# US 9,438,178 B1 · Mixer impairment correction based on volterra series > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,438,178 B1 - Document ID: US9438178B1 - Status: Granted - Kind: B1 - Application number: 14/843,174 - Filed: 2015-09-02 - Granted: 2016-09-06 - Earliest claimed: 2015-09-02 - Assignees: Intel IP Corporation - Applicants: Intel IP Corporation - Inventors: Avi Sulimarski; Itay Almog; Michael Kerner - Web page: https://patentgrep.com/patent/US9438178B1 ## CPC - H03F 1/3258: {based on polynomial terms} - H03F 1/3282: {Acting on the phase and the amplitude of the input signal} - H03F 3/19: with semiconductor devices only - H03F 3/21: with semiconductor devices only {(H03F3/245 takes precedence)} - H03F 3/245: {with semiconductor devices only} - H04B 1/0475: {with means for limiting noise, interference or distortion (H04B1/0483 takes precedence)} - H03F 2200/336: A I/Q, i.e. phase quadrature, modulator or demodulator being used in an amplifying circuit - H03F 2200/451: the amplifier being a radio frequency amplifier - H03F 2201/3224: Predistortion being done for compensating memory effects - H04B 2001/0425: {with linearisation using predistortion} - H03F: AMPLIFIERS - H04B: TRANSMISSION ## Abstract Techniques for compensating for signal impairments introduced by a mixer are discussed. One example system employing such techniques can include mixer predistortion circuitry configured to receive signal in-phase (I) and signal quadrature (Q) components of a signal and to generate a mixer predistortion signal based at least in part on the signal I and Q components, wherein the mixer predistortion signal compensates for nonlinearities caused by a mixer that upconverts the signal. Optionally, imbalance correction circuitry to compensate for gain and phase imbalance and/or skew correction circuitry to compensate for gain and phase skew can also be included. ## Claims ### Claim 1 A system configured for use in a transmitter, comprising: baseband circuitry that generates a first signal comprising signal in-phase (I) and signal quadrature (Q) components; a mixer that up-converts the first signal into a radio-frequency (RF) output signal, wherein the mixer generates nonlinearities into the RF output signal; mixer predistortion circuitry configured to receive the first signal and generate a mixer predistortion signal to compensate for at least some of the nonlinearities based at least in part on the signal I and Q components of the first signal; a radio-frequency amplifier that receives and amplifies the RF output signal; and skew correction circuitry configured to receive the signal I and Q components of the signal and to generate a skew correction signal based at least in part on the signal I and Q components, wherein the skew correction signal compensates for a gain and phase skew caused by the mixer, wherein the skew correction circuitry is additionally configured to receive at least one time-delayed signal I component and at least one time-delayed signal Q component, wherein the skew correction signal is based at least in part on the at least one time-delayed signal I component and the at least one time-delayed signal Q component, and wherein the skew correction signal comprises a skew correction I component and a skew correction Q component, wherein each of the skew correction I component and the skew correction Q component are linear combinations of the signal I component, the signal Q component, the at least one time-delayed signal I component, and the at least one time-delayed signal Q component. ### Claim 2 (depends on 1) The system of claim 1, wherein the mixer predistortion circuitry is additionally configured to receive at least one time-delayed signal I component and at least one time-delayed signal Q component, wherein the mixer predistortion signal compensates for memory effects caused by the mixer. ### Claim 3 (depends on 1) The system of claim 1, wherein the mixer predistortion circuitry is configured to generate the mixer predistortion signal based on a polynomial approximation involving the signal I and Q components. ### Claim 4 (depends on 3) The system of claim 3, wherein the polynomial approximation comprises one or more odd order terms of at least third order. ### Claim 5 (depends on 4) The system of claim 4, wherein the one or more odd order terms comprise cross terms between the signal I component and the signal Q component. ### Claim 6 (depends on 4) The system of claim 4, wherein at least one of the one or more odd order terms of at least third order is based at least in part on at least one time-delayed signal I component or at least one time-delayed signal Q component. ### Claim 7 (depends on 1) The system of claim 1, wherein the mixer predistortion signal is based at least in part on a least squares approximation of at least one of the nonlinearities or memory effects caused by the mixer. ### Claim 8 (depends on 1) The system of claim 1, further comprising imbalance correction circuitry configured to receive the signal I and Q components of the signal and to generate an imbalance correction signal based at least in part on the signal I and Q components, wherein the imbalance correction signal compensates for a gain and phase imbalance caused by the mixer. ### Claim 9 (depends on 8) The system of claim 8, wherein the imbalance correction signal comprises an imbalance correction I component and an imbalance correction Q component, wherein each of the imbalance correction I component and the imbalance correction Q component are linear combinations of the signal I and Q components. ### Claim 10 (depends on 9) The system of claim 9, wherein each of the imbalance correction I component and the imbalance correction Q component are linear combinations of the signal I and Q components based on real coefficients. ### Claim 11 (depends on 8) The system of claim 8, wherein the imbalance correction signal is based at least in part on a least squares approximation of the gain and phase imbalance caused by the mixer. ### Claim 12 (depends on 1) The system of claim 1, wherein each of the imbalance correction I component and the imbalance correction Q component are linear combinations of the signal I component, the signal Q component, the at least one time-delayed signal I component, and the at least one time-delayed signal Q component based on real coefficients. ### Claim 13 (depends on 1) The system of claim 1, wherein the skew correction signal is based at least in part on a least squares approximation of the gain and phase skew caused by the mixer. ### Claim 14 A non-transitory machine readable medium comprising instructions that, when executed, cause a machine to: receive an in-phase (I) component of a signal and a quadrature (Q) component of the signal; generate a mixer predistortion signal that compensates for nonlinearities introduced by a mixer that upconverts the signal; and receive at least one time-delayed I component of the signal and at least one time-delayed Q component of the signal, wherein the skew correction signal comprises a skew correction I component and a skew correction Q component that are each based on a linear combination of the signal I component, the signal Q component, the at least one time-delayed I component of the signal, and the at least one time-delayed Q component of the signal. ### Claim 15 (depends on 14) The non-transitory machine readable medium of claim 14, wherein the mixer predistortion signal compensates for memory effects introduced by the mixer. ### Claim 16 (depends on 14) The non-transitory machine readable medium of claim 14, wherein the instructions, when executed, further cause the machine to generate a skew correction signal that compensates for a gain and phase skew introduced by the mixer. ### Claim 17 (depends on 14) The non-transitory machine readable medium of claim 14, wherein the instructions, when executed, further cause the machine to generate an imbalance correction signal that compensates for a gain and phase imbalance introduced by the mixer. ### Claim 18 (depends on 17) The non-transitory machine readable medium of claim 17, wherein the imbalance correction signal comprises an imbalance correction I component and an imbalance correction Q component that are each based on a linear combination of the signal I component and the signal Q component. ### Claim 19 A system configured for use in a transmitter, comprising: mixer predistortion circuitry configured to receive an in-phase (I) component of a signal, a quadrature (Q) component of the signal, at least one time-delayed I component of the signal, and at least one time-delayed Q component of the signal, wherein the mixer predistortion circuitry is configured to generate a mixer predistortion signal based at least in part on the I and Q components, the at least one time-delayed I component, and the at least one time-delayed Q component, wherein the mixer predistortion signal compensates for nonlinearities and memory effects caused by a mixer that upconverts the signal; imbalance correction circuitry configured to receive the I and Q components of the signal and to generate an imbalance correction signal based at least in part on the I and Q components, wherein the imbalance correction signal compensates for a gain and phase imbalance caused by the mixer; skew correction circuitry configured to receive the I and Q components of the signal, the at least one time-delayed I component, and the at least one time-delayed Q component, wherein the skew correction circuitry is configured to generate a skew correction signal based at least in part on the I component, the Q component, the at least one time-delayed I component, and the at least one time-delayed Q component, wherein the skew correction signal compensates for a gain and phase skew caused by the mixer; and power amplifier (PA) predistortion circuitry configured to receive the I and Q components, the at least one time-delayed I component of the signal, and the at least one time-delayed Q component of the signal, and to generate a PA predistortion signal based at least in part on the I and Q components, the at least one time-delayed I component of the signal, and the at least one time-delayed Q component of the signal, wherein the PA predistortion signal compensates for nonlinearities and memory effects caused by a PA that amplifies the signal. ### Claim 20 (depends on 19) The system of claim 19, wherein the mixer predistortion circuitry is configured to generate the mixer predistortion signal based on a polynomial approximation involving the I and Q components of the signal. ### Claim 21 (depends on 19) The system of claim 19, wherein at least one of the mixer predistortion signal, the imbalance correction signal, or the skew correction signal is based on a least squares approximation. ### Claim 22 An apparatus configured for use in a transmitter, comprising: a mixer that up-converts a first signal into a radio-frequency (RF) output signal, wherein the mixer introduces nonlinearities into the RF output signal; mixer predistortion circuitry configured to receive the first signal having signal in-phase (I) and signal quadrature (Q) components and configured to generate a mixer predistortion signal that compensates for at least some of the nonlinearities introduced by the mixer, wherein the mixer predistortion circuitry is further configured to generate the mixer predistortion signal based at least in part on the signal I and Q components of the first signal; and skew correction circuitry configured to receive the signal I and Q components of the signal and to generate a skew correction signal based at least in part on the signal I and Q components, wherein the skew correction signal compensates for a gain and phase skew caused by the mixer, wherein the skew correction circuitry is additionally configured to receive at least one time-delayed signal I component and at least one time-delayed signal Q component, wherein the skew correction signal is based at least in part on the at least one time-delayed signal I component and the at least one time-delayed signal Q component, and wherein the skew correction signal comprises a skew correction I component and a skew correction Q component, wherein each of the skew correction I component and the skew correction Q component are linear combinations of the signal I component, the signal Q component, the at least one time-delayed signal I component, and the at least one time-delayed signal Q component. ### Claim 23 (depends on 22) The apparatus of claim 22, wherein the mixer predistortion signal is based at least in part on a polynomial approximation of the nonlinearities. ### Claim 24 (depends on 23) The apparatus of claim 23, wherein the polynomial approximation is based at least in part on a truncated Volterra series. ### Claim 25 (depends on 23) The apparatus of claim 23, wherein the polynomial approximation comprises one or more odd order cross terms between the signal I component and the signal Q component.