DEVICES AND METHODS FOR REDUCING SIGNAL DISTORTION IN I/Q MODULATION TRANSCEIVERS

• US 20160173317A1
• Filed: 12/15/2014
• Published: 06/16/2016
• Est. Priority Date: 12/15/2014
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Bitton, Guy
• Granted Patent: US 9,491,029 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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

Abstract

Devices and methods for reducing or substantially eliminating I/Q mismatch and/or LO leakage in I/Q transceivers are provided. By way of example, an electronic device includes a transceiver configured to receive an in-phase/quadrature (I/Q) signal, and to generate an electromagnetic signal based on the I/Q signal. However, the electromagnetic signal may also include a distortion. Accordingly, the transceiver is also configured to receive a feedback signal based on the electromagnetic signal, measure an energy of the distortion by way of the feedback signal, and to generate one or more correction factors based at least in part on the energy of the distortion. The one or more correction factors may be utilized to reduce or substantially eliminate the distortion of the electromagnetic signal.

Claims

1. An electronic device, comprising:

a transceiver configured to;

receive an in-phase/quadrature (I/Q) signal;

generate an electromagnetic signal based on the I/Q signal;

receive a feedback signal based on the electromagnetic signal;

measure a spectral energy of an I/Q mismatch (IQMM) component or a local oscillator (LO) leakage component in a frequency domain by way of the feedback signal; and

generate one or more correction factors based at least in part on the spectral energy, wherein generating the one or more correction factors comprises reducing or substantially eliminating the IQMM component or the LO leakage component of the electromagnetic signal.

2. The electronic device of claim 1, wherein the transceiver comprises a transmitter configured to receive the I/Q signal and to generate the electromagnetic signal.

3. The electronic device of claim 1, wherein the transceiver comprises a receiver configured to receive the feedback signal based on the electromagnetic signal.

4. The electronic device of claim 1, wherein the transceiver is configured to downconvert the feedback signal into an intermediate frequency (IF) signal prior to measuring the spectral energy.

5. The electronic device of claim 4, wherein the transceiver is configured to downconvert the IF signal into a zero intermediate frequency (ZIF) signal prior to measuring the spectral energy of the distortion.

6. The electronic device of claim 1, wherein the transceiver is configured to apply the one or more correction factors to the I/Q signal to reduce or substantially eliminate the IQMM component or the LO leakage component of the electromagnetic signal.

7. The electronic device of claim 1, wherein the transceiver is configured to:

perform a discrete Fourier transform (DFT) of the feedback signal; and

measure the spectral energy by measuring a spectral energy of the DFT of the feedback signal.

8. The electronic device of claim 7, wherein the transceiver is configured to measure a spectral energy of the DFT an indication of IQMM component or the local oscillator LO leakage component within the feedback signal.

9. A non-transitory computer-readable medium having computer executable code stored thereon, the code comprising instructions to:

receive an in-phase/quadrature (I/Q) data signal;

cause one or more processing devices to generate a radio frequency (RF) transmission signal based on the I/Q data signal;

receive a sampling signal of the RF transmission signal;

derive a spectral energy component of an I/Q mismatch component in a frequency domain based on the sampling signal; and

cause the one or more processing devices to generate one or more correction signals based at least in part on the spectral energy of the I/Q mismatch component reduce or substantially eliminate the I/Q mismatch component.

10. The non-transitory computer-readable medium of claim 9, wherein the code comprises instructions to derive the spectral energy component of the I/Q mismatch component by causing the one or more processing devices to compute a discrete Fourier transform (DFT) of the sampling signal.

11. The non-transitory computer-readable medium of claim 10, wherein the code comprises instructions to derive the spectral energy component of the I/Q mismatch component by causing the one or more processing devices to measure the spectral energy of the DFT of the sampling signal.

12. The non-transitory computer-readable medium of claim 9, wherein the code comprises instructions to cause the one or more processing devices to adjust the I/Q data signal based on the one or more correction signals.

13. A method, comprising:

receiving a Cartesian representation of a data signal via a transceiver of an electronic device;

generating a radio frequency (RF) signal based on the data signal;

receiving a monitoring signal based on the RF signal;

downconverting the monitoring signal into an intermediate frequency (IF) signal;

measuring a spectral energy of the of IF signal in a digital domain, wherein the spectral energy comprises an indication of an in-phase/quadrature (I/Q) mismatch component or a local oscillator (LO) leakage component present on the RF signal; and

generating one or more correction factors based at least in part on the spectral energy, wherein the one or more correction factors are generated to remove the I/Q mismatch component or the LO leakage component from the RF signal.

14. The method of claim 13, wherein receiving the Cartesian representation of the data signal comprises receiving a data signal comprising an in-phase (I) component and a quadrature (Q) component.

15. The method of claim 13, wherein downconverting the monitoring signal into the IF signal comprises downconverting the monitoring signal into a zero intermediate frequency (ZIF) signal.

16. The method of claim 13, wherein measuring the spectral energy of the IF signal comprises measuring the spectral energy of each of a plurality of Fourier coefficients derived based on a Fourier transform of the IF signal.

17. The method of claim 13, comprising:

correcting the RF signal based on the one or more correction factors; and

transmitting the RF signal.

18. An electronic device, comprising:

a network interface configured to allow the electronic device to communicate over one or more channels of a wireless network;

a transmitter configured to transmit in-phase/quadrature (I/Q) signals over the one or more channels; and

a receiver coupled to the transmitter and configured to receive I/Q signals over the one or more channels, wherein the receiver comprises;

one or more processors communicatively coupled to the transmitter and the receiver and configured to;

receive a feedback signal based on I/Q signals to be transmitted by the transmitter, wherein the feedback signal comprises an I/Q distortion, an oscillator distortion, or a combination thereof;

detect a spectral energy of the feedback signal in a frequency domain as indication of a presence of the I/Q distortion, the oscillator distortion, or the combination thereof; and

generate a plurality of error correction factors based at least in part on the spectral energy when present, wherein the plurality of error correction factors are configured to reduce or substantially eliminate the I/Q distortion, the oscillator distortion, or the combination thereof.

19. The electronic device of claim 18, wherein the network interface comprises a personal area network (PAN) interface, a wireless local area network (WLAN) interface, a wide area network (WAN) interface, a broadband fixed wireless access network (WiMAX) interface, a mobile broadband wireless network (mobile WiMAX) interface, an asynchronous digital subscriber line (ADSL) interface, a digital video broadcasting-terrestrial (DVB-T) interface, an ultra wideband (UWB) interface, or any combination thereof.

20. The electronic device of claim 18, wherein the one or more processors are configured to downconvert the feedback signal into a zero intermediate frequency (ZIF) signal prior to detecting the spectral energy of the feedback signal.

21. The electronic device of claim 20, wherein the receiver comprises a numerically controlled oscillator (NCO) configured to generate the ZIF signal in a frequency domain.

22. The electronic device of claim 18, wherein the one or more processors are configured to compute a Fourier transform of the feedback signal and to detect the spectral energy by analyzing one or more coefficients of the Fourier transform.

23. The electronic device of claim 18, wherein the one or more processors are configured to provide the plurality of error correction factors to the transmitter to correct the I/Q signals to be transmitted by the transmitter.