Systems and methods for I-Q imbalance calibration

Patent metadata

Field	Value
Publication number	US-9641126-B2
Application number	US-201314134813-A
Country	US
Kind code	B2
Filing date	Dec 19, 2013
Priority date	Dec 19, 2013
Publication date	May 2, 2017
Grant date	May 2, 2017

Abstract

A method for in-phase-quadrature (I-Q) imbalance calibration is described. A signal is transmitted by a first transmitter in a first system. The signal includes a constant value. The signal is received at a second receiver in a second system. An I-Q imbalance is estimated for the second receiver based on the received signal.

First claim

What is claimed is:

1. A method for in-phase-quadrature (I-Q) imbalance calibration, comprising:
transmitting a signal by a first transmitter in a first system, the signal comprising a constant value;
receiving the signal at a second receiver in a second system, wherein the first system and the second system are included in a same wireless communication device, and wherein the first system and the second system are different types of wireless systems; and
estimating an I-Q imbalance for the second receiver based on the received signals, wherein estimating the I-Q imbalance comprises: measuring power on an in-phase branch and a quadrature branch, and
measuring a cross-correlation between the in-phase branch and the quadrature branch, wherein a switch is configured to selectively couple the first transmitter in the first system to the second receiver in the second system during I-Q imbalance calibration, and
wherein a first adder combines a transmit path of the first system and a transmit path of the second system, and a second adder is coupled to a receive path of the first system and a receive path of the second system, wherein the switch is coupled between the first adder and the second adder.

2. The method of claim 1 , wherein estimating the I-Q imbalance further comprises:
determining a gain imbalance of the second receiver based on the power on the in-phase branch and the power on the quadrature branch; and determining a phase imbalance of the second receiver based on the cross-correlation between the in-phase branch and the quadrature branch and the power on the in-phase branch.

3. The method of claim 1 , further comprising:
transmitting a digital tone by a second transmitter in the second system; receiving the digital tone at the second receiver in the second system; and
estimating the I-Q imbalance for the second transmitter in the second system based on the received digital tone.

4. The method of claim 1 , wherein the first system is a WiFi system, a Bluetooth system, or a Long-Term Evolution system, and the second system is a WiFi system, a Bluetooth system, or a Long-Term Evolution system.

5. The method of claim 1 , wherein the signal further comprises an in-phase component set to a first constant value and a quadrature component set to a second constant value.

6. The method of claim 1 , wherein the first system and the second system are on a combined system on chip.

7. A method for in-phase-quadrature (I-Q) imbalance calibration, comprising:
setting a first synthesizer in a first system to a first frequency, the first system comprising a first transmitter and a first receiver;
setting a second synthesizer in a second system to a second frequency, wherein the first frequency and the second frequency differ by a third frequency, the second system comprising a second transmitter and a second receiver, wherein the first system and the second system are included in a same wireless communication device;
transmitting a signal by the first transmitter in the first system, the signal comprising a constant value;
receiving the signal at the second receiver in the second system; and estimating an I-Q imbalance for the second receiver based on the received signal, wherein estimating the I-Q imbalance comprises:

determining a gain imbalance of the second receiver based on power measured on an in-phase branch and power measured on a quadrature branch, and
determining a phase imbalance of the second receiver based on a cross-correlation measured between the in-phase branch and the quadrature branch, and the power measured on the in-phase branch.

8. The method of claim 7 , wherein the first frequency and the second frequency are within a valid bandwidth range for the second receiver.

9. A wireless communication device configured for in-phase-quadrature (I-Q) imbalance calibration, comprising:
a processor;
memory in electronic communication with the processor;
instructions stored in the memory, the instructions being executable by the processor to: transmit a signal by a first transmitter in a first system in the wireless communication device, the signal comprising a constant value;
receive the signal at a second receiver in a second system in the wireless communication device, wherein the first system and the second system are different types of wireless systems; and
estimate an I-Q imbalance for the second receiver based on the received signal, wherein the instructions executable to estimate the I-Q imbalance comprise instructions executable to:
measure power on an in-phase branch and a quadrature branch, and
measure a cross-correlation between the in-phase branch and the quadrature branch;
a switch configured to selectively couple the first transmitter in the first system to the second receiver in the second system during I-Q imbalance calibration;

a first adder configured to combine a transmit path of the first system and a transmit path of the second system; and
a second adder coupled to a receive path of the first system and a receive path of the second system, wherein the switch is coupled between the first adder and the second adder.

10. The wireless communication device of claim 9 , wherein the instructions executable to estimate the I-Q imbalance further comprise instructions executable to:
determine a gain imbalance of the second receiver based on the power on the in-phase branch and the power on the quadrature branch; and determine a phase imbalance of the second receiver based on the cross-correlation between the in-phase branch and the quadrature branch and the power on the in-phase branch.

11. The wireless communication device of claim 9 , wherein the instructions are further executable to:
transmit a digital tone by a second transmitter in the second system; receive the digital tone at the second receiver in the second system; and estimate the I-Q imbalance for the second transmitter in the second system based on the received digital tone.

12. The wireless communication device of claim 9 , wherein the first system is a WiFi system, a Bluetooth system, or a Long-Term Evolution system, and the second system is a WiFi system, a Bluetooth system, or a Long-Term Evolution system.

13. The wireless communication device of claim 9 , wherein the signal further comprises an in-phase component set to a first constant value and a quadrature component set to a second constant value.

14. The wireless communication device of claim 9 , wherein the first system and the second system are on a combined system on chip.

15. A wireless communication device configured for in-phase-quadrature (I-Q) imbalance calibration, comprising:
a processor;
memory in electronic communication with the processor; and

instructions stored in the memory, the instructions being executable by the processor to: set a first synthesizer in a first system in the wireless communication device to a first frequency, the first system comprising a first transmitter and a first receiver;
set a second synthesizer in a second system in the wireless communication device to a second frequency, wherein the first frequency and the second frequency differ by a third frequency, the second system comprising a second transmitter and a second receiver;
transmit a signal by the first transmitter in the first system, the signal comprising a constant value;
receive the signal at the second receiver in the second system; and estimate an I-Q imbalance for the second receiver based on the received signal, wherein the instructions executable to estimate the I-Q imbalance comprise instructions executable to:
determine a

Assignees

• Qualcomm Inc

Inventors

• Fernandes Barros Daniel Jose

Classifications

• H04B17/22

  for calibration of the receiver components · CPC title

• H03D3/009 Primary

  Compensating quadrature phase or amplitude imbalances · CPC title

• H04L2027/0067

  Phase error detectors · CPC title

• H04L27/0014

  Carrier regulation (of chaotic carriers H04L27/001; for multicarrier receivers H04L27/2657) · CPC title

• H04B7/0413

  MIMO systems · CPC title