ANTENNA ELEMENT AS CAPACITIVE PROXIMITY/TOUCH SENSOR FOR ADAPTIVE ANTENNA PERFORMANCE IMPROVEMENT

• US 20130217342A1
• Filed: 02/22/2012
• Published: 08/22/2013
• Est. Priority Date: 02/22/2012
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola Mobility, Inc. (Lenovo Group Ltd.)
• Inventors: Abdul-Gaffoor, Mohammed R., Breunig, Brian, Li, Qiuming, Mehrotra, Akshat
• Granted Patent: US 8,971,826 B2
• Time in Patent Office: Days
• US Class Current: 455/77
• CPC Class Codes: H01Q 1/245 with means for shaping the antenna pattern, e.g. in order to protect user against rf exposure
• CPC Class Codes: H01Q 1/52 Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure absorbing means H01Q17/00
• CPC Class Codes: H03K 17/955 using a capacitive detector
• CPC Class Codes: H03K 17/962 Capacitive touch switches

Abstract

A method and communications device for providing antenna tuning to compensate for antenna de-tuning caused by a presence of an object detected using an antenna element within a capacitive touch and proximity sensor (CTPS). The CTPS propagates object detection signals associated with a detected object to a detection IC. An object detection and antenna tuning (ODAT) logic uses object detection signal information to generate tuning control signals to trigger compensatory antenna tuning, based on pre-established mappings of object detection signal data and antenna tuning states. The tuning control signals indicate at least one of (a) a level of compensatory antenna impedance tuning and (b) an amount of compensatory antenna length adjustment. In response to generating the tuning control signals, the ODAT logic triggers the propagation of the tuning control signals to the antenna matching and control circuit to provide the corresponding antenna tuning.

Claims

1. A wireless communications device comprising:

a radio frequency (RF) transceiver;

an antenna matching and tuning circuit (AMTC) coupled to an output of the RF transceiver;

an antenna element (AE) coupled to an output of the AMTC by a first coupling capacitor and RF connected by a second low frequency blocking capacitor to ground to prevent a flow of low frequency signals to ground, wherein the AE is a first component of a capacitive touch and proximity sensor (CTPS) which includes a high impedance component (HIC) directly coupled to the AE;

a detection integrated circuit (IC) connected to the HIC of the CTPS and which;

detects a change in capacitance of the CTPS caused proximity of an object to the antenna element, while the antenna element is being used to communicate RF signals; and

responsive to detection of the change in capacitance of the CTPS, triggers a transmission of at least one control signal to the AMTC to provide an appropriate antenna tuning to offset antenna de-tuning caused by the proximity of the object to the antenna element.

2. The wireless communications device of claim 1, further comprising:

a modem coupled to the RF transceiver; and

an application processor (AP) that is coupled to the detection IC and the modem, wherein the application processor;

(a) selectively enables operation of the detection IC based on information received from the modem about RF signal power at the AE;

(b) receives object detection signal information from the detection IC; and

(c) generates, using the information about RF signal power and the object detection signal information, (i) antenna tuning control signals and (ii) power tuning parameters to trigger a transmit power adjustment.

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

the ATMC is coupled to the detection IC, and the detection IC;

responsive to receiving, (a) an activation signal from the application processor to enable operation of said detection IC and (b) at least one object detection signal from the CTPS, forwards object detection signal information to the application processor;

the application processor, in response to receiving the object detection signal information;

generates antenna tuning control signals that provide at least one of (a) a level of compensatory antenna impedance tuning and (b) an amount of compensatory antenna length adjustment in the antenna tuning and matching circuit;

forwards the antenna tuning control signals to the detection IC to cause the detection IC to send the antenna tuning control signals to the AMTC to provide the corresponding antenna tuning; and

forwards the power tuning parameters to the modem;

the modem generates transmit power control signals to adjust the transmit power of the RF transceiver responsive to the tuning parameters being received from the AP.

4. The wireless communications device of claim 2, wherein the modem is coupled to an output port of the detection IC and generates transmit power control signals to adjust the transmit power of the RF transceiver based on object detection signal information received directly from the output port of the detection IC.

5. The wireless communications device of claim 2, wherein the modem is coupled to an output port of the detection IC, and the modem:

generates (a) transmit power control signals to adjust the transmit power of the RF transceiver, and (b) an antenna tuning control signal; and

propagates the antenna tuning control signal to the AMTC to provide the appropriate antenna tuning.

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

the application processor;

(a) generates, using the received RF signal power information and the object detection signal information, a tuning control signal and a power control signal;

(b) forwards the tuning control signal to the AMTC to trigger a corresponding antenna tuning; and

(c) forwards the power control signal to the modem to trigger a transmit signal power adjustment at the RF transceiver.

7. The wireless communications device of claim 2, further comprising:

a Field Programmable Gate Array (FPGA) component coupled to at least one output of the application processor and to a control signal input of the AMTC;

wherein the application processor;

generates a transmit power control signal and multiple tuning control signals;

forwards the transmit power control signal to the modem to trigger a transmit signal power adjustment at the RF transceiver; and

forwards the multiple tuning control signals to the FPGA component to cause the FPGA component to selectively provide the AMTC with at least one of (a) a first control signal for antenna tuning in response to switching an operating frequency band of the AE and (b) a second control signal for antenna tuning based on an at least one object detection signal.

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

the antenna element has multiple antenna arms that are connected together by coupling capacitors which enables a change in capacitance of each of the multiple arms to be independently and separately detected through multiple input ports of the detection IC;

the at least one HIC comprises multiple RF chokes that are coupled to each antenna arm and to each of a plurality of input ports of the detection IC;

the antenna element, the coupling capacitors that connect the multiple antenna arms, and the multiple RF chokes constitute the CTPS;

the detection IC;

determines, using multiple object detection signals received from the CTPS at multiple input ports of the detection IC, a change in capacitance in each of the multiple antenna arms caused by a presence of at least one object, and generates object detection signal information associated with object detection corresponding to at least one individual antenna arm of the AE; and

the application processor generates said tuning parameters by using a collective object detection signal information received from the detection IC corresponding to the multiple object detection signals received by the detection IC.

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

in response to receipt of the object detection signal information associated with multiple, independent object detection signals, the application processor uses the object detection signal information associated with object detection by several antenna arms of the antenna element to determine whether a localized proximity of a detected object can be identified; and

in response to identifying the localized proximity of the detected object, (a) determines a current operating condition of the wireless communications device and (b) selects the appropriate antenna tuning to be performed by the antenna matching and tuning circuit by using a pre-established association between operating conditions and antenna tuning.

10. The wireless communications device of claim 2, wherein the application processor:

in response to receiving the object detection signal information, retrieves a stored data structure that comprises associations of operating condition with pre-established object detection signal data corresponding to a type and proximity of object detection by the CTPS;

identifies, from the pre-established object detection signal data, a first object detection signal data that matches the received object detection signal information;

identifies an operating condition that is associated with the first object detection signal data, wherein the identified operating condition indicates a current operating condition of the wireless communications device with a detected object;

determines an appropriate antenna tuning adjustment required to effectively compensate for an antenna de-tuning that is associated with the identified current operating condition;

wherein the appropriate antenna tuning adjustment is determined based on at least one of;

(a) the current operating condition;

(b) a current operating frequency band utilized by the wireless communications device; and

(c) preset associations of operating conditions and antenna tuning states; and

automatically generates control signals to effect the determined appropriate antenna tuning adjustment required.

11. In a wireless communications device having an antenna element that is capacitively coupled to an antenna matching and tuning circuit (AMTC) and is connected to at least one radio frequency (RF) choke to constitute a capacitive touch and proximity sensor (CTPS), a method comprising:

detecting via the CTPS a presence of an object within a specific proximity to the antenna element, wherein said detecting is caused by a change in a capacitance of the CTPS indicated by at least one object detection signal that is received by a detection IC;

determining an antenna tuning state corresponding to the at least one object detection signal to compensate for antenna de-tuning caused by the presence of the object;

generating at least one control signal to provide antenna tuning to compensate for the presence of the object; and

propagating the at least one control signal to the AMTC to trigger antenna tuning that can compensate for antenna de-tuning caused by the proximity of the object to the capacitive touch and proximity sensor.

12. The method of claim 11, wherein said wireless communications device includes an application processor coupled to the detection IC, and the method further comprising:

receiving, at the application processor, object detection signal information from the detection IC, wherein the object detection signal information includes a signal amplitude for a corresponding object detection signal; and

determining, at the application processor, a type and amount of antenna tuning that corresponds to the received object detection signal information.

13. The method of claim 12, wherein:

the detection IC is coupled to the AMTC;

said wireless communications device includes an RF transceiver that is coupled to the AMTC and a modem that is coupled to the RF transceiver and to the application processor; and

the method further comprises;

receiving RF signal power information at the application processor from the modem; and

generating at least one control signal to provide antenna tuning corresponding to the object detection signal information and the RF signal power information received;

responsive to generating the at least one control signal, forwarding, by the application processor, the control signal to the detection IC to cause the detection IC to propagate the at least one control signal to the AMTC.

14. The method of claim 13, wherein said detection IC is coupled to said modem, and the method further comprises:

generating, at the application processor, power control information to indicate a signal power adjustment that is appropriate at the RF transceiver, corresponding to the RF signal power information and the object detection signal information;

forwarding the power control information to the modem to trigger the modem to generate a power control signal and to propagate the power control signal to the RF transceiver in order to provide a corresponding signal power adjustment.

15. The method of claim 11, wherein said wireless communications device includes an application processor coupled to the detection IC, an RF transceiver that is coupled to the AMTC, and a modem that is coupled to each of the RF transceiver, the detection IC, the AMTC, and the application processor, and the method further comprises:

receiving RF signal power information at the application processor from the modem;

generating, at the application processor, (a) power control information and (b) at least one antenna tuning control signal, utilizing the RF signal power information and the object detection signal information;

forwarding the generated power control information and the at least one antenna tuning control signal to the modem, wherein the generated power control information triggers the modem to (a) generate a first control signal to trigger a corresponding signal power adjustment at the RF transceiver, and (b) propagate the at least one antenna tuning control signal to the AMTC to provide the compensatory antenna tuning.

16. The method of claim 11, wherein said wireless communications device includes (a) an application processor coupled to the detection IC and to a control input of the AMTC, (b) an RF transceiver that is coupled to the AMTC, and (c) a modem that is coupled to the RF transceiver and to the application processor, the method further comprising:

generating, at the application processor, at least one tuning control signal and a power control signal;

propagating the at least one tuning control signal to the AMTC; and

propagating the power control signal to the modem to trigger an appropriate level of signal power adjustment at the RF transceiver.

17. The method of claim 16, wherein:

said wireless communications device includes a Field Programmable Gate Array (FPGA) component that is coupled between at least two outputs of the application processor and the control input of said antenna matching and tuning circuit;

the at least one tuning control signal comprises multiple tuning control signals including (a) a first control signal for antenna tuning in response to the device switching an operating frequency band and (b) a second control signal for antenna tuning in response to an object being detected via the CTPS; and

the method further comprises;

propagating the first control signal and the second control signal to the FPGA component; and

selectively providing, via the FPGA component, the AMTC with at least one of (a) the first control signal and (b) the second control signal.

18. The method of claim 11, wherein the first antenna element has multiple antenna arms that are connected together by coupling capacitors, wherein the at least one RF choke comprises multiple RF chokes coupled to each antenna arm and to each of a plurality of input ports of the detection IC, wherein the detection IC determines, using multiple object detection signals received at multiple input ports of the detection IC, a change in capacitance in each of the multiple antenna arms, wherein the application processor generates tuning parameters using the collective object detection signal information that is received from the detection IC and which collective object detection signal information corresponds to the multiple object detection signals received by the detection IC.

19. The method of claim 11, further comprising:

in response to receiving the object detection signal information, retrieving a stored data structure that comprises associations of operating condition with pre-established object detection signal data corresponding to a type and proximity of object detection by the CTPS;

identifying, from the pre-established object detection signal data, a first object detection signal data that matches the received object detection signal information;

identifying an operating condition that is associated with the first object detection signal data, wherein the identified operating condition indicates a current operating condition of the wireless communications device and antenna element relative to a presence of an object;

determining an appropriate antenna tuning adjustment required to effectively compensate for an antenna de-tuning that is associated with the identified current operating condition;

wherein the appropriate antenna tuning adjustment is determined based on at least one of;

(a) the current operating condition;

(b) a current operating frequency band utilized by the wireless communications device; and

(c) preset associations of operating conditions and antenna tuning states; and

automatically generating control signals to effect the determined appropriate antenna tuning adjustment required.