Device and method for receiving 1-bit amplitude-modulated signals

Abstract

Device and method for receiving 1-bit amplitude-modulated signals. This description relates to a device (100) for receiving a 1-bit amplitude-modulated input signal, comprising at least: - a differential amplifier circuit (102) comprising first and second differential inputs (104, 106), the first input (104) being configured to receive the input signal and the second input (106) being configured to receive a common-mode signal whose value is variable; - a circuit (128) for modifying the value of the common-mode signal as a function of the value of an output signal of the receiving device (100) obtained from an output signal of the differential amplifier circuit (102). Figure for the abstract: Fig. 1

Description

Title of the invention: Device and method for receiving 1-bit amplitude-modulated signals. Technical field

[0001] This description relates generally to the field of communications and telecommunications, and more particularly to the reception of 1-bit amplitude-modulated signals. This description relates in particular to the field of wireless communications, especially contactless communications and for example those implemented using NFC (Near Field Communication) technology. Previous technique

[0002] Amplitude modulation on 1 bit is used for many types of communication, such as certain wireless communications.

[0003] A contactless communication device is a device capable of exchanging information via an antenna with another contactless device, for example a reader, according to one or more contactless communication protocols.

[0004] Near field communication, or NFC, is a wireless connectivity technology enabling communication over a short distance, for example on the order of ten centimeters, between electronic devices, such as between a contactless smart card and a reader.

[0005] An NFC device, which is a contactless device, is a device compatible with NFC technology. NFC technology is an open technology platform standardized in ISO / IEC 18092 and ISO / IEC 21481, but it incorporates many existing standards, such as the Type A and Type B protocols defined in ISO 14443, which can be used as communication protocols in NFC technology.

[0006] There are other types of contactless devices such as bank cards with contactless functions, contactless labels, contactless access cards, etc.

[0007] During information transmission between a reader and a contactless card, the reader generates an electromagnetic field via its antenna, which is generally, according to commonly used standards, a sinusoidal wave with a frequency of 13.56 MHz. Inductive coupling between the reader and the contactless card is used to power and transmit data to the contactless card using the electromagnetic field generated by the reader.

[0008] Data transmission is, for example, carried out using 1-bit amplitude modulation such as OOK (On-Off Keying) modulation. Various modulations are possible, employing different coding schemes (modified Miller, NRZ, Manchester, etc.), different modulation indices (from a few percent to 100%), and different signal shapes, including rising or falling edges of varying lengths.

[0009] Various parasitic phenomena and noise can alter the shape of the received signal. For example, overshoot and undershoot phenomena can occur. An overshoot corresponds to a rise in the value of a received signal above an expected nominal value, followed by a phase of adjustment until the signal value returns to the expected nominal value. An undershoot is the same phenomenon as an overshoot but occurring in the opposite direction, that is, a fall in the value of the received signal below an expected nominal value, followed by a phase of adjustment until the signal value returns to the expected nominal value.

[0010] For reasons of interoperability with different transmitting devices, a contactless 1-bit amplitude-modulated signal receiver must be able to operate with different types of modulation. Furthermore, it is important that the receiver tolerate noise and / or parasitic phenomena present in the received modulated signals.

[0011] These constraints also apply to other types of receiving devices, contactless or not, for 1-bit amplitude-modulated signals. Summary of the invention

[0012] There is a need to propose a solution to address the problems encountered with existing solutions.

[0013] An embodiment overcomes all or part of the drawbacks of known solutions and provides a device for receiving a 1-bit amplitude-modulated input signal, comprising at least:

[0014] - a differential amplifier circuit comprising first and second inputs differential, the first input being configured to receive the input signal and the second input being configured to receive a common mode signal whose value is variable;

[0015] - a circuit for modifying the value of the common-mode signal as a function of the value of an output signal from the receiving device obtained from an output signal from the differential amplifier circuit.

[0016] According to a particular embodiment, the differential amplifier circuit is mounted in a differentiator configuration.

[0017] According to a particular embodiment, the differential amplifier circuit comprises at least:

[0018] - an operational amplifier comprising a non-inverting input forming the second input of the differential amplifier circuit;

[0019] - a first resistive element comprising a first electrode coupled to an input operational amplifier inverter;

[0020] - a capacitive element comprising a first electrode coupled to a second electrode of the first resistive element, and a second electrode forming the first input of the differential amplifier circuit;

[0021] - a second resistive element forming a feedback element coupled between an output of the operational amplifier and the inverting input of the operational amplifier.

[0022] According to a particular embodiment, the receiving device further includes a comparator circuit configured to compare the output signal of the differential amplifier circuit with high and low threshold values, and to deliver at the output the output signal of the receiving device taking a first output value when that of the output signal of the differential amplifier circuit goes from a value lower than the high threshold value to a value higher than the high threshold value, and taking a second output value when that of the output signal of the differential amplifier circuit goes from a value higher than the low threshold value to a value lower than the low threshold value;

[0023] and the common mode signal value modification circuit is configured to set the common mode signal value to a high common mode value when the output signal of the receiving device takes the first output value, and to set the common mode signal value to a low common mode value, lower than the high common mode value, when the output signal of the receiving device takes the second output value.

[0024] According to a particular embodiment, the output of the comparator circuit is coupled to a control input of the circuit for modifying the value of the common mode signal.

[0025] According to a particular embodiment, the comparator circuit comprises at least:

[0026] - a first comparator including a non-inverting input coupled to an output of the differential amplifier circuit, and an inverting input configured to receive the low threshold value;

[0027] - a second comparator comprising a non-inverting input coupled to the output of the differential amplifier circuit, and an inverting input configured to receive the high threshold value;

[0028] - a first inverter comprising an input coupled to an output of the first comparator;

[0029] - an RS flip-flop comprising a low-state input coupled to an output of the first inverter, and a high-state input coupled to an output of the second comparator.

[0030] According to a particular embodiment, the comparator circuit further comprises a second inverter including an input coupled to an output of the RS flip-flop, and an output forming the output of the comparator circuit.

[0031] According to a particular embodiment, the comparator circuit comprises at least:

[0032] - a threshold value switch configured to couple a first input of the threshold value switch, on which the lower threshold value is intended to be applied, to an output of the threshold value switch when the output signal of the receiving device takes the first output value, and to couple a second input of the threshold value switch, on which the upper threshold value is intended to be applied, to the output of the threshold value switch when the output signal of the receiving device takes the second output value;

[0033] - a third comparator comprising a first input coupled to the output of the threshold value switch and a second input coupled to an output of the differential amplifier circuit.

[0034] According to a particular embodiment, the common mode signal value modification circuit includes at least one first switch configured to couple a first input of the first switch, on which the high common mode value is intended to be applied, to an output of the first switch when the output signal of the receiving device takes the first output value, and to couple a second input of the first switch, on which the low common mode value is intended to be applied, to the output of the first switch when the output signal of the receiving device takes the second output value, and in which the output of the first switch is coupled to the second input of the differential amplifier circuit.

[0035] According to a particular embodiment, the common-mode signal value modification circuit further comprises a second switch configured to couple the output of the first switch, or an input of the second switch to which a constant-value common-mode signal is intended to be applied, to the second input of the differential amplifier circuit, or the common-mode signal value modification circuit is configured to set, in a mode of static operation of the common mode signal value, the high and low common mode values ​​being equal to each other.

[0036] According to a particular embodiment, a difference between the upper threshold value and the lower common mode value is equal to the difference between the upper common mode value and the lower threshold value.

[0037] According to a particular embodiment, the upper threshold value is greater than the upper common mode value, and the lower threshold value is less than the lower common mode value.

[0038] A contactless communication device is also proposed comprising at least one device for receiving an amplitude-modulated input signal on 1 bit according to a particular embodiment.

[0039] A method for receiving a 1-bit amplitude-modulated input signal is also proposed, comprising at least:

[0040] - pre-condition the input signal based on a difference between a common mode signal and input signal, delivering at output an amplification output signal;

[0041] - modify the value of the common-mode signal according to the value of a signal received output obtained from the amplification output signal.

[0042] According to a particular embodiment, the preconditioning of the input signal includes an amplification of a derivative of the difference between the common mode signal and the input signal.

[0043] According to a particular embodiment, the method further comprises, between amplification and modification, a comparison of the amplification output signal with high and low threshold values, delivering the received output signal taking a first output value when that of the amplification output signal changes from a value lower than the high threshold value to a value higher than the high threshold value, and taking a second output value when that of the amplification output signal changes from a value higher than the low threshold value to a value lower than the low threshold value, and wherein the modification is implemented such that the value of the common-mode signal is equal to a high common-mode value when the received output signal takes the first output value, and that the value of the common-mode signal is equal to a low common-mode value,lower than the high common-mode value, when the received output signal takes the second output value. Brief description of the drawings

[0044] These features and advantages, as well as others, will be described in detail in the following non-limiting descriptions of specific embodiments, in connection with the accompanying figures, among which:

[0045] - Fig. 1 schematically represents an example of a receiving device amplitude modulated input signal on 1 bit, according to a particular embodiment;

[0046] - Figure 2 schematically represents examples of signals obtained in a device for receiving an amplitude-modulated input signal on 1 bit, according to a particular embodiment;

[0047] - Figure 3 schematically represents examples of signals obtained in a device for receiving a 1-bit amplitude-modulated input signal in the absence of modification of the common-mode signal value;

[0048] - [Fig. 4] schematically represents an example of a communication device without contact according to a particular embodiment;

[0049] - Figure 5 schematically represents the steps of a process for receiving a amplitude modulated input signal on 1 bit according to a particular embodiment;

[0050] - [Fig. 6] schematically represents a variant of an example device receiving an amplitude-modulated input signal on 1 bit, according to a particular embodiment. Description of the implementation methods

[0051] The same elements have been designated by the same reference numerals in the different figures. In particular, the structural and / or functional elements common to the different embodiments may have the same reference numerals and may have identical structural, dimensional and material properties.

[0052] For the sake of clarity, only the steps and elements necessary for understanding the described embodiments and examples have been shown and are detailed. In particular, the implementation of the various elements and circuits (differential amplifier, comparator circuit, common-mode signal value modification circuit, comparator, inverter, RS flip-flop, switch, etc.) of the device is not detailed. A person skilled in the art will be able to implement the various functions of the device in detail from the functional description given here.

[0053] Unless otherwise specified, when referring to two elements connected together, this means directly connected without intermediate elements other than conductors, and when referring to two elements coupled together, this means that these two elements can be connected or linked through one or more other elements.

[0054] Unless otherwise specified, the expressions "approximately", "roughly", "about", and "in the order of" mean to the nearest 10%, preferably to the nearest 5%. Furthermore, the ranges of values ​​given below should be understood, unless explicitly stated otherwise, as including the bounds of these ranges of values.

[0055] In addition, the signals in the timing diagrams of figures 2 and 3 are represented schematically and not to scale with respect to each other, both for the amplitudes and for the durations of the different parts of these signals.

[0056] An example of a device 100 for receiving an amplitude-modulated input signal on 1 bit according to a particular embodiment is described below in relation to [Fig.1].

[0057] The device 100 includes a differential amplifier circuit 102. The circuit 102 comprises first and second differential inputs 104, 106. The first input 104 is configured to receive the 1-bit amplitude-modulated input signal, called Vin in [Fig. 1]. The second input 106 is configured to receive a common-mode signal, called Vcm in [Fig. 1]. The input signal Vin is, for example, modulated using OOK modulation or another type of ASK (Amplitude Shift Keying) modulation on 1 bit.

[0058] In the example of [Fig. 1], the circuit 102 is configured as a differentiator. In this example, the circuit 102 comprises an operational amplifier 108 having a non-inverting input forming the second input 106, to which the common-mode signal Vcm is applied. In this example, the circuit 102 further comprises a first resistive element 110, for example a resistor, comprising a first electrode coupled to an inverting input of the operational amplifier 108 and a second electrode coupled to a first electrode of a capacitive element 112, for example a capacitor. A second electrode of the capacitive element 112 forms the first input 104 of the circuit 102. In this example, the circuit 102 further includes a second resistive element 114, for example a resistor, forming a feedback element coupled between an output of the operational amplifier 108 which forms an output of the circuit 102, and its inverting input.

[0059] In the described embodiment example, the circuit 102 therefore delivers an output signal, called Vaop on the [Fig.1], whose amplitude is proportional to the derivative of the difference Vcm - Vin.

[0060] Following the example of [Fig. 1], the device 100 further comprises a comparator circuit 116 configured to compare the output signal Vaop of the circuit 102 with high and low threshold values, respectively called Vrefp and Vrefn in [Fig. 1], and to deliver an output signal, called Vont in [Fig. 1], taking a first output value, corresponding for example to a logic '0', when the value of the output signal Vaop changes from a value lower than the high threshold value Vrefp to a value higher than the high threshold value Vrefp. Furthermore, the signal of The output signal Vout takes on a second output value, corresponding for example to a logic '1', when the value of the output signal Vaop changes from a value above the lower threshold value Vrefii to a value below the lower threshold value Vrefii. The output signal Vout delivered by circuit 116 corresponds to the output signal of device 100.

[0061] In the example of [Fig. 1], the circuit 116 includes a first comparator 118 comprising a non-inverting input coupled to the output of the circuit 102 on which the Vaop signal is delivered, and an inverting input configured to receive the lower threshold value Vrefii. In this example, the circuit 116 also includes a second comparator 120 comprising a non-inverting input coupled to the output of the circuit 102 and an inverting input configured to receive the upper threshold value Vrefp. In this example, circuit 116 also includes a first inverter 122 comprising an input coupled to an output of the first comparator 118. In addition, in this example, circuit 116 includes an RS flip-flop 124 comprising a low-state input, or "Reset" input, coupled to an output of the first inverter 122, and a high-state input, or "Set" input, coupled to an output of the second comparator 120.Finally, in this example, circuit 116 includes a second inverter 126 comprising an input coupled to an output of the RS flip-flop 124, and an output forming an output of circuit 116 on which the Vout signal is delivered.

[0062] In this example, the circuit 116 implements an analog-to-digital conversion of the signal delivered at the output of the circuit 102, with the low and high threshold values ​​Vrefii and Vrefp as the threshold for change of value of the signal Vout.

[0063] The device 100 also includes a circuit 128 for modifying the value of the common-mode signal Vcm according to the value of the output signal Vout. The circuit 128 is configured to set the value of this signal Vcm to a high common-mode value, called Vcmp in [Fig. 1], when the output signal Vout reaches its first output value. The circuit 128 is also configured to set the value of the signal Vcm to a low common-mode value Vcmn, lower than the high common-mode value Vcmp in [Fig. 1], when the output signal Vout reaches its second output value.

[0064] In the described embodiment, the output of circuit 116 is coupled to a control input of circuit 128, such that circuit 128 forms part of a feedback loop of device 100. In the example shown in [Fig. 1], circuit 128 includes a switch, for example, a CMOS type switch. This switch is configured to couple a first input 130, to which the high common-mode value Vcmp is applied, to an output 132 of the switch when the output signal Vout takes the first output value, and to couple a second input 134, to which the low common-mode value Vcmn is applied, to the output 132 when the signal The output value takes the second output value. In this example, the output 132 of the switch is coupled to the second input 106 of circuit 102.

[0065] In the example of [Fig.1], all the signals Vin, Vcm, Vaop, Vrefp, Vrefii, Vaut, Vcmp and Vcmp correspond to voltages.

[0066] As an alternative to the example described above, at least one of the circuits 102, 116 and 128 can be made with components different from those described in the examples above.

[0067] The operation of the device 100 described above is explained below in relation to [Fig.2] representing signals obtained in the device 100.

[0068] In the example of [Fig. 2], the input signal Vin received by device 100 includes an initial transition from a low state (logic '0') to a high state (logic '1'), a holding of the high state for a certain duration, and then a transition from the high state to the low state. In this example, the Vin signal exhibits, during the transition from the low state to the high state, an overshoot causing, for a short time, an exceedance of the value corresponding to the high state, followed by a return to the nominal value of the high state.

[0069] In this example, as long as the input signal Vin remains low, the value of the common-mode signal Vcm is equal to the high common-mode value Vcmp, and the value of the signal Vaop obtained at the output of circuit 102 is equal to or close to the value of Vcmp. The output signal Vont remains low.

[0070] When the input signal Vin increases to go to the high state, the value of the signal Vaop falls and when it becomes less than the value Vrefn, the value of the signal Vaut goes to the high state, which also triggers, by the circuit 128, the change in the value of the common mode signal which becomes equal to the low common mode value Vcmn.

[0071] When the value of the input signal Vin decreases to return to the nominal high state value, due to the overshoot phenomenon occurring on the Vin signal, the value of the Vaop signal rises again. However, since the value of the Vaop signal does not exceed the high threshold value Vrefp during the decrease of the input signal Vin, the value of the Vaut signal remains high. When the value of Vin stabilizes at the nominal high state value, the value of the Vaop signal is equal to or close to the value Vcmn.

[0072] When the input signal Vin falls to the low state, the value of the signal Vaop increases and when it becomes greater than the value Vrefp, the value of the signal Vaut goes to the low state, which also triggers, by the circuit 128, the change in the value of the common mode signal which becomes equal to the high common mode value Vcmp.

[0073] Thus, in device 100, the value of the common mode signal Vcm is dynamic and is determined as a function of the value of the output signal Vaut, and therefore of the value of the data received by device 100.

[0074] The use of high and low threshold values ​​Vrefp, Vrefn, different from each other, creates hysteresis in the operation of the device 100 so that only significant changes in the value of Vin, i.e. the values ​​of the transmitted data, are found in the output signal Vaut, and not the variations related to noise and parasitic phenomena.

[0075] Furthermore, in the device 100, the difference between the values ​​Vcmn and Vrefp forms a tolerance interval for upward variation of the value of the Vaop signal, and therefore a tolerance interval for downward variation of the value of the Vin signal, within which these signals can vary without causing a change in the value of the Vaut signal. This tolerance interval is particularly useful when the Vin signal is subject to overshoot phenomena as described in the example in [Fig. 2].

[0076] Similarly, the difference between the values ​​Vcm p and Vrefn forms a tolerance interval for downward variation of the value of the Vaop signal, and therefore a tolerance interval for upward variation of the value of the Vin signal, within which these signals can vary without causing a change in the value of the Vont signal. This tolerance interval is particularly useful when the Vin signal is subject to undershooting phenomena, that is, when the value of the Vin signal falls, for a short time, to a value lower than that corresponding to the low state, and then returns to the nominal value of the low state.

[0077] In the device 100, because the value of the common mode signal Vcm varies and goes to a high common mode value Vcmp when the value of the output signal Vaop of the circuit 102 goes above the high threshold value Vrefp, and goes to a low common mode value Vcmn which is less than the high common mode value Vcmp, when the value of Vaop goes below the low threshold value Vrefn, it is possible to have low and high threshold values ​​Vrefn, Vrefp which are closer to each other than if the value of the common mode signal Vcm were constant, for given intervals of tolerance of variation of the value of Vaop.Thus, a smaller difference between the Vrefn and Vrefp values ​​allows, for a certain tolerance to variations in the Vin signal, the operation of device 100 with a lower supply voltage because the Vrefp value is less than or equal to a high supply potential Vdd and the Vrefn value is greater than or equal to a low supply potential Gnd, corresponding, for example, to ground. Furthermore, for a given difference between the Vrefn and Vrefp values, the variation in the common-mode signal Vcm value as implemented by device 100 allows for greater tolerance to variations in the Vin signal.

[0078] For example, the difference Vcmp - Vcmn can be between approximately 100 mV and 200 mV.

[0079] Device 100 facilitates the compromise between a large difference between Vrefp and Vrefn, necessary for good tolerance to noise and overshoot / undershoot phenomena, and sufficient gain and linearity of amplification with a relatively low supply voltage. The use of a variable common-mode signal reduces the operating dynamics of the differential amplifier circuit 102 and the comparator circuit 116 without reducing the tolerance intervals corresponding to the differences between the high and low threshold values ​​Vrefp, Vrefii, and the value of the common-mode signal Vcm, thus ensuring good robustness against possible parasitic variations in the input signal Vin.The use of a variable-value common-mode signal Vcm also allows, compared to a receiving device using a fixed or constant-value common-mode signal, a reduction in the supply voltage of the device 100 without impacting the constraints related to the tolerance intervals with respect to variations in the input signal Vin.

[0080] By way of comparison, [Fig. 3] represents signals analogous to those previously described in connection with [Fig. 2] and obtained in a receiver of a 1-bit amplitude-modulated input signal in which the value of the common-mode signal Vcm is constant. To obtain the same tolerances to overshoot and undershoot variations as in device 100, it is necessary to have a greater difference between the values ​​Vrefn and Vrefp than in device 100, i.e., a greater operating dynamic range of the amplification circuit.

[0081] In the example of device 100 described above, the difference between the high threshold value Vrefp and the low common-mode value Vcmn is equal to the difference between the high common-mode value Vcmp and the low threshold value Vrefn. This results in similar tolerance intervals for overshoot and undershoot phenomena. Alternatively, it is possible to have tolerance intervals for these phenomena that are not similar or identical to each other, and therefore to have a difference between the high threshold value Vrefp and the low common-mode value Vcmn that is not equal to that between the high common-mode value Vcmp and the low threshold value Vrefn.

[0082] In the example of device 100 described above, the upper threshold value Vrefp is greater than the upper common-mode value Vcmp, and the lower threshold value Vrefn is less than the lower common-mode value Vcmn. Alternatively, depending on the desired tolerance intervals, it is possible to have the upper threshold value Vrefp that is less than or equal to the upper common-mode value Vcmp, and / or to have the low threshold value Vrejh greater than or equal to the low common mode value Vcmn, with the low threshold value Vrejh less than the high common mode value Vcmp, and the high threshold value Vrefp greater than the low common mode value Vcmn.

[0083] According to an alternative embodiment shown in [Fig. 6], the circuit 116 may include a single comparator 136, for example called the third comparator, configured to compare the Vaop signal with one of the high and low threshold values ​​Vrefp, Vrejh, depending on the value of the signal Vaut. In this case, the circuit 116 includes an additional device 138, for example a switch called the threshold value switch, to switch and apply the desired threshold value to the input of this single comparator 136 depending on the value of Vaut.In the example described, the threshold value switch 138 is configured to couple a first input 140 of the threshold value switch 138, on which the low threshold value Vrejh is intended to be applied, to an output 142 of the threshold value switch 138 when the output signal Vaut takes the first output value, and to couple a second input 144 of the threshold value switch 138, on which the high threshold value Vrefp is intended to be applied, to the output 142 of the threshold value switch 138 when the output signal Vaut takes the second output value. Furthermore, in the example of [Fig.1], a first input of the third comparator 136 (the non-inverting input in [Fig.1]) is coupled to the output 142 of the threshold value switch 138, and a second input of the third comparator 136 (the inverting input in [Fig.1]) is coupled to the output of the differential amplifier circuit 102.

[0084] According to another embodiment, the circuit 128 may include a second switch for applying to the second input 106 of the circuit 102 either the variable-value common-mode signal Vcm as previously described, or a fixed-value common-mode signal, i.e., one whose value is constant regardless of the value of the signal Vout. Such a variant allows for compatibility with environments where the common-mode voltage is not dynamic. For example, a fixed-value common-mode signal can be used in communication standards where overshoot or undershoot are less frequent, for example, when the data transmission speed is higher.

[0085] Alternatively, an operating mode with a fixed-value common-mode signal can be obtained by implementing the circuit 128 so that it is configured to define, when the device 100 enters this operating mode, the low common-mode value Vcmn as being equal to the high common-mode value Vcmp.

[0086] The variants and alternatives described above are compatible with each other and can be combined.

[0087] Device 100 is advantageously used within a contactless communication device 1000 as shown, for example, in [Fig. 4]. In this example, device 100 is part of the receiving chain of device 1000. In addition to device 100, device 1000 also includes an antenna 1002 configured to receive an input electromagnetic field, and a signal extraction circuit 1004 configured to output the signal Vin from the signal delivered by antenna 1002.

[0088] The device 1000 may include other components not described here.

[0089] According to a particular embodiment, the device 1000 is of the NFC type and can be configured to receive data via an electromagnetic field with a frequency of 13.56 MHz.

[0090] When device 100 is used during signal reception within a contactless communication device such as device 1000, the modification of the value of the common mode signal Vcm made allows a greater tolerance towards variations in the shapes of electromagnetic fields used for data transmission, and allows for better interoperability of device 1000 with other contactless communication devices and / or lower power consumption of device 100 which forms the demodulator of device 1000.When device 1000 is intended to be electrically powered by the received electromagnetic field and transmitting data, for example when device 1000 corresponds to a contactless card, the fact that device 1000 can operate with a lower supply voltage also means that device 1000 can operate with weaker electromagnetic fields, thus reducing this constraint on the data-emitting device.

[0091] Device 1000 can correspond to a contactless communication device, for example a contactless bank card, an NFC device, a contactless tag, a contactless access card, etc. Device 1000 can be compatible with several different types of readers.

[0092] In the example described above, device 1000 corresponds to a contactless communication device in which the received electromagnetic field is used for data transmission and to power device 1000. For example, device 1000 can be configured to communicate with a reader emitting the received electromagnetic field. Device 1000 can be configured to implement passive load modulation (PLM).

[0093] Alternatively, the device 1000 may have its own power supply. For example, the device 100 may correspond to a device emulated in card mode (or CE for "Card Emulation") such as a mobile phone or a connected object.

[0094] Alternatively, the device 100 can be used for demodulating signals other than contactless transmitted data. In this case, the device 100 can be used in a communication device 1000 other than a contactless device.

[0095] Device 100 can be used for any conversion of an analog signal into a 1-bit digital signal (sensor, etc.).

[0096] In general, it is proposed to implement a method for receiving a 1-bit amplitude-modulated input signal Vin, comprising at least:

[0097] - amplification of a derivative of a difference between a common-mode signal Vcm and the input signal Vin, delivering at the output an amplification output signal Vaop;

[0098] - modification of the value of the common mode signal Vcm as a function of the value of a received output signal Vont obtained from the amplification output signal Vaop.

[0099] In the examples described above, the amplification function is implemented by a differentiator. Alternatively, the amplification can be implemented without this differentiator function.

[0100] It is also proposed to implement a method for receiving a 1-bit amplitude-modulated input signal Vin, comprising at least:

[0101] - preconditioning, or preprocessing, of the input signal Vin, based on a difference between a common mode signal Vcm and the input signal Vin, delivering at the output an amplification output signal Vaop;

[0102] - modification of the value of the common mode signal Vcm as a function of the value of a received output signal Vaut obtained from the amplification output signal Vaop.

[0103] In such a method, the preconditioning of the input signal may include an amplification of a derivative of the difference between the common mode signal and the input signal.

[0104] Figure 5 represents steps in an example of a receiving process, comprising at least:

[0105] - amplification of a derivative of a difference between the common-mode signal Vcm and the input signal Vin, delivering the amplification output signal Vaop (step 202);

[0106] - comparison of the amplification output signal Vaop with threshold values high and low Vrefp, Vrefii, delivering the receive output signal Vont taking a first output value when that of the amplification output signal Vaop goes from a value lower than the high threshold value Vrefp to a value higher than the high threshold value Vrefp, and taking a second output value when that of the amplification output signal Vaop goes from a value higher than the low threshold value Vrejh to a value lower than the low threshold value Vrejh (step 204);

[0107] - modification of the value of the common-mode signal Vcm such that it is equal to a high common mode value Vcmp when the receive output signal Vout takes the first output value, and that it is equal to a low common mode value Vcmn, less than the high common mode value Vcmp, when the receive output signal Vout takes the second output value (step 206).

[0108] These steps are repeated in a loop throughout a reception of the input signal Vin.

[0109] Various embodiments and variations have been described. A person skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will become apparent to a person skilled in the art.

[0110] Finally, the practical implementation of the described examples of realization and variants is within the reach of a person skilled in the art, based on the functional indications given above.

Claims

Demands

1. A receiving device (100) for a 1-bit amplitude-modulated input signal, comprising at least: - a differential amplifier circuit (102) comprising first and second differential inputs (104, 106), the first input (104) being configured to receive the input signal and the second input (106) being configured to receive a common-mode signal whose value is variable; - a circuit (128) for modifying the value of the common-mode signal as a function of the value of an output signal of the receiving device (100) obtained from an output signal of the differential amplifier circuit (102).

2. Receiving device (100) according to claim 1, wherein the differential amplifier circuit (102) is mounted in a differentiator.

3. A receiving device (100) according to claim 2, wherein the differential amplifier circuit (102) comprises at least: - an operational amplifier (108) including a non-inverting input forming the second input (106) of the differential amplifier circuit (102); - a first resistive element (110) including a first electrode coupled to an inverting input of the operational amplifier (108); - a capacitive element (112) including a first electrode coupled to a second electrode of the first resistive element (110), and a second electrode forming the first input (104) of the differential amplifier circuit (102); - a second resistive element (114) forming a feedback element coupled between an output of the operational amplifier (108) and the inverting input of the operational amplifier (108).

4. A receiving device (100) according to any one of the preceding claims, further comprising a comparator circuit (116) configured to compare the output signal of the differential amplifier circuit (102) with high and low threshold values, and to deliver at output the output signal of the receiving device (100) taking a first output value when that of the output signal of the differential amplifier circuit (102) goes from a value lower than the upper threshold value to a value higher than the upper threshold value, and taking a second output value when that of the output signal of the differential amplifier circuit (102) goes from a value higher than the lower threshold value to a value lower than the lower threshold value; and wherein the common mode signal value modification circuit (128) is configured to set the common mode signal value to a high common mode value when the output signal of the receiving device (100) takes the first output value, and to set the common mode signal value to a low common mode value, lower than the high common mode value, when the output signal of the receiving device (100) takes the second output value.

5. A receiving device (100) according to claim 4, wherein the output of the comparator circuit (116) is coupled to a control input of the circuit (128) for modifying the value of the common mode signal.

6. A receiving device (100) according to any one of claims 4 or 5, wherein the comparator circuit (116) comprises at least: - a first comparator (118) comprising a non-inverting input coupled to an output of the differential amplifier circuit (102), and an inverting input configured to receive the low threshold value; - a second comparator (120) comprising a non-inverting input coupled to the output of the differential amplifier circuit (102), and an inverting input configured to receive the high threshold value; - a first inverter (122) comprising an input coupled to an output of the first comparator (118); - an RS flip-flop (124) comprising a low input coupled to an output of the first inverter (122), and a high input coupled to an output of the second comparator (120).

7. Receiving device (100) according to claim 6, wherein the comparator circuit (116) further comprises a second inverter (126) including an input coupled to an output of the RS flip-flop (124), and an output forming the output of the comparator circuit (116).

8. A receiving device (100) according to any one of claims 4 or 5, wherein the comparator circuit (116) comprises at least: - a threshold value switch (138) configured to couple a first input (140) of the threshold value switch, on which the low threshold value is intended to be applied, to an output (142) of the threshold value switch when the output signal of the receiving device (100) takes the first output value, and to couple a second input (144) of the threshold value switch, on which the high threshold value is intended to be applied, to the output (142) of the threshold value switch (138) when the output signal of the receiving device (100) takes the second output value;- a third comparator (136) comprising a first input coupled to the output (142) of the threshold value switch (138) and a second input coupled to an output of the differential amplifier circuit (102).

9. A receiving device (100) according to any one of claims 4 to 8, wherein the common mode signal value modification circuit (128) comprises at least one first switch configured to couple a first input (130) of the first switch, on which the high common mode value is intended to be applied, to an output (132) of the first switch when the output signal of the receiving device (100) takes the first output value, and to couple a second input (134) of the first switch, on which the low common mode value is intended to be applied, to the output of the first switch when the output signal of the receiving device (100) takes the second output value, and wherein the output (132) of the first switch is coupled to the second input (106) of the differential amplifier circuit (102).

10. A receiving device (100) according to claim 9, wherein the common mode signal value modification circuit (128) further comprises a second switch configured to couple the output of the first switch or an input of the second switch to which a constant-value common mode signal is intended to be applied, to the second input (106) of the differential amplifier circuit (102), or wherein the common mode signal value modification circuit (128) is configured to set, in a static common mode signal value operating mode, the high and low common mode values ​​equal to each other.

11. Receiving device (100) according to any one of claims 4 to 10, wherein a difference between the upper threshold value and the lower common mode value is equal to the difference between the upper common mode value and the lower threshold value.

12. Receiving device (100) according to any one of claims 4 to 11, wherein the upper threshold value is greater than the upper common mode value, and the lower threshold value is less than the lower common mode value.

13. Contactless communication device (1000), comprising at least one receiving device (100) for an amplitude-modulated input signal on 1 bit according to any one of the preceding claims.

14. Method for receiving a 1-bit amplitude-modulated input signal, comprising at least: - preconditioning the input signal based on a difference between a common-mode signal and the input signal, delivering an amplification output signal; - modifying the value of the common-mode signal as a function of the value of a received output signal obtained from the amplification output signal.

15. A method according to claim 14, wherein the preconditioning of the input signal includes an amplification of a derivative of the difference between the common mode signal and the input signal.

16. A method according to claim 15, further comprising, between amplification and modification, a comparison of the amplification output signal with high and low threshold values, delivering the received output signal taking a first output value when that of the amplification output signal changes from a value lower than the high threshold value to a value higher than the high threshold value, and taking a second output value when that of the amplification output signal changes from a value higher than the low threshold value to a value lower than the low threshold value, and wherein the modification is implemented such that the value of the common-mode signal is equal to a high common-mode value when the received output signal takes the first output value, and that the value of the common-mode signal is equal to a low common-mode value, lower than the high common-mode value.when the received output signal takes the second output value.

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