# US 2014/0191892 A1 · Digital analog converter > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0191892 A1 - Document ID: US20140191892A1 - Status: Published application - Kind: A1 - Application number: 14/202,754 - Filed: 2014-03-10 - Published: 2014-07-10 - Earliest claimed: 2012-08-29 - Assignees: Telefonaktiebolaget L M Ericsson (publ) - Applicants: Telefonaktiebolaget L M Ericsson (publ) - Inventors: Russell Clifford Smiley; Mark Wyville - Web page: https://patentgrep.com/patent/US20140191892A1 ## CPC - H03M 1/66: Digital/analogue converters ({H03M1/001 – } H03M1/10 take precedence) - H03M 1/661: {Improving the reconstruction of the analogue output signal beyond the resolution of the digital input signal, e.g. by interpolation, by curve-fitting, by smoothing} - 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 Embodiments of a digital-to-analog conversion system that utilizes a specialized clock signal to reshape an analog impulse response of a digital-to-analog converter (DAC) are disclosed. Preferably, a shape of the specialized clock signal is such that Nyquist images resulting from digital-to-analog conversion are controlled in a desired manner. In one embodiment, the digital-to-analog conversion system includes a DAC that converts a digital input signal into an analog output signal. A specialized clock signal is applied to the analog output signal of the DAC such that an analog impulse response of the DAC is reshaped according to a shape of the specialized clock signal, thereby providing a modified analog output signal. The specialized clock signal reshapes the analog impulse response of the DAC such that Nyquist images resulting from digital-to-analog conversion are controlled in a desired manner. ## Claims ### Claim 1 A method of operation of a system, comprising: converting a digital input signal into an analog output signal via a digital-to-analog converter; and applying a specialized clock signal to the analog output signal to provide a modified analog output signal. ### Claim 2 (depends on 1) The method of claim 1 wherein applying the specialized clock signal to the analog output signal reshapes an analog impulse response of the digital-to-analog converter such that one or more Nyquist images of the digital input signal that result from digital-to-analog conversion of the digital input signal by the digital-to-analog converter are controlled in a desired manner. ### Claim 3 (depends on 1) The method of claim 1 wherein applying the specialized clock signal to the analog output signal reshapes an analog impulse response of the digital-to-analog converter such that one or more undesired Nyquist images of the digital input signal that result from digital-to-analog conversion of the digital input signal by the digital-to-analog converter are attenuated. ### Claim 4 (depends on 1) The method of claim 1 wherein the specialized clock signal is a periodic signal that has a period that is equal to a sampling period of the digital-to-analog converter and is synchronized to a clock of the digital-to-analog converter. ### Claim 5 (depends on 4) The method of claim 4 wherein each period of the specialized clock signal has a low-pass frequency response. ### Claim 6 (depends on 4) The method of claim 4 wherein each period of the specialized clock signal has a band-pass frequency response. ### Claim 7 (depends on 4) The method of claim 4 wherein each period of the specialized clock signal has a notch frequency response. ### Claim 8 (depends on 4) The method of claim 4 wherein each period of the specialized clock signal has a multi-notch frequency response. ### Claim 9 (depends on 4) The method of claim 4 wherein each period of the specialized clock signal is shaped according to one of a group consisting of: a truncated sinc function, a rectified sinusoid function, a triangular function, a saw-tooth function, a Hann window, a Hamming window, a Tukey window, a cosine window, a Lanczos window, a Bartlett window, a Gaussian window, a Bartlett-Hann window, a Blackman window, a Kaiser window, a Nuttall window, a Blackman-Harris window, a Blackman-Nuttall window, a Flat top window, a Bessel window, a Dolph-Chebyshev window, a Hann-Poisson window, an Exponential window, a Rife-Vincent window, and a Digital Prolate Spheriodal Sequence window. ### Claim 10 (depends on 4) The method of claim 4 wherein each period of the specialized clock signal is shaped according to multiple repeating window functions. ### Claim 11 (depends on 10) The method of claim 10 wherein each period of the specialized clock signal is shaped according to multiple repeating window functions selected from a group consisting of: two or more repeating truncated sinc functions, two or more repeating rectified sinusoid functions, two or more repeating triangular functions, two or more repeating saw-tooth functions, two or more repeating Hann windows, two or more repeating Hamming windows, two or more repeating Tukey windows, two or more repeating cosine windows, two or more repeating Lanczos windows, two or more repeating Bartlett windows, two or more repeating Gaussian windows, two or more repeating Bartlett-Hann windows, two or more repeating Blackman windows, two or more repeating Kaiser windows, two or more repeating Nuttall windows, two or more repeating Blackman-Harris windows, two or more repeating Blackman-Nuttall windows, two or more repeating Flat top windows, two or more repeating Bessel windows, two or more repeating Dolph-Chebyshev windows, two or more repeating Hann-Poisson windows, two or more repeating Exponential windows, two or more repeating Rife-Vincent windows, and two or more repeating Digital Prolate Spheriodal Sequence windows. ### Claim 12 (depends on 4) The method of claim 4 wherein applying the specialized clock signal to the analog output signal comprises: multiplying the analog output signal and the specialized clock signal to provide the modified analog output signal. ### Claim 13 (depends on 4) The method of claim 4 wherein applying the specialized clock signal to the analog output signal comprises: amplifying the analog output signal as a function of the specialized clock signal to provide the modified analog output signal. ### Claim 14 (depends on 4) The method of claim 4 wherein applying the specialized clock signal to the analog output signal comprises: amplifying the specialized clock signal as a function of the analog output signal to provide the modified analog output signal. ### Claim 15 (depends on 4) The method of claim 4 wherein the digital-to-analog converter is a zero-order hold digital-to-analog converter. ### Claim 16 (depends on 1) The method of claim 1 further comprising: converting a plurality of digital input signals, including the digital input signal, into a plurality of analog output signals, including the analog output signal, via a plurality of digital-to-analog converters, including the digital-to-analog converter; applying the specialized clock signal to each of the plurality of analog output signals to provide a plurality of modified analog output signals; and combiner circuitry configured to combine the plurality of modified analog output signals to provide a combined analog output signal. ### Claim 17 (depends on 16) The method of claim 16 wherein the plurality of digital input signals is a number, N, of streams of different digital samples from a primary digital input signal, and a sampling period of each of the plurality of digital-to-analog converters is equal to N divided by a sampling rate of the primary digital input signal. ### Claim 18 (depends on 17) The method of claim 17 wherein, for each analog output signal of the plurality of analog output signals, the specialized clock signal applied to the analog output signal by the combiner circuitry is periodic and has a period that is equal to the sampling period of each of the plurality of digital-to-analog converters and is synchronized to a clock of a corresponding one of the plurality of digital-to-analog converters. ### Claim 19 (depends on 17) The method of claim 17 wherein applying the specialized clock signal to each of the plurality of analog output signals comprises: for each analog output signal of the plurality of analog output signals, multiplying the specialized clock signal and the analog output signal to provide a corresponding one of the plurality of modified analog output signals. ### Claim 20 (depends on 19) The method of claim 19 wherein, for each analog output signal of the plurality of analog output signals, the specialized clock signal is periodic and has a period that is equal to the sampling period of each of the plurality of digital-to-analog converters and is synchronized to a clock of a corresponding one of the plurality of digital-to-analog converters. ### Claim 21 (depends on 17) The method of claim 17 wherein applying the specialized clock signal to each of the plurality of analog output signals comprises: for each analog output signal of the plurality of analog output signals, amplifying the specialized clock signal as a function of the analog output signal to provide a corresponding one of the plurality of modified analog output signals. ### Claim 22 (depends on 21) The method of claim 21 wherein, for each analog output signal of the plurality of analog output signals, the specialized clock signal is periodic and has a period that is equal to the sampling period of each of the plurality of digital-to-analog converters and is synchronized to a clock of a corresponding one of the plurality of digital-to-analog converters. ### Claim 23 (depends on 17) The method of claim 17 wherein applying the specialized clock signal to each of the plurality of analog output signals comprises: for each analog output signal of the plurality of analog output signals, amplifying the analog output signal as a function of the specialized clock signal to provide a corresponding one of the plurality of modified analog output signals. ### Claim 24 (depends on 23) The method of claim 23 wherein, for each analog output signal of the plurality of analog output signals, the specialized clock signal is periodic and has a period that is equal to the sampling period of each of the plurality of digital-to-analog converters and is synchronized to a clock of a corresponding one of the plurality of digital-to-analog converters. ### Claim 25 (depends on 17) The method of claim 17 wherein each period of the specialized clock signal has a low-pass frequency response. ### Claim 26 (depends on 17) The method of claim 17 wherein each period of the specialized clock signal has a band-pass frequency response. ### Claim 27 (depends on 17) The method of claim 17 wherein each period of the specialized clock signal has a notch frequency response. ### Claim 28 (depends on 17) The method of claim 17 wherein each period of the specialized clock signal has a multi-notch frequency response. ### Claim 29 (depends on 17) The method of claim 17 wherein each period of the specialized clock signal is shaped according to one of a group consisting of: a truncated sinc function, a rectified sinusoid function, a triangular function, a saw-tooth function, a Hann window, a Hamming window, a Tukey window, a cosine window, a Lanczos window, a Bartlett window, a Gaussian window, a Bartlett-Hann window, a Blackman window, a Kaiser window, a Nuttall window, a Blackman-Harris window, a Blackman-Nuttall window, a Flat top window, a Bessel window, a Dolph-Chebyshev window, a Hann-Poisson window, an Exponential window, a Rife-Vincent window, and a Digital Prolate Spheriodal Sequence window. ### Claim 30 (depends on 17) The method of claim 17 wherein each period of the specialized clock signal is shaped according to multiple repeating window functions. ### Claim 31 (depends on 30) The method of claim 30 wherein each period of the specialized clock signal is shaped according to multiple repeating window functions selected from a group consisting of: two or more repeating truncated sinc functions, two or more repeating rectified sinusoid functions, two or more repeating triangular functions, two or more repeating saw-tooth functions, two or more repeating Hann windows, two or more repeating Hamming windows, two or more repeating Tukey windows, two or more repeating cosine windows, two or more repeating Lanczos windows, two or more repeating Bartlett windows, two or more repeating Gaussian windows, two or more repeating Bartlett-Hann windows, two or more repeating Blackman windows, two or more repeating Kaiser windows, two or more repeating Nuttall windows, two or more repeating Blackman-Harris windows, two or more repeating Blackman-Nuttall windows, two or more repeating Flat top windows, two or more repeating Bessel windows, two or more repeating Dolph-Chebyshev windows, two or more repeating Hann-Poisson windows, two or more repeating Exponential windows, two or more repeating Rife-Vincent windows, and two or more repeating Digital Prolate Spheriodal Sequence windows.