# US 8,571,137 B2 · Distortion and aliasing reduction for digital to analog conversion > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,571,137 B2 - Document ID: US8571137B2 - Status: Granted - Kind: B2 - Application number: 13/223,094 - Filed: 2011-08-31 - Published: 2012-07-19 - Granted: 2013-10-29 - Earliest claimed: 2011-01-14 - Assignees: Broadcom Corporation - Applicants: Thomas J. Kolze; Bruce J. Currivan; Ramon A. Gomez; Kevin Lee Miller - Inventors: Thomas J. Kolze; Bruce J. Currivan; Ramon A. Gomez; Kevin Lee Miller - Web page: https://patentgrep.com/patent/US8571137B2 ## CPC - H04B 1/10: Means associated with receiver for limiting or suppressing noise or interference - H03M 1/0614: {of harmonic distortion (H03M1/0617 takes precedence)} - H03M 1/68: with conversions of different sensitivity, i.e. one conversion relating to the more significant digital bits and another conversion to the less significant bits - H04B: TRANSMISSION - H03M: CODING; DECODING; CODE CONVERSION IN GENERAL (using fluidic means F15C4/00; optical analogue/digital converters G02F7/00; coding, decoding or code conversion, specially adapted for particular applications, see the relevant subclasses, e.g. G01D, G01R, G06F, G06T, G09G, G10L, G11B, G11C, H04B, H04L, H04M, H04N; ciphering or deciphering for cryptography or other purposes involving the need for secrecy G09C) ## Abstract 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. ## Claims ### Claim 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 an analog signal; a power detector configured to measure power of a spectral band component of the analog signal; a synthesizer configured to provide at least one distortion term, based on the at least one codeword or a portion thereof, corresponding to a DAC operational characteristic; a controller configured to generate a control signal based on dithering operations that are based on the measured power of the spectral band component; and an adapter configured to perform adaptation of at least one of filtering, gain, phase, and delay adjustment of the at least one distortion term based on the control signal, and wherein the modified at least one distortion term operative to reduce distortion associated with the analog signal. ### Claim 2 (depends on 1) The apparatus of claim 1, further comprising: a combiner configured to combine the modified at least one distortion term and the at least one codeword to generate a modified at least one codeword; and wherein: the DAC is further configured to process the modified at least one codeword to generate the analog signal. ### Claim 3 (depends on 1) The apparatus of claim 1, further comprising: at least one additional DAC configured to process the modified at least one distortion term to generate at least one additional analog signal; and a combiner configured to combine the analog signal and the at least one additional analog signal. ### Claim 4 (depends on 3) The apparatus of claim 3, wherein: wherein the DAC operative at a first frequency; and the at least one additional DAC operative at a second frequency. ### Claim 5 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 an analog signal; a synthesizer configured to provide at least one distortion term, based on the at least one codeword or a portion thereof, corresponding to a DAC operational characteristic; and an adapter configured to modify the at least one distortion term based on at least one frequency selective measurement corresponding to the analog signal or at least one additional signal derived there from; and wherein: from, and wherein the modified at least one distortion term operative to reduce distortion associated with the analog signal. ### Claim 6 (depends on 5) The apparatus of claim 5, further comprising: a combiner configured to combine the modified at least one distortion term and the at least one codeword to generate a modified at least one codeword; and wherein: the DAC for processing the modified at least one codeword to generate the analog signal. ### Claim 7 (depends on 5) The apparatus of claim 5, further comprising: at least one additional DAC configured to process the modified at least one distortion term to generate at least one additional analog signal; and a combiner configured to combine the analog signal and the at least one additional analog signal. ### Claim 8 (depends on 7) The apparatus of claim 7, wherein the DAC operative at a first frequency; and the at least one additional DAC operative at a second frequency. ### Claim 9 (depends on 5) The apparatus of claim 5, further comprising: at least one of an amplifier and a filter configured to process the analog signal to generate a processed analog signal; a coupler configured to output at least a portion of the processed analog signal; a frequency selective filter configured to select a spectral band component of the at least a portion of the processed analog 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. ### Claim 10 (depends on 5) The apparatus of claim 5, wherein the at least one distortion term being predetermined. ### Claim 11 (depends on 5) The apparatus of claim 5, wherein the synthesizer is further configured to generate the at least one distortion term in real time based on a measurement corresponding to the DAC operational characteristic. ### Claim 12 (depends on 5) The apparatus of claim 5, wherein the synthesizer is further configured to provide at least one distortion term based on the at least one codeword and the portion thereof. ### Claim 13 (depends on 5) The apparatus of claim 5, wherein the adapter is further configured to perform adaptation of at least one of filtering, gain, phase, and delay adjustment of the at least one distortion term. ### Claim 14 (depends on 5) The apparatus of claim 5, wherein the apparatus includes 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. ### Claim 15 A method for execution by a communication device, the method comprising: processing digital data thereby generating at least one codeword; operating a digital to analog converter (DAC) of the communication device for processing the at least one codeword thereby generating an analog signal; synthesizing at least one distortion term, based on the at least one codeword or a portion thereof, corresponding to a DAC operational characteristic; modifying the at least one distortion term based on at least one frequency selective measurement corresponding to the analog signal or at least one additional signal derived there from; and employing the modified at least one distortion term operative for reducing distortion associated with the analog signal. ### Claim 16 (depends on 15) The method of claim 15, further comprising: combining the modified at least one distortion term and the at least one codeword thereby generating a modified at least one codeword; and operating the DAC for processing the modified at least one codeword thereby generating the analog signal. ### Claim 17 (depends on 15) The method of claim 15, further comprising: operating at least one additional DAC for processing the modified at least one distortion term thereby generating at least one additional analog signal; and combining the analog signal and the at least one additional analog signal. ### Claim 18 (depends on 15) The method of claim 15, wherein the at least one distortion term being predetermined. ### Claim 19 (depends on 15) The method of claim 15, wherein the modifying the at least one distortion term including performing adaptation of at least one of filtering, gain, phase, and delay adjustment of the at least one distortion term. ### Claim 20 (depends on 15) The method of claim 15, wherein the communication device is operative within at least one of a satellite communication system, a wireless communication system, a wired communication system, and a fiber-optic communication system.