Communication device and method for determining a load impedance

Patent metadata

Field	Value
Publication number	US-10170822-B2
Application number	US-201715610697-A
Country	US
Kind code	B2
Filing date	Jun 1, 2017
Priority date	Jun 6, 2016
Publication date	Jan 1, 2019
Grant date	Jan 1, 2019

Abstract

According to one embodiment, a communication device is described comprising an antenna, a signal path for supplying a signal to the antenna, two directional couplers arranged within the signal path, wherein each directional coupler is coupled to an adjustable impedance defining the characteristic impedance of the directional coupler, a controller configured to set, for each of a plurality of impedances, the adjustable impedances of the directional couplers to the impedance, a return loss measurement circuit configured to determine, for each of the plurality of impedances, a return loss of the signal path when the adjustable impedances of the directional couplers are set to the impedance and a load impedance determination circuit configured to determine a load impedance of the signal path based on the determined return losses.

First claim

What is claimed is:

1. A communication device comprising:
a signal path for supplying a signal;
two directional couplers arranged within the signal path, wherein each directional coupler is coupled to an adjustable impedance defining a characteristic impedance of each directional coupler;
a controller configured to set, for each of a plurality of impedances, the adjustable impedances of the directional couplers to an impedance;
a return loss measurement circuit configured to determine, for each of the plurality of impedances, a return loss of the signal path when the adjustable impedances of the directional couplers are set to the impedance;
a load impedance determination circuit configured to determine a load impedance of the signal path based on the determined return losses.

2. The communication device of claim 1 , wherein each directional coupler comprises an input port, an output port, a coupled port and an isolated port,
and wherein for each directional coupler the adjustable impedance is coupled to the isolated port of each directional coupler.

3. The communication device of claim 2 , further comprising a cross-switching element for at least one of the directional couplers,
wherein the cross-switching element is configured to exchange the coupled port and the isolated port of the directional coupler, and
the adjustable impedance is coupled to the directional coupler via the cross-switch.

4. The communication device of claim 2 , wherein each directional coupler comprises
a first conductive path coupled between the input port and the output port of said directional coupler,
and a second conductive path coupled between the coupled port and the isolated port of said directional coupler, wherein
the first conductive path and the second conductive path are electrostatically and electromagnetically coupled with each other.

5. The communication device of claim 2 , wherein the adjustable impedance is coupled between the isolated port and ground.

6. The communication device of claim 1 , wherein the directional couplers are serially connected in the signal path.

7. The communication device of claim 1 , wherein the directional couplers are arranged back-to-back.

8. The communication device of claim 1 , wherein each directional coupler comprises an input port, wherein the input ports of the directional couplers are connected together.

9. The communication device of claim 1 , further comprising a load connected to the signal path at an antenna side, wherein the load impedance of the signal path is an impedance of the load.

10. The communication device of claim 9 , wherein the load comprises an antenna.

11. The communication device of claim 1 , wherein the signal is a radio frequency signal.

12. The communication device of claim 1 , further comprising a signal source configured to supply the signal to the signal path.

13. The communication device of claim 1 , wherein the two directional couplers form two directional coupler cells or two coupled branches of one of the directional couplers arranged in the signal path.

14. The communication device of claim 13 , wherein the directional coupler comprises an input port and an output port and the signal path leads through the directional coupler from the input port to the output port.

15. The communication device of claim 13 , wherein the directional coupler comprises an isolated port and a coupled port connected to the return loss measurement circuit.

16. The communication device of claim 1 , wherein the signal path comprises a main line and each directional coupler comprises a coupled line coupled to the main line.

17. The communication device of claim 16 , wherein the coupled lines of both directional couplers are at least partially arranged next to the same section of the main line.

18. The communication device of claim 1 , wherein the load impedance determination circuit is configured to determine the load impedance of the signal path based on a mapping of return losses measured for directional coupler characteristic impedances to load impedances.

19. The communication device of claim 18 , further comprising a memory storing a representation of the mapping.

20. The communication device of claim 19 , wherein the representation is a look-up table indicating the mapping.

21. The communication device of claim 1 , wherein the load impedance determination circuit is configured to determine the load impedance based on an intersection of a first circle in a smith diagram representing a first return loss of the determined return losses with a second circle in the smith diagram representing a second return loss of the determined return losses.

22. The communication device of claim 21 , wherein the load impedance determination circuit is configured to determine the load impedance based on a decision between two intersection points of the first circle and the second circle based on a third return loss of the determined return losses.

23. The communication device of claim 1 , further comprising an antenna tuner configured to tune the antenna based on the determined load impedance.

24. The communication device of claim 1 , further comprising
an antenna comprising a feed connection plane and an aperture connection plane,
the communication device further comprising any of:
a first impedance tuner, and
a second impedance tuner, and
an aperture tuner,
wherein the first impedance tuner is coupled to the signal path and the second impedance tuner is coupled to the signal path,
the antenna is coupled to the signal path via the feed connection plane, and
the aperture tuner is coupled to the antenna aperture connection plane.

25. The communication device of claim 24 , wherein the controller is configured to tune any of the first impedance tuner, the second impedance tuner and the aperture tuner based on the determined load impedance to minimize a reflection in the signal path.

26. The communication device of claim 25 , wherein controller is configured to tune any of the first impedance tuner, the second impedance tuner and the aperture tuner based on a mapping of load impedance to settings of the tuners.

27. The communication device of claim 24 , wherein the controller is configured to tune iteratively any of the first impedance tuner, the second impedance tuner and the aperture tuner until a target load impedance in the signal path reaches a predefined threshold value.

28. The communication device of claim 1 further comprising
a power amplifier, a harmonic termination and impedance transformation, an impedance measurements system and a first impedance tuner coupled to the signal path, and
a multiplexing switch which couples the signal path to any of n output paths.

29. The communication device of claim 28 , wherein the controller is configured to tune the first impedance tuner based on the determined load impedance to increase the power added efficiency of the power amplifier in the signal path by setting a best loadline for a defined supply voltage at a given target output power.

30. The communication device of claim 29 , wherein the controller is configured to tune the first impedance tuner based on the determined load impedance to increase a linearity of the power amplifier in the signal path by setting a best loadline for a defined supply voltage at a given target out

Assignees

• Infineon Technologies Ag

Inventors

• Solomko Valentyn
• Thomas Anthony
• Bakalski Winfried
• Bauder Ruediger

Classifications

• H01Q1/248 Primary

  provided with an AC/DC converting device, e.g. rectennas · CPC title

• H01Q1/241

  used in mobile communications, e.g. GSM (H01Q1/247, H01Q1/248 take precedence) · CPC title

• G01R27/2694

  Measuring dielectric loss, e.g. loss angle, loss factor or power factor · CPC title

• H04B1/04 Primary

  Circuits · CPC title

• H04L25/0278 Primary

  Arrangements for impedance matching · CPC title