Method and wireless communication device for using an antenna as a sensor device in guiding selection of optimized tuning networks

• US 9,407,335 B2
• Filed: 10/31/2013
• Issued: 08/02/2016
• Est. Priority Date: 08/06/2013
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Inventors: Ramasamy, Suresh K., Black, Gregory R., Dietrich, Aaron L., Leizerovich, Gustavo D., Minasi, David H., Shee, Koon K.
• Primary Examiner(s): TRAN, PABLO N
• Application Number:
  US14/068,404
• Publication Number:
  US 20150044977A1
• Time in Patent Office: 1,006 Days
• Field of Search: 455/77, 455/566, 333/32
• US Class Current: 1/1
• CPC Class Codes: H01Q 1/243 with built-in antennas
• CPC Class Codes: H01Q 1/44 using equipment having another main function to serve additionally as an antenna , e.g. means for giving an antenna an aesthetic aspectH01Q1/27 - H01Q1/34 take precedence
• CPC Class Codes: H03K 17/955 using a capacitive detector
• CPC Class Codes: H04B 7/0404 the mobile station comprising multiple antennas, e.g. to provide uplink diversity

Abstract

A method and system performs antenna tuning using detected changes in antenna self-capacitance in a wireless communication device. A modem detects changes in antenna self-capacitance by utilizing multiple antenna elements. The modem determines a current antenna loading condition using the detected changes in antenna self-capacitance. The modem determines appropriate tuning states for each antenna matching and tuning circuit (AMTC) associated with a respective antenna element. In order to determine the appropriate tuning states, the modem utilizes pre-established antenna self-capacitance information which is mapped to antenna tuning states. The antenna tuning states which are respectively mapped to pre-established antenna self-capacitance are empirically pre-determined by correlating antenna self-capacitance changes to antenna impedance changes. The modem is thus able to change the tuning states of multiple tunable matching circuits and perform antenna tuning using (a) detected real-time changes in antenna self-capacitance and (b) pre-established mappings of antenna self-capacitance and antenna tuning states.

Claims

1. A wireless communication device comprising:

multiple radio frequency (RF) transceivers;

multiple antenna matching and tuning circuits (AMTCs) each respectively coupled to a corresponding RF transceiver;

multiple antenna elements (AEs) each respectively coupled to a corresponding AMTC by a first coupling capacitor, wherein each AE is a first component of a corresponding capacitive touch and proximity sensor (CTPS);

a detection integrated circuit (IC) communicatively coupled to each respective CTPS and which detects a change in capacitance of a corresponding CTPS caused by proximity of an object to the antenna element, while the antenna element can be used to communicate RF signals; and

a modem coupled to the detection IC and each of the multiple RF transceivers and which;

responsive to detection of the respective change in capacitance corresponding to each of the multiple CTPSes, determines an antenna loading condition presented to the wireless communication device by the object located within specific proximity of corresponding antenna elements, based on a detected change in antenna self-capacitance associated with a corresponding antenna element;

determines antenna tuning states associated with each respective antenna element by using a pre-established mapping of antenna tuning states and changes in antenna self-capacitance correlated to antenna impedance, based on the determined antenna loading condition; and

performs antenna impedance tuning by respectively providing the determined antenna tuning states to the multiple AMTCs.

2. The wireless communications device of claim 1, wherein:

the modem comprises an application processor (AP) and (a) receives, from the detection IC, object detection signal information corresponding to the multiple AEs;

(b) determines the antenna loading condition by identifying a match for the received object detection signal information from among pre-established information about loading conditions;

(c) retrieves stored information identifying antenna tuning states mapped to changes in antenna self-capacitance, based on the determined antenna loading condition;

(d) determines the respective antenna tuning states to provide appropriate antenna impedance tuning, from the retrieved stored information; and

(e) transmits a respective control signal to each AMTC to provide an appropriate antenna tuning to offset antenna de-tuning caused by a respective proximity of the object to each of the multiple antenna elements.

3. The wireless communications device of claim 1, wherein:

the multiple antenna elements comprise multiple simplex antennas including at least one transmit antenna and at least one receive antenna.

4. The wireless communications device of claim 1, wherein:

the multiple antenna elements are at least one of (a) a set of simplex antennas and (b) a set of duplex antennas.

5. The wireless communications device of claim 1, wherein:

each of the multiple AMTCs is communicatively coupled to a corresponding high pass filter circuit that comprises a shunt inductor and a series capacitor coupled to the shunt inductor, wherein the high pass filter circuit isolates the detection IC from a corresponding AMTC by preventing the additional capacitive loading associated with tuning state adjustments at a corresponding AMTC from impacting a low frequency operation of the detection IC, wherein the high pass filter circuit enables the detection IC to attain operation within a suitable dynamic operating range and provide a suitable and expected level of detection resolution.

6. The wireless communications device of claim 5, wherein:

the detection IC is respectively communicatively coupled via multiple RF decoupling circuits to the antenna elements, wherein the RF decoupling circuits (a) prevent a propagation of RF communication signals to the detection IC, (b) ensure that detect signals which indicate changes in antenna self-capacitance satisfy pre-specified power levels and (c) serve to alleviate potential desensitization at corresponding receivers as a result of noise propagated onto the respective receivers from the respective detect input lines.

7. The wireless communications device of claim 1, wherein:

each of the multiple antenna elements are placed about a periphery of the wireless communication device to provide (a) sensory coverage over substantially all of the device periphery and (b) a pre-specified, corresponding level of sensitivity for various types of antenna loading conditions.

8. The wireless communications device of claim 1, wherein the detection IC:

enables detection of (a) changes in antenna self-capacitance, which changes match first pre-established changes in antenna self-capacitance respectively associated with the at least one antenna element, wherein said first pre-established changes are collectively mapped to a first pre-established loading condition which indicates that the device is being held in the right hand, and (b) changes in antenna self-capacitance, which changes match second pre-established changes in antenna self-capacitance respectively associated with the at least one antenna element, wherein said second pre-established changes are collectively mapped to a second pre-established loading condition which indicate that the device is being held in the left hand.

9. The wireless communications device of claim 8, wherein the modem:

in response to detecting changes in antenna self-capacitance, which changes match first pre-established changes, identifies a first loading condition in which the device is being held in the right hand as a current loading condition that impacts the wireless communication device; and

determines the antenna tuning states associated with respective antenna elements by using a pre-established mapping of antenna tuning states and changes in antenna self-capacitance, corresponding to the first loading condition that is associated with the device being held in the user'"'"'s right hand; and

in response to detecting changes in antenna self-capacitance, which changes match second pre-established changes, identifies a second loading condition in which the device is being held in the left hand as a current loading condition that impacts the wireless communication device; and

determines the antenna tuning states associated with respective antenna elements by using a pre-established mapping of antenna tuning states and changes in antenna self-capacitance, corresponding to the second loading condition that is associated with the device being held in the user'"'"'s left hand; and

wherein the antenna tuning states are respectively determined using the corresponding, detected changes in antenna self capacitance.

10. The wireless communications device of claim 1, wherein:

the detection IC operates at a pre-established low frequency to detect changes in antenna self-capacitance; and

a correlation between low frequency antenna self-capacitance and changes in antenna impedance for a given antenna loading condition at antenna operating frequency is pre-established to provide information that can be used within the wireless communication device in an open loop antenna tuning system that utilizes pre-established information, wherein the pre-established information is used to perform antenna tuning to compensate for antenna de-tuning using real-time changes in antenna self-capacitance.

11. In a wireless communications device having multiple antenna elements that are capacitively coupled to antenna matching and tuning circuits (AMTCs), respectively, and are each connected to at least one radio frequency (RF) choke to constitute a corresponding capacitive touch and proximity sensor (CTPS), a method comprising:

a detection integrated circuit (IC) detecting a change in antenna self-capacitance caused by an object located within specific proximity of a corresponding antenna element for each antenna element of a wireless communication device;

determining an antenna loading condition presented to the wireless communication device by the object located within specific proximity of corresponding antenna elements, based on a detected change in antenna self-capacitance associated with a corresponding antenna element;

determining an antenna tuning state corresponding to each of the antenna elements by using a pre-established mapping of antenna tuning states and changes in antenna self-capacitance correlated to antenna impedance, based on the determined antenna loading condition; and

performing antenna impedance tuning by using the generated antenna tuning states.

12. The method of claim 11, further comprising:

detecting the change in antenna self-capacitance caused by a proximate object using object detection signal information corresponding to the multiple AEs;

determining the antenna loading condition by identifying a match for the object detection signal information from among pre-established information for defining loading conditions;

retrieving stored information identifying antenna tuning states mapped to changes in antenna self-capacitance, based on the determined antenna loading condition, in order to determine the respective antenna tuning states to provide appropriate antenna impedance tuning; and

transmitting a respective control signal to each AMTC to provide an appropriate antenna tuning to offset antenna de-tuning caused by a respective proximity of the object to each of the multiple antenna elements.

13. The method of claim 11, wherein:

the multiple antenna elements comprise multiple simplex antennas including at least one transmit antenna and at least one receive antenna.

14. The method of claim 11, wherein:

the multiple antenna elements are at least one of (a) a set of simplex antennas and (b) a set of duplex antennas.

15. The method of claim 11, wherein:

each of the multiple AMTCs is communicatively coupled to a corresponding high pass filter circuit that comprises a shunt inductor and a series capacitor coupled to the shunt inductor, wherein the high pass filter circuit isolates the detection IC from a corresponding AMTC by preventing the additional capacitive loading associated with tuning state adjustments at a corresponding AMTC from impacting a low frequency operation of the detection IC, wherein the high pass filter circuit enables the detection IC to attain operation within a suitable dynamic operating range and provide a suitable and expected level of detection resolution.

16. The method of claim 15, wherein:

the detection IC is respectively communicatively coupled via multiple RF decoupling circuits to the antenna elements, wherein the RF decoupling circuits (a) prevent a propagation of RF communication signals to the detection IC, (b) ensure that detect signals which indicate changes in antenna self-capacitance satisfy pre-specified power levels and (c) serve to alleviate potential desensitization at corresponding receivers as a result of noise propagated onto the respective receivers from the respective detect input lines.

17. The method of claim 11, wherein:

each of the multiple antenna elements are placed about a periphery of the wireless communication device to provide (a) sensory coverage over substantially all of the device periphery and (b) a pre-specified, corresponding level of sensitivity for various types of antenna loading conditions.

18. The method of claim 11, wherein the detection IC:

enables detection of (a) changes in antenna self-capacitance, which changes match first pre-established changes in antenna self-capacitance respectively associated with the at least one antenna element, wherein said first pre-established changes are collectively mapped to a first pre-established loading condition which indicates that the device is being held in the right hand, and (b) changes in antenna self-capacitance, which changes match second pre-established changes in antenna self-capacitance respectively associated with the at least one antenna element, wherein said second pre-established changes are collectively mapped to a second pre-established loading condition which indicate that the device is being held in the left hand.

19. The method of claim 18, wherein the modem:

in response to detecting changes in antenna self-capacitance, which changes match first pre-established changes, identifies a first loading condition in which the device is being held in the right hand as a current loading condition that impacts the wireless communication device; and

determines the antenna tuning states associated with respective antenna elements by using a pre-established mapping of antenna tuning states and changes in antenna self-capacitance, corresponding to the first loading condition that is associated with the device being held in the user'"'"'s right hand; and

in response to detecting changes in antenna self-capacitance, which changes match second pre-established changes, identifies a second loading condition in which the device is being held in the left hand as a current loading condition that impacts the wireless communication device; and

determines the antenna tuning states associated with respective antenna elements by using a pre-established mapping of antenna tuning states and changes in antenna self-capacitance, corresponding to the second loading condition that is associated with the device being held in the user'"'"'s left hand; and

wherein the antenna tuning states are respectively determined using the corresponding, detected changes in antenna self capacitance.

20. The method of claim 11, wherein:

the detection IC operates at a pre-established low frequency to detect changes in antenna self-capacitance; and

a correlation between low frequency antenna self-capacitance and changes in antenna impedance for a given antenna loading condition at antenna operating frequency is pre-established to provide information that can be used within the wireless communication device in an open loop antenna tuning system that utilizes pre-established information, wherein the pre-established information is used to perform antenna tuning to compensate for antenna de-tuning using real-time changes in antenna self-capacitance.