Active shielding device and active shielding method

Abstract

An active shielding device comprising a current source; an analog line shield unit; a switch; a current-to-voltage converter configured to generate a voltage in response to a current generated by the current source and a digital control sequence for the switch; a voltage comparator configured to compare the voltage generated by the current-to-voltage converter to a reference voltage; a digital active shield unit; digital logic configured to process the digital control sequence before and after conducting the digital control sequence through the digital active shield unit to generate a first processed result signal and a second result signal; and a digital comparator configured to compare the first processed result signal to the second result signal.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to active shielding devices and active shielding methods. BACKGROUND

[0002] Invasive attacks can be used to illegally access information from a circuit, such as an encryption circuit or a security circuit, or to alter information at the circuit. Probing is one type of invasive attack that an attacker can use to read data from or write data into an integrated circuit (IC) chip through a port, i.e., a probe head. For example, a focused ion beam (FIB) device can cut one or more traces in a metal layer of the IC chip and then alter the structure of the IC chip, such as by depositing one or more new traces or isolation layers into the IC chip and / or by implanting ions to change the doping of a region of a semiconductor substrate (e.g., silicon) of the IC chip. To prevent invasive attacks, active shielding techniques can be used to detect whether a circuit has been tampered with. For example, digital active shielding can form a physical barrier across signal lines of the IC chip and disable the IC chip in the event that the IC chip has been tampered with. However, although digital active shielding can provide protection against invasive attacks, a digital signal at a 0 / 1 level can be compromised through long-term monitoring. Thus, there is a need for active shielding techniques that can provide more sophisticated protection against invasive attacks. SUMMARY

[0003] Embodiments of an active shielding device and a method for active shielding are disclosed. In an embodiment, an active shielding device includes a current source configured to generate a current, an analog line shielding unit connected to the current source, a switch connected between the current source and the analog line shielding unit, a current-to-voltage converter connected to the analog line shielding unit and configured to generate a voltage in response to the current generated by the current source and a digital control sequence for the switch, a voltage comparator connected to the current-to-voltage converter and configured to compare the voltage generated by the current-to-voltage converter to a reference voltage, a digital active shielding unit connected to the current source, digital logic configured to process the digital control sequence to generate a first processed result signal and a second result signal before causing the digital control sequence to pass through the digital active shielding unit and after causing the digital control sequence to pass through the digital active shielding unit, and a digital comparator configured to compare the first processed result signal to the second result signal.

[0004] In an embodiment, the digital active shielding unit includes an even number of inverters.

[0005] In an embodiment, the digital logic are identical to each other.

[0006] In embodiments, one of the digital logics is connected to the switch through a digital active shield unit.

[0007] In embodiments, the current sources are connected in parallel to each other.

[0008] In embodiments, the analog line shield unit comprises analog line windings connected between the current sources and a current-to-voltage converter.

[0009] In embodiments, each of the analog line windings is connected to a different one of the current sources.

[0010] In embodiments, the active shielding device additionally comprises a controller configured to generate the digital control sequence.

[0011] In embodiments, the controller comprises a random number generator.

[0012] In embodiments, an active shielding device comprises: first, second, third, and fourth sets of current sources, wherein each of the first, second, third, and fourth sets of current sources is configured to generate a current; an analog line shield unit connected to the second and fourth sets of current sources; first, second, third, and fourth sets of switches connected to the first, second, third, and fourth sets of current sources, respectively, and controlled by a digital control sequence; a first current-to-voltage converter connected to the first set of current sources through the analog line shield unit and to the fourth set of current sources, and configured to generate a first voltage in response to the currents generated by the first and fourth sets of current sources; a first voltage comparator connected to the first current-to-voltage converter and configured to compare the first voltage to a first reference voltage; a second current-to-voltage converter connected to the second set of current sources through the analog line shield unit and to the third set of current sources, and configured to generate a second voltage in response to the currents generated by the second and third sets of current sources; a second voltage comparator connected to the second current-to-voltage converter and configured to compare the second voltage to a second reference voltage; a third voltage comparator configured to compare a result from the first voltage comparator to a result from the second voltage comparator; a digital active shield unit connected to the second and third sets of current sources; digital logics configured to process the digital control sequence before and after conducting the digital control sequence through the digital active shield unit to generate a first processed result signal and a second result signal; and a digital comparator configured to compare the first processed result signal to the second result signal.

[0013] In an embodiment, the digital active shielding unit comprises an even number of inverters.

[0014] In an embodiment, the digital logics are identical to each other.

[0015] In an embodiment, one of the digital logics is connected to the switch through the digital active shielding unit.

[0016] In an embodiment, each of the current sources within one of the first, second, third, and fourth groups of current sources is connected in parallel to each other.

[0017] In an embodiment, the analog line shielding unit comprises an analog line winding connected between the fourth group of current sources and the first current-voltage converter, and connected between the second group of current sources and the second current-voltage converter.

[0018] In an embodiment, the first group of switches is connected between the first group of current sources and the first current-voltage converter, the second group of switches is connected between the second group of current sources and the analog line shielding unit, the third group of switches is connected between the third group of current sources and the second current-voltage converter, and the fourth group of switches is connected between the fourth group of current sources and the analog line shielding unit.

[0019] In an embodiment, the active shielding device additionally comprises a controller configured to generate a sequence of digital signals to control the first, second, third, and fourth groups of switches.

[0020] In an embodiment, the controller comprises a random number generator.

[0021] In an embodiment, a method for active shielding involves: generating a current using an active shielding device; conducting the current through an analog line winding of an active shielding unit of the active shielding device in response to a sequence of digital controls; generating a voltage using a current-voltage converter of the active shielding device in response to the current; comparing the voltage to a reference voltage using a voltage comparator of the active shielding device; processing the sequence of digital controls using digital logics of the active shielding device to generate a first processed result signal and a second result signal, respectively, before conducting the sequence of digital controls through an inverter of the active shielding unit of the active shielding device and after conducting the sequence of digital controls through the inverter; and comparing the first processed result signal to the second result signal.

[0022] In an embodiment, the digital active shielding unit comprises an even number of inverters, and wherein the digital logics are identical to each other.

[0023] Other aspects of the application will become apparent by consideration of the detailed description and accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 An active shielding device according to an embodiment of the present application is depicted.

[0025] Figure 2 An embodiment of a current-voltage converter of the active shielding device depicted in Figure 1

[0026] Figure 3 An embodiment of a voltage comparator of the active shielding device depicted in Figure 1

[0027] Figure 4 An embodiment of a voltage comparator of the active shielding device depicted in Figure 1

[0028] An active shielding device according to an embodiment of the present application is depicted. Figure 5

[0029] An active shielding device according to an embodiment of the present application is depicted. Figure 6 An active shielding device according to an embodiment of the present application is depicted.

[0030] Figure 7 An active shielding device according to an embodiment of the present application is depicted.

[0031] Figure 8 An active shielding device according to an embodiment of the present application is depicted.

[0032] Figure 9 A process flow diagram of a communication method according to an embodiment of the present application.

[0033] Figure 10 A process flow diagram of a communication method according to another embodiment of the present application.

[0034] Throughout the description, like reference numerals can be used to identify like elements throughout the description and the figures. DETAILED DESCRIPTION

[0035] It will be readily understood that the components of the embodiments, as generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the various embodiments, as represented in the figures, is not intended to limit the scope of the present disclosure, but is merely representative of various embodiments. While the various aspects of the embodiments are presented in the drawings, the drawings depict only typical aspects in connection with which they are used, and are therefore not intended to limit the scope of the present disclosure, unless specifically recited in the specification.

[0036] ​​The application can be implemented in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the application is, therefore, indicated by the appended claims rather than by this detailed description. All changes that come within the meaning of and equivalency of the claims are intended to be embraced within the scope of the claims.

[0037] Throughout this specification, references have been made to particular features, benefits, or similar language. Such references do not imply that the application will necessarily achieve the referenced feature or benefit or that a "reference" feature or benefit must exist in any

[0038] Furthermore, the described features, advantages, and characteristics of the application can be combined in any suitable manner in one or more embodiments. One skilled in the relevant art will recognize, in light of the description herein, that the application can be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages can be recognized in certain embodiments that can not be present in all embodiments of the application.

[0039] Throughout this specification, references have been made to particular features, benefits, or similar language. Such references do not imply that the application will necessarily achieve the referenced feature or benefit or that a "reference" feature or benefit must exist in any

[0040] Figure 1 An active shielding device 100 according to an embodiment of the application is depicted. In Figure 1In the depicted embodiment, the active shielding device includes a plurality of current sources 102-1, 102-2,..., 102-N, where N is an integer greater than one; an analog line shielding unit 104 connected to the current sources; a current-to-voltage converter 106 connected to the analog line shielding unit; and a voltage comparator 108 connected to the current-to-voltage converter. A circuit to be protected 110, which can be a cryptographic circuit, a secure circuit, or other circuit, can be protected using the active shielding device, and can be connected to a wire or cable within the analog line shielding unit, a wire or cable between the current sources and the analog line shielding unit, or a wire or cable between the analog line shielding unit and the current-to-voltage converter. The active shielding device can be used in various applications, such as automotive applications, communications applications, industrial applications, medical applications, computer applications, and / or consumer or appliance applications. Although the depicted active shielding device 100 is shown in connection with certain components and described in connection with certain functionality, other embodiments of the active shielding device can include fewer or more components to achieve the same, fewer, or more functionality. For example, the active shielding device can include more than one analog line shielding unit. In another example, in some embodiments, the active shielding device can include more than one current-to-voltage converter and more than one voltage comparator. In yet another example, although the current sources 102-1, 102-2,..., 102-N are shown as part of the active shielding device in Figure 1 In some embodiments, the active shielding device is an active shielding circuit. The components of the active shielding circuit can be implemented on a single substrate (e.g., integrated into the same IC chip) or distributed across multiple substrates (e.g., implemented on multiple IC chips). For example, at least one of the current sources, the analog line shielding unit, the current-to-voltage converter, and the voltage comparator are implemented on a single substrate (e.g., integrated into one IC chip) or distributed across multiple substrates (e.g., implemented on multiple IC chips). In some embodiments, the active shielding device and the circuit to be protected are integrated into the same IC chip.

[0041] In comparison to active shielding devices that rely only on digital shielding, Figure 1 The active shielding device 100 depicted in FIG. 1 implements analog active shielding that can be used independently of digital active shielding or in conjunction with digital active shielding. In Figure 1In the embodiments depicted, the active shielding device utilizes multiple current sources 102-1, 102-2, ..., 102-N and an analog wire shielding unit 104 for active shielding. Due to less injected noise, active shielding in the current domain performs better than active shielding in the voltage domain. The current values ​​from the analog current sources can be generated randomly, in a known pattern, or randomly and in a known pattern. Furthermore, digital probing or application of 0 / 1 to the analog wire shielding unit can be easily detected. For example, any invasive attack such as cutting one or more wires or cables within the analog wire shielding unit 104 or applying 0 / 1 to one or more wires or cables within the analog wire shielding unit will affect one or more currents generated by the current sources 102-1, 102-2, ..., 102-N and alter the voltage range.

[0042] exist Figure 1 In the embodiments depicted, current sources 102-1, 102-2, ..., 102-N are configured to generate multiple currents I1, I2, ..., I... N Various types of current sources known in the art can be used to implement the current source. In some embodiments, the currents produced by the current sources are different from each other (i.e., each current source produces a unique current). In other embodiments, the current sources produce currents I1, I2, ..., I... N At least two currents in the sample are the same as each other. Figure 1 In the embodiments depicted, the current sources are connected in parallel with each other, such that currents I1, I2, ..., I... N Each current flows in parallel through the analog line shielding unit 104. In some embodiments, the current sources are connected to positive voltages, which may be the same as or different from each other.

[0043] exist Figure 1 In the embodiments depicted, analog wire shielding unit 104 is connected between current sources 102-1, 102-2, ..., 102-N and current-to-voltage converter 106. The analog wire shielding unit may include one or more cables or wires made of a conductive material (e.g., metal). In some embodiments, the analog wire shielding unit includes multiple analog wire windings connected between the current sources and the current-to-voltage converter. In these embodiments, each current source is connected to a different analog wire winding in the analog wire windings.

[0044] Figure 2 A simulated line shielding unit 204 is depicted, the simulated line shielding unit 204 being... Figure 1 The embodiment of the analog line shielding unit 104 depicted herein. However, Figure 1 The analog line shielding unit 104 depicted is not limited toFigure 2 The embodiment shown. In Figure 3 In the embodiment depicted, the analog wire shielding unit 204 includes a plurality of analog wire windings 228-1, 228-2, ..., 228-N, which are connected to current sources 102-1, 102-2, ..., 102-N and to a current-to-voltage converter 106. In the analog wire shielding unit, each analog wire winding is connected to a different current source. For example, current I1 is conducted to the current-to-voltage converter through analog wire winding 228-1, current I2 is conducted to the current-to-voltage converter through analog wire winding 228-2, and current I... N Conducted to a current-to-voltage converter via analog wire winding 228-N. In some embodiments, at least one of the analog wire windings 228-1, 228-2, ..., 228-N is implemented on one or more top layers of the IC chip in which the active shielding device 100 is packaged. Secure routing can be implemented on metal layers to achieve minimum spacing and arithmetic logic unit (Alu) width. In some embodiments, unused channels and / or spaces are filled to create a shielding layout that can prevent optical inspection and / or probing. In some embodiments, random routing is used in parallel, and multilayer interconnects are combined with high metal density, making it more difficult for attackers to obtain relevant information in lower metal layers. In some embodiments, lower metal layers are used for signal lines and supply lines that are invisible and not accessible via pin connections. In some embodiments, lower metal layers are used for analog blocks other than ground lines and supply lines. While the illustrated analog wire shielding unit is shown and described herein in conjunction with certain components and certain functions, other embodiments of the analog wire shielding unit may include fewer or more components to achieve the same, fewer or more functions. For example, the analog wire shielding unit may include, as Figure 2 The example shows more or fewer analog wire windings. In another example, although... Figure 2 The simulated wire windings 228-1, 228-2, ..., 228-N shown have wire windings of certain forms or patterns, but in other embodiments, at least one of the simulated wire windings 228-1, 228-2, ..., 228-N may have a form or pattern similar to... Figure 2 The wire windings shown are of different forms or styles.

[0045] Back Figure 1 The current-voltage converter 106 of the active shielding device 100 is configured to respond to the currents I1, I2, ..., I3 generated by the current sources 102-1, 102-2, ..., 102-N. NThis generates at least one voltage. In some embodiments, the current-to-voltage converter is configured to generate a voltage corresponding to currents I1, I2, ..., I... N Or related to currents I1, I2, ..., I N The voltage is proportional to the sum of the voltages.

[0046] Figure 3 A current-to-voltage converter 306 is depicted, the current-to-voltage converter 306 is Figure 1 The embodiment of the current-to-voltage converter 106 depicted herein. However, Figure 1 The current-to-voltage converter 106 described herein is not limited to Figure 3 The example shown. In Figure 3 In the embodiments depicted, the current-to-voltage converter 306 includes a resistor 336 and an amplifier 338. In some embodiments, the amplifier is an operational amplifier (op-amp). Figure 3 In the embodiments depicted, the resistor has a fixed resistance value "R". However, in other embodiments, the resistor may have a variable resistance value. In the example of the operation of the current-to-voltage converter 206, the amplifier and the resistor receive power from the input voltage. Figure 1 The active shielding device 100 depicted in the diagram generates currents I1, I2, ..., IN from current sources 102-1, 102-2, ..., 102-N. N And generate currents I1, I2, ..., I N The total output voltage "V" is proportional to the sum of the values. OUT In the embodiment, the output voltage V OUT This can be expressed as:

[0047] V OUT =R×(I1+I2+…+I) N (1)

[0048] While this document illustrates and describes the illustrated current-to-voltage converter in conjunction with certain components and functions, other embodiments of the current-to-voltage converter may include fewer or more components to achieve the same, fewer or more functions. For example, the current-to-voltage converter may include more than one amplifier and / or resistor or use different schemes / designs.

[0049] Back Figure 1The voltage comparator 108 of the active shielding device 100 is configured to compare at least one voltage generated by the current-to-voltage converter 106 to at least one reference voltage. In some embodiments, the voltage comparator is configured to compare the voltage generated by the current-to-voltage converter 106 to a plurality of reference voltages. Based on the comparison between the voltage generated by the current-to-voltage converter and the at least one reference voltage, it can be determined whether the cable or wire within the analog line shielding unit 104 has been tampered with (e.g., a voltage probe involving at least one of intruding the cable or wire within the analog line shielding unit or altering the cable or wire within the analog line shielding unit). In some embodiments, if the voltage generated by the current-to-voltage converter is the same as, or within a threshold (e.g., ±1%) of, the at least one reference voltage, it is determined that the cable or wire within the analog line shielding unit has not been tampered with. In these embodiments, if the voltage generated by the current-to-voltage converter is different from, or not within the threshold (e.g., ±1%) of, the at least one reference voltage, it is determined that the cable or wire within the analog line shielding unit has been tampered with. In some embodiments, the active shielding device includes a controller configured to determine whether the cable or wire within the analog line shielding unit has been tampered with. The controller can be implemented in hardware (e.g., one or more circuits), software, firmware, or a combination thereof. In embodiments, the controller is implemented using a processor such as a microcontroller, a host processor, a host computer, a digital signal processor (DSP), or a central processing unit (CPU). In some embodiments, the controller is configured to shut down or disable the circuit 110 to be protected in the event that the cable or wire within the analog line shielding unit has been tampered with.

[0050] Figure 4 The voltage comparator 408 is depicted as an embodiment of the voltage comparator 108 depicted in Figure 1 However, the voltage comparator 408 depicted in Figure 1 is not limited to the embodiment shown in Figure 4 In the embodiment depicted in Figure 4 The voltage comparator 408 includes two voltage comparison circuits 446-1, 446-2. In an example of the operation of the voltage comparator, the voltage comparison circuit 446-1 compares the output voltage V OUT from the current-to-voltage converter 306 to the reference voltage Vref+Δ, while the voltage comparison circuit 446-2 compares the output voltage V OUTcompared to a reference voltage Vref-Δ. A result signal is generated based on the comparison result of the voltage comparison circuits 446-1, 446-2. Although the illustrated voltage comparators are shown in conjunction with certain components and described in conjunction with certain functionality herein, other embodiments of the voltage comparators can include fewer or more components to achieve the same, fewer, or more functionality. For example, the voltage comparators can include a single voltage comparison circuit or more than two voltage comparison circuits for different degrees of voltage comparison accuracy.

[0051] In some embodiments, one or more switches are used to select one or more of the current sources 102-1, 102-2,..., 102-N to apply to the analog line shield unit 104. Thus, the voltage on the analog line shield unit can vary depending on the number of selected current sources or the selected current source, which makes it more difficult for an attacker to access information by probing the voltage of the analog line shield unit. Figure 5 An active shield device 500 including a plurality of switches 550-1, 550-2,..., 550-N that control a plurality of current sources 502-1, 502-2,..., 502-N is depicted in accordance with an embodiment of the present application. The active shield device 500 includes a plurality of current sources 502-1, 502-2,..., 502-N, an analog line shield unit 504 connected to the current sources, a current-to-voltage converter 506 connected to the analog line shield unit, a voltage comparator 508 connected to the current-to-voltage converter, switches 550-1, 550-2,..., 550-N, and an optional controller 552. Figure 5 In the embodiment depicted in FIG. 5, the active shield device includes a plurality of current sources 502-1, 502-2,..., 502-N, an analog line shield unit 504 connected to the current sources, a current-to-voltage converter 506 connected to the analog line shield unit, a voltage comparator 508 connected to the current-to-voltage converter, switches 550-1, 550-2,..., 550-N, and an optional controller 552. Figure 5 In the embodiment depicted in FIG. 5, the current sources 502-1, 502-2,..., 502-N, the analog line shield unit 504, the current-to-voltage converter 506, and the voltage comparator 508 are respectively the same as the current sources 102-1, 102-2,..., 102-N, the analog line shield unit 104, the current-to-voltage converter 106, and the voltage comparator 108. Figure 1The current sources 102-1, 102-2, ..., 102-N, analog line shielding unit 104, current-to-voltage converter 106, and voltage comparator 108 in the embodiments depicted herein are the same or similar. While the active shielding device 500 shown herein is illustrated with reference to certain components and described with reference to certain functions, other embodiments of the active shielding device may include fewer or more components to achieve the same, fewer, or more functions. For example, the active shielding device may include more than one analog line shielding unit. In another example, in some embodiments, the active shielding device may include more than one current-to-voltage converter and more than one voltage comparator. The active shielding device may operate in a first operating mode, wherein the active shielding device uses random data or a known sequence to drive values ​​on the cable or wire between the current source and the current-to-voltage converter, and subsequently checks the results from the voltage comparator. The active shielding device may also operate in a second operating mode, which allows specific values ​​to be written to the active shielding device and the results to be read back, making the active shielding device a confidential component, the confidentiality of which is lost in the event of damage to the active shielding device.

[0052] exist Figure 5 In the embodiments depicted, current sources 502-1, 502-2, ..., 502-N are configured to generate multiple currents I1, I2, ..., I... N Various types of current sources known in the art can be used to implement the current source. In some embodiments, the currents produced by the current sources are different from each other (i.e., each current source produces a unique current). In other embodiments, the current sources produce currents I1, I2, ..., I... N At least two currents in the sample are the same as each other. Figure 5 In the embodiments depicted, the current sources are connected in parallel with each other, such that currents I1, I2, ..., I... N Each current flows in parallel through the analog line shielding unit 504.

[0053] exist Figure 5 In the embodiments depicted, an analog wire shielding unit 504 is connected between current sources 502-1, 502-2, ..., 502-N and a current-to-voltage converter 506. The analog wire shielding unit may include one or more cables or wires made of a conductive material (e.g., metal). In some embodiments, the analog wire shielding unit includes a plurality of analog wire windings connected between the current sources and the current-to-voltage converter. In these embodiments, each of the current sources is connected to a different analog wire winding of the analog wire windings.

[0054] exist Figure 5In the embodiments depicted, the current-to-voltage converter 506 is configured to respond to currents I1, I2, ..., I3 generated by current sources 502-1, 502-2, ..., 502-N. N This generates at least one voltage. In some embodiments, the current-to-voltage converter is configured to generate a voltage corresponding to currents I1, I2, ..., I... N Or related to currents I1, I2, ..., I N The voltage is proportional to the sum of the voltages.

[0055] exist Figure 5 In the embodiments depicted, voltage comparator 508 is configured to compare at least one voltage generated by current-to-voltage converter 506 with at least one reference voltage. In some embodiments, the voltage comparator is configured to compare the voltage generated by current-to-voltage converter 506 with a plurality of reference voltages. Based on the comparison result between the voltage generated by current-to-voltage converter and at least one reference voltage, it can be determined whether the cable or wire within the analog line shielding unit 504 has been tampered with (e.g., voltage detection involving intrusion into the cable or wire within the analog line shielding unit or alteration of at least one voltage or current in the cable or wire within the analog line shielding unit). In some embodiments, if the voltage generated by current-to-voltage converter is the same as at least one reference voltage, or within a threshold (e.g., ±1%) of at least one reference voltage, it is determined that the cable or wire within the analog line shielding unit has not been tampered with. In these embodiments, if the voltage generated by current-to-voltage converter is different from at least one reference voltage, or is not within a threshold (e.g., ±1%) of at least one reference voltage, it is determined that the cable or wire within the analog line shielding unit has been tampered with.

[0056] exist Figure 5 In the embodiment depicted, switches 550-1, 550-2, ..., 550-N are connected between current sources 502-1, 502-2, ..., 502-N and analog line shielding unit 504, and are configured based on control signals D1, D2, ..., D N Select one or more current sources to apply to the analog line shielding unit. Figure 5 In the embodiments depicted, controller 552 is configured to generate control signals D1, D2, ..., D... Nto control switches 550-1, 550-2,..., 550-N and / or current-voltage converter 506. By controlling the switches and / or current-voltage converter, the voltage on the analog line shield unit can vary (e.g., depending on the number of selected current sources or the selected current sources), which makes it more difficult for an attacker to access information by probing the voltage of the analog line shield unit. The controller can be implemented in hardware (e.g., one or more circuits), software, firmware, or a combination thereof. In embodiments, a processor such as a microcontroller, host processor, host computer, DSP, or CPU is used to implement the controller. Control signals D1, D2,..., DN N The digital signals can be random digital signals / sequences or predefined digital signals / sequences. In some embodiments, the controller includes a random number generator configured to generate a random digital sequence. Although the controller is shown in FIG. 6 as a component of active shield device 600, in other embodiments, the controller is external to the active shield device. In some embodiments, the controller is configured to determine whether a cable or wire within the analog line shield unit is tampered with. In some embodiments, the controller is configured to shut down or disable a circuit to be protected in the event that a cable or wire within the analog line shield unit is tampered with, the circuit to be protected can be connected to a wire or cable within the analog line shield unit, a wire or cable between a current source and the analog line shield unit, or a wire or cable between the analog line shield unit and the current-voltage converter. In some embodiments, digital active shielding can be combined with analog active shielding to provide more sophisticated protection against invasive attacks. In some embodiments, one or more digital logic circuits are connected in series with the cable or wire, such that the digital logic circuits can change the signal in the cable or wire. For example, the voltage on the cable or wire can vary depending on where or which section of the cable or wire is probed, which makes it more difficult for an attacker to access information by probing the voltage at the cable or wire. Figure 5 Although the controller is shown in FIG. 6 as a component of active shield device 600, in other embodiments, the controller is external to the active shield device. In some embodiments, the controller is configured to determine whether a cable or wire within the analog line shield unit is tampered with. In some embodiments, the controller is configured to shut down or disable a circuit to be protected in the event that a cable or wire within the analog line shield unit is tampered with, the circuit to be protected can be connected to a wire or cable within the analog line shield unit, a wire or cable between a current source and the analog line shield unit, or a wire or cable between the analog line shield unit and the current-voltage converter. In some embodiments, digital active shielding can be combined with analog active shielding to provide more sophisticated protection against invasive attacks. In some embodiments, one or more digital logic circuits are connected in series with the cable or wire, such that the digital logic circuits can change the signal in the cable or wire. For example, the voltage on the cable or wire can vary depending on where or which section of the cable or wire is probed, which makes it more difficult for an attacker to access information by probing the voltage at the cable or wire.

[0057] In some embodiments, multiple sets of current sources, current-voltage converters, and voltage comparators are used with the analog line shield unit. Thus, the voltage on the analog line shield unit can be repeatedly checked or verified, which makes it more difficult for an attacker to access information by probing the voltage of the analog line shield unit. Figure 6 An active shield device 600 according to embodiments of the present application is depicted, which includes multiple sets of current sources 602-1, 602-2,..., 602-N, 612-1, 612-2,..., 612-N, 622-1, 622-2,..., 622-N, 632-1, 632-2,..., 632-N; current-voltage converters 606-1, 606-2; and voltage comparators 608-1, 608-2, 608-3. In Figure 6In the embodiments depicted, the active shielding device includes: a first group of current sources 602-1, 602-2, ..., 602-N; a second group of current sources 612-1, 612-2, ..., 612-N; a third group of current sources 622-1, 622-2, ..., 622-N; and a fourth group of current sources 632-1, 632-2, ..., 632-N; an analog line shielding unit 604 connected to the current sources; a first current-to-voltage converter 606-1; and a fourth group of current sources 602-N. Two current-to-voltage converters 606-2, the first current-to-voltage converter 606-1 and the second current-to-voltage converter 606-2 are connected to the analog line shielding unit; a first voltage comparator 608-1 and a second voltage comparator 608-2 are connected to the current-to-voltage converters; and a third voltage comparator 608-3 is connected to the first voltage comparator 608-1 and the second voltage comparator 608-2. Figure 6 The current sources 602-1, 602-2, ..., 602-N, 612-1, 612-2, ..., 612-N, 622-1, 622-2, ..., 622-N, 632-1, 632-2, ..., 632-N, the analog line shielding unit 604, the current-to-voltage converters 606-1, 606-2, and the voltage comparators 608-1, 608-2, and 608-3 in the embodiments depicted herein are respectively connected to... Figure 1 The current sources 102-1, 102-2, ..., 102-N, analog line shielding unit 104, current-to-voltage converter 106, and voltage comparator 108 in the embodiments depicted herein are the same or similar. While the illustrated active shielding device 600 is shown and described herein in conjunction with certain components and certain functions, other embodiments of the active shielding device may include fewer or more components to achieve the same, fewer, or more functions. For example, the active shielding device may include more than one analog line shielding unit.

[0058] exist Figure 6 In the embodiments depicted, each of the following current sources is configured to generate multiple currents I1, I2, ..., I... N Various types of current sources known in the art can be used to implement the current source. In some embodiments, the currents produced by the current sources are different from each other (i.e., each current source produces a unique current). In other embodiments, the current sources produce currents I1, I2, ..., I...N At least two currents in the sample are the same as each other. Figure 6 In the embodiments depicted, each current source within one of the first, second, third, and fourth groups of current sources is connected in parallel with each other, such that currents I1, I2, ..., I... N Each current flows in parallel through the analog line shielding unit 604.

[0059] exist Figure 6 In the embodiments depicted, the analog wire shielding unit 604 is connected to a second set of current sources 612-1, 612-2, ..., 612-N and a fourth set of current sources 632-1, 632-2, ..., 632-N. The analog wire shielding unit may include one or more cables or wires made of a conductive material (e.g., metal). In some embodiments, the analog wire shielding unit includes a plurality of analog wire windings connected between the second set of current sources 612-1, 612-2, ..., 612-N or the fourth set of current sources 632-1, 632-2, ..., 632-N and the current-to-voltage converters 606-1, 606-2. In these embodiments, each current source in the second group of current sources 612-1, 612-2, ..., 612-N is connected to a different analog wire winding in the analog wire winding, and / or each current source in the fourth group of current sources 632-1, 632-2, ..., 632-N is connected to a different analog wire winding in the analog wire winding.

[0060] exist Figure 6 In the embodiment depicted, a first current-to-voltage converter 606-1 is connected via an analog line shielding unit 604 to a first group of current sources 602-1, 602-2, ..., 602-N and a fourth group of current sources 632-1, 632-2, ..., 632-N. A first current-to-voltage converter 604-1 is configured to respond to currents I1, I2, ..., I... generated by the first group of current sources 602-1, 602-2, ..., 602-N and the fourth group of current sources 632-1, 632-2, ..., 632-N. N And thus generate the first output voltage V out1 In some embodiments, the first output voltage V out1 With currents I1, I2, ..., I N Or related to currents I1, I2, ..., I N The sum is proportional.

[0061] exist Figure 6 In the embodiment depicted, the first voltage comparator 608-1 is connected to the first current-to-voltage converter 606-1 and is configured to convert the first output voltage V out1comparing the first output voltage V out1 to a plurality of reference voltages.

[0062] In the embodiment depicted in Figure 6 In the embodiment depicted in The second current-voltage converter 606-2 is configured to generate a second output voltage V N In the embodiment depicted in out2 In some embodiments, the second output voltage V out2 In some embodiments, the second output voltage V N is proportional to the sum of the currents II, I2,..., IN. N In some embodiments, the second output voltage V

[0063] In the embodiment depicted in Figure 6 In the embodiment depicted in out2 comparing the first output voltage V out2 to a plurality of reference voltages.

[0064] In the embodiment depicted in Figure 6In the depicted embodiment, the third voltage comparator 608-3 is configured to compare the result signal CMP1 from the first voltage comparator 608-1 with the result signal CMP2 from the second voltage comparator 608-2 to produce a comparison result. Based on the comparison result from the third voltage comparator, it can be determined whether the cable or wire within the analog line shield unit 604 is tampered (e.g., a voltage probe involving at least one of intruding the cable or wire within the analog line shield unit or changing the voltage or current in the cable or wire within the analog line shield unit). In some embodiments, if the result signal CMP1 from the first voltage comparator 608-1 is the same as the result signal CMP2 from the second voltage comparator 608-2, or within a threshold (e.g., ±1%) of the result signal CMP2 from the second voltage comparator 608-2, it is determined that the cable or wire within the analog line shield unit is not tampered. In these embodiments, if the result signal CMP1 from the first voltage comparator 608-1 is different from the result signal CMP2 from the second voltage comparator 608-2, or not within the threshold (e.g., ±1%) of the result signal CMP2 from the second voltage comparator 608-2, it is determined that the cable or wire within the analog line shield unit is tampered. In some embodiments, the active shield device includes a controller configured to determine whether the cable or wire within the analog line shield unit is tampered. The controller can be implemented in hardware (e.g., one or more circuits), software, firmware, or a combination thereof. In embodiments, the controller is implemented using a processor such as a microcontroller, a host processor, a host computer, a DSP, or a CPU. In some embodiments, the controller is configured to shut down or disable the circuit to be protected in the event that the cable or wire within the analog line shield unit is tampered, which can be connected to the wire or cable within the analog line shield unit, the wire or cable between the current source and the analog line shield unit, or the wire or cable between the analog line shield unit and the current-voltage converter. In some embodiments, a digital active shield can be combined with an analog active shield to provide more sophisticated protection against invasive attacks. In some embodiments, one or more digital logic circuits are connected in series with the cable or wire so that the digital logic circuits can change the signal in the cable or wire. For example, the voltage on the cable or wire can vary depending on the location or section of the cable or wire that is probed, which makes it more difficult for an attacker to access information by probing the voltage at the cable or wire.

[0065] In some embodiments, one or more switches are used to select one or more of the current sources 602-1, 602-2,..., 602-N, 612-1, 612-2,..., 612-N, 622-1, 622-2,..., 622-N, 632-1, 632-2,..., 632-N to apply to the analog line shield unit 604, the first current-voltage converter 606-1, or the second current-voltage converter 606-2. Thus, the voltage on the analog line shield unit can vary depending on the number of selected current sources or the selected current source, which makes it more difficult for an attacker to access information by probing the voltage of the analog line shield unit. Figure 7 An active shielding device 700 according to embodiments of the present application is depicted, which includes a plurality of switches 750-1, 750-2,..., 750-N, 760-1, 760-2,..., 760-N, 770-1, 770-2,..., 770-N, 780-1, 780-2,..., 780-N to control the current sources 602-1, 602-2,..., 602-N, 612-1, 612-2,..., 612-N, 622-1, 622-2,..., 622-N, 632-1, 632-2,..., 632-N. In the depicted embodiment, the active shielding device includes the current sources 602-1, 602-2,..., 602-N, 612-1, 612-2,..., 612-N, 622-1, 622-2,..., 622-N, 632-1, 632-2,..., 632-N; the analog line shield unit 604 connected to the current sources; the first current-voltage converter 606-1 and the second current-voltage converter 606-2 connected to the analog line shield unit; the first voltage comparator 608-1 and the second voltage comparator 608-2 connected to the current-voltage converters; the third voltage comparator 608-3 connected to the first voltage comparator 608-1 and the second voltage comparator 608-2; the switches 750-1, 750-2,..., 750-N, 760-1, 760-2,..., 760-N, 770-1, 770-2,..., 770-N, 780-1, 780-2,..., 780-N; and optionally the controller 752. Figure 7 In the depicted embodiment, the active shielding device includes the current sources 602-1, 602-2,..., 602-N, 612-1, 612-2,..., 612-N, 622-1, 622-2,..., 622-N, 632-1, 632-2,..., 632-N; the analog line shield unit 604 connected to the current sources; the first current-voltage converter 606-1 and the second current-voltage converter 606-2 connected to the analog line shield unit; the first voltage comparator 608-1 and the second voltage comparator 608-2 connected to the current-voltage converters; the third voltage comparator 608-3 connected to the first voltage comparator 608-1 and the second voltage comparator 608-2; the switches 750-1, 750-2,..., 750-N, 760-1, 760-2,..., 760-N, 770-1, 770-2,..., 770-N, 780-1, 780-2,..., 780-N; and optionally the controller 752. Figure 7The switches 750-1, 750-2,..., 750-N, 760-1, 760-2,..., 760-N, 770-1, 770-2,..., 770-N, 780-1, 780-2,..., 780-N and the controller 752 in the depicted embodiment in FIG. 8 are respectively the same as or similar to the switches 750-1, 750-2,..., 750-N, 760-1, 760-2,..., 760-N, 770-1, 770-2,..., 770-N, 780-1, 780-2,..., 780-N and the controller 752 in the depicted embodiment in FIG. 7. Figure 5 The switches 550-1, 550-2,..., 550-N and the controller 552 in the depicted embodiment in FIG. 5 are the same as or similar to the switches 550-1, 550-2,..., 550-N and the controller 552 in the depicted embodiment in FIG. 4. Although the illustrated active shield device 500 is shown in connection with certain components and described in connection with certain functionality herein, other embodiments of the active shield device can include fewer or more components to achieve the same, less or more functionality. For example, the active shield device can include more than one analog line shield unit.

[0066] In the depicted embodiment in FIG. 5, the switches 550-1, 550-2,..., 550-N and the controller 552 are configured to control the voltage on the analog line shield unit 504 based on the control signals D1, D2,..., D Figure 7 In the depicted embodiment in FIG. 5, the switches 550-1, 550-2,..., 550-N and the controller 552 are configured to control the voltage on the analog line shield unit 504 based on the control signals D1, D2,..., D N One or more of the current sources 602-1, 602-2,..., 602-N, 612-1, 612-2,..., 612-N, 622-1, 622-2,..., 622-N, 632-1, 632-2,..., 632-N are selected to apply to the analog line shield unit 604, the first current-to-voltage converter 606-1, or the second current-to-voltage converter 606-2. In Figure 7 In the depicted embodiment in FIG. 8, the controller 752 is configured to generate control signals D1, D2,..., D N to control the switches 750-1, 750-2,..., 750-N, 760-1, 760-2,..., 760-N, 770-1, 770-2,..., 770-N, 780-1, 780-2,..., 780-N and / or at least one of the first current-to-voltage converter 606-1 and the second current-to-voltage converter 606-2. By controlling the switches and / or the current-to-voltage converters, the voltage on the analog line shield unit can vary (e.g., depending on the number of selected current sources or the selected current source), which makes it difficult for an attacker to access information by probing the voltage of the analog line shield unit. The controller can be implemented in hardware (e.g., one or more circuits), software, firmware, or a combination thereof. In an embodiment, a processor such as a microcontroller, a host processor, a host computer, a DSP, or a CPU is used to implement the controller. The control signals D1, D2,..., D Nmay be a digital signal, which can be a random digital signal / sequence or a predefined digital signal / sequence. In some embodiments, the controller includes a random number generator configured to generate a random digital sequence. While the controller is shown in Figure 7 In some embodiments, the controller is configured to shut down or disable the circuitry to be protected in the event that a cable or wire within the analog line shielding unit is tampered with, which can be connected to a wire or cable within the analog line shielding unit, a wire or cable between the current source and the analog line shielding unit, or a wire or cable between the analog line shielding unit and the current-voltage converter 606-1, 606-2.

[0067] Digital active shielding can be combined with analog active shielding to provide more sophisticated protection against invasive attacks. In some embodiments, one or more digital logic circuits are connected in series with the cable or wire, such that the digital logic circuits can change the signal in the cable or wire. For example, an even number (e.g., 2, 4, 6, 8, 14, 20) of inverters can be connected in series with the cable or wire, such that when a digital signal flows through the inverters, the output signal of the even number of inverters is the same as the original signal. However, when an attacker probes the cable or wire, the probed voltage can not correspond to the original digital signal. For example, when an attacker probes the cable or wire after an odd number of inverters, the probed voltage corresponds to an inverted version of the original digital signal. However, when an attacker probes the cable or wire after an even number of inverters, the probed voltage corresponds to the original digital signal. Thus, the voltage on the cable or wire can vary depending on where or in which section the cable or wire is probed, which makes it more difficult for an attacker to access information by probing the voltage at the cable or wire.

[0068] Figure 8 An active shielding device 800 including a combination of a digital shielding unit 854 and an analog line shielding unit 604 is depicted in accordance with an embodiment of the present application. In Figure 8In the embodiments depicted, the active shielding device includes: current sources 602-1, 602-2, ..., 602-N, 612-1, 612-2, ..., 612-N, 622-1, 622-2, ..., 622-N, 632-1, 632-2, ..., 632-N; an analog line shielding unit 604 connected to the current sources; a first current-to-voltage converter 606-1 and a second current-to-voltage converter 606-2 connected to the analog line shielding unit; a first voltage comparator 608-1 and a second voltage comparator 608-2, the first voltage comparator being connected to the analog line shielding unit; and a first voltage comparator 608-1 and a second voltage comparator 608-2. Comparator 608-1 and second voltage comparator 608-2 are connected to a current-to-voltage converter; a third voltage comparator 608-3 is connected to the first voltage comparator 608-1 and the second voltage comparator 608-2; switches 750-1, 750-2, ..., 750-N, 760-1, 760-2, ..., 760-N, 770-1, 770-2, ..., 770-N, 780-1, 780-2, ..., 780-N; an optional controller 852; a digital shielding unit 854 connected to a current source; two digital logic units 856-1 and 856-2; and a digital comparator 858. Figure 8 In the embodiments depicted, switches 750-1, 750-2, ..., 750-N, 760-1, 760-2, ..., 760-N, 770-1, 770-2, ..., 770-N, 780-1, 780-2, ..., 780-N and controller 852 are respectively connected to... Figure 5 The switches 550-1, 550-2, ..., 550-N and controller 552 in the embodiments depicted herein are identical or similar. While the illustrated active shielding device 800 is shown and described herein in conjunction with certain components and certain functions, other embodiments of the active shielding device may include fewer or more components to achieve the same, fewer, or more functions. For example, the active shielding device may include more than one digital shielding unit and / or more than one analog line shielding unit.

[0069] exist Figure 8 In the embodiment depicted, the digital shielding unit 854 is connected between the second group of current sources 612-1, 612-2, ..., 612-N and the third group of current sources 622-1, 622-2, ..., 622-N. Figure 8In the depicted embodiment, the digital shielding unit includes a first set of inverters 866-1, 866-2,..., 866-K, where K is a positive even integer, connected between the second set of current sources 612-1, 612-2,..., 612-N and the third set of current sources 622-1, 622-2,..., 622, and a second set of inverters 876-1, 876-2,..., 876-K connected between the digital logic 856-2 and the digital comparator 858. The digital shielding unit can include one or more cables or wires made of an electrically conductive material (e.g., metal). In some embodiments, the cables or wires within the digital shielding unit are in the top metal layer of the digital shielding unit 854. When an attacker probes the cables or wires, the probed voltage can not correspond to the original digital signal. For example, when an attacker probes the cables or wires after an odd number of inverters, the probed voltage corresponds to an inverted version of the original digital signal. However, when an attacker probes the cables or wires after an even number of inverters, the probed voltage corresponds to the original digital signal. Thus, the voltage on the cables or wires can vary depending on where or in which section the cables or wires are probed, making it more difficult for an attacker to access information by probing the voltage at the cables or wires. Although the illustrated digital shielding unit 854 is shown in connection with certain components and described in connection with certain functionality, other embodiments of the digital shielding unit can include fewer or more components to achieve the same, less or more functionality. For example, the digital shielding unit can include only a set of even number of inverters.

[0070] In Figure 8 In the depicted embodiment, the controller 852 is configured to generate digital control signals D1, D2,..., D M where M is a positive integer greater than one, the digital control signals D1, D2,..., D M may be a random digital signal / sequence or a predefined digital signal / sequence. The controller can be implemented in hardware (e.g., one or more circuits), software, firmware, or a combination thereof. In embodiments, the controller is implemented using a processor such as a microcontroller, a host processor, a host computer, a DSP, or a CPU. In some embodiments, the controller includes a random number generator configured to generate a random digital sequence. The control signals D1, D2,..., D NControl switches 750-1, 750-2,..., 750-N, 760-1, 760-2,..., 760-N, 770-1, 770-2,..., 770-N, 780-1, 780-2,..., 780-N, where N is an integer less than M. By controlling the switches, the voltage on the analog line shield unit 604 can vary (e.g., depending on the number of selected current sources or the selected current source), which makes it difficult for an attacker to access information by probing the voltage of the analog line shield unit. Although the controller is shown as a component of the active shield device 800 in Figure 8 In some embodiments, the controller is configured to shut down or disable the circuit to be protected in the event that a cable or wire within the analog line shield unit is tampered with, which can be connected to a wire or cable within the analog line shield unit, a wire or cable between the current source and the analog line shield unit, or a wire or cable between the current-to-voltage converter 606-1, 606-2 and the analog line shield unit.

[0071] In the embodiment depicted in Figure 8 the digital logic 856-1 is configured to generate a result signal OUTi based on the digital signals D1, D2,..., D M the digital logic 856-2 is configured to generate a result signal OUTi based on the digital signals D1, D2,..., D MA result signal OUT0is generated. The digital logic 856-1, 856-2 are identical digital circuits and / or configured to perform identical functions. In some embodiments, the digital logic is a digital gate, such as an "AND NOT" gate, an "OR" gate, or an "XOR" gate, or more complex digital logic. The digital comparator 858 is configured to compare the result signal OUTi from the digital logic 856-1 with the result signal OUT0from the digital logic 856-2 to generate a digital comparison result. Based on the digital comparison result from the digital comparator, it can be determined whether a cable or wire within the digital shield unit 854 is tampered (e.g., a voltage probe involving intruding into the cable or wire within the digital shield unit or changing at least one voltage or current in the cable or wire within the digital shield unit). In some embodiments, if the result signal OUTi from the digital logic 856-1 is the same as the result OUT0from the digital logic 856-2, it is determined that the cable or wire within the digital shield unit is not tampered. In these embodiments, if the result signal OUTi from the digital logic 856-1 is different from the result OUT0from the digital logic 856-2, it is determined that the cable or wire within the digital shield unit is tampered. In some embodiments, the active shield device includes a controller (e.g., the controller 852) configured to determine whether a cable or wire within the digital shield unit is tampered. The controller can be implemented in hardware (e.g., one or more circuits), software, firmware, or a combination thereof. In embodiments, the controller is implemented using a processor, such as a microcontroller, a host processor, a host computer, a DSP, or a CPU. In some embodiments, the controller is configured to shut down or disable a circuit to be protected in the event that a cable or wire within the digital shield unit is tampered, which can be connected to a wire or cable within the digital shield unit, a wire or cable between the current source and the digital shield unit, or a wire or cable between the digital shield unit and the digital comparator.

[0072] Figure 9 is a process flow diagram of a method for active shielding according to embodiments of the present invention. According to the method, at block 902, a current is generated using an active shield device. At block 904, the current is conducted through an analog wire winding of the active shield device. At block 906, a voltage is generated using a current-to-voltage converter of the active shield device in response to the current. At block 908, the voltage is compared to a reference voltage using a voltage comparator of the active shield device. The active shield device can be similar, identical, or a component of the active shield device 100 depicted in FIG. 1, Figure 1 the active shield device 500 depicted in FIG. 5, Figure 5 the active shield device 600 depicted in FIG. 6, and / or Figure 6 the active shield device 700 depicted in FIG. 7. Figure 7 ​

[0073] Figure 10 is a process flow diagram of a method for active shielding according to another embodiment of the present application. According to the method, at block 1002, a current is generated using an active shielding device. At block 1004, the current is conducted through an analog wire winding of the active shielding device in response to a digital control sequence. At block 1006, a voltage is generated using a current-to-voltage converter of the active shielding device in response to the current. At block 1008, the voltage is compared to a reference voltage using a voltage comparator of the active shielding device. At block 1010, the digital control sequence is processed using digital logic of the active shielding device to generate a first processed result signal and a second result signal, respectively, before and after conducting the digital control sequence through an inverter of an active shielding cell of the active shielding device. At block 1012, the first processed result signal is compared to the second result signal. The active shielding device can be similar, identical, or a component of the active shielding device 800 depicted in FIG. 8. Figure 8

[0074] While the operations of the methods herein are shown and described in a particular order, the order of the operations of each method can be altered so that certain operations can be performed in an inverse order, or so that certain operations can be performed, at least in part, concurrently with other operations. In another embodiment, instructions or sub-operations of distinct operations can be implemented in an intermittent and / or alternating manner.

[0075] It is also noted that at least some of the operations of the methods described herein can be implemented using software instructions stored in a computer usable medium for execution by a computer. As an example, an embodiment of a computer program product includes a computer-usable storage medium to store a computer readable program.

[0076] The computer-usable or computer-readable storage media can be a system- or device- readable entity or medium for teaming, storing, and / or providing computer program instructions to be executed by a computer. The computer-usable or computer-readable storage media can also be a computer-usable storage medium. The computer-usable storage medium can include, at least in part, a semiconductor-based or other integrated circuit (ic) (e.g., a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC)), a semiconductor memory (e.g., a

[0077] Alternatively, embodiments of the present application can be implemented in whole or in part in hardware or in an embodiment that includes both hardware and software elements. In an embodiment that uses software, the software can comprise, but is not limited to, firmware, resident software, microcode, and the like.

[0078] ​While particular embodiments of the present application have been described and illustrated, the application is not to be limited to such particular forms and arrangements of parts only as described and illustrated. The scope of the present application is defined by the appended claims and their equivalents.

Claims

1. An active shielding device, characterized by The active shielding device comprises: a plurality of current sources configured to generate a plurality of currents; an analog line shield unit connected to the current sources; a plurality of switches connected between the current sources and the analog line shield unit; a current-to-voltage converter connected to the analog line shield unit and configured to generate a voltage in response to the currents generated by the current sources and a digital control sequence for the switches; a voltage comparator connected to the current-to-voltage converter and configured to compare the voltage generated by the current-to-voltage converter to a reference voltage; a digital active shield unit connected to the current sources; a plurality of digital logics configured to process the digital control sequence before and after conducting the digital control sequence through the digital active shield unit to generate a first processed result signal and a second result signal; and a digital comparator configured to compare the first processed result signal to the second result signal.

2. The active shielding device of claim 1, wherein, The digital active shield unit comprises an even number of inverters.

3. The active shielding device of claim 1, wherein, The digital logics are identical to each other.

4. The active shielding device of claim 1, wherein, One of the digital logics is connected to the switches through the digital active shield unit.

5. The active shielding device of claim 1, wherein, The current sources are connected in parallel to each other.

6. The active shielding device of claim 1, wherein, The analog line shield unit comprises a plurality of analog line windings connected between the current sources and the current-to-voltage converter.

7. The active shielding device of claim 6, wherein, Each of the analog line windings is connected to a different one of the current sources.

8. The active shielding device of claim 1, wherein, Further comprising: a controller configured to generate the digital control sequence.

9. An active shielding device, characterized by The active shielding device comprises: a first, second, third, and fourth set of current sources, wherein each of the first, second, third, and fourth set of current sources is configured to generate a plurality of currents; an analog line shield unit connected to the second and fourth set of current sources; a first, second, third, and fourth set of switches connected to the first, second, third, and fourth set of current sources, respectively, and controlled by a digital control sequence; a first current-to-voltage converter connected to the first set of current sources and to the fourth set of current sources through the analog line shield unit, wherein the first current-to-voltage converter is configured to generate a first voltage in response to the currents generated by the first and fourth set of current sources; a first voltage comparator connected to the first current-to-voltage converter and configured to compare the first voltage to a first reference voltage; a second current-to-voltage converter connected to the second set of current sources and to the third set of current sources through the analog line shield unit, wherein the second current-to-voltage converter is configured to generate a second voltage in response to the currents generated by the second and third set of current sources; a second voltage comparator connected to the second current-to-voltage converter and configured to compare the second voltage to a second reference voltage; and a digital active shield unit connected to the first, second, third, and fourth set of current sources. a second current-to-voltage converter connected to the second set of current sources and to the third set of current sources by the analog line shield unit, wherein the second current-to-voltage converter is configured to generate a second voltage in response to the currents generated by the second and third sets of current sources; a second voltage comparator connected to the second current-to-voltage converter and configured to compare the second voltage to a second reference voltage; a third voltage comparator configured to compare a result from the first voltage comparator to a result from the second voltage comparator; a digital active shield unit connected to the second and third sets of current sources; a plurality of digital logic configured to process the digital control sequence before and after conducting the digital control sequence through the digital active shield unit to generate a first processed result signal and a second result signal; and a digital comparator configured to compare the first processed result signal to the second result signal.

10. A method for active shielding, characterized by, The method comprises: generating a plurality of currents using an active shield device; conducting the currents through a plurality of analog line windings of an active shield unit of the active shield device in response to a digital control sequence; generating voltages using current-to-voltage converters of the active shield device in response to the currents; comparing the voltages to reference voltages using voltage comparators of the active shield device; processing the digital control sequence using digital logic of the active shield device before and after conducting the digital control sequence through a plurality of inverters of the active shield unit of the active shield device to generate a first processed result signal and a second result signal, respectively; and comparing the first processed result signal to the second result signal.

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