# US 2015/0147987 A1 · Transmitter with a Reduced Complexity Digital Up-Converter > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2015/0147987 A1 - Document ID: US20150147987A1 - Status: Published application - Kind: A1 - Application number: 14/163,783 - Filed: 2014-01-24 - Published: 2015-05-28 - Earliest claimed: 2013-11-26 - Assignees: Broadcom Corporation - Applicants: Broadcom Corporation - Inventors: David Money HARRIS; David GARRETT; Bob LORENZ - Web page: https://patentgrep.com/patent/US20150147987A1 ## CPC - H04B 1/0007: {wherein the AD/DA conversion occurs at radiofrequency or intermediate frequency stage} - H04B: TRANSMISSION ## Abstract The present disclosure is directed to a system and method for performing digital up-conversion of a signal to a desired RF carrier frequency. The system and method efficiently perform digital up-conversion of the signal, in one example, by controlling a sample clock that is used by a DAC to sample and convert the up-converted signal from the digital domain to the analog domain to have a frequency that is four or eight times the desired RF carrier frequency. By controlling the sample clock of the DAC to have a frequency that is four or eight times the desired RF carrier frequency, the system and method can be implemented using currently available IC process geometries such that the implementation consumes much less area and/or power than an analog up-converter configured to have equivalent up-conversion functionality. ## Claims ### Claim 1 A transmitter comprising: a sample clock generator configured to generate a sample clock to have a frequency that is 4, 8, or 8/3 times a carrier frequency; a radio frequency (RF) digital up-converter configured to up-convert a baseband or intermediate frequency (IF) signal to provide a digital RF signal at the carrier frequency; and a digital-to-analog converter (DAC) configured to sample the digital RF signal using the sample clock and convert the samples of the digital RF signal to an analog RF signal for transmission over a channel. ### Claim 2 (depends on 1) The transmitter of claim 1, wherein the RF digital up-converter is configured to up-convert the baseband or IF signal to provide the digital RF signal at the carrier frequency by effectively multiplying an in-phase component of the baseband or IF signal by the sequence {1, 0, −1, 0} and a quadrature component of the baseband or IF signal by the sequence {0, 1, 0, −1}. ### Claim 3 (depends on 1) The transmitter of claim 1, wherein the RF digital up-converter is configured to up-convert the baseband or IF signal to provide the digital RF signal at the carrier frequency by effectively multiplying an in-phase component of the baseband or IF signal by the sequence {1, √{square root over (2)}/2, 0, −√{square root over (2)}/2, −1, −√{square root over (2)}/2, 0, and √{square root over (2)}/2} and a quadrature component of the baseband or IF signal by the sequence {0, √{square root over (2)}/2, 1, √{square root over (2)}/2, 0, −√{square root over (2)}/2, −1, −√{square root over (2)}/2,}. ### Claim 4 (depends on 1) The transmitter of claim 1, wherein the RF digital up-converter is configured to up-convert the baseband or IF signal to provide the digital RF signal at the carrier frequency by effectively multiplying an in-phase component of the baseband or IF signal by the sequence {1, −√{square root over (2)}/2, 0, √{square root over (2)}/2, −1, √{square root over (2)}/2, 0, −√{square root over (2)}/2} and a quadrature component of the baseband or IF signal by the sequence {0, √{square root over (2)}/2, −1, √{square root over (2)}/2, 0, −√{square root over (2)}/2, 1, −√{square root over (2)}/2}. ### Claim 5 (depends on 1) The transmitter of claim 1, wherein the sample clock generator is configured to generate the sample clock to have a frequency that is either 4 or 8 times the carrier frequency based on anticipated image noise from an unwanted sideband of the baseband signal. ### Claim 6 (depends on 1) The transmitter of claim 1, wherein the RF digital up-converter comprises a multiplexer configured to select between a sample of a first component of the baseband or IF signal, a negated version of the sample of the first component of the baseband or IF signal, a sample of a second component of the baseband or IF signal, or a negated version of the sample of the second component of the baseband or IF signal to provide a sample of the digital RF signal at the carrier frequency. ### Claim 7 (depends on 1) The transmitter of claim 1, further comprising a sample rate converter configured to convert the sample rate of the baseband or IF signal to match the frequency of the sample clock. ### Claim 8 A transmitter comprising: a sample clock generator configured to generate a sample clock to have a frequency that is 4, 8, or 8/3 times a carrier frequency plus an offset frequency; an intermediate frequency (IF) digital frequency-shifter configured to frequency-shift a baseband signal by the offset frequency divided by 4, 8, or 8/3 to provide an IF signal; a radio frequency (RF) digital up-converter configured to up-convert the IF signal to provide a digital RF signal at the carrier frequency; and a digital-to-analog converter (DAC) configured to sample the digital RF signal using the sample clock and convert the samples of the digital RF signal to an analog RF signal for transmission over a channel. ### Claim 9 (depends on 8) The transmitter of claim 8, wherein the RF digital up-converter is configured to up-convert the IF signal to provide the digital RF signal at the carrier frequency by effectively multiplying an in-phase component of the IF signal by the sequence {1, 0, −1, 0} and a quadrature component of the IF signal by the sequence {0, 1, 0, −1}. ### Claim 10 (depends on 8) The transmitter of claim 8, wherein the RF digital up-converter is configured to up-convert the IF signal to provide the digital RF signal at the carrier frequency by effectively multiplying an in-phase component of the IF signal by the sequence {1, √{square root over (2)}/2, 0, −√{square root over (2)}/2, −1, −√{square root over (2)}/2, 0, and √{square root over (2)}/2} and a quadrature component of the IF signal by the sequence {0, √{square root over (2)}/2, 1, √{square root over (2)}/2, 0, −√{square root over (2)}/2, −1, −√{square root over (2)}/2,}. ### Claim 11 (depends on 8) The transmitter of claim 8, wherein the RF digital up-converter is configured to up-convert the IF signal to provide the digital RF signal at the carrier frequency by effectively multiplying an in-phase component of the IF signal by the sequence {1, −√{square root over (2)}/2, 0, √{square root over (2)}/2, −1, √{square root over (2)}/2, 0, −√{square root over (2)}/2} and a quadrature component of the IF signal by the sequence {0, √{square root over (2)}/2, −1, √{square root over (2)}/2, 0, −√{square root over (2)}/2, 1, −√{square root over (2)}/2}. ### Claim 12 (depends on 8) The transmitter of claim 8, wherein the sample clock generator is configured to generate the sample clock to have a frequency that is either 4 or 8 times the carrier frequency based on anticipated image noise from an unwanted sideband of the baseband signal. ### Claim 13 (depends on 8) The transmitter of claim 8, wherein the RF digital up-converter comprises a multiplexer configured to select between a sample of a first component of the IF signal, a negated version of the sample of the first component of the IF signal, a sample of a second component of the IF signal, or a negated version of the sample of the second component of the IF signal to provide a sample of the digital RF signal at the carrier frequency. ### Claim 14 (depends on 8) The transmitter of claim 8, further comprising a sample rate converter configured to convert the sample rate of the IF signal to match a frequency of the sample clock. ### Claim 15 A transmitter comprising: an intermediate frequency (IF) digital frequency-shifter configured to frequency-shift a baseband signal by an offset frequency to provide an IF signal; a radio frequency (RF) digital up-converter configured to up-convert the IF signal, using a digital carrier wave, to provide a digital RF signal at a carrier frequency, wherein the RF digital up-converter comprises a numerically controlled oscillator (NCO) configured to generate the digital carrier wave with a frequency of the carrier frequency plus the offset frequency; and a digital-to-analog converter (DAC) configured to sample the digital RF signal and convert the samples of the digital RF signal to an analog RF signal for transmission over a channel. ### Claim 16 (depends on 15) The transmitter of claim 15, further comprising a controller configured to generate a tuning word for the NCO of the RF digital up-converter based on the carrier frequency, wherein the tuning word for the NCO of the RF digital up-converter adjusts the frequency of the digital carrier wave generated by the NCO. ### Claim 17 (depends on 16) The transmitter of claim 16, wherein the controller is further configured to generate a tuning word for an NCO of the IF digital frequency-shifter based on the tuning word generated for the NCO of the RF digital up-converter, wherein the tuning word for the NCO of the IF digital frequency-shifter adjusts a frequency of the IF signal. ### Claim 18 (depends on 15) The transmitter of claim 15, wherein the NCO of the RF digital up-converter comprises a phase accumulator (PA) and a phase-to-amplitude converter (PAC). ### Claim 19 (depends on 18) The transmitter of claim 18, wherein the PAC has 32 entries that each correspond to amplitudes of a sine or cosine wave at 32 different evenly spaced phase angles between 0 and 360 degrees. ### Claim 20 (depends on 18) The transmitter of claim 18, wherein the PAC has X entries that each correspond to amplitudes of a sine or cosine wave at X different evenly spaced phase angles between 0 and 360 degrees, wherein X is an integer. ### Claim 21 (depends on 15) The transmitter of claim 15, wherein the transmitter is configured to be operate within a cellular device or a local area network device.