# US 7,610,026 B2 · Transmitter non-data-related direct current (DC) offset cancellation scheme > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,610,026 B2 - Document ID: US7610026B2 - Status: Granted - Kind: B2 - Application number: 11/503,422 - Filed: 2006-08-11 - Published: 2008-02-14 - Granted: 2009-10-27 - Earliest claimed: 2006-08-11 - Assignees: Broadcom Corporation - Inventors: Meng-An (Michael) Pan - Web page: https://patentgrep.com/patent/US7610026B2 ## CPC - H04B 1/0475: {with means for limiting noise, interference or distortion (H04B1/0483 takes precedence)} - H04B: TRANSMISSION ## Abstract The present invention provides a transmitter architecture operable to cancel non-data-related direct current (DC) components therein. One method to cancel transmitter non-data-related DC offsets includes generating a baseband digital null signal. Then the digital null signal is converted to a pair of differential analog voltage null signals. The pair of differential analog voltage null signals may be converted to a pair of differential analog current null signals. The pair of differential analog current null signals is provided to a pair of matched impedances to generate a pair of voltage signals across the pair of matched impedances. A voltage offset results from comparing the pair of voltages generated across the pair of matched impedances. Then a current offset is determined based on the voltage offset. ## Claims ### Claim 1 A method to cancel transmitter non-data-related direct current (DC) offsets comprising: generating a baseband digital null signal; converting the digital null signal to a pair of differential analog voltage null signals; converting the pair of differential analog voltage null signals to a pair of differential analog current null signals; applying the pair of differential analog current null signals to a pair of matched impedances to generate a pair of voltage signals across the pair of matched impedances; determining a voltage offset between the pair of voltages generated across the pair of matched impedances; and determining a current offset based on the voltage offset. ### Claim 2 (depends on 1) The method of claim 1, wherein the digital null signal comprises an in-phase (I) component and a quadrature (Q) component wherein the I component and the Q component have separate non-data-related DC offsets. ### Claim 3 (depends on 2) The method of claim 2, wherein I component non-data-related DC offset and the Q component non-data-related DC offset are determined in series. ### Claim 4 (depends on 2) The method of claim 2, wherein I component non-data-related DC offset and the Q component non-data-related DC offset are determined in parallel. ### Claim 5 (depends on 1) The method of claim 1, further comprising: producing a baseband digital signal; converting the baseband digital signal to a pair of differential analog voltage signals; converting the pair of differential analog voltage signals to a pair of differential analog current signals; applying the current offset to the pair of analog current signals. ### Claim 6 (depends on 5) The method of claim 5, further comprising up converting the pair of analog current signals to produce an RF signal. ### Claim 7 (depends on 6) The method of claim 6, wherein the RF signal is an 802.11 compliant signal. ### Claim 8 (depends on 1) The method of claim 1, further comprising low pass filtering the differential analog voltage null signals and differential analog voltage signals. ### Claim 9 A wireless terminal that comprises: a Radio Frequency (RF) front end operable to receive RF burst(s); a baseband processor operable to output a baseband digital null signal; a digital to analog converter (DAC) operable to convert the baseband digital signal to a baseband analog voltage signal; a GM stage operable to convert the baseband analog voltage signal to a baseband analog current signal; a non-data-related DC offset processing module to determine an offset current based on the null signal; and an offset current source operable to apply the offset current to the baseband analog current signal wherein the offset current is operable to cancel a non-data-related direct current (DC) component of the baseband analog current signal. ### Claim 10 (depends on 9) The wireless terminal of claim 9, wherein the baseband digital signal, baseband analog voltage signal, and baseband analog current signal comprise an in-phase (I) component and a quadrature (Q) component wherein the I component and the Q component have separate non-data-related DC offsets. ### Claim 11 (depends on 10) The wireless terminal of claim 10, wherein I component offset current and the Q component offset current are determined in series. ### Claim 12 (depends on 10) The wireless terminal of claim 10, wherein I component offset current and the Q component offset current are determined in parallel. ### Claim 13 (depends on 9) The wireless terminal of claim 9, further comprising an RF back end operable to up convert a non-data-related DC offset baseband signal and transmit an RF signal based on the non-data-related DC offset baseband signal. ### Claim 14 (depends on 13) The wireless terminal of claim 13, wherein the RF signal is an 802.11 compliant signal. ### Claim 15 A method to cancel transmitter non-data-related direct current (DC) offsets comprising: generating a baseband digital null signal; converting the digital null signal to a pair of differential analog voltage null signals; converting the pair of differential analog voltage null signals to a pair of differential analog current null signals; applying the pair of differential analog current null signals to a pair of matched impedances to generate a pair of voltage signals across the pair of matched impedances; determining a voltage offset between the pair of voltages generated across the pair of matched impedances; determining a current offset based on the voltage offset; producing a baseband digital signal; converting the baseband digital signal to a pair of differential analog voltage signals; converting the pair of differential analog voltage signals to a pair of differential analog current signals; and applying the current offset to the pair of analog current signals. ### Claim 16 (depends on 15) The method of claim 15, wherein the digital null signal comprises an in-phase (I) component and a quadrature (Q) component wherein the I component and the Q component have separate non-data-related DC offsets. ### Claim 17 (depends on 16) The method of claim 16, wherein I component non-data-related DC offset and the Q component non-data-related DC offset are determined in series. ### Claim 18 (depends on 16) The method of claim 16, wherein I component non-data-related DC offset and the Q component non-data-related DC offset are determined in parallel. ### Claim 19 (depends on 15) The method of claim 15, flirt her comprising up converting the pair of analog current signals to produce an RF signal. ### Claim 20 (depends on 19) The method of claim 19, wherein the RF signal is an 802.11 compliant signal. ### Claim 21 (depends on 15) The method of claim 15, further comprising low pass filtering the differential analog voltage null signals and differential analog voltage signals.