Method for generating a pulse and circuitry for an electronic device for generating a pulse

Abstract

Method for generating a pulse (7, 9; 207, 209; 307, 309; 407, 409), wherein a predetermined first boundary curve (3) and a predetermined second boundary curve (5) are defined for a pulse shape of the pulse (7, 9; 207, 209; 307, 309; 407, 409), wherein the boundary curves (3, 5) describe the time course of a current quantity (I), and wherein the second boundary curve (5) lies completely within the first boundary curve (3), characterized in that a curve inscribed between the boundary curves (3, 5) is generated as the pulse shape for the pulse (7, 9; 207, 209; 307, 309; 407, 409) by means of a current sink (37), which – compared to a rectangular pulse inscribed between the boundary curves (3, 5) – is located in a first region of the current quantity that is away from an extremum. (I) is deformed towards the first limit curve (3), and in a second region of the current quantity (I) facing the extremum is deformed towards the second limit curve (5).

Description

[0001] The invention relates to a method for generating a pulse for data transmission according to the preamble of claim 1, and a circuit device according to claim 7. State of the art

[0002] Methods and circuit devices of the type discussed here are known. For a pulse shape of a pulse to be generated, a predetermined first boundary curve and a predetermined second boundary curve are defined, wherein the boundary curves describe the time course of a current quantity, for example, a current or a voltage, and wherein the second boundary curve lies completely within the first boundary curve. The boundary curves thus form envelopes that define the specification limits for the pulse to be generated. It is known that rectangular pulses, also called square-wave pulses, are generated for data transmission. These are inscribed—typically maintaining a certain safety margin from the specification limits—between the boundary curves, with the aim of achieving the steepest possible edges for a change in the current quantity from a resting level to a data level and back.Transitions between the resting level and the edges on the one hand, and between the data level and the edges on the other, are preferably defined as sharply as possible, i.e., shaped as sharply as possible. This should result in pulses that are as well-defined as possible and can be recorded without errors.

[0003] A disadvantage of this is that such rectangular pulses have a high harmonic content and therefore lead to increased electromagnetic radiation during data transmission. The invention therefore aims to provide a method and a circuit device that specifically avoid this disadvantage.

[0004] A method for generating a pulse is known, for example, from DE 10 2012 201 711 A1. Disclosure of the invention

[0005] The problem is solved by creating a method comprising the steps of claim 1. This method is characterized in that, as the pulse shape, a curve inscribed between the limit curves is generated by means of a current sink. Compared to a rectangular pulse inscribed between the limit curves, this curve is deformed towards the first limit curve in a first region of the current quantity opposite an extremum of the curve, and in a second region of the current quantity opposite the extremum, it is deformed towards the second limit curve. In this way, the specification limits are better utilized to generate less steep edges and / or less sharp corners compared to the conventional rectangular pulse.It is evident that the curve describing the pulse shape is less steep at the edges when, starting from a standard rectangular pulse, it is deformed outwards towards the first limit curve in the region away from the extremum, while inwards towards the second limit curve in the region closer to the extremum, it is deformed towards the second limit curve. This results in a lower harmonic content than with a rectangular pulse, thus reducing electromagnetic radiation. At the same time, the specified limits are met, so the pulse can still be easily recognized, and in particular, unambiguously identified and detected as such.

[0006] The first region of the current quantity, located away from the extremum, preferably extends from the resting level to at most 50% of the signal swing, i.e., the difference between the extremum value and the resting level, and particularly preferably from the resting level to at most 30% of the signal swing. The second region of the current quantity, located closer to the extremum, preferably adjoins the first region and preferably extends from at least 50% of the signal swing to the extremum value, and particularly preferably from at least 30% of the signal swing to the extremum value. The extremum value is preferably identical to the data level.

[0007] It is possible to generate a positive pulse where the resting level corresponds to a low current level, while the data level corresponds to a higher current level. Thus, during the pulse, the signal switches from the low resting level to the higher data level and back again.

[0008] Alternatively, the pulse can be generated as a negative pulse, with the resting level having a higher current value (high-level) and the data level corresponding to a lower current value (low-level). During the pulse waveform, the signal then switches from the higher resting level to the lower data level and back again.

[0009] In the case of a positive pulse, the extremum represents a maximum of the curve describing the pulse shape. In the case of a negative pulse, the extremum represents a minimum of the curve describing the pulse shape.

[0010] The first and second boundary curves result from predetermined specifications for the pulse shape, where, in particular, maxima and minima for the rise and fall times of the pulse in the region of the edges, a duty cycle, and a signal amplitude (difference in current magnitude between the data level and the quiescent level) are specified. The first boundary curve is then preferably obtained for a positive pulse using the maximum specification values ​​and for a negative pulse preferably using the minimum specification values. The second boundary curve, which lies entirely within the first boundary curve, is similarly obtained for a positive pulse preferably using the minimum specification values ​​and for a negative pulse preferably using the maximum specification values.

[0011] Preferably, a voltage or a current is used as the current quantity; the pulse is therefore preferably generated as a voltage pulse or as a current pulse.

[0012] The method is preferably used for transmitting sensor data to a central control unit, particularly in a motor vehicle. Current interfaces are typically used, especially for peripheral sensors of occupant protection systems. A bus operation is preferably implemented by means of synchronization, with several sensors connected to a receiver via a data bus. For the synchronization function, the central control unit generates a clock signal in the form of voltage pulses, which are detected by the sensors connected to the bus and mark the beginning of a new data transmission cycle. These voltage pulses are also referred to as synchronization pulses. Data transmission from the sensors to the receiver occurs in the form of current pulses, which in known systems are designed as rectangular pulses.

[0013] Within the framework of the method proposed here, current pulses are preferably generated for data transmission from the sensor to the receiver, namely the central control unit, the pulse shape of which deviates from the shape of a rectangular pulse in the manner described. Additionally or alternatively, it is possible to apply a corresponding pulse shape to the synchronization pulse as well.

[0014] A preferred embodiment of the method is characterized by the generation of a pulse with a pulse shape exhibiting the flattest possible edges within the specified curves. The rise and fall are preferably designed to be as slow as possible, thus fully utilizing the specified limits. In this way, deviating from the usual approach of making the edges of a rectangular pulse as steep as possible, this method achieves the slowest possible rise and fall of the pulse in order to minimize the harmonic content and thus the electromagnetic radiation. The specified limits are adhered to in order to ensure unambiguous pulse identification.

[0015] A preferred embodiment of the method is characterized by the generation of a substantially rectangular pulse with rounded corners. In this case, the pulse edges are only slightly modified or not modified at all, while rounding is created in the corners, namely the transition regions between the resting level and the edges, or between the data level and the edges. This significantly reduces the harmonic content and decreases electromagnetic radiation. In particular, this avoids indistinguishable areas of the pulse shape. The pulse is generated such that the radius of curvature of the curve in the corner region is larger than that of a standard rectangular pulse.

[0016] Preferably, by fully exploiting the specification limits, a maximum possible radius of curvature is sought in the area of ​​the corners, i.e. the transitions between the edges and the rest level or the edges and the data level, in order to minimize the harmonic content and the electromagnetic radiation.

[0017] A preferred embodiment of the method is characterized by the generation of a step-like waveform with a predetermined number of steps in the pulse's flanks. In particular, a step-like rise or fall is generated with a predetermined resolution, especially with a resolution of N bits, where N is a predetermined natural number. This represents a particularly advantageous and technically simple method of pulse generation, as the step-like waveform readily produces a slower or flatter rise compared to the standard rectangular waveform, thereby reducing the harmonic content of the pulse and decreasing electromagnetic radiation. It is evident that this effect is amplified the higher the predetermined number of steps, and thus the resolution for the step-like waveform, and especially the larger the number N.

[0018] A preferred embodiment of the method is characterized in that the pulse shape is a curve that exhibits non-zero curvature everywhere except, at most, in the region of an extremum value of the pulse. The extremum value refers to the value corresponding to the data level, which, depending on whether the pulse is positive or negative, can be configured as a minimum or a maximum. A curve that exhibits non-zero curvature everywhere except in the region of the extremum value is obtained, in particular, as a limiting case of a pulse with step-shaped flanks when the predetermined number of steps for the step shape, the resolution, or the value of the number N approaches infinity.It is also possible that a continuous pulse waveform with non-zero curvature is generated by a circuit designed to produce the pulse if the circuit is driven by a stepped waveform with a predetermined, finite number of steps. In particular, inductances and / or capacitances present in the circuit can contribute to a rounding of the waveform, which is actually stepped due to the drive signal, so that ultimately a quasi-continuous or continuous waveform results whose curvature is non-zero everywhere except at most at its extreme value. Because the curvature of the waveform vanishes everywhere except at most at its extreme value and, of course, in the region of the resting level (which is not considered in this context), the harmonic component of the pulse and also the electromagnetic radiation are minimized.

[0019] A particularly preferred method is one characterized by the generation of a current waveform for the pulse. Thus, a current intensity is used as the current quantity, resulting in a current pulse – as opposed to a voltage pulse. This design of the method is especially advantageous for use with sensors that communicate with a central control unit via a current interface.

[0020] A preferred embodiment of the method is characterized by the fact that the pulse shape is optimized for minimal electromagnetic radiation. In particular, this makes it possible to minimize the harmonic content and electromagnetic radiation.

[0021] The problem is also solved by creating a circuit device with the features of claim 7. This device is configured for use in an electronic device and for generating a pulse for data transmission between the electronic device and a receiving device. Preferably, the circuit device is configured to carry out a method according to one of the embodiments described above. The circuit device has a conductor section that carries a supply voltage, wherein the conductor section is also intended for data transmission. The conductor section is electrically connected to a data generation device. This connection serves in particular to supply the data generation device with electrical power.The circuit is characterized by a pulse shape generator that is operatively connected to the data generator, enabling data transmission from the data generator to the pulse shape generator. The pulse shape generator is operatively connected to the conductor section and configured to impose a pulse shape onto the conductor section. A predetermined first boundary curve and a predetermined second boundary curve are defined for the pulse shape, wherein the boundary curves describe the time course of a current quantity, and wherein the second boundary curve lies entirely within the first boundary curve.The pulse shape generation device is designed to generate a pulse on the line section with a pulse shape inscribed between the boundary curves. Compared to a rectangular pulse inscribed between the boundary curves, the pulse shape is distorted towards the first boundary curve in a first region of the current quantity away from an extremum, and towards the second boundary curve in a second region of the current quantity closer to the extremum. For definitions and explanations of terms, please refer to the explanations related to the method. The advantages of the circuit design are those already explained in connection with the method.

[0022] A circuit arrangement is preferred which is characterized in that the pulse shape generation means is configured to generate step-shaped pulse edges with a predetermined resolution. The step-shaped pulse edges preferably have a resolution of N bits, where N is a predetermined natural number. Due to the step-shaped pulse edges, harmonic content and electromagnetic radiation of the pulse are minimized. At the same time, a particularly simple and cost-effective pulse shape generation means can readily be used to generate such step-shaped pulse edges.

[0023] According to the invention, a current sink is electrically connected to the line section in parallel with the data generation device, wherein the pulse shape generation device is operatively connected to the current sink. The pulse shape generation device has a digital control unit operatively connected to the data generation device and a digital-to-analog converter operatively connected to the digital control unit. The digital-to-analog converter is configured to influence a current in the current sink according to a predefined setting or depending on the digital control unit. For this purpose, the digital-to-analog converter is preferably directly operatively connected to the current sink. The digital control unit receives the data to be transmitted from the data generation device and generates a signal from it, which is transmitted to the digital-to-analog converter. The converter transforms the signal into a signal suitable for controlling the current sink and, in turn, uses this signal to control the current sink.Since the current sink is electrically connected to the conductor section, the current in the conductor section is modulated in this way, so that current pulses for data transmission can ultimately be generated on the conductor section by the pulse shape generation device. In particular, the digital control is configured to generate a signal suitable for generating a pulse shape according to the invention.

[0024] In a preferred embodiment of the method, the digital control generates a signal with a resolution of N bits, which is used via the digital / analog converter to control the current sink.

[0025] A preferred embodiment of the circuit is characterized in that a series arrangement consisting of a transistor and a resistor is electrically connected to the line section in parallel with the data generation device. The transistor has a control terminal, a first transistor terminal, and a second transistor terminal, the first transistor terminal being electrically connected to the line section. The resistor is electrically connected at one end to the second transistor terminal and at the other end to ground. The circuit includes an amplifier having a first amplifier input, a second amplifier input, and an amplifier output, the amplifier output being electrically connected to the control terminal of the transistor. The second amplifier input is electrically connected to the first end of the resistor.The first amplifier input is electrically connected to a reference voltage source. The pulse shape generation device is operatively connected to the reference voltage source and comprises a digital control circuit operatively connected to the data generation device and a digital-to-analog converter operatively connected to the digital control circuit. The digital-to-analog converter is configured to influence the voltage of the reference voltage source according to a predefined value or depending on the digital control signal. In particular, the digital control circuit is configured to generate a signal suitable for generating a pulse shape according to the invention.

[0026] The transistor is preferably designed as a field-effect transistor, wherein the control terminal is designed as the gate, the first transistor terminal as the source and the second transistor terminal as the drain - or vice versa.

[0027] The amplifier is preferably designed as an operational amplifier, in particular as a comparator, wherein preferably the first amplifier input is designed as a non-inverting input, wherein the second amplifier input is designed as an inverting input, or vice versa.

[0028] The digital control is preferably designed to generate a signal with a resolution of N bits, wherein the reference voltage source is controlled by the signal via the digital / analog converter in such a way that the transistor is switched via the amplifier so that a current in the line section is influenced in such a way that current pulses of the type mentioned here can be generated for data transmission.

[0029] The electronic device is preferably designed as a sensor that is set up to communicate with a central control unit via a power interface.

[0030] The line section is preferably connected to a data bus or represents a section of a data bus, whereby both a supply voltage for the electronic device and data transmission take place via the data bus.

[0031] The invention also relates to an electronic device comprising the circuitry described above. The electronic device is preferably designed as a sensor, in particular as a sensor configured for communication with a central control unit via a current interface.

[0032] The electronic device is particularly preferably a sensor used in a motor vehicle as part of an occupant protection system.

[0033] The description of the method, on the one hand, and the circuitry and electronic device, on the other, are to be understood as complementary to each other. In particular, features of the circuitry or electronic device that have been explained implicitly or explicitly in connection with the method are preferably, individually or in combination, features of a preferred embodiment of the circuitry or electronic device. A circuitry or electronic device is particularly preferred if it has at least one feature that is dictated by a step of the method. Method steps that have been described explicitly or implicitly in connection with the circuitry or electronic device are preferably, individually or in combination, steps of a preferred embodiment of the method.In particular, a method is preferred which includes at least one process step that is conditioned by at least one feature of the circuit device or electronic device.

[0034] The invention will be explained in more detail below with reference to the drawing. The drawing shows: Fig. 1 a diagrammatic representation of conventional rectangular pulses; Fig. 2 a diagrammatic representation of pulses generated according to a first embodiment of the method; Fig. 3 a diagrammatic representation of pulses generated according to a second embodiment of the method; Fig. 4 a diagrammatic representation of pulses generated according to a third embodiment of the method; Fig. 5 a schematic representation of a first embodiment of a circuit device, and Fig. 6 a schematic representation of a second embodiment of the circuit device.

[0035] Fig. Figure 1 shows a diagrammatic plot of a current quantity, here the current I, against time t. The diagram includes a first limit curve 3 and a second limit curve 5, the shape of which is determined by predetermined specification limits for the pulses to be generated, specifically for signal amplitude, rise and fall times of the pulse edges, and a duty cycle. The second limit curve 5 lies entirely within the first limit curve 3 and thus defines the minimum values ​​for the pulses to be generated. The first limit curve 3 lies entirely outside the second limit curve 5 and defines the maximum values ​​for the parameters of the pulses to be generated.Inscribed within the boundary curves 3 and 5 is a signal curve 1, which has a first pulse 7 and a second pulse 9, the second pulse 9 being longer than the first pulse 7, in particular exhibiting a longer data level or high phase. During pulses 7 and 9, the signal curve 1 transitions from a resting level I. R to a data level I D the current I. The signal curve 1 remains within the limit curves 3, 5 in the area of ​​pulses 7, 9, thus ensuring that pulses 7, 9 can be clearly identified as such.

[0036] Out of Fig. 1 It is clearly recognizable that with conventional rectangular pulses 7, 9 there is a steep rise or fall in the pulse edges, which differ from the resting level I R to data level I D and vice versa, is achieved, whereby at the same time in the transition areas between the resting level I R and the flanks, and between data level ID and the edges have sharp corners. A Fourier transform of signal curve 1 therefore exhibits a high harmonic content, which also results in high electromagnetic radiation during data transmission using signal curve 1.

[0037] Fig. Figure 2 shows a diagrammatic representation of two pulses 207, 209 of a signal curve 201 generated according to a first embodiment of the method. Identical and functionally equivalent elements are marked with the same reference numerals, so reference is made to the preceding description. Also shown are the first limit curve 3 and the second limit curve 5, as well as, for comparison, the dashed lines in Fig. The signal curve shown in Figure 1 contains the rectangular pulses 7 and 9. It is evident that pulses 207 and 209 exhibit a pulse shape that differs from that of rectangular pulses 7 and 9 in a first step, the pulse maximum at data level I. DThe signal curve 1 deviates from a rectangular shape in the first region, deviating towards the first limit curve 3, while in a second region, deviating towards the maximum, it deviates towards the second limit curve 5. This behavior applies to the edges of pulses 207 and 209. The first and second regions of the current I are bounded at a limiting current I. G next to each other, whose value is approximately 50% of the difference in the value of data level I D and thus the maximum of pulses 207, 209 to the resting level I R This is the first range from the resting level I. R up to the limiting current strength I G ; the second range extends from the limiting current I G up to data level I D. By comparing the pulse edges of pulses 207, 209 with the pulse edges of pulses 7, 9, it is readily apparent that the edges of pulses 207, 209 deviate from the edges of rectangular pulses 7, 9 in the lower, first area in the direction of the first boundary curve 3, while in the upper, second area they deviate towards the second boundary curve 5.

[0038] It is further shown that pulses 207 and 209 are essentially rectangular in shape, although they have rounded corners in the transition areas between the resting level I. R and the pulse edges as well as between data level I D and exhibit pulse edges. The radius of curvature of signal curve 201 is larger in the corner region than that of signal curve 1.

[0039] Due to the rounding of the corners of the signal curve 201, its harmonic content decreases, and consequently, so does the electromagnetic radiation during data transmission.

[0040] Fig. Figure 3 shows a diagrammatic representation of pulses 307 and 309 of a signal curve 301, which are generated according to a second embodiment of the method. Identical and functionally equivalent elements are designated with the same reference numerals, so reference is made to the preceding description. Pulses 307 and 309 exhibit pulse edges that have a step shape with a predetermined number of steps. In the illustrated embodiment, the edges have a total of three steps.

[0041] The step shape of the pulse edges of pulses 307, 309 is preferably generated with a resolution of N bits, where N is a predetermined natural number.

[0042] Here too, it is evident that the step-shaped pulse edges in the first, lower range up to the limiting current I G , which in turn is at approximately 50% of data level I D - calculated from the resting level I Rfrom - deviating from the pulse edges of the dashed pulses 7, 9 of the signal curve 1 towards the first limit curve 3, whereby they are above the limit current I G in the second area, they deviate towards the second limit curve 5. Overall, this results in a slower rise or fall of the pulse edges, which reduces the harmonic content of signal curve 301 and the electromagnetic radiation during data transmission.

[0043] Fig. Figure 4 shows a diagrammatic representation of pulses 407 and 409 of a signal curve 401. For comparison, signal curve 1 with rectangular pulses 7 and 9 is also shown. Furthermore, identical and functionally equivalent elements are marked with the same reference symbols, so reference is made to the preceding description. The pulse shape of pulses 407 and 409, or rather the curve describing the pulse shape of these pulses, is uniform throughout the range of pulses 407 and 409—except for the range of the maximum value of the longer pulse 409 at data level I. D - a non-zero curvature. The pulse shapes of pulses 407 and 409 are particularly favored and optimized for minimal electromagnetic radiation.

[0044] The specification limits in the form of limit curves 3 and 5 are utilized here as fully as possible – preferably taking into account a certain safety margin – in order to produce the smoothest possible signal curve 401 with gently rising pulse edges and the largest possible radii of curvature, avoiding sharp corners. In this way, the harmonic content and electromagnetic radiation of the signal curve 401 are minimized.

[0045] The limiting current I G This is at approximately 30% of data level I. D - calculated from the resting level I R from -, thus the extremal or maximum value of pulses 407, 409.

[0046] The in Fig. The pulse shapes of pulses 407 and 409 shown in section 4 are preferably considered as limiting cases of the pulse shapes of pulses 307 and 309 according to... Fig. 3 for an infinite number of steps in the area of ​​the edges or an infinitely large resolution of the pulse edges, i.e., when the number N tends towards infinity.

[0047] Real will be in Fig. The signal curve 401 shown in section 4 is already obtained with a finite resolution when controlling a suitable circuit device, because inductances and / or capacitances included in the circuit device lead to a rounding of the curve shape. A step-like control for generating the pulse edges therefore leads to the result shown in section 401 when using a real circuit device. Fig. 4 signal shape 401 shown, if the resolution is sufficiently high.

[0048] The signal curve 401 with pulses 407, 409 according to Fig. 4 is particularly advantageous because not only are rounded corners and / or slowly rising, especially step-shaped, flanks provided, but because the entire shape of the pulses 407, 409 is optimized for a reduced harmonic content and reduced electromagnetic radiation, in particular by rounding the entire pulses 407, 409.

[0049] It also shows that all pulse shapes shown here are according to the Fig. 2 to 4 always remain within the specification limits, i.e. within the first limit curve 3 and the second limit curve 5, so that the pulses, despite their pulse shape deviating from the standard rectangular shape of pulses 7, 9, are easily detected by a receiver device and correctly recognized as pulses.

[0050] Fig. Figure 5 shows a first embodiment of an electronic device 11, which here is configured as a sensor 13, in particular as a peripheral sensor for an occupant protection system of a motor vehicle. The electronic device 11 has a circuitry 15 configured to generate a pulse for data transmission between the electronic device 11 and a receiver 17, which here is configured as the central control unit 19 of a motor vehicle. The electronic device 11 is connected to the receiver 17 via a data bus 21 for data transmission.

[0051] The circuit device 15 has a conductor section 23 that carries a supply voltage. In the illustrated embodiment, the conductor section 23 is connected to the data bus 21, the data bus 21 and thus also the conductor section 23 being used both for data transmission between the electronic device 11 and the receiving device 17 and for supplying the electronic device 11 with electrical power. A current interface is implemented for data transmission, which is schematically designated here by reference numeral 25.

[0052] Preferably, the electronic device 11 and also the circuit device 15 have only two connections, namely the supply connection realized via the line section 23, which also serves for data transmission, and a ground connection 27, which is shown here only symbolically.

[0053] The line section 23 is electrically connected to a data generation device 29, which can be designed, for example, as a sensor circuit that takes over all the tasks of the sensor 13 except for data transmission, and it is possible that the data transmission is at least partially integrated into the data generation device 29.

[0054] Furthermore, a pulse shape generation device 31 is provided, which is operatively connected to the data generation device 29 in such a way that data can be transferred from the data generation device 29 to the pulse shape generation device 31, and which is operatively connected to the line section 23 in order to imprint a signal curve 1 on it, which comprises the data to be sent as a sequence of pulses.

[0055] The pulse-shaping means 31 is designed such that at least one of the components in the Fig. Pulse shapes 2 to 4 shown can be generated using the pulse shape generating device 31.

[0056] At the in Fig. In the embodiment shown in Figure 5, the pulse shape generation device 31 has a digital control unit 33 integrated here into the data generation device 29, as well as a digital-to-analog converter 35 operatively connected to the digital control unit 33. Furthermore, the pulse shape generation device 31 has a current sink 37 which is electrically connected to the line section 23. The digital-to-analog converter 35 is controlled by the digital control unit 33 with a predetermined resolution, acting on the current sink 37 in such a way that the current waveform in the line section 23 is modified to imprint a current waveform with pulses on the line section 23, which has an improved shape with regard to electromagnetic radiation, in particular one of those described in the Fig. 2 to 4 shown pulse shapes, wherein the current curve as signal curve represents the data generated by the data generating means 29 and to be transmitted to the receiving device 17.

[0057] Particularly preferred is the digital control 33 configured to generate a pulse shape with step-shaped edges with a predetermined resolution, in particular of N bits, where N is a predetermined natural number.

[0058] Fig. Figure 6 shows a second embodiment of an electronic device 11 or a circuit arrangement 15. Identical and functionally equivalent elements are designated with the same reference numerals, so reference is made to the preceding description. In the embodiment shown here, a serial arrangement 39, comprising a transistor 41 and a resistor 43, is connected in parallel to the data generation device 29, which is preferably configured as the remaining sensor circuit of the electronic device 11 designed as sensor 13, via the line section 23.

[0059] The transistor has a control terminal 45, a first transistor terminal 47, and a second transistor terminal 49. Transistor 41 is located in the Fig. In the embodiment shown in Figure 6, the transistor is configured as a field-effect transistor, wherein the control terminal 45 is a gate terminal, and wherein preferably the first transistor terminal 47 is a source terminal, and the second transistor terminal 49 is a drain terminal. Alternatively, it is also possible that the first transistor terminal 47 is a drain terminal, and the second transistor terminal 49 is a source terminal.

[0060] Alternatively, transistor 41 can be configured as a bipolar transistor, in which case the control terminal 45 is configured as the base. Transistor terminals 47 and 49 are configured as collector and emitter, respectively, although this configuration may vary depending on the specific embodiment.

[0061] The resistance 43 has a first end 51 and a second end 53.

[0062] Transistor 41 is electrically connected to the conductor section 23 via its first terminal 47, and to the first end 51 of resistor 43 via its second terminal 49. The second end 53 of resistor 43 is electrically connected to ground.

[0063] The circuit assembly 15 further comprises an amplifier 55, which in the illustrated embodiment is configured as an operational amplifier. The amplifier 55 has a supply input 57, a first amplifier input 59, a second amplifier input 61, and an amplifier output 63. Preferably, the first amplifier input 59 is configured as a non-inverting input of the operational amplifier, while the second amplifier input 61 is configured as an inverting input. However, depending on the specific embodiment, a reverse configuration is also possible.

[0064] The power input 57 is connected to the conductor section 23 for supplying the amplifier 55 with electrical power. The amplifier output 63 is electrically connected to the control terminal 45 of the transistor 41. The second amplifier input 61 is electrically connected to the first end 51 of the resistor 43 and thus also to the second transistor terminal 49. In particular, the second amplifier input 61 is electrically connected here to a conductor section that electrically connects the second transistor terminal 49 to the first end 51 of the resistor 43.

[0065] The first amplifier input 59 is electrically connected to a reference voltage source 65, which is operatively connected to the digital / analog converter 35, so that it can be controlled via the digital control 33 and the digital / analog converter 35.

[0066] In this respect, the pulse shape generation device 31 is operatively connected to the reference voltage source 65. Fig. Figure 6 does not show a connection between the data generation device 29 and the digital control unit 33, through which data can be transferred from the data generation device 29 to the digital control unit 33. This connection is already mentioned in connection with... Fig. As explained in section 5, the digital control unit 33 controls the digital-to-analog converter 35 with a predetermined resolution. Depending on the input from the digital control unit 33, the converter then acts on the reference voltage source 65, thereby influencing the voltage applied to the first amplifier input 59. The amplifier 55 controls the control terminal 45 of the transistor 41 based on a voltage difference between the first amplifier input 59 and the second amplifier input 61. This changes the current flow through the transistor 41 and consequently also through the resistor 43. This, in turn, affects the voltage applied to the second amplifier input 61.

[0067] The current flowing through transistor 41 and resistor 43 also affects the current flowing in line section 23.

[0068] In this way it is possible to imprint a current curve on the conductor section 23, which carries the data to be transmitted to the receiving device 17 as a signal curve, wherein, due to the digital control 33 provided for this purpose, the pulses of the signal curve have a favorable shape with regard to a reduced harmonic content and minimized electromagnetic radiation, particularly preferably one of the ones described in the Fig. 2 to 4 pulse shapes shown.

[0069] Overall, it is shown that the method and the circuit device make it possible to reduce the electromagnetic radiation during operation during data transmission, in particular of a peripheral sensor for an occupant protection system of a motor vehicle with a power interface.

Claims

[1] Method for generating a pulse (7,9;207,209;307,309;407,409), wherein for a pulse shape of the pulse (7,9;207,209;307,309;407,409) a predetermined first limit curve (3) and a predetermined second limit curve (5) are defined, wherein the limit curves (3,5) describe the time course of a current quantity (I), and wherein the second limit curve (5) lies completely within the first limit curve (3), characterized by , that as pulse shape for the pulse (7,9;207,209;307,309;407,409) a curve inscribed between the limit curves (3,5) is generated by means of a current sink (37) which - in comparison to a rectangular pulse inscribed between the limit curves (3,5) - is deformed in a first region of the current quantity (I) away from an extremum towards the first limit curve (3), and which is deformed in a second region of the current quantity (I) towards the second limit curve (5). [2] Method according to claim 1, characterized by, that a pulse shape with as flat a flank as possible is generated within the limit curves (3,5). [3] Method according to any one of the preceding claims, characterized by , that an essentially rectangular pulse (7,9;207,209;307,309;407,409) with rounded corners is generated, with a radius of curvature of the curve in the area of ​​the corners being larger than in a rectangular pulse. [4] Method according to any one of the preceding claims, characterized by , that in the area of ​​the flanks of the pulse (7,9;207,209;307,309;407,409) a staircase shape with a predetermined number of steps is generated. [5] Method according to any one of the preceding claims, characterized by , that the pulse shape is a curve which everywhere - except at most in the area of ​​an extremal value - has a non-zero curvature. [6] Method according to any one of the preceding claims, characterized by that a current curve is generated. [7] Circuit arrangement (15) for an electronic device (11) for generating a pulse (7, 9; 207, 209; 307, 309; 407, 409) for data transmission between the electronic device (11) and a receiving device (17), configured for carrying out a method according to one of claims 1 to 6, comprising a conductor section (23) carrying a supply voltage, which is also provided for data transmission, wherein the conductor section (23) is electrically connected to a data generation means (29), and to a pulse shape generation means (31) which is operatively connected to the data generation means (29) so that data can be transmitted from the data generation means (29) to the pulse shape generation means (31), wherein the pulse shape generation means (31) is operatively connected to the conductor section (23) and is configured to imprint a pulse shape onto the conductor section (23), wherein a predetermined first limit curve is defined for the pulse shape (3) and a predetermined,second boundary curve (5) are defined, wherein the boundary curves (3, 5) describe the time course of a current quantity (I), and wherein the second boundary curve (5) lies completely within the first boundary curve (3), wherein the pulse shape generating means (31) is configured to generate a pulse shape inscribed between the boundary curves (3, 5) and, compared to a rectangular pulse inscribed between the boundary curves (3, 5), is distorted towards the first boundary curve (3) in a first region of the current quantity (I) away from an extremum, and is distorted towards the second boundary curve (5) in a second region of the current quantity (I) towards the extremum, and wherein a current sink (37) is electrically connected to the line section (23) in parallel with the data generating means (29), and the pulse shape generating means (31) is operatively connected to it.wherein the pulse shape generating means (31) comprises a digital control unit (33) operatively connected to the data generating means (29) and a digital-to-analog converter (35) operatively connected to the digital control unit (33), wherein the digital-to-analog converter (35) is configured to influence a current in the current sink (37) depending on the digital control unit (33). [8] Circuit device (15) according to claim 7, characterized by , that the pulse shape generation means (31) is configured to generate step-shaped pulse edges with a predetermined resolution. [9] Circuit device (15) according to one of claims 7 and 8, characterized by, that a series arrangement (39) consisting of a transistor (41) and a resistor (43) is electrically connected in parallel to the data generation means (29) and the line section (23), wherein the transistor (41) has a control terminal (45), a first transistor terminal (47) and a second transistor terminal (49), and wherein the resistor (43) is electrically connected at a first end (51) to the second transistor terminal (49) and at a second end (53) to ground, wherein the circuit arrangement (15) comprises an amplifier (55) having a first amplifier input (59), a second amplifier input (61) and an amplifier output (63), wherein the amplifier output (63) is electrically connected to the control terminal (45) of the transistor (41), and wherein the second amplifier input (61) is electrically connected to the first end (51) of the resistor (43),and wherein the first amplifier input (59) is electrically connected to a reference voltage source (65), wherein the pulse shape generation means (31) is operatively connected to the reference voltage source (65), wherein the pulse shape generation means (31) comprises a digital control (33) operatively connected to the data generation means (29) and a digital-to-analog converter (35) operatively connected to the digital control (33), wherein the digital-to-analog converter (35) is configured to influence a voltage of the reference voltage source (65) depending on the digital control (33).

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