CN114337861A

CN114337861A - Method and device for determining a phase shift between two signals

Info

Publication number: CN114337861A
Application number: CN202111174846.3A
Authority: CN
Inventors: J·福雷; V·诺皮克
Original assignee: STMicroelectronics SA
Current assignee: STMicroelectronics SA
Priority date: 2020-10-09
Filing date: 2021-10-09
Publication date: 2022-04-12

Abstract

Embodiments of the present disclosure relate to methods and apparatus for determining a phase shift between two signals. In one embodiment, a method for determining a phase shift between a first signal and a second signal comprises: passing the first signal to a first input of a 90 ° hybrid coupler; passing the second signal to a second input of the 90 ° hybrid coupler; determining a first piece of information about the power of the first output signal delivered to the first output of the 90 ° hybrid coupler; determining a second piece of information related to the power of a second output signal delivered to a second output of the coupler; and adjusting the phase of the second signal until a calibration phase is obtained for which the first piece of information is substantially equal to the second piece of information, wherein the first and second signals have the same frequency, and wherein the phase shift between the first and second signals is equal to the calibration phase.

Description

Method and device for determining a phase shift between two signals

Cross Reference to Related Applications

The present application claims the benefit of french patent application No.2010322, filed on 9/10/2020, which is incorporated herein by reference.

Technical Field

The present invention relates generally to an electronic system and method, and more particularly, in particular embodiments, to a method and apparatus for determining a phase shift between two signals.

Background

Generally, an electronic device dedicated to the transmission of information comprises a transmission chain comprising a plurality of transmission lines, each transmission line being connected to an antenna. Each transmission line performs a spatial filtering operation (beamforming) allowing the phase and amplitude of the signals transmitted by each antenna of the device to be controlled so as to produce constructive or destructive interference between the transmitted electromagnetic waves.

It is therefore advantageous to be able to determine the phase shift between different signals transmitted on different transmission lines.

Conventional phase detectors typically include analog components (e.g., analog multipliers) or digital circuits (e.g., logic gates or flip-flops).

However, such detectors are not suitable for applications in the radio frequency domain, in particular in the millimeter wave domain.

Disclosure of Invention

There is a need to provide a low complexity technical solution that allows determining the phase shift between two signals, in particular for very high frequency applications, such as those considered in the 5G technique.

Some embodiments relate to information transmission, in particular for radio frequency applications considered for 5G technology. Some embodiments relate to determining a phase shift between two signals, e.g., two Radio Frequency (RF) signals.

Some embodiments are advantageously applied, but in a non-limiting manner, to beamforming techniques for signal-directed transmission.

According to one implementation and embodiment, a solution is proposed that can be easily implemented in an integrated circuit manufacturing method, has a non-intrusive topology, thus has no impact on the power supply lines, and has low power consumption.

According to one implementation and embodiment, it is proposed to determine the phase shift between two signals without performing an actual phase calculation.

In this regard, according to one implementation and embodiment, a hybrid coupler is proposed.

Thus, according to one aspect, a method for determining a phase shift between a first signal and a second signal, in particular a radio frequency signal, is provided. In some embodiments, the first signal and the second signal both have the same frequency.

In some embodiments, the second signal has an adjustable phase.

In some embodiments, the method according to this aspect comprises:

-passing the first signal to a first input of a 90 degree hybrid coupler,

-passing the second signal to a second input of the hybrid coupler,

-determining a first piece of information related to the power of the first output signal delivered to the first output of the coupler,

-determining a second piece of information related to the power of a second output signal delivered to a second output of the coupler, an

-adjusting the phase of the second signal until a calibrated phase is obtained, wherein said first piece of information is equal or substantially equal to the second piece of information within a tolerance range.

In some embodiments, the tolerance is dependent on the sensitivity of the device used to acquire the two pieces of information (e.g., a peak detector) and the sensitivity of a comparator used to compare the two pieces of information.

As an indication, in some embodiments, the magnitude of the sensitivity is on the order of between 10mV and 20 mV.

The phase shift between the first signal and the second signal is equal to the calibration phase.

Thus, the phase shift is determined without any phase calculation, but only by adjusting the phase of the second signal until an equal value is obtained within a tolerance range between the two power information of the two output signals.

Although the piece of information relating to the signal power may be determined in any manner known to the person skilled in the art, it is particularly advantageous that the determination of the first piece of information comprises a determination of a peak value of the DC voltage of the first output signal and the determination of the second piece of information also comprises a determination of a peak value of the DC voltage of the second output signal.

The calibration phase is obtained advantageously corresponding to a zero or substantially zero difference (for example, a tolerance between two peaks of about 10mV to 20 mV).

The use of a DC voltage of the output signal is particularly advantageous as it does not cause attenuation of the radio frequency signal.

According to another aspect, means are provided for determining a phase shift between a first signal and a second signal, the two signals having the same frequency, the second signal having an adjustable phase.

The apparatus according to this aspect comprises:

a 90 ° hybrid coupler having a first input for receiving a first signal, a second input for receiving a second signal,

a first circuit configured to determine a first piece of information related to the power of a first output signal delivered to a first output of the coupler,

-a second circuit configured to determine a second piece of information related to the power of a second output signal delivered to a second output of the coupler,

-a processor configured to analyze the first piece of information and the second piece of information with respect to each other, an

-an adjustment circuit configured to adjust the phase of the second signal until a calibrated phase is obtained in which the first piece of information is equal or substantially equal to the second piece of information.

According to one embodiment, the first circuit includes a first peak detector coupled to the first output, and the first peak detector is configured to determine a peak value of the DC voltage of the first output signal. The second circuit includes a second peak detector coupled to the second output, and the second peak detector is configured to determine a peak value of the DC voltage of the second output signal. The processor is then configured to determine a difference between the two peaks, the calibration phase corresponding to a zero or substantially zero difference within tolerance.

In some embodiments, in order to ensure symmetry of the device, which may be particularly advantageous in radio frequency applications, it is advantageous if the device further comprises two further peak detectors coupled to the first input and the second input of the coupler, respectively.

According to another aspect, there is provided a communication device, such as a cellular mobile telephone, comprising at least one transmit chain including a transmit chain of a power amplifier, and at least one device as defined above, upstream or downstream of the power amplifier.

This allows, for example, to determine the phase shift introduced by components located upstream and/or downstream of the power amplifier in order to correct it.

Drawings

Other advantages and features of the invention will become apparent upon examination of the detailed description of embodiments and implementations (which are not limiting), and the accompanying drawings, in which:

fig. 1 to 5 schematically illustrate examples and embodiments of the present invention.

Corresponding numerals and symbols in the various drawings generally refer to corresponding parts unless otherwise indicated. The drawings are drawn to clearly illustrate the relevant aspects of the preferred embodiments and are not necessarily drawn to scale.

Detailed Description

The making and using of the disclosed embodiments are discussed in detail below. It should be appreciated, however, that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative of specific ways to make and use the invention, and do not limit the scope of the invention.

The following description sets forth various specific details to provide a thorough understanding of several exemplary embodiments in accordance with the description. Embodiments may be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to not obscure the different aspects of the embodiments. Reference in the specification to "an embodiment" means that a particular configuration, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, phrases such as "in one embodiment" that may appear at different points in the description do not necessarily all refer to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

In fig. 1, reference numeral DIS denotes an apparatus that allows determining a phase shift between the first signal SG1 and the second signal SG 2.

In this example, the two signals SG1 and SG2 are radio frequency signals.

As an indication, in some embodiments, the frequencies of the two signals are included between 10GHz and 80GHz, and the signals may be used for 5G technology.

In some embodiments, both signals SG1 and SG2 have the same frequency.

The second signal SG2 has an adjustable phase.

The device DIS comprises a 90 ° hybrid coupler, referenced 1, having a first input IN1 receiving a first signal SG1 and a second input IN2 receiving a second signal SG 2.

The structure of a 90 hybrid coupler is well known to those skilled in the art and includes, inter alia, quarter-wave transmission lines suitable for the frequencies of signals SG1 and SG 2.

The device DIS further comprises a first circuit DC3, here a peak detector, an exemplary structure of which, as will be described in more detail below, is configured to determine a first piece of information INF1 related to the power of the first output signal delivered to the first output ISO of the coupler 1.

The device DIS further comprises a second circuit DC4, here a peak detector, configured to determine a second piece of information INF2 related to the power of a second output signal output from the coupler 1 to a second output OUT.

The device DIS further comprises a processing circuit MTR, for example a logic gate based processing circuit MTR, which is configured to analyze the first piece of information INF1 and the second piece of information INF2 with respect to each other.

The device DIS further comprises an adjusting circuit MRG configured to adjust the phase of the second signal SG 2.

The adjustment circuit MRG comprises a phase shifter DPH (conventional and known structure) controlled by a control circuit MCM.

Reference is now made more specifically to fig. 2 to describe an example of implementation of a method that allows determining the phase shift between the two signals SG1 and SG 2.

IN step STP1, first signal SG1 is passed to first input IN1 of hybrid coupler 1.

IN step STP2, a second signal SG2 is passed to the second input IN2 of coupler 1.

In step STP3, hybrid coupler 1 passes the first output signal to output ISO.

In step STP4, hybrid coupler 1 passes the second output signal to output OUT.

The first circuit DC3 then determines the first piece of information INF1 in step STP5, and the second circuit DC4 determines the second piece of information INF2 in step STP 6.

The processing circuit MTR then analyzes the cross-correlated information INF1 and INF2 in step STP 7.

If the two pieces of information are equal within a tolerance range, for example equal to a few mV, the two signals SG1 and SG2 are considered to be in phase.

On the other hand, if the two pieces of information INF1 and INF2 are not equal, the adjustment circuit MRG adjusts the phase of the signal SG2 in step STP 8.

In this respect, the control circuit MCM may send control signals to the phase shifter DPH to increase or decrease the initial phase of the signal SG2 by a given phase pitch, for example by 5 °.

The signal SG2, the phase of which is modified, is then passed again in step STP2, and steps STP4 and STP6 are repeated to obtain a new second piece of information INF 2.

Also, in step STP7, as long as the two pieces of information INF1 and INF2 are not equal within the tolerance range, step STP8 is repeated, for example, each time the phase of signal SG2 is increased by a selected phase pitch.

Also, when the two pieces of information INF1 and INF2 are equal within the tolerance range in step STP7, signal SG2 has been phase-shifted from its initial phase by a phase PHE called calibration phase. This phase PHE is equal to the difference between the final phase of signal SG2 and its initial phase, i.e., for example, the product of the number of pitches and the phase pitch value. And equality between the two pieces of information INF1 and INF2 means that the phase-shifted signal SG1 of the phase PHE is in phase with the phase-shifted signal SG 1.

Calibration phase PHE corresponds to the phase shift between signal SG1 and signal SG2 before adjusting the phase.

This value PHE may be obtained by a phase shift value introduced by the phase shifter DPH.

Fig. 3 shows an example of the structure of the peak detector DCi, for example the peak detector DC3, it being understood that the other peak detectors may advantageously have the same structure.

The detector DC3 comprises a first radio-frequency stage ET1, comprising a capacitor Cin, one terminal of which is connected to the output ISO terminal of the coupler 1 and a second terminal of which is connected to the gate of a MOS transistor M2.

The gate of this transistor M2 is biased using a resistor Rbias connected to a bias voltage Vbias.

The source of the transistor M2 is connected to the output terminal BS3 of the peak detector DC 3.

The peak detector DC3 further comprises a second stage ET2 comprising a current mirror based on two NMOS transistors M0 and M1, whose input receives the reference current Iref and whose output is also connected to the output terminal BS3 of the detector DC 3.

Finally, the detector DC3 comprises a direct current output stage ET3 comprising a capacitor Cpeak connected between the output terminal BS3 and ground.

The detector DC3 delivers at the output the peak value VC3 of the output signal DC voltage delivered to the output BS 3.

It is noted that the coupling of the two other peak detectors DC1 and DC2 on the two input terminals IN1 and IN2 as shown IN fig. 1 is optional, but may be particularly advantageous IN the case of radio frequency applications, as this symmetrizes the structure of the coupler.

In the case of a peak detector, the analysis performed by the processing circuitry in step STP7 includes: as shown in fig. 4, the absolute value of the difference between the peak DC voltage VC3 of the output signal delivered to the output terminal ISO and the peak DC voltage VC4 of the output signal delivered to the output terminal OUT of the coupler is determined.

And, the phase of the signal SG2 is adjusted until the absolute value of the difference is obtained as zero or almost zero (within a tolerance range, equal to a few mV for example), so as to determine the calibration phase and thus the phase shift between the two signals SG1 and SG 2.

Fig. 5 schematically shows a communication device APP, such as a cellular mobile phone, comprising a transmit chain CHT comprising a power amplifier PA and a device DIS, as described above.

In the example described here, the device DIS is used to determine, for example, the phase shift generated upstream of the power amplifier PA.

The device DIS then receives a signal SG1 and a signal SG2 from the transmit chain, signal SG2 may be a reference signal or, for example in case of a beamforming application, a signal from another transmit channel.

The device DIS then provides a phase shift PHE between the two signals SG1 and SG 2.

This phase shift in the phase shifter DPH1 coupled upstream of the amplifier PA may then be corrected to obtain a desired effective phase shift upstream of the amplifier PA, which is zero or none.

Of course, the same operation may be performed downstream of the power amplifier PA.

This calibration may be performed in a laboratory after all the detailed description of the illustrative embodiments is installed.

While the present invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is therefore intended that the appended claims encompass any such modifications or embodiments.

Claims

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

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

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

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

determining a second piece of information relating to the 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 a calibration phase is obtained for which the first piece of information is substantially equal to the second piece of information, wherein the first signal and the second signal have the same frequency, and wherein a phase shift between the first signal and the second signal is equal to the calibration 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 calibration phase corresponds to a substantially zero difference between the first peak value and the second peak value.

3. The method of claim 2, wherein determining the first peak of a 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 of a 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 peak detector and a fourth peak detector are coupled to the first input and the second input of the 90 ° hybrid coupler, respectively.

4. The method of claim 3, wherein the first peak detector, the second peak detector, the third peak detector, and the fourth peak detector are identical to one another.

5. The method of claim 2, wherein determining the first peak value of a 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 coupled to a current path of the first transistor; and

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

6. The method of claim 1, wherein the first signal and the second signal are radio frequency signals.

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

8. An apparatus for determining a phase shift between a first signal and a second signal, the apparatus 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 convey a first output signal, and a second output configured to convey a second output signal;

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

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

an adjustment circuit configured to adjust a phase of the second signal until a calibration phase is obtained 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 calibration phase, wherein the first signal and the second signal have the same frequency.

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

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

11. The apparatus of claim 9, wherein the first signal and the second signal are radio frequency signals.

12. The apparatus 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 power supply terminal and the output terminal; and

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

13. A communication device, comprising:

a transmit chain including a power amplifier; and

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

a 90 DEG 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 convey a first output signal, and a second output configured to convey a second output signal,

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

a second circuit configured to determine a second piece of information related to the power of the second output signal, an

An adjustment circuit configured to adjust a phase of the second signal until a calibration phase is obtained 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 calibration phase, wherein the first signal and the second signal have the same frequency.

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

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

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

17. The communication device of claim 15, wherein the first signal and the second signal are radio frequency signals.

18. The communication device 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 current mirror coupled to the current path of the first transistor.

19. The communication device of claim 13, wherein the communication device is a mobile phone.

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