Mobile device with a short circuit switch to processes a wireless communication and a wireless charging application

Abstract

Mobile device (16) to enable a wireless communication application with another device and to enable an energy harvesting application to charge a battery (17) or to power a processing stage of the mobile device (16), both applications based on a magnetic field with a specified carrier frequency in the HF frequency area, which mobile device (16) comprises an integrated circuit (18) with: a communication stage (19) that comprises a modulator (20) and a demodulator (21) built to enable load modulated wireless communication with the other device and with a harvesting stage (22) built for wireless harvesting of energy for the mobile device (16), which harvesting stage (22) comprises a rectifier (23) to provide a rectified DC-Voltage (VDDC), which rectifier (23) is connected via a first pin (27) and a second pin (28) of the integrated circuit (18) to a matching circuit (26) of the mobile device (16), which matching circuit (26) is connected with an antenna (25) of the mobile device (16), wherein that the communication stage (19) and the harvesting stage (22) are built to process the magnetic field with the same specified carrier frequency for both applications and, wherein the modulator (20) and the demodulator (21) are connected via a third pin (31) and a fourth pin (32) of the integrated circuit (18) directly to the antenna (25) and, that the integrated circuit (18) comprises a switch (33) connected parallel and directly to the rectifier (23) and directly with the first pin (27) and the second pin (28) of the integrated circuit (18) and, wherein the switch (33) is switched in its connecting status to short circuit the first pin (27) and the second pin (28) to enable the wireless communication application with only parallel to the antenna (25) arranged capacities (29, 30) in the matching circuit (26) and, wherein the switch (33) is switched in its disconnecting status to enable the charge application with only serial to the antenna (25) arranged capacities (29, 30) in the matching circuit (26).

Description

[0001] MOBILE DEVICE WITH A SHORT CIRCUIT SWITCH TO PROCESSES A WIRELESS COMMUNICATION AND A WIRELESS CHARGING APPLICATION

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to a mobile device to enable a wireless communication application with another device and to enable an energy harvesting application to charge a battery or to power a processing stage of the mobile device, both applications based on a magnetic field with a specified carrier frequency in the HF frequency area, which mobile device comprises an integrated circuit with: a communication stage that comprises a modulator and a demodulator built to enable load modulated wireless communication with the other device and with a harvesting stage built for wireless harvesting of energy for the mobile device, which harvesting stage comprises a rectifier to provide a rectified DC-Voltage, which rectifier is connected via a first pin and a second pin of the integrated circuit to a matching unit of the mobile device, which matching unit is connected with an antenna of the mobile device.

[0004] BACKGROUND OF THE INVENTION

[0005] There are mobile devices on the market like for instance the Samsung Galaxy Watch Active2 or the Samsung Galaxy Watch4 (SM-R870NZKKASIO) or Galaxy Fit SM-R370 device which are smart watches to be worn on a person’s wrist. Mobile devices like these smart watches comprises a communication stage that is realized by a dedicated payment communication integrated circuit connected via a first antenna matching unit to a first antenna to communicate at the frequency of 13.56 MHz. Most of these smart watches have poor performance with regard to the communication range. Some smart watches realize a payment application that complies with the Near Field Communication Standard ISO / IEC 18000-3 to enable payments at point of sales reader devices. These smart watches furthermore comprises a charge stage that is realized by a dedicated charge integrated circuit connected via a second antenna matching unit to a second antenna to charge the battery of the smart watch with energy harvested from the electromagnetic field or HF field with the frequency of 13.56 MHz or other frequencies in the HF field like typically 100 to 300kHz for Qi wireless charging. Some of these smart watches realize a proprietary system for wireless charging of the smart watch and for other charging applications a Wireless Charging Technical Specification has been released based on the NFC standard provided by the NFC Forum. Some of these wireless charging applications comprise a communication channel as well to communicate information related to wireless charging. Those smart watches that use the antenna with the antenna matching unit tuned for the energy harvesting application also for the communication application without any adoptions have a poor performance with regard to the communication range.

[0006] The wireless communication application and the wireless charging application of the smart watch are different applications with complete different needs for the wireless transfer and HF field. For the communication application of the smart watch with load modulation of a low field strength HF field by the smart watch the input impedance of the communication stage for its first antenna in the HF field needs to have an impedance in the range of a few kilo Ohm. For the wireless charging application the mobile device needs to harvest as much power from the HF field as possible to charge the internal battery. To achieve that, the charge stage with its second antenna needs to have a very low impedance in the HF field and the second antenna needs to be tuned by the second matching circuit at a resonance frequency ident to the carrier frequency of the magnetic field. These different impedances and for most applications also different resonance frequencies of the first and second antenna in the HF field for the different applications define the need for different matching circuits for the first and second matching unit to ensure, that the first antenna and the second antenna both work optimized for the different applications.

[0007] It is quite a disadvantage for a small device, like a smart wrist watch, to realize two different antennas and two different matching circuits in the limited volume of the wrist watch available. This increases the technical complexity and costs for such mobile devices. Furthermore, these two antennas influence each other in the HF field, what reduces the possible efficiency.

[0008] Figure 1 discloses a mobile phone 1 of the state of the art, which comprises an integrated circuit 2 with a communication stage 3, which comprises a modulator 4 and a demodulator 5 to enable wireless communication based on the NFC standard with another NFC device. Mobile phone 1 furthermore comprises a harvesting stage realized as charge stage 6 with a rectifier 7 and a battery charger 8 for wireless charging of a battery 9 of smart watch 1. An antenna 10 is connected via a matching circuit 11 with a first pin 12 and a second pin 13 of integrated circuit 2, wherein a first contact of the antenna 10 is connected via a first capacity 14 of matching circuit 11 with a first pin 12 and a second contact of the antenna 10 is connected via a second capacity 15 of matching circuit 11 with a second pin 13. This known concept of smart watch 1, that enables the NFC communication application and the NFC charging application, comprises the disadvantage, that matching circuit 11 can only be optimized for one of these two applications. The NFC wireless charging application requires a serial matching circuit for high power charging above 0.75W power level. Serial matching is not suitable for the NFC communication application as the impedance of rectifier 7 is high due to no or low charging power, that causes a low quality factor of the serial matching circuit. A low quality factor of the resonance leads to low voltage between the first pin 12 and the second pin 13, which is the input voltage for communication stage 3 and the charge stage 6.

[0009] US 2015 / 0054345 Al discloses a mobile device to enable a wireless communication application with another device at a carrier frequency of 13.56 MHz and to enable an energy harvesting application to charge a battery of the mobile device at another carrier frequency of 6.78 MHz. To enable resonant matching for these two different carrier frequencies, a matching circuit of this mobile device comprises four switches to switch several inductors and capacities of the matching circuit to tune for these different carrier frequencies. Furthermore two of these switches are used as overvolt protection to protect the harvesting stage.

[0010] SUMMARY OF THE INVENTION

[0011] It is an object of the invention to provide a mobile device and a method that realizes an optimized wireless communication application and a wireless charging application with less volume consumption in the mobile device and higher efficiency.

[0012] This object is achieved with a mobile device according to claim 1 and a method according to claim 6.

[0013] The integrated circuit of the inventive mobile device comprises a switch that short circuits the antenna input pins for the charge application in the wireless communication application to ensure optimal matching for the wireless communication application, which is achieved without any capacities of the matching circuit in the signal path to the communication stage. Therefore, the matching circuit for the wireless communication application realizes only parallel matching with capacities parallel to the antenna and the communication stage. With the switch in its disconnecting status the matching of the antenna at the input pins for the charge application is optimized for the charge application, which is achieved with only serial matching. Therefore, the matching circuit for the charge application realizes only serial matching with capacities serial in the connection from the antenna to the harvesting stage. Furthermore, both applications are processed with the same magnetic field with the one specific carrier frequency, in particular with the carrier frequency of 13.56 MHz. These features ensure a large communication range in the communication application and maximum energy transfer in the charging application and all of that with the same carrier frequency, what reduces the technical complexity of two different carrier frequencies at the other device (reader) and the mobile device.

[0014] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. The person skilled in the art will understand that various embodiments may be combined.

[0015] BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figures 1 shows a mobile device according to state of the art.

[0017] Figure 2 shows a mobile device according to a preferred embodiment of the invention.

[0018] Figure 3 shows a principle circuit drawing of a poller device and a listener device to enable simulation of a first use case of a wireless communication application with a mobile device of the state of the art according to figure 1 as listener.

[0019] Figure 4 shows a principle circuit drawing of a poller device and a listener device to enable simulation of a second use case of wireless communication application with a mobile device with the switch according to figure 2 as listener.

[0020] Figure 5 shows a principle circuit drawing of a poller device and a listener device to enable simulation of a third use case of a charge application with a mobile device with the switch according to figure 2 as listener.

[0021] DETAILED DESCRIPTION OF EMBODIMENTS

[0022] Figure 2 shows a mobile device 16 according to a preferred embodiment of the invention to wirelessly communicate with other devices and to charge a battery of the mobile device 16 via a magnetic field with a carrier frequency of 13.56 MHz. Such a wireless communication application is for instance known from standards like ISO 14443 or ISO 15693. Other frequencies in the HF frequency area could be used as well. The mobile device 16 could be a mobile phone or smart wrist watch or any other mobile smart device, that combines the features to enable the wireless communication application with another device and to enable a harvesting and in particular a charge application to charge a battery 17 of the mobile device 16.

[0023] Mobile device 16 comprises an integrated circuit 18 with a communication stage 19, which comprises a modulator 20 and a demodulator 21 to enable wireless communication based on the NFC standard with another NFC device. The communication partner that starts the communication is called a poller and the other a listener and the communication partner that provides the magnetic field is in its active mode. Mobile device 16 furthermore comprises a harvesting stage 22 with a rectifier 23 that generates and provides a rectified DC-Voltage VDDC of e.g. 5 Volt and supplies it to a battery charger 24 of the harvesting stage 22 for wireless charging of the battery 17 of mobile device 16. DC-Voltage VDDC furthermore is provided from the rectifier 23 to a power pin 40 of the integrated circuit 18, to which power pin 40 a micro controller unit or other processing stage of the mobile device 16 may be attached to power the processing stage. An antenna 25 is connected with the integrated circuit 18 via a matching circuit 26 with a first pin 27 and a second pin 28 of integrated circuit 18. The first pin 27 and a second pin 28 are directly connected within the integrated circuit 18 with rectifier 23 of harvesting stage 22. A first contact of the antenna 25 is connected via a first capacity 29 of matching circuit 26 with the first pin 27 and a second contact of the antenna 25 is connected via a second capacity 30 of matching circuit 26 with the second pin 28.

[0024] The integrated circuit 18 of mobile device 16 furthermore comprises a third pin 31 and a fourth pin 32 to directly connect the communication stage 19 with the antenna 25, while the first pin 27 and second pin 28 are arranged at the integrated circuit 28 to connect the harvesting stage 22 via matching circuit 26 with the sole antenna 25. The integrated circuit 18 furthermore comprises a switch 33 connected parallel and directly to the rectifier 23 and directly with the first pin 27 and the second pin 28 of the integrated circuit 18. Switch 33 may be switched into its connecting or closed status to short circuit the first pin 27 and the second pin 28 to enable the wireless communication mode or application with an increased communication range. This increased communication range is achieved as there is only parallel matching, with the first capacities 29 and the second capacity 30 in series to each other and parallel to the antenna 25, and no capacity in the direct signal path from the antenna 25 to the communication stage 19. Switch 33 furthermore may be switched into its disconnecting or open status to enable the charge application with high power energy transfer from the other device in its active mode. This high power transfer is achieved as there is only serial matching with the signal path from the antenna 25 to the first capacity 29 to the rectifier 23 and from the rectifier 23 to the second capacity 30 to the antenna 25.

[0025] As use case of mobile device 16 realized by a wrist watch will be explained below, wherein a method to enable a wireless communication application with another device and to enable a charge application to charge the battery 17 of the mobile device 16 is implemented. As example, the wrist watch processes a sports application where movement data and heart rate data are monitored and stored during a day, which sports data may be downloaded onto a computer via a NFC reader connected to the computer. The NFC reader, not shown in figure 2, is in its active mode and generates a magnetic field with a carrier frequency of 13.56 MHz and is active as a poller to interrogate, if a wrist watch, like mobile device 16, entered the magnetic field to start the wireless communication application to download sports data from the wrist watch.

[0026] In a first step of the method mobile device 16 activates the connecting status of the switch 33 to enable an increased communication range for the communication application. The closed switch 33 short circuits first pin 27 with second pin 28 what creates a low impedance path and leads to a high quality of the resonance. The transfer of with modulator 20 modulated to be transmitted data to the antenna 25 and the transfer of from the antenna 25 received modulated data to be demodulated with demodulator 21 is done via the third pin 31 and the fourth pin 32, which directly connect the modulator 20 and the demodulator 21 with the antenna 25, what enable high voltages and a large communication range. This enables a qualitative stable and good communication between the NFC reader and the mobile device 16 as soon as mobile device 16 enters the magnetic field of the NFC reader. During this wireless communication sports data are downloaded from the mobile device 16 to the computer.

[0027] In a second step of the method mobile device 16 communicates with the NFC reader via the magnetic field generated by the NFC reader and it is decided that the charge application of the mobile device 16 should be started to charge the battery 17 of the mobile device 16. This decision may be taken by the computer / NFC reader or by the mobile device 16. The charge application is processed with the same specified carrier frequency of 13.56 MHz like the communication application.

[0028] In a third step of the method mobile device 16 activates the disconnecting status of the switch 33 to enable high power charging of the battery 17 with the energy transferred in the magnetic field during the charge application, as it has been decided to charge the battery 17. The opened switch 33 enables a serial matching from the first contact of antenna 25 via first capacity 29 and first pin 27 to rectifier 23 and via second pin 28 and second capacity 30 to second contact of antenna 25. This serial matching enables a wireless high power charging of above 0.75W power level. Although the communication range in the charge application is not as large as in the communication application, communication between the NFC reader and the mobile device 16 is still possible. This communication may for instance be used to adopt the signal strength of the magnetic field during different phases of the charging process.

[0029] In a fourth step of the method mobile device 16 activates the connecting status of the switch 33 to again enable an increased communication range for the communication application, after the battery 17 is fully charged. This again increased communication range enables that mobile device 16 may be moved away a few centimeters from the NFC reader, what eases for instance a manual input at the wrist watch by the user.

[0030] Figure 3 shows a principle circuit drawing 34 of a poller device 35 and a listener device 36 to enable simulation of a first use case of the wireless communication application with mobile phone 1 of the state of the art according to figure 1 as listener 36. First capacity 14 and second capacity 15 of matching circuitry 11 both are simulated with 275 pF and the input impedance of rectifier 7 is simulated with 1 kOhm.

[0031] Figure 4 shows a principle circuit drawing 37 of a poller device 38 and a listener device 39 to enable simulation of a second use case of the wireless communication application with mobile device 16 with the switch 33 in its connected status according to figure 2 as listener 39. First capacity 29 and second capacity 30 of matching circuitry 26 both are simulated with 275 pF and the input impedance of rectifier 23 is simulated with 1 kOhm as well, but switch 33 in its connected status is closed and short circuits the input impedance of rectifier 23 for antenna 25.

[0032] Figure 5 shows the same principle circuit drawing 37 of poller device 38 and a listener device 39 of figure 4, but to enable the simulation of a third use case of the charge application, with switch 33 of mobile device 16 in its disconnected status and input impedance of the communication stage 19 simulated with 50 Ohm.

[0033] The result of the simulation of above three use cases can be seen in below table: This simulation result proves the technical advantage of the inventive embodiment of figure 2, that the voltage at antenna 25 is high in the wireless communication application of figure 4, what results in a high quality of the communication, and that the coupling and voltage at the receiver 23 is high for the high power transfer of the charge application in figure 5.

[0034] In a further embodiment of the invention DC-Voltage VDDC provided during the energy harvesting application at power pin 40 is used to power a processing stage of the wrist watch. This processing stage could be a micro controller unit to process sensor data or a sensor to measure the heart rate. This provides the advantage that the energy to power this device internal processing stage is provided by the NFC reader in its active mode during charging of the battery 17.

Claims

CLAIMS1. Mobile device (16) to enable a wireless communication application with another device and to enable an energy harvesting application to charge a battery (17) or to power a processing stage of the mobile device (16), both applications based on a magnetic field with a specified carrier frequency in the HF frequency area, which mobile device (16) comprises an integrated circuit (18) with: a communication stage (19) that comprises a modulator (20) and a demodulator (21) built to enable load modulated wireless communication with the other device and with a harvesting stage (22) built for wireless harvesting of energy for the mobile device (16), which harvesting stage (22) comprises a rectifier (23) to provide a rectified DC-Voltage (VDDC), which rectifier (23) is connected via a first pin (27) and a second pin (28) of the integrated circuit (18) to a matching circuit (26) of the mobile device (16), which matching circuit (26) is connected with an antenna (25) of the mobile device (16), characterized in that the communication stage (19) and the harvesting stage (22) are built to operate with the same specified carrier frequency for both applications and, wherein the modulator (20) and the demodulator (21) are connected via a third pin (31) and a fourth pin (32) of the integrated circuit (18) directly to the antenna (25) and, that the integrated circuit (18) comprises a switch (33) connected parallel and directly to the rectifier (23) and connected directly with the first pin (27) and the second pin (28) of the integrated circuit (18) and, wherein the switch (33) is switched in its connecting status to short circuit the first pin (27) and the second pin (28) to enable the wireless communication application with only parallel to the antenna (25) arranged capacities (29, 30) in the matching circuit (26) and, wherein the switch (33) is switched in its disconnecting status to enable the charge application with only serial to the antenna (25) arranged capacities (29, 30) in the matching circuit (26).

2. Mobile device (16) according to claim 1, wherein the matching circuit comprises only two capacities, namely the first capacity (29) and the second capacity (30).

3. Mobile device (16) according to any of the claims 1 or 2, wherein the communication stage is built to communicate with the other device although the switch (33) is switched in its disconnecting status to enable the charge application.

4. Mobile device (16) according to any of the claims 1 to 3, wherein harvesting stage (22) comprises a battery charger (24) powered by the rectified DC-Voltage (VDDC) and connected to the battery (17) to use the harvested energy to charge the battery (17).

5. Mobile device (16) according to any of the claims 1 to 4, wherein harvesting stage (22) is connected to a power pin (40) of the integrated circuit (18) to provide the rectified DC- Voltage (VDDC) at the power pin (40) and to use the harvested energy to power the processing stage of the mobile device (16).

6. Method to enable a wireless communication application with another device and to enable a charge application to charge a battery (17) of the mobile device (16) both applications based on a magnetic field with the same specified carrier frequency in the HF frequency area, which method is processed with a mobile device (16) according to one of the claims 1 to 4 and comprises the following steps:Activate the connecting status of a switch (33) to enable an increased communication range for the communication application;Communicate with another device in the same magnetic field and decide whether or not the charge application should be started to charge the battery (17) of the mobile device (16);Activate the disconnecting status of the switch (33) to enable high power charging of the battery (17) with the energy transferred in the magnetic field during the charge application, if it has been decided to charge the battery (17).

7. Method according to claim 6, which furthermore comprises the following step:Activate the connecting status of the switch (33) to enable an increased communication range for the communication application, after the battery (17) is fully charged.

8. Method according to any of the claims 6 or 7, which furthermore comprises the following step:Communicate with the other device in the same magnetic field with reduced communication range while the switch (33) is in its disconnected status during the charge application.

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