowband filtered distortion terms.
3. The apparatus of claim 2 , further comprising:
a coupler to output at least a portion of the analog signal;
a frequency selective filter to select a spectral band component of the at least a portion of analog signal;
a power detector to measure power of the spectral band component; and
a controller to direct operation of at least one of the plurality of adapters based on the measured power of the spectral band component.
4. The apparatus of claim 1 , wherein:
the signal including at least one codeword; and further comprising:
a modulator to process a digital signal to generate the first signal; and wherein:
the DAC to process a modified version of the first signal, which is the second signal, to generate the analog signal.
5. The apparatus of claim 1 , wherein:
the apparatus being a communication device operative within at least one of a satellite communication system, a wireless communication system, a wired communication system, and a fiber-optic communication system.
6. An apparatus, comprising:
a synthesizer to process a signal to generate a plurality of distortion terms;
a plurality of narrowband filters to receive, respectively, the plurality of distortion terms and to generate a plurality of narrowband filtered distortion terms, wherein:
a first of the plurality of narrowband filters to receive a first of the plurality of distortion terms and to generate a first of the plurality of narrowband filtered distortion terms; and
a second of the plurality of narrowband filters to receive a second of the plurality of distortion terms and to generate a second of the plurality of narrowband filtered distortion terms; and
a combiner to combine the plurality of narrowband filtered distortion terms to generate a combined signal for use to reduce distortion associated with the signal or another signal generated there from.
7. The apparatus of claim 6 , further comprising:
at least one additional combiner to combine the combined signal and the signal to generate at least one additional signal; and
a digital to analog converter (DAC) to process the at least one additional signal to generate an analog signal.
8. The apparatus of claim 6 , further comprising:
a plurality of adapters to process, respectively, the plurality of narrowband filtered distortion terms, before undergoing combination by the combiner, based on at least one frequency selective measurement corresponding to an analog signal which is the another signal generated from the signal, wherein:
a first of the plurality of adapters to process the first of the plurality of narrowband filtered distortion terms; and
a second of the plurality of adapters to process the second of the plurality of narrowband filtered distortion terms.
9. The apparatus of claim 8 , wherein:
at least one of the plurality of adapters to perform adaptation of at least one of filtering, gain, phase, and delay adjustment of at least one of the plurality of distortion terms.
10. The apparatus of claim 8 , further comprising:
a coupler to output at least a portion of an analog signal which is the another signal generated from the signal;
a frequency selective filter to select a spectral band component of the at least a portion of analog signal;
a power detector to measure power of the spectral band component; and
a controller to direct operation of at least one of the plurality of adapters based on the measured power of the spectral band component.
11. The apparatus of claim 6 , wherein:
the signal including at least one codeword; and further comprising:
a modulator to process a digital signal to generate the signal; and
a digital to analog converter (DAC) to process a modified version of the signal to generate an analog signal.
12. The apparatus of claim 6 , further comprising:
a first digital to analog converter (DAC) to process the signal to generate a first analog signal;
a second DAC to process the combined signal to generate a second analog signal; and
at least one additional combiner to combine the a first analog signal and the second analog signal.
13. The apparatus of claim 6 , wherein:
the apparatus being a communication device operative within at least one of a satellite communication system, a wireless communication system, a wired communication system, and a fiber-optic communication system.
14. A method for operating a communication device, the method comprising:
processing a signal to generate a plurality of distortion terms;
operating a plurality of narrowband filters to receive, respectively, the plurality of distortion terms and to generate a plurality of narrowband filtered distortion terms, wherein:
a first of the plurality of narrowband filters to receive a first of the plurality of distortion terms and to generate a first of the plurality of narrowband filtered distortion terms; and
a second of the plurality of narrowband filters to receive a second of the plurality of distortion terms and to generate a second of the plurality of narrowband filtered distortion terms; and
combining the plurality of narrowband filtered distortion terms to generate a combined signal for use to reduce distortion associated with the signal or another signal generated by a digital to analog converter (DAC) within the communication device.
15. The method of claim 14 , further comprising:
combining the combined signal and the signal to generate at least one additional signal; and
operating the DAC to process the at least one additional signal to generate an analog signal.
16. The method of claim 14 , further comprising:
a plurality of adapters to process, respectively, the plurality of narrowband filtered distortion terms, before undergoing combination by the combiner, based on at least one frequency selective measurement corresponding to an analog signal which is the another signal generated from the signal, wherein:
a first of the plurality of adapters to process the first of the plurality of narrowband filtered distortion terms; and
a second of the plurality of adapters to process the second of the plurality of narrowband filtered distortion terms.
17. The method of claim 14 , further comprising:
operating at least one of the plurality of adapters to perform adaptation of at least one of filtering, gain, phase, and delay adjustment of at least one of the plurality of distortion terms.
18. The method of claim 14 , wherein:
the signal including at least one codeword; and further comprising:
operating a modulator to process a digital signal to generate the signal; and
operating the DAC to process a modified version of the signal to generate an analog signal.
19. The method of claim 14 , further comprising:
operating the DAC to process the signal to generate a first analog signal;
operating at least one additional DAC to process the combined signal to generate a second analog signal; and
combining the a first analog signal and the second analog signal.
20. The method of claim 14 , wherein:
the communication device operative within at least one of a satellite communication system, a wireless communication system, a wired communication system, and a fiber-optic communication system.