Wireless transceiver with TX/FBRX sequential QMC calibration using separate/shared PLLS

• US 9,654,326 B2
• Filed: 04/07/2016
• Issued: 05/16/2017
• Est. Priority Date: 08/08/2014
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Choo, Hunsoo, Sestok, IV, Charles K.
• Primary Examiner(s): Tran, Khanh C
• Application Number:
  US15/093,724
• Publication Number:
  US 20160234055A1
• Time in Patent Office: 404 Days
• Field of Search: 375219, 375221, 375226, 375229, 375232, 375285, 375295, 375346, 375350, 455 631, 455 6711, 455 6713, 455 68- 69, 4551142-1143, 455296
• CPC Class Codes: H04B 1/30 for homodyne or synchrodyne receivers demodulator circuits H03D1/22
• CPC Class Codes: H04B 17/14 of the whole transmission and reception path, e.g. self-test loop-back
• CPC Class Codes: H04L 27/364 Arrangements for overcoming imperfections in the modulator, e.g. quadrature error or unbalanced I and Q levels
• CPC Class Codes: H04L 27/3863 Compensation for quadrature error in the received signal
• CPC Class Codes: H04L 7/0331 with a digital phase-locked loop [PLL] processing binary samples, e.g. add/subtract logic for correction of receiver clock H04L7/0337 takes precedence

Abstract

A direct conversion wireless transceiver is configured for TX/FBRX sequential QMC calibration (coefficient generation) using separate/shared PLLs. A TX LO drives upconversion, and an RX LO drives downconversion. TX/RX digital QMC compensators compensate for IQ mismatch (with optional DPD compensation), and QMC calibration is used to calibrate the TX/RX QMC filter coefficients based on a QMC calibration procedure. The TX LO signal source is a TX PLL, and the RX LO signal source is selectively the TX PLL or a separate FBRX PLL. A QMC controller performs QMC calibration to generate calibrated TX/FBRX QMC filter coefficients, including: disconnecting the TX PLL from, and connecting the FBRX PLL to, the RX LO; generating calibrated TX QMC filter coefficients; generating calibrated FBRX QMC filter coefficients; disconnecting the FBRX PLL from, and connecting the TX PLL to, the RX LO; generating re-calibrated FBRX QMC filter coefficients.

Claims

1. A wireless transceiver circuit, comprising

a transmit (TX) signal chain to transmit TX radio frequency (TXRF) signals, including

an IQ modulator, and

an RF upconverter including a TX mixer driven by a TX local oscillator (TX LO),

a TX QMC compensator to

in TX QMC compensation mode, perform TX QMC compensation for TX IQ mismatch based on TX QMC filter coefficients, and

in QMC calibration mode, calibrate the TX QMC filter coefficients based on a QMC calibration procedure;

a receive (RX) signal chain to receive at least feedback TXRF (FBRX) signals including

an IQ demodulator, and

an RF downconverter including an RX mixer driven by a RX local oscillator (RX LO),

an RX QMC compensator to

in RX QMC compensation mode, perform RX QMC compensation for RX IQ mismatch based on RX QMC filter coefficients, and

in QMC calibration mode, calibrate the RX QMC filter coefficients based on a QMC calibration procedure;

separate TX PLL (phase-locked loop) and FBRX PLL signal sources,

in normal operating mode, the TX PLL signal source connected to the TX LO, and selectively connected to the RX LO;

in QMC calibration mode, the TX PLL selectively disconnected from the RX LO, and the FBRX PLL signal source selectively connected to the RX LO;

a QMC controller to perform the QMC calibration procedure to generate calibrated TX and RX QMC filter coefficients, including

disconnecting the TX PLL from, and connecting the FBRX PLL to, the RX LO, and then

generating calibrated RX QMC filter coefficients, and

generating calibrated TX QMC filter coefficients, and then

disconnecting the FBRX PLL from, and connecting the TX PLL to, the RX LO, and then

generating re-calibrated RX QMC filter coefficients.

2. The circuit of claim 1, further comprising a DPD (digital pre-distortion) compensator to perform, in normal operating mode, TX DPD compensation using TX data and FBRX data respectively based on TX QMC compensation and RX QMC compensation.

3. The circuit of claim 2, wherein TX QMC compensation and RX QMC compensation are performed prior to TX DPD compensation.

4. The circuit of claim 2, wherein TX QMC compensation is selectively performed independent of selectively performing RX QMC compensation.

5. The circuit of claim 1, wherein the QMC calibration procedure generates the calibrated TX QMC filter coefficients and the calibrated RX QMC filter coefficients based on phase rotation.

6. The circuit of claim 1, wherein the QMC calibration procedure generates the re-calibrated RX QMC filter coefficients using least squares.

7. A wireless transmitter circuit, comprising

a transmit (TX) signal chain to transmit a TX wireless signal, including

an IQ modulator, and

an RF upconverter including a TX mixer driven by a TX local oscillator (TX LO),

a TX digital compensator, including

a TX QMC compensator for IQ mismatch compensation

in normal operating mode, to perform TX QMC compensation for TX IQ mismatch based on TX QMC filter coefficients,

in QMC calibration mode, calibrate the TX QMC filter coefficients based on a QMC calibration procedure, and

a DPD (digital pre-distortion) compensator to perform TX DPD compensation in TX operating mode;

a receive (RX) signal chain receiving the TX wireless signal including

an IQ demodulator, and

an RF downconverter including an RX mixer driven by a RX local oscillator (RX LO),

an RX digital compensator, including an RX QMC compensator operable

in normal operating mode, to perform RX QMC compensation for RX IQ mismatch based on RX QMC filter coefficients,

in QMC calibration mode, to calibrate the RX QMC filter coefficients based on a QMC calibration procedure;

the TX digital compensator performing TX DPD compensation in TX operating mode using TX data and FBRX data respectively based on TX QMC compensation and RX QMC compensation;

separate TX PLL (phase-locked loop) and FBRX PLL signal sources,

in normal operating mode, the TX PLL signal source connected to the TX LO, and selectively connected to the RX LO;

in QMC calibration mode, the TX PLL selectively disconnected from the RX LO, and the FBRX PLL signal source selectively connected to the RX LO;

a QMC controller to perform the QMC calibration procedure to generate calibrated TX and RX QMC filter coefficients, including

disconnecting the TX PLL from, and connecting the FBRX PLL to, the RX LO, and then

generating calibrated RX QMC filter coefficients, and

generating calibrated TX QMC filter coefficients, and then

disconnecting the FBRX PLL from, and connecting the TX PLL to, the RX LO, and then

generating re-calibrated RX QMC filter coefficients.

8. The circuit of claim 7, wherein TX QMC compensation and RX QMC compensation are performed prior to the DPD compensator performing TX DPD compensation.

9. The circuit of claim 7, wherein TX QMC compensation is selectively performed independent of selectively performing RX QMC compensation.

10. The circuit of claim 7, wherein the QMC controller, during the QMC calibration procedure, generates the calibrated TX QMC filter coefficients and the calibrated RX QMC filter coefficients based on phase rotation.

11. The circuit of claim 7, wherein the QMC controller, during the QMC calibration procedure, generates the re-calibrated RX QMC filter coefficients using least squares.

12. A method for direct conversion wireless communication, comprising

transmitting through a TX signal chain a TX wireless signal, including performing IQ modulation, RF upconversion using a TX mixer driven by a TX local oscillator (TX LO);

and

receiving through an RX signal chain, a RX feedback (FBRX) wireless signal corresponding to the TX wireless signal, including performing IQ demodulation, and RF downconversion using a RX mixer driven by an RX local oscillator (RX LO);

in a TX operating mode to transmit the TX wireless signal,

driving the TX LO and the RX LO with a TX PLL (phase-locked loop) signal,

performing TX QMC compensation for IQ mismatch based on TX QMC filter coefficients,

performing FBRX QMC compensation on the FBRX wireless signal for RX IQ mismatch based on RX QMC filter coefficients, and

performing TX DPD (digital pre-distortion) compensation using TX data and FBRX data respectively based on TX QMC compensation and FBRX QMC compensation;

in a QMC calibration mode, performing a QMC calibration procedure to calibrate respectively the TX QMC filter coefficients and RX QMC filter coefficients, including

driving the TX LO with the TX PLL signal, and driving the RX LO with a FBRX PLL signal, and then

generating calibrated RX QMC filter coefficients, and

generating calibrated TX QMC filter coefficients, and then

driving the TX LO and the RX LO with the TX PLL signal, and then

generating re-calibrated RX QMC filter coefficients.

13. The method of claim 12, wherein during the QMC calibration procedure, the calibrated TX QMC filter coefficients and the calibrated RX QMC filter coefficients are generated based on phase rotation.

14. The method of claim 12, wherein, during the QMC calibration procedure, the re-calibrated RX QMC filter coefficients are generated using least squares.

15. The method of claim 12, wherein TX QMC compensation is selectively performed independent of selectively performing RX QMC compensation.