US 10,484,108 B1Granted

Transmitter image calibration using phase shift estimation

AssigneeFuturewei Technologies, Inc.

InventorWael Al-Qaq

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Abstract

Techniques are presented to improve the accuracy of and reduce the time required for calibration of an in-phase/quadrature (I/Q) transmission circuit. A measurement receiver measures the I/Q mismatch, where an RF phase shift is introduced to help distinguish between the transmitter and measurement receiver I/Q mismatches. Rather than assuming an amount of introduced phase shift, a measurement is used to estimate the phase shift. This phase estimate is then used to determine and correct the I/Q mismatch in the transmitter and measurement receiver. An iterative process can be used to improve the I/Q correction factors. Using simple signal processing to measure the phase shift during calibration and using it to carry out the image calibration calculations, the phase shifter requirements can be significantly relaxed, resulting in faster design time and reduced design area/cost. This approach results in reduced calibration time, thus contributing to reduced factory production time and enabling faster live mode image calibration.

Claims20

Dependent claims

An apparatus, comprising:

a transmitter in-phase/quadrature mismatch correction circuit configured to receive an in-phase/quadrature signal and transmitter correction coefficients and generate a corrected in-phase/quadrature signal based on the transmitter correction coefficients to reduce an amount of in-phase/quadrature mismatch in the received in-phase/quadrature signal;
a transmission circuit configured to receive the corrected in-phase/quadrature signal and to generate therefrom a transmission signal;
a measurement receiver circuit configured to receive the transmission signal and to generate therefrom a measured in-phase/quadrature signal;
a measurement receiver in-phase/quadrature mismatch correction circuit configured to receive the measured in-phase/quadrature signal and receiver correction coefficients and generate a corrected measured in-phase/quadrature signal based on the receiver correction coefficients to reduce an amount of in-phase/quadrature mismatch in the measured in-phase/quadrature signal;
and
an in-phase/quadrature mismatch estimation circuit configured to receive the corrected measured in-phase/quadrature signal, estimate a phase in the corrected measured in-phase/quadrature signal and generate the transmitter correction coefficients and receiver correction coefficients from the estimated phase.

3 more elements

A method of correcting for in-phase/quadrature mismatch, comprising:

receiving an in-phase/quadrature signal;
generating a first transmission signal from the received in-phase/quadrature signal;
estimating an in-phase/quadrature mismatch from a measurement of the first transmission signal;
performing a correction of the in-phase/quadrature signal based on the estimated in-phase/quadrature mismatch;
generating a second transmission signal from the corrected in-phase/quadrature signal;
performing a correction of a measurement of the second transmission signal based on the estimated in-phase/quadrature mismatch;
and
performing a further correction of the in-phase/quadrature signal based on an estimated in-phase/quadrature mismatch from the corrected second measurement in-phase/quadrature signal.

5 more elements

A wireless communication system, comprising:

a signal generation circuit configured to generate a communication signal;
a quadrature generator configured to generate an in-phase/quadrature signal from the communication signal;
a transmitter comprising:
a transmitter in-phase/quadrature mismatch correction circuit configured to receive an in-phase/quadrature signal and transmitter correction coefficients and generate a corrected in-phase/quadrature signal based on the transmitter correction coefficients to reduce an amount of in-phase/quadrature mismatch in the received in-phase/quadrature signal;
and
a transmission circuit configured to receive the corrected in-phase/quadrature signal generate therefrom a transmission signal;
and
a calibration section comprising:
a measurement receiver circuit configured to receive the transmission signal and to generate therefrom a measured in-phase/quadrature signal;
and
an in-phase/quadrature mismatch estimation circuit configured to receive the measured in-phase/quadrature signal, estimate a phase in the measured in-phase/quadrature signal and to generate the transmitter correction coefficients from the estimated phase.

8 more elements

Dependencies are inferred from the claim text.

Facts

Application: 16/007,241Filed 13 Jun 2018
Granted: 19 Nov 2019
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

H04B 17/12
For calibration: of transmit antennas, e.g. of the amplitude or phase
H04L 27/3863
Using a non - coherent carrier, including systems with baseband correction for phase or frequency offset: compensation for quadrature error in the…
H04B 17/11
Of transmitters: for calibration
H04L 7/0331
Using the transitions of the received signal to control the phase of the synchronising-signal-generating means, e.g. using a phase-locked loop:…

Family

No related US applications are recorded in the indexed filing history.

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