Method and device for determining the phase shift between two signals

1. A method for determining a phase shift between a first signal and a second signal, the method comprising:

delivering the first signal to a first input of a 90° hybrid coupler;

delivering the second signal to a second input of the 90° hybrid coupler;

determining a first piece of information relating to a power of a first output signal delivered to a first output of the 90° hybrid coupler;

determining a second piece of information relating to a power of a second output signal delivered to a second output of the 90° hybrid coupler; and

adjusting a phase of the second signal until obtaining a calibrated phase for which the first piece of information is substantially equal to the second piece of information, wherein the first and second signals have identical frequencies, and wherein the phase shift between the first signal and the second signal is equal to the calibrated phase.

2. The method of claim 1 , wherein determining the first piece of information comprises determining a first peak value of a DC voltage of the first output signal, wherein determining the second piece of information comprises determining a second peak value of a DC voltage of the second output signal, and wherein obtaining the calibrated phase corresponds to a difference which is substantially zero between the first and second peak values.

3. The method of claim 2 , wherein determining the first peak value of the DC voltage of the first output signal comprises using a first peak detector coupled to the first output of the 90° hybrid coupler, wherein determining the second peak value of the DC voltage of the second output signal comprises using a second peak detector coupled to the second output of the 90° hybrid coupler, and wherein a third and fourth peak detectors are coupled to the first and second inputs of the 90° hybrid coupler, respectively.

4. The method of claim 3 , wherein the first, second, third, and fourth peak detectors are identical to each other.

5. The method of claim 2 , wherein determining the first peak value of the DC voltage of the first output signal comprises:

receiving the first output signal via a capacitor with a control terminal of a first transistor;

mirroring a reference current with a current mirror that is coupled to a current path of the first transistor; and

delivering the first peak value of the DC voltage at a node coupled to the current path of the first transistor and to further coupled to an output capacitor.

6. The method of claim 1 , wherein the first and second signals are radiofrequency signals.

7. The method of claim 6 , wherein the first and second signals are millimeter-wave signals.

8. A device for determining a phase shift between a first signal and a second signal, the device comprising:

a 90° hybrid coupler having a first input configured to receive the first signal, a second input configured to receive the second signal, a first output configured to deliver a first output signal, and a second output configured to deliver a second output signal;

a first circuit configured to determine a first piece of information relating to a power of the first output signal;

a second circuit configured to determine a second piece of information relating to a power of the second output signal; and

an adjustment circuit configured to adjust a phase of the second signal until obtaining a calibrated phase for which the first piece of information is substantially equal to the second piece of information, the phase shift between the first signal and the second signal being equal to the calibrated phase, wherein the first and second signals have identical frequencies.

9. The device of claim 8 , wherein the first circuit comprises a first peak detector coupled to the first output of the 90° hybrid coupler and configured to determine a first peak value of a DC voltage of the first output signal, wherein the second circuit comprising a second peak detector coupled to the second output of the 90° hybrid coupler and configured to determine a second peak value of a DC voltage of the second output signal, wherein the calibrated phase corresponds to a substantially zero difference between the first and second peak values.

10. The device of claim 9 , further comprising two other peak detectors respectively coupled to the first input and to the second input of the 90° hybrid coupler.

11. The device of claim 9 , wherein the first and second signals are radiofrequency signals.

12. The device of claim 9 , wherein the first peak detector comprises:

an output terminal;

an output capacitor coupled to the output terminal of the first peak detector;

a first transistor having a control terminal capacitively coupled to the first output of the 90° hybrid coupler, and a current path coupled between a first supply terminal and the output terminal; and

a current mirror coupled to the current path of the first transistor.

13. A communication apparatus comprising:

an emission chain comprising a power amplifier; and

a device disposed upstream or downstream of the power amplifier, the device comprising:

a 90° hybrid coupler having a first input configured to receive a first signal, a second input configured to receive a second signal, a first output configured to deliver a first output signal, and a second output configured to deliver a second output signal,

a first circuit configured to determine a first piece of information relating to a power of the first output signal,

a second circuit configured to determine a second piece of information relating to a power of the second output signal, and

an adjustment circuit configured to adjust a phase of the second signal until obtaining a calibrated phase for which the first piece of information is substantially equal to the second piece of information, wherein a phase shift between the first signal and the second signal is equal to the calibrated phase, wherein the first and second signals have identical frequencies.

14. The communication apparatus of claim 13 , wherein the emission chain further comprises a phase shifter having a first input configured to receive the first signal, a second input configured to receive the calibrated phase, and an output coupled to an input of the power amplifier.

15. The communication apparatus of claim 13 , wherein the first circuit comprises a first peak detector coupled to the first output of the 90° hybrid coupler and configured to determine a first peak value of a DC voltage of the first output signal, wherein the second circuit comprising a second peak detector coupled to the second output of the 90° hybrid coupler and configured to determine a second peak value of a DC voltage of the second output signal, wherein the calibrated phase corresponds to a substantially zero difference between the first and second peak values.

16. The communication apparatus of claim 15 , further comprising two other peak detectors respectively coupled to the first input and to the second input of the 90° hybrid coupler.

17. The communication apparatus of claim 15 , wherein the first and second signals are radiofrequency signals.

18. The communication apparatus of claim 15 , wherein the first peak detector comprises:

an output terminal;

an output capacitor coupled to the output terminal of the first peak detector;

a first transistor having a control terminal capacitively coupled to the first output of the 90° hybrid coupler, and a current path coupled between a first supply terminal and the output terminal; and

a current mirror coupled to the current path of the first transistor.

19. The communication apparatus of claim 13 , wherein the communication apparatus is a mobile telephone.

20. The communication apparatus of claim 13 , wherein the frequencies of the first and second signals are comprised between 10 GHz and 80 GHz.