RFID transponder and corresponding method of operation

Abstract

According to a first aspect of the present disclosure, there is provided a radio frequency identification (RFID) transponder, comprising: at least one functional component, the functional component being configured to perform a function of the RFID transponder; a charge pump, the charge pump being configured to supply an output voltage to the functional component, wherein the charge pump comprises a plurality of charge pump stages; a charge pump controller, the charge pump controller being configured to control the number of charge pump stages contributing to the output voltage. According to a second aspect of the present disclosure, a corresponding method of operating an RFID transponder is contemplated.

Description

Technical Field

[0001] The present disclosure relates to a radio frequency identification transponder. In addition, the present disclosure relates to a method of operating a radio frequency identification transponder. Background Art

[0002] Nowadays, radio frequency identification (RFID) transponders are widely used in different industrial and commercial fields and for various purposes. For example, RFID transponders can be implemented as so-called RFID tags or RFID cards. It should be noted that in the present disclosure, near field communication (NFC) transponders are regarded as a specific type of RFID transponders. Therefore, the principles described herein can also be applied to NFC transponders. Summary of the invention

[0003] According to a first aspect of the present disclosure, there is provided a radio frequency identification (RFID) transponder, comprising: at least one functional component configured to perform a function of the RFID transponder; a charge pump configured to supply an output voltage to the functional component, wherein the charge pump comprises a plurality of charge pump stages; and a charge pump controller configured to control the number of charge pump stages contributing to the output voltage.

[0004] In one or more embodiments, the charge pump controller is configured to control the number of the charge pump stages according to the output voltage.

[0005] In one or more embodiments, the charge pump controller is configured to deactivate one or more of the charge pump stages.

[0006] In one or more embodiments, the charge pump controller is configured to deactivate more charge pump stages as the output voltage increases.

[0007] In one or more embodiments, the charge pump controller is configured to deactivate fewer charge pump stages as the output voltage decreases.

[0008] In one or more embodiments, the charge pump controller is configured to control the number of the charge pump stages according to a status indicator.

[0009] In one or more embodiments, the charge pump includes a sequence of n charge pump stages, wherein the charge pump stages are coupled to ground through multiple first controllable switches, wherein the charge pump stages are coupled to each other through multiple second controllable switches, and wherein the charge pump controller is configured to deactivate one or more specific charge pump stages i = {1, 2, 3, ..., n} by: opening the second controllable switch between the charge pump stage i and the next charge pump stage i+1; closing the first controllable switch between the next charge pump stage i+1 and ground.

[0010] According to a second aspect of the present disclosure, a method of operating a radio frequency identification (RFID) transponder is contemplated, comprising: controlling, by a charge pump controller of the RFID transponder, a number of charge pump stages contributing to an output voltage of a charge pump; supplying, by the charge pump, the output voltage to at least one functional component of the RFID transponder; and performing a function of the RFID transponder by the functional component.

[0011] In one or more embodiments, the charge pump controller controls the number of the charge pump stages according to the output voltage.

[0012] In one or more embodiments, the charge pump controller disables one or more of the charge pump stages.

[0013] In one or more embodiments, the charge pump controller disables more charge pump stages as the output voltage increases.

[0014] In one or more embodiments, the charge pump controller deactivates fewer charge pump stages as the output voltage decreases.

[0015] In one or more embodiments, the charge pump controller controls the number of charge pump stages according to a status indicator.

[0016] In one or more embodiments, the charge pump includes a sequence of n charge pump stages, wherein the charge pump stages are coupled to ground through multiple first controllable switches, wherein the charge pump stages are coupled to each other through multiple second controllable switches, and wherein the charge pump controller deactivates one or more specific charge pump stages i = {1, 2, 3, ..., n} by: opening the second controllable switch between the charge pump stage i and the next charge pump stage i+1; and closing the first controllable switch between the next charge pump stage i+1 and ground. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Embodiments will be described in more detail with reference to the accompanying drawings, in which:

[0018] Figure 1 An illustrative embodiment of an RFID transponder is shown;

[0019] Figure 2 An illustrative embodiment of a method of operating an RFID transponder is shown;

[0020] Figure 3 Another exemplary embodiment of an RFID transponder is shown;

[0021] Figure 4 shows a further exemplary embodiment of an RFID transponder;

[0022] Figure 5 shows a further exemplary embodiment of an RFID transponder;

[0023] Figure 6 Further exemplary embodiments of RFID transponders are shown. DETAILED DESCRIPTION

[0024] Nowadays, radio frequency identification (RFID) transponders are widely used in different industrial and commercial fields and for various purposes. For example, RFID transponders can be implemented as so-called RFID tags or RFID cards. It should be noted that in the present disclosure, near field communication (NFC) transponders are regarded as a specific type of RFID transponders. Therefore, the principles described herein can also be applied to NFC transponders.

[0025] RFID communication can be based on inductive coupling. Communication between an RFID reader and an RFID transponder, such as an RFID tag, is usually achieved by means of load modulation and can be split into a forward link and a return link. More specifically, the RFID reader can transmit commands to the RFID transponder via the forward link, and the RFID transponder can transmit responses to those commands back to the RFID reader via the return link. The RFID transponder includes a modulator that load modulates a carrier signal. There are different types of load modulation, such as active load modulation (ALM) and passive load modulation (PLM). The return link can also be referred to as a "backscatter signal" or more succinctly as "backscatter".

[0026] In order to perform load modulation and other functions, the integrated circuit in the RFID transponder needs to be supplied with power. In a passive transponder, this power is extracted from the field generated by the reader. The transponder of the described type usually includes a charge pump, which is configured to convert a low input voltage into a higher output voltage. The higher output voltage generated by the charge pump is supplied to the integrated circuit of the transponder, which includes one or more functional components (e.g., a modulator). In other words, the charge pump ensures that the transponder can operate at a low input voltage.

[0027] RFID systems, especially ultra-high frequency (UHF) RFID systems, should cover a wide range of input powers and voltages. As mentioned above, charge pumps are usually used to convert low input voltages into higher output voltages. This ensures that the RFID transponder can be properly operated even at low input powers. The number of stages used is usually fixed. Therefore, under high input voltage conditions, the output voltage should be limited to avoid damaging the integrated circuit (IC) of the transponder. This results in a change in the input impedance of the IC, which in turn has a negative impact on the RFID system. What is now discussed is an RFID transponder and a corresponding method of operating the RFID transponder that helps reduce this negative impact on the RFID system.

[0028] Figure 1 An illustrative embodiment of an RFID transponder 100 is shown. The RFID transponder includes a functional component 102, a charge pump 104, and a charge pump controller 106. The functional component 102 is configured to perform a function of the RFID transponder 100, such as load modulation. The charge pump 104 is configured to supply an output voltage to the functional component 102 so that the functional component 102 can perform the function. The charge pump 104 receives an input voltage, which is derived from a field generated by an RFID reader (not shown) outside the RFID transponder 100. This input voltage is converted into a higher output voltage by the charge pump 104 and then supplied to the functional component 102. It should be noted that the RFID transponder 100 may include other functional components (not shown) that receive the output voltage of the charge pump 104. The charge pump 104 includes a plurality of charge pump stages (not shown). In addition, the charge pump controller 106 is configured to control the number of charge pump stages that contribute to the output voltage. In other words, not all charge pump stages can be used to generate the output voltage, but only a subset of the charge pump stages can be used to generate the output voltage. However, it should be noted that, although only a subset of the stages contribute to the output voltage, all stages can also remain in an active state, thereby ensuring that the input impedance will not change significantly. More specifically, the stages can remain active in the sense that, for example, the switching input of the RF field or the clock of the stage is not removed and they remain operational. For example, a signal received from an antenna and / or a clock signal can still be supplied to the stage that does not contribute to the output voltage. In this way, it can be avoided that the output voltage of, for example, the charge pump 104 is too high. Therefore, there is no need to limit the output voltage. This, in turn, may have several advantages: the IC input impedance will not change significantly - thereby avoiding negative impacts on the RFID system - and no additional components (i.e., voltage limiters) are required.

[0029] In one or more embodiments, the charge pump controller 106 is configured to control the number of charge pump stages according to the output voltage. Therefore, the output voltage of the charge pump 104 can be supplied back to the charge pump controller 106, and the charge pump controller 106 can reduce or increase the number of charge pump stages that contribute to the output voltage according to the output voltage. In this way, the output voltage of the charge pump 104 can be dynamically or effectively adjusted. Alternatively or in addition, the charge pump controller 106 can be configured to control the number of charge pump stages according to a state indicator. This state indicator can be provided, for example, by a power sensor, one or more voltage sensors, one or more current sensors, a temperature sensor, a light sensor, or indicate an internal state, an application field, and / or a required operating mode (certification, testing, production, etc.). All of these indicators help configure the charge pump controller 106 to prevent damage caused by overvoltage generated by the charge pump 104. Therefore, by controlling the number of charge pump stages according to the state indicator, effective overvoltage protection can be achieved.

[0030] In one or more embodiments, the charge pump controller 106 is configured to disable one or more of the charge pump stages. For example, if the charge pump stages are connected to each other in a chain, one or more of the stages can be disconnected from the chain, thereby reducing the output voltage generated by the charge pump 104. It should be noted that in the context of the present disclosure, disabling a charge pump stage refers to preventing the stage from contributing to the output voltage of the charge pump. In other words, disabling a charge pump stage does not mean invalidating a state. In a practical and effective embodiment, the charge pump controller 106 is configured to disable more (i.e., a larger number) of charge pump stages as the output voltage increases. In this way, an excessive output voltage can be avoided. In addition, in a practical and effective embodiment, the charge pump controller 106 is configured to disable fewer (i.e., a smaller number) of charge pump stages as the output voltage decreases. In this way, the output voltage can be easily and quickly increased when necessary.

[0031] In one or more embodiments, the charge pump comprises a sequence of n charge pump stages, the charge pump stages are coupled to ground via a plurality of first controllable switches, the charge pump stages are coupled to each other via a plurality of second controllable switches, and the charge pump controller is configured to deactivate one or more specific charge pump stages i={1, 2, 3, ..., n} by opening the second controllable switch between the charge pump stage i and the next charge pump stage i+1, and closing the first controllable switch between the next charge pump stage i+1 and ground. In this way, it is easy to deactivate the subset of charge pump stages, resulting in minimal change in the input impedance of the IC. In addition, there is no need to shorten or change the drive signal for the charge pump, which is received via antenna terminals RFp and RFn and originates from the radio frequency field generated by an external RFID reader.

[0032] Figure 2 An illustrative embodiment of a method 200 of operating an RFID transponder is shown. The method 200 includes the following steps: at 202, controlling, by a charge pump controller of the RFID transponder, a number of charge pump stages contributing to an output voltage of the charge pump; at 204, supplying, by the charge pump, the output voltage to at least one functional component of the RFID transponder; and at 206, performing, by the functional component, a function of the RFID transponder.

[0033] Figure 3 Another illustrative embodiment of an RFID transponder 300 is shown. The RFID transponder 300 includes a plurality of charge pump stages 302, 304, 306, 308 and a control logic 312, the control logic 312 being configured to control the plurality of charge pump stages 302, 304, 306, 308. The charge pump stages 302, 304, 306, 308 are coupled to antenna terminals RFp and RFn. In operation, the charge pump stages 302, 304, 306, 308 generate an output voltage that can be received by an IC supply module 310. The IC supply module 310 can supply power to one or more functional components 316 of the RFID transponder 300. According to the present disclosure, the control logic 312 is configured to control the number of charge pump stages 302, 304, 306, 308 that contribute to generating the output voltage. For example, the control logic 312 may be configured to control the number of charge pump stages 302, 304, 306, 308 according to the output voltage and / or according to the IC indicator 314 (i.e., the status indicator). A controllable switch is provided between each pair of charge pump stages 302, 304, 306, 308. In addition, a controllable switch is provided between the charge pump stages 302, 304, 306, 308 and the ground terminal.

[0034] It should be noted that each pair of switches present between two sequential charge pump stages comprises a switch for connecting the two charge pump stages to each other and a switch for connecting the first of the stages to ground. The switches in each pair are complementary in the sense that if one of the switches is closed the other switch will be open. Figures 4 to 6 Describe the operation of an RFID transponder.

[0035] Figure 4 4 shows another exemplary embodiment of an RFID transponder 400. The RFID transponder 400 includes a reference Figure 3 Parts described. Figure 4 308 so that all stages contribute to the output voltage. To this end, the control logic 312 controls the controllable switches so that all switches between the charge pump stages 302, 304, 306, 308 are closed and all switches between the charge pump stages 302, 304, 306, 308 and ground are open.

[0036] Figure 5 1 shows another exemplary embodiment of an RFID transponder 500. The RFID transponder 500 includes a reference Figure 3 Parts described. Figure 5 It is shown how the control logic 312 controls the charge pump stages 302, 304, 306, 308 so that the switch between the first charge pump stage 302 and the second charge pump stage 304 is opened and all switches between the second charge pump stage 304 to the nth charge pump stage 308 are closed. In addition, the control logic 312 controls the charge pump stages 302, 304, 306, 308 so that the switch between the second charge pump stage 304 and ground is closed and all switches between the third charge pump stage 306 to the nth charge pump stage 308 and ground are opened. Thus, the first charge pump stage 302 is disabled and only the second charge pump stage 304 to the nth charge pump stage 308 contribute to the output voltage. Therefore, in this case, i=1, and the charge pump controller (i.e., control logic 312) is configured to deactivate charge pump stage 1 by opening the controllable switch between charge pump stage 1 and the next charge pump stage i+1=2, and closing the controllable switch between the next charge pump stage i+1=2 and ground. Note that it is assumed that in the default state, all controllable switches between charge pump stages are closed and all controllable switches between charge pump stages and ground are open. Thus, the charge pump controller only needs to perform the operations described above to deactivate charge pump stage 1.

[0037] Figure 6 1 shows another exemplary embodiment of an RFID transponder 600. The RFID transponder 600 includes a reference Figure 3 Parts described. Figure 6It is shown how the control logic 312 controls the charge pump stages 302, 304, 306, 308 so that the switch between the first charge pump stage 302 and the third charge pump stage 306 is opened, and all switches between the third charge pump stage 306 to the nth charge pump stage 308 are closed. In addition, the control logic 312 controls the charge pump stages 302, 304, 306, 308 so that the switch between the second charge pump stage 304 and the ground and the switch between the third charge pump stage 306 and the ground are closed, respectively, and all remaining switches between the nth charge pump stage 308 and the ground are opened. Thus, the first charge pump stage 302 and the second charge pump stage 304 are disabled, and only the third charge pump stage 306 to the nth charge pump stage 308 contribute to the output voltage. Therefore, in this case, in the first operation of the charge pump controller, i=1, and the charge pump controller (i.e., the control logic 312) is configured to disable charge pump stage 1 by opening the controllable switch between charge pump stage 1 and the next charge pump stage i+1=2, and closing the controllable switch between the next charge pump stage i+1=2 and ground. In addition, in the second operation of the charge pump controller, i=2, and the charge pump controller is configured to disable charge pump stage 2 by opening the controllable switch between charge pump stage 2 and the next charge pump stage i+1=3, and closing the controllable switch between the next charge pump stage i+1=3 and ground. Note that in the default state, it is assumed that all controllable switches between charge pump stages are closed and all controllable switches between charge pump stages and ground are open. Thus, the charge pump controller only needs to perform the operations described above to disable charge pump stage 1 and charge pump stage 2. In addition, it should be noted that the charge pump controller does not need to perform two separate operations as described above. Alternatively, the charge pump controller can, for example, disable both stages simultaneously (i.e., in one control cycle).

[0038] It should be noted that the embodiments described above are presented for illustrative purposes only. In particular, the skilled person will appreciate that other embodiments are also possible. For example, in Figure 6 In the embodiment shown in , once the second operation has been performed, the state of the switch between charge pump stage 1 and charge pump stage 2 is no longer relevant to the state of the switch between charge pump stage 2 and ground, insofar as the change in the state of those switches does not affect the functionality of the sequence of charge pump stage 3 to the nth charge pump stage. Thus, the switch between charge pump stage 1 and charge pump stage 2 can be closed again, while the switch between charge pump stage 2 and ground can be opened. This may be beneficial for certain applications of RFID transponders.

[0039] It should be noted that the above embodiments have been described with reference to different subject matters. In particular, some embodiments may have been described with reference to method-type claims, while other embodiments may have been described with reference to apparatus-type claims. However, a person skilled in the art will conclude from the above that, unless otherwise indicated, any combination of features relating to different subject matters, in addition to any combination of features belonging to one type of subject matter, in particular a combination of features of method-type claims and features of apparatus-type claims, is also considered to be disclosed by this document.

[0040] In addition, it should be noted that the drawings are schematic. In different drawings, similar or identical elements are represented by the same figure mark. In addition, it should be noted that in order to provide a concise description of the illustrative embodiments, the implementation details that belong to the customary practices of technicians may not be described. It should be understood that in the development of any such implementation, as in any engineering or design project, a large number of implementation-specific decisions must be made to achieve the specific goals of the developer, such as complying with system-related and business-related constraints, which may vary depending on the implementation. In addition, it should be understood that such development work may be complex and time-consuming, but it is nothing more than a routine task of design, manufacturing and production for ordinary technicians who benefit from the present disclosure.

[0041] Finally, it should be noted that a skilled person should be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference numerals placed between parentheses should not be interpreted as limiting the claims. The word "comprise / comprising" does not exclude the presence of elements or steps other than those listed in the claims. The word "a / an" before an element does not exclude the presence of multiple such elements. The measures recited in the claims can be implemented by means of hardware comprising several unique elements and / or by means of a processor that is appropriately programmed. In a device claim that lists several components, several of these components can be implemented by one and the same hardware. The mere fact that certain measures are recited in different dependent claims does not mean that a combination of these measures cannot be used to advantage.

[0042] Reference numerals list

[0043] 100 RFID transponders

[0044] 102 functional components

[0045] 104 Charge Pump

[0046] 106 Charge Pump Controller

[0047] 200 Method of operating an RFID transponder

[0048] 202 Controlling the number of charge pump stages contributing to the output voltage of the charge pump by a charge pump controller of the RFID transponder

[0049] 204 Supplying an output voltage to at least one functional component of the RFID transponder via a charge pump

[0050] 206 Execution of the RFID transponder function by means of a functional component

[0051] 300 RFID transponders

[0052] 302 Charge Pump Stage

[0053] 304 Charge Pump Stage

[0054] 306 Charge Pump Stage

[0055] 308 Charge Pump Stage

[0056] 310 IC Supply

[0057] 312 Control Logic

[0058] 314 IC indicator

[0059] 316 (multiple) functional components

[0060] 400 RFID transponders

[0061] 500 RFID transponders

[0062] 600 RFID transponders.

Claims

1. A radio frequency identification (RFID) transponder, characterized in that: include: at least one functional component configured to perform a function of the RFID transponder; a charge pump configured to supply an output voltage to the functional component, wherein the charge pump comprises a plurality of charge pump stages; a charge pump controller configured to control a number of charge pump stages contributing to the output voltage, wherein the charge pump comprises a sequence of n charge pump stages; wherein the charge pump stage is coupled to ground via a plurality of first controllable switches; wherein the charge pump stages are coupled to each other via a plurality of second controllable switches; And wherein the charge pump controller is configured to deactivate one or more specific charge pump stages i={1, 2, 3, ..., n} by: disconnecting the second controllable switch between the charge pump stage i and the next charge pump stage i+1; The first controllable switch between the next charge pump stage i+1 and ground is closed.

2. The RFID transponder according to claim 1, characterized in that: The charge pump controller is configured to control the number of the charge pump stages according to the output voltage.

3. The RFID transponder according to claim 1 or 2, characterized in that: The charge pump controller is configured to deactivate one or more of the charge pump stages.

4. The RFID transponder according to claim 3, characterized in that: The charge pump controller is configured to deactivate more charge pump stages as the output voltage increases.

5. The RFID transponder according to claim 3 or 4, characterized in that: The charge pump controller is configured to deactivate fewer charge pump stages as the output voltage decreases.

6. An RFID transponder according to any of the preceding claims, characterized in that The charge pump controller is configured to control a number of the charge pump stages based on a status indicator.

7. A method of operating a radio frequency identification (RFID) transponder, characterized in that: include: controlling, by a charge pump controller of the RFID transponder, a number of charge pump stages contributing to an output voltage of a charge pump; supplying the output voltage to at least one functional component of the RFID transponder via the charge pump; The function of the RFID transponder is performed by the functional component, wherein the charge pump comprises a sequence of n charge pump stages; wherein the charge pump stage is coupled to ground via a plurality of first controllable switches; wherein the charge pump stages are coupled to each other via a plurality of second controllable switches; And wherein the charge pump controller is configured to deactivate one or more specific charge pump stages i={1, 2, 3, ..., n} by: disconnecting the second controllable switch between the charge pump stage i and the next charge pump stage i+1; The first controllable switch between the next charge pump stage i+1 and ground is closed.

8. The method according to claim 7, characterized in that The charge pump controller controls the number of the charge pump stages according to the output voltage.

9. The method according to claim 7 or 8, characterized in that: The charge pump controller disables one or more of the charge pump stages.

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