# US 2014/0155006 A1 · Transmitter, signal generation device, calibration method, and signal generation method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0155006 A1 - Document ID: US20140155006A1 - Status: Published application - Kind: A1 - Application number: 14/131,652 - Filed: 2013-03-28 - Published: 2014-06-05 - Earliest claimed: 2012-03-28 - Assignees: Panasonic Corporation - Applicants: Panasonic Corporation - Inventors: Toru Matsuura - Web page: https://patentgrep.com/patent/US20140155006A1 ## CPC - H04B 17/11: for calibration - H04B 7/005: Control of transmission; Equalising - H04B 17/14: of the whole transmission and reception path, e.g. self-test loop-back - H04L 27/00: Modulated-carrier systems - H04L 27/18: Phase-modulated carrier systems, i.e. using phase-shift keying (H04L27/32 takes precedence) - H04L 27/36: Modulator circuits; Transmitter circuits - H04L 27/364: {Arrangements for overcoming imperfections in the modulator, e.g. quadrature error or unbalanced I and Q levels} - H04B: TRANSMISSION - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract It is intended to provide a transmitter capable of correcting signal distortion with high accuracy. Provided are a test signal generator; a frequency characteristics corrector for correcting an amplitude characteristic and a phase characteristic of a test signal; a modulator; an envelope detector; a frequency characteristics calculator for calculating frequency characteristics of an envelope signal; and a coefficients calculator for calculating, on the basis of the frequency characteristics, correction coefficients to be used for correcting the amplitude characteristic and the phase characteristic of the test signal. The test signal generator generates a test signal in which signal loci in each of at least two pairs of quadrants of first to fourth quadrants of the IQ plane are not symmetrical with each other. ## Claims ### Claim 1 A transmitter comprising: a test signal generator configured to generate a test signal; a frequency characteristics corrector configured to correct an amplitude characteristic and a phase characteristic of the test signal generated by the test signal generator; a modulator configured to modulate a corrected signal produced by the frequency characteristics corrector through the correction; an envelope detector configured to detect an envelope of a modulated signal produced by the modulator through the modulation; a frequency characteristics calculator configured to calculate frequency characteristics of an envelope signal detected by the envelope detector; and a coefficients calculator configured to calculate, on the basis of the frequency characteristics calculated by the frequency characteristics calculator, correction coefficients to be used by the frequency characteristics corrector to correct the amplitude characteristic and the phase characteristic of the test signal, wherein the test signal generator generates a test signal in which signal loci in at least two of quadrants of first to fourth quadrants of the IQ plane are not symmetrical with each other. ### Claim 2 (depends on 1) The transmitter according to claim 1, wherein the test signal generator generates a test signal that rotates along a signal locus line that is offset by a prescribed amount in the IQ plane and is symmetrical with respect to a reference axis. ### Claim 3 (depends on 1) The transmitter according to claim 1, wherein the test signal is a signal that rotates along a signal locus line at a constant speed. ### Claim 4 (depends on 2) The transmitter according to claim 2, wherein the test signal generator generates a test signal that rotates along a circle that is offset by a prescribed amount in the IQ plane. ### Claim 5 (depends on 4) The transmitter according to claim 4, wherein the test signal is a signal that rotates at a constant speed along the circle that is offset by the prescribed amount in the IQ plane. ### Claim 6 (depends on 1) The transmitter according to claim 1, wherein the test signal generator sweeps the frequency of the test signal in a prescribed frequency range; wherein the frequency characteristics calculator extracts complex data from an envelope signal corresponding to each angular frequency component of the test signal; and wherein the coefficients calculator calculates each correction coefficient on the basis of each complex data extracted by the frequency characteristics calculator. ### Claim 7 (depends on 6) The transmitter according to claim 6, wherein the coefficients calculator calculates reciprocals of the complex data as the correction coefficients, respectively. ### Claim 8 (depends on 6) The transmitter according to claim 6, wherein the coefficients calculator calculates correction coefficients on the basis of an amplitude characteristic of the complex data and a difference between a phase characteristic of the complex data and a linear phase characteristic. ### Claim 9 (depends on 6) The transmitter according to claim 6, further comprising: a storage configured to store the correction coefficients, wherein the coefficients calculator calculates correction coefficients repeatedly while updating the correction coefficients stored in the storage. ### Claim 10 (depends on 9) The transmitter according to claim 9, wherein the coefficients calculator calculates coefficients for calculation of the correction coefficients on the basis of the complex data extracted by the frequency characteristics calculator, and updates the correction coefficients stored in the storage to a result of adding a weighted version of the coefficients calculated by the coefficients calculator to the correction coefficients stored in the storage. ### Claim 11 (depends on 1) The transmitter according to claim 1, wherein the frequency characteristics corrector includes: a converter configured to convert the test signal which is a time-domain signal into a frequency-domain signal; a multiplier configured to multiply the frequency-domain signal by the coefficients calculated by the coefficients calculator; and an inverse converter configured to convert an output signal of the multiplier which is a frequency-domain signal into a time-domain signal. ### Claim 12 (depends on 1) The transmitter according to claim 1, wherein the frequency characteristics calculator includes a converter configured to convert the envelope signal which is a time-domain signal into a frequency-domain signal. ### Claim 13 (depends on 1) The transmitter according to claim 1, further comprising: a baseband signal generator configured to generate a baseband signal; and a transmitter configured to transmit the modulated signal, wherein the frequency characteristics corrector generates a corrected signal by correcting the baseband signal on the basis of the correction coefficients calculated by the coefficients calculator. ### Claim 14 A transmitter comprising: a test signal generator configured to generate a first test signal and a second test signal; a signal corrector configured to correct IQ imbalance of a test signal generated by the test signal generator; a modulator configured to modulate a corrected signal produced by the signal corrector through the correction; an envelope detector configured to detect an envelope of a modulated signal produced by the modulator through the modulation; and a correction coefficients processor configured to calculate, on the basis of the envelope detected by the envelope detector, correction coefficients to be used by the signal corrector to correct the IQ imbalance, wherein the test signal generator generates a first test signal and a second test signal according to a detectable range of the envelope detector; and wherein the correction coefficients processor calculates a reference phase of the test signal on the basis of a first envelope corresponding to the first test signal, calculates a measurement phase of the test signal on the basis of a second envelope corresponding to the second test signal, and calculates correction coefficients on the basis of the measurement phase and the reference phase. ### Claim 15 (depends on 14) The transmitter according to claim 14, wherein the correction coefficients processor calculates a phase of the second test signal by subtracting the reference phase from the measurement phase, and calculates correction coefficients on the basis of the phase. ### Claim 16 (depends on 15) The transmitter according to claim 15, wherein the correction coefficients processor estimates a direction of an amplitude error or a phase error contained in the IQ imbalance, and calculates correction coefficients according to the direction of the amplitude error or the phase error. ### Claim 17 (depends on 14) The transmitter according to claim 14, wherein the first test signal is an IQ signal for an amplitude modulation signal; wherein the second test signal is an IQ signal for a single-sideband signal that rotates in the IQ plane around the origin; and wherein the first test signal has a frequency that is two times a frequency of the second test signal. ### Claim 18 (depends on 14) The transmitter according to claim 14, further comprising: a storage configured to store information of the correction coefficients, wherein the correction coefficients processor updates the information of the correction coefficients stored in the storage to the calculated correction coefficients. ### Claim 19 (depends on 18) The transmitter according to any one of claim 18, wherein the correction coefficients processor calculates a measurement phase of the test signal plural times, and repeatedly calculates correction coefficients plural times on the basis of the calculated measurement phase and reference phase. ### Claim 20 (depends on 14) The transmitter according to claim 14, further comprising: a baseband signal generator configured to generate a baseband signal; and a transmitter configured to transmit the modulated signal, wherein the signal corrector generates a corrected signal by correcting the baseband signal on the basis of the correction coefficients calculated by the correction coefficients processor. ### Claim 21 A signal generation device comprising: a test signal generator configured to generate a test signal; a frequency characteristics corrector configured to correct an amplitude characteristic and a phase characteristic of the test signal generated by the test signal generator; a frequency characteristics calculator configured to calculate frequency characteristics of an envelope signal of a modulated signal produced by modulating a corrected signal that is produced by the frequency characteristics corrector through the correction; and a coefficients calculator configured to calculate, on the basis of the frequency characteristics calculated by the frequency characteristics calculator, correction coefficients to be used by the frequency characteristics corrector to correct the amplitude characteristic and the phase characteristic of the test signal, wherein the test signal generator generates a test signal in which signal loci in at least two of quadrants of first to fourth quadrants of the IQ plane are not symmetrical with each other. ### Claim 22 A signal generation device comprising: a test signal generator configured to generate a first test signal and a second test signal; a signal corrector configured to correct IQ imbalance of a test signal generated by the test signal generator; and a correction coefficients processor configured to calculate, on the basis of an envelope of a modulated signal produced by modulating a corrected signal that is produced by the signal corrector through the correction, wherein the test signal generator generates a first test signal and a second test signal according to a detectable range of an envelope detector for detecting the envelope; and wherein the correction coefficients processor calculates a reference phase of the test signal on the basis of a first envelope corresponding to the first test signal, calculates a measurement phase of the test signal on the basis of a second envelope corresponding to the second test signal, and calculates correction coefficients on the basis of the measurement phase and the reference phase. ### Claim 23 A calibration method comprising: a test signal generation step of generating a test signal; a frequency characteristics correction step of correcting an amplitude characteristic and a phase characteristic of the generated test signal; a frequency characteristics calculation step of calculating frequency characteristics of an envelope signal of a modulated signal produced by modulating a corrected signal produced through the correction; and a coefficients calculation step of calculating, on the basis of the calculated frequency characteristics, correction coefficients to be used for correcting the amplitude characteristic and the phase characteristic of the test signal, wherein the test signal generation step generates a test signal in which signal loci in each of at least two pairs of quadrants of first to fourth quadrants of the IQ plane are not symmetrical with each other. ### Claim 24 A signal generation method comprising: a test signal generation step of generating a first test signal and a second test signal; a correction step of correcting IQ imbalance of a generated test signal; and a calculation step of calculating, on the basis of an envelope of a modulated signal produced by modulating a corrected signal that is produced through the correction, wherein the test signal generation step generates a first test signal and a second test signal according to a detectable range of an envelope detector for detecting the envelope; and wherein the calculation step calculates a reference phase of the test signal on the basis of a first envelope corresponding to the first test signal, calculates a measurement phase of the test signal on the basis of a second envelope corresponding to the second test signal, and calculates correction coefficients on the basis of the measurement phase and the reference phase.