Pulse generation device, driver circuit and pulse generation process

Description

[0001] The present invention relates to a pulse generation device for generating output pulses with pulse durations in the range of nanoseconds or shorter, a driver circuit and a pulse generation method.

[0002] A pulse generation device is an electrical or electronic circuit that generates electronic pulses of a defined duration. This application primarily concerns pulse durations in the nanosecond range, for example, single-digit nanoseconds, or shorter. Such short pulses are used, for example, in the generation of laser pulses. High accuracy is desirable in this context.

[0003] Pulse generation devices can be based on various technical principles. This application considers pulse generation devices based on a delay line. Due to the signal propagation time of the pulse along the line, the delay line provides an electrical pulse applied to it at its output after a defined delay. This signal propagation time is subject to thermal fluctuations, among other factors, because electrical conductivity changes with temperature. For example, a 30 cm long delay line generates a delay of two nanoseconds. A change in the temperature of the delay line by 100 Kelvin, for instance, changes the delay by 100 picoseconds, which is approximately five percent of the nominal value of two nanoseconds.

[0004] While existing delay lines can mitigate these temperature drifts to some extent, an uncertainty of several hundred picoseconds often remains. This is usually insufficient, especially considering the eye protection required for laser power classes. Therefore, the laser power, which incorporates a delay-line-based driver in its control circuitry, must be reduced. However, reduced laser power decreases measurement accuracy.

[0005] DE 10 2017 127505 A1 describes a pulse generation device for generating a voltage pulse, in which the pulse duration of the output pulse is regulated by changing the position of a reflector within a delay line. DE 10 2013 212702 A1 discloses an optoelectronic circuit for transmitting an optical clock signal to an electronic component, wherein the circuit is configured to adjust the delay time of an optical delay line by heating the optical line using a heating element. CN 115 454 168 A discusses a method for the soft start of a laser temperature control system, in which the laser temperature is controlled via a thermoelectric cooling / heating element.

[0006] It is possible to overcome the temperature-dependent uncertainty of delay lines using a temperature controller and a Peltier element. However, the necessary circuitry increases the overall cost and size of the solution.

[0007] One object of the present invention is therefore to provide a pulse generation device that is improved compared to the known prior art, especially with regard to its thermal properties.

[0008] The problem is solved by the pulse generation device of claim 1, as well as by the pulse generation method of claim 11. Further developments and embodiments are defined in the dependent patent claims.

[0009] In one embodiment, a pulse generation device for producing output pulses with pulse durations in the nanosecond range or shorter comprises a signal source, a pulse shortening circuit coupled to the signal source, and a heating source coupled to the pulse shortening circuit. The signal source is configured to provide an input current comprising input pulses of a specified input pulse duration. The pulse shortening circuit has a delay line and is configured to provide the output pulses based on the input current. The output pulse duration is shorter than the input pulse duration. The heating source is configured to provide a heating current for the delay line of the pulse shortening circuit. The delay line is designed to heat up to an at least substantially constant operating temperature using the heating current.

[0010] In the pulse generation device according to the invention, input pulses are shortened by means of the delay line of the pulse shortening circuit and provided as output pulses. The heating source heats the delay line to an at least substantially constant operating temperature. According to the invention, the delay line is thus used both to delay input pulses and simultaneously as a heating element. This allows the delay line to operate at a nearly constant temperature, for example, with a deviation of only 0.5 percent, thereby avoiding temperature-related changes in the pulse duration of the output pulses, which can also be caused by other environmental influences such as humidity. The pulse generation device according to the invention can be implemented in a space-saving and cost-effective manner, as it does not require an additional Peltier element or a temperature controller.Typical pulse durations of the output pulses range from a few nanoseconds, for example two nanoseconds, up to picoseconds, about 100 picoseconds.

[0011] The definitions described at the beginning also apply to the following text, unless otherwise stated.

[0012] According to further training, the frequency of the input current is higher than the frequency of the heating current. Specifically, the heating source comprises a DC voltage source or a DC current source.

[0013] The frequency of the input current provided by the signal source is therefore higher, preferably much higher, for example by a factor of 1000 or more, than the frequency of the heating current. In one possible implementation of the invention, the heating source is designed as a DC current or DC voltage source and generates a nearly constant DC signal. In contrast, the signal source generates a pulsed input current, for example using a square wave generator, a field-programmable gate array (FPGA), or a microcontroller. Ideally, the duty cycle of the heating current is nearly one.

[0014] In other words, the input current provided by the signal source is pulsed and therefore broadband. The width in the spectrum depends on the pulse's edge steepness. The DC component is filtered out, so the pulse shape is only negligibly affected in the time domain. Compared to the repetition rate, short pulses are generated, for example, 20-100 ns at a repetition rate of 1-5 MHz, because this is easy to generate and allows for the creation of pulse patterns. For example, five pulses with a 20 ns interval and a 100 ns pause between each are provided with the input current. This is followed by a pause of, for example, 1 µs before the next five pulses are sent.

[0015] According to a further development, the pulse generation device has a signal isolation device which is designed to electrically decouple the input current provided by the signal source from the heating current provided by the heating source as far as possible.

[0016] The signal isolation device thus decouples the input current from the heating current, resulting in one signal path, primarily formed by the pulse shortening circuit, and one heating path. Interference between the currents in the two paths is therefore largely prevented.

[0017] According to one implementation, the signal isolation device is realized by a suitable combination of a low-pass and a high-pass filter. For example, the heating current is filtered by means of a suitably dimensioned inductor, while the output signal is filtered by a suitably dimensioned capacitor. Alternatively, instead of separate filters in the form of inductors and capacitors, a so-called bias filter can also be used.

[0018] In a further embodiment, the pulse generation device additionally includes a control circuit. The control circuit is coupled to the heating source and is configured to provide a control signal for the heating source depending on the temperature of the delay line.

[0019] The control signal thus regulates the level of the heating current supplied by the heating source as a function of the temperature on the delay line. According to the invention, the level of the heating current is therefore actively thermally controlled. A further advantage is the very high accuracy of the pulse duration of the output pulses, even with temperature fluctuations.

[0020] According to further training, the control signal is provided depending on the output pulses, in particular depending on the pulse duration of the output pulses. Specifically, an increase in the pulse duration of the output pulses results in a reduction of the heating current.

[0021] The control system according to the invention therefore utilizes the temperature-dependent change in the pulse duration or pulse width of the output pulses. An increase in the temperature of the delay line causes a lengthening of the pulse duration of the output pulses due to the extended signal propagation time, i.e., a broadening of these pulses. To counteract additional heating of the delay line, i.e., heating to above the nearly constant operating temperature, the heating current is reduced in this case by means of the control signal. This achieves thermal control of the pulse generation device in a simple manner.

[0022] In a further training course, the control signal is provided depending on an amplification and an integration, or depending on the amplification or the integration of the output pulses.

[0023] In an alternative embodiment, the control circuit includes a measuring device for detecting the temperature of the delay line and a signal generation device coupled to the measuring device for generating the control signal. The temperature of the delay line is detected using a temperature sensor, or based on a capacitance or inductance measurement, or a combination of both.

[0024] Alternatively or in addition to the control described above, which is based on the pulse width of the output pulses, the temperature of the delay line can be determined by measurement and the control signal generated based on the measured temperature. This is achieved using a temperature sensor or by determining the instantaneous capacitance or inductance of the line.

[0025] According to further training, the operating temperature of the delay line is at least essentially constant and lies above a maximum temperature that can be reached by the components of the pulse generation device surrounding the delay line.

[0026] The operating temperature to which the delay line is heated by means of the heating current is, for example, above 50 degrees Celsius. Since the operating temperature is above a temperature that can be assumed at most by the other components of the pulse generation device, or by a higher-level circuit in which the pulse generation device is used, additional thermal influences or changes in humidity have virtually no negative effect on the accuracy of the pulse duration of the output pulses provided by the pulse generation device according to the invention.

[0027] In this advanced training, the delay line comprises one or a combination of the following elements: an inductor, a capacitor, a coaxial cable, or a conductor located on or within a printed circuit board. The delay line is designed to delay an input pulse by a preset duration. This preset duration varies depending on the temperature of the delay line.

[0028] An input pulse fed to the delay line is, for example, provided as an output pulse after a delay of the preset duration. Alternatively, the output pulse terminates after the preset duration (or even after twice the preset duration). The preset duration is thus a nominal value of the delay implemented by the delay line. Due to the temperature dependence of the permittivity or dielectric conductivity, the duration fluctuates with temperature changes. The pulse generation device according to the invention counteracts this effect, as already described, by simultaneously using the delay line as a heating element.

[0029] According to one embodiment, the signal source is electrically coupled to a first terminal of the delay line, which also serves as the signal output for the output pulse. A second terminal of the delay line can be coupled to a signal reflection device, which can be, for example, a ground terminal or an open end of the line. This means that the signal source, delay line, and signal reflection device can be connected in series (in the order mentioned).

[0030] An input pulse generated by the signal source is fed into the delay line at the first terminal, while simultaneously the input pulse is already present at the signal output as an output pulse. The input pulse then travels through the delay line and is reflected at the signal reflection device (specifically with inverted phase), travels through the delay line again, and cancels out the input pulse at the first terminal, thus ending the output pulse. In this example, the output pulse has a duration twice the preset time.

[0031] The signal reflection device can, for example, be formed by a closed end of an electrical conductor, i.e., the signal reflection device includes an electrical connection to a reference potential, in particular to ground. For this purpose, a terminal of the delay line opposite the input of the delay line connected to the signal source (i.e., the second terminal mentioned above) can be connected directly to ground, for example. Alternatively, the signal reflection device can also include an open end of an electrical conductor, whereby the second terminal of the delay line can, in particular, remain unconnected or be connected to ground, for example, by means of a resistor of several megaohms.

[0032] According to another embodiment, the pulse shortening circuit comprises a logic gate, in particular an exclusive-OR (XOR) gate. A first input of the logic gate is directly coupled to the signal source (first signal path), whereas a second input of the logic gate is electrically connected to the signal source via the delay line (second signal path). An output of the logic gate can serve as a signal output.

[0033] For an XOR gate, the following sequence can occur: An input pulse is fed into both the first and second signal paths. The first signal path has no delay line, which is why the input pulse is present at the first input of the exclusive-OR gate almost instantaneously. At this point, there is no signal from the input pulse at the second input of the exclusive-OR gate, as the input pulse is delayed by the delay line in the second signal path. The exclusive-OR condition of the gate is therefore satisfied, which is why the exclusive-OR gate "switches on" and outputs a signal. After the preset time interval (e.g., after 2 ns), the input pulse is also present at the second input of the exclusive-OR gate. Consequently, the exclusive-OR condition is no longer satisfied, which is why no signal is now output at the exclusive-OR gate.As a result, a signal is output at the output of the exclusive-OR gate for 2 ns; that is, an output pulse with a pulse duration of 2 ns is generated. This pulse duration corresponds to the delay time of the delay line. The process described above occurs on the rising edge of an input pulse. Similarly, on the falling edge of an input pulse, an output pulse with a pulse duration corresponding to the delay time of the delay line is also generated. If necessary, this second pulse can be suppressed by additionally combining the output of the exclusive-OR gate with the output of the signal source in an AND gate or a non-AND gate.

[0034] The output pulses emitted by the pulse generation device preferably have logic levels, meaning that the voltage and / or current of the respective output pulse is compatible with logic circuits. For example, compatibility with TTL logic, CMOS logic, or low-voltage CMOS logic can be implemented. In particular, the output pulses (i.e., an output signal at the signal output) can have a voltage magnitude, for example, between 2 and 5 V, preferably up to 5 V, and most preferably up to 3.3 V. Alternatively, low voltages are also possible, in particular voltages with a magnitude up to 48 V or 60 V, and / or output currents of less than 20 A, preferably less than 10 A or 5 A, more preferably less than 500 mA, and most preferably less than 20 mA.

[0035] In one embodiment, a driver circuit comprises a pulse generation device as described above and a laser signal source. The laser signal source is configured to generate a driver signal for a laser diode. The driver signal is a function of the output pulses of the pulse generation device.

[0036] The driver circuit is used, for example, in a time-of-flight sensor. The pulses generated by a laser diode operated by the driver circuit according to the invention are advantageously produced with high pulse duration accuracy. This reduces the safety margin required in the prior art for the eye protection limit defined for a specific laser class. The higher transmission power made possible by the invention contributes to an improvement in the range of a measurement system, e.g., a LiDAR sensor in which the invention is used, and improves the detectability of dark targets.

[0037] A further object of the invention is a pulse generation method which comprises the following steps: Generating an input current through a signal source, wherein the input current comprises input pulses of an input pulse duration, heating a delay line to an at least substantially constant operating temperature by means of a heating current, shortening the input pulse duration by delaying the input pulses by means of the delay line, and providing output pulses with pulse durations in the range of nanoseconds or shorter, wherein a pulse duration of the output pulses is shorter than the input pulse duration.

[0038] According to the invention, the delay line used in the pulse generation method serves both to shorten the input pulse duration and as a heating element with a nearly constant operating temperature. This advantageously improves the accuracy of the output pulse duration compared to the prior art.

[0039] Furthermore, the explanations relating to the pulse generation device according to the invention apply accordingly to the method, in particular with regard to advantages and embodiments.

[0040] According to one possible implementation, the pulse generation method is implemented using the pulse generation device described above.

[0041] According to further training, the input pulses are delayed depending on a preset time duration, which varies depending on the temperature during the delay.

[0042] In a further training, the pulse generation method additionally features a control of the heating current level depending on a temperature during the delay of the input pulses.

[0043] The invention is explained in more detail below by way of example with reference to the figures. Functionally or operationally identical components and circuit parts bear the same reference numerals. The figures show: Figure 1 a first exemplary embodiment of the pulse-generating device as proposed, Figure 2 a second exemplary embodiment of the pulse-generating device as proposed, Figure 3 a third exemplary embodiment of the pulse-generating device as proposed, Figure 4 a fourth exemplary embodiment of a pulse-generating device as proposed, Figure 5 a fifth exemplary embodiment of a pulse-generating device as proposed, Figure 6 an example signal diagram, Figure 7 a sixth exemplary embodiment of the pulse-generating device as proposed, and Figure 8 a seventh exemplary embodiment of the pulse-generating device as proposed.

[0044] Figure 1Figure 1 shows a first embodiment of a pulse generation device as proposed in a block diagram. The pulse generation device comprises a signal source 10 for providing an input current I1, a pulse shortening circuit 20, and a heating source 30 coupled to the pulse shortening circuit 20. The input current I1 provided by the signal source 10 has input pulses P1, each with an input pulse duration. The pulse shortening circuit 20 comprises a delay line and provides output pulses P2 based on the input current I1. Each pulse duration of the output pulses P2 is shorter than the input pulse duration of the pulses P1. The heating source 30 generates a heating current I2. Using the heating current I2, the delay line of the pulse shortening circuit 20 is heated to an at least substantially or nearly constant operating temperature.The heating source 30 is shown here purely as an example and schematically in parallel with the pulse shortening circuit 20. Other circuit configurations are within the realm of expert knowledge.

[0045] The input current I1 provided by the signal source 10 is therefore a time-varying signal with a periodic oscillation and input pulses P1. Optionally, the pulse generation device includes a matching element 40, which is connected in series with the signal source 10 and the pulse shortening circuit 20. Alternatively, the matching element 40 can also be connected downstream of the pulse shortening circuit 20. The matching element 40 adapts the signal source 10 to a characteristic impedance of the delay line of the pulse shortening circuit 20 in order to prevent changes in the signal shape due to unwanted or parasitic reflections.

[0046] For example, heating source 30 comprises a nearly ideal current source, which behaves similarly to an open circuit and has virtually no influence on the input current I1 provided by signal source 10. Signal source 10 comprises, for example, an ideal voltage source, which behaves like a short circuit when deactivated. An ohmic loss within the delay line is much smaller than the impedance of the delay line, which corresponds approximately to a resistance implemented by the matching element 40. Thus, a large portion of the heating current I2 flows through the delay line, while the smaller portion flows through signal source 10. If the signal source is implemented as an ideal voltage source with a series resistance, as shown in the diagram... Figure 1Assume that the matching element 40 includes an additional resistor. If the sum of both resistances equals the characteristic impedance of the delay line, then impedance matching is achieved.

[0047] Figure 2 A second exemplary embodiment of the pulse-generating device as proposed is also shown in block diagram form. In addition to the circuit of the Figure 1 The pulse generation device of the Figure 2 A signal isolation device 50 is provided. This device largely decouples the input current I1 from the heating current I2. This takes into account the fact that the heating source 30 cannot be realized as an ideal current source.

[0048] The signal isolation device 50 comprises a low-pass filter 51 and a high-pass filter 52. The high-pass filter 52 allows time-varying signals, such as the output pulses P2, to pass through and attenuates the heating current I2, which does not change over time or changes only very slowly. The low-pass filter 51, connected in series with the heating source 30, prevents the time-varying output signal V2 from being absorbed by the heating source. The in Figure 2 The illustrated embodiment of the signal isolation device 50 corresponds to the bias T described above.

[0049] Alternatively, the low-pass filter 51 can be arranged between the matching element 40 and the heating source 30.

[0050] Figure 3 A third exemplary embodiment of a pulse-generating device as proposed is also shown in block diagram form. In addition to the embodiment of Figure 2This embodiment includes a control circuit 60 as shown. This circuit provides a control signal S for the heating source 30 to adjust the level of the heating current I2. The pulse shortening circuit 20 is also shown in more detail. It includes the delay line 21 and a logic gate 22, which is implemented here as an example of an exclusive-OR (XOR) gate.

[0051] The pulse shortening circuit 20 generates output pulses P2 from the input pulses P1 with a shortened pulse duration compared to P1, as follows: The input signal I1, i.e., the input current I1, is fed to the XOR gate 22 once directly and once via the delay line 21, i.e., in delayed form. The output pulses P2 provided at the output of gate 22 have a pulse duration or pulse width that corresponds to the delay on the delay line 21. This delay represents the preset time duration. The preset time duration depends, among other things, on the current temperature on the delay line 21. The delay line 21 is implemented, for example, as a line integrated into a circuit board. A 30 cm long delay line, for example, produces a delay of two nanoseconds.A change in the temperature of the delay line by 100 Kelvin, for example, changes the delay by 100 picoseconds, which is approximately five percent of the nominal value of two seconds.

[0052] Such thermal fluctuations in the signal propagation time across the delay line 21 are countered by heating the delay line 21 to a nearly constant operating temperature according to the invention. The heating process is also continuously regulated by the control circuit 60. The control circuit 60 integrates the output pulses P2 in an integrator 61 and amplifies its output signal in the amplifier 62. The integrator 61 also includes a reducer, which periodically resets the level of the output signal. A level of the control signal S thus corresponds to a pulse duration of the output pulses P2. This level therefore reflects the current temperature effects or other environmental influences such as humidity on the delay line 21.

[0053] The control signal S is therefore used to increase or decrease the heating current I2 until the output pulses P2 again reach the desired pulse width.

[0054] The output pulses P2 can be considered or described as voltage or current pulses. In the pulse generation circuit according to the invention, fluctuations in the pulse duration of the output pulses are significantly reduced. For example, the fluctuations are less than five percent at 100 Kelvin.

[0055] Figure 4Figure 4 shows a fourth exemplary embodiment of a pulse generation device in block diagram form. In contrast to the embodiment of Figure 3, the pulse shortening circuit 20 is implemented differently here. As shown, the pulse shortening circuit 20 comprises the delay line 21 and a signal reflection device 23. The signal reflection device 23 can, for example, be implemented as a ground potential, as indicated in Figure 4. The pulse shortening circuit 20 operates here according to the reflection principle. An input pulse P1 from the signal source 10, for example a voltage pulse P1, travels through the delay line 21, is reflected by the reflection device 23 with inverted polarity, and travels through the delay line 21 a second time in the opposite direction.Due to the partial temporal overlap of an input pulse P1 with its reflected and inverted counterpart, the original input pulse P1 is partially canceled out, resulting in a shortened preliminary output pulse P2'. The preliminary output signal V2' obtained in this way is smoothed by a diode D1 and passed through the high-pass filter 52 to a signal divider 63. The diode D1 filters out, for example, negative pulses of the preliminary output signal V2', which may be caused by switching off the signal source 10. Furthermore, the preliminary output signal V2' is only detected above a certain level or voltage level.

[0056] The signal divider 63 divides the preliminary output signal V2' such that the largest part, for example 99.9%, is provided as output signal V2, and only a small part, for example 0.1%, is used to generate the control signal S. The signal divider 63 is implemented, for example, as a high-impedance voltage tap. The control signal S is then used equivalently to the embodiment of Figure 3 generated using the integrator 61 and the amplifier 62.

[0057] The delay line 21, for example, consists of a copper layer and a base material, such as FR4, and has a small diameter. This makes it particularly suitable as a heating element.

[0058] Figure 5 Figure 1 shows a fifth exemplary embodiment of a pulse generation circuit as proposed. This embodiment shows a possible circuit-technical implementation of the circuit described in Figure 2. Figure 3The third embodiment shown, however without the control circuit 60. The signal source 10 is implemented as a voltage source. The component dimensions given are purely exemplary. Each of the matching elements 40 and 41 is implemented as a resistor R4 and R6, respectively. The delay line 21 is represented as a delay element T2 referenced to ground potential 24 with a resistor R5 connected in series, which represents the ohmic loss.

[0059] Figure 6 shows an exemplary signal diagram for the implementation of Figure 5 The diagram shows the current through resistor R5, which largely corresponds to the input current I1, and the output signal V2, each in relation to time t. It can be seen that the pulse duration of the input pulse P1 is approximately halved, and a corresponding output pulse P2 is provided.

[0060] Figure 7 Figure 6 shows a sixth exemplary embodiment of the pulse generation device as proposed. Here is a circuit-technical example implementation corresponding to the fourth embodiment from Figure 7. Figure 4 The diagram shows the control circuitry omitted. The shortened output pulses P2 are thus generated by passing through the delay line 21 twice and reflecting off the reflector 23.

[0061] Figure 8 Figure 7 shows a seventh exemplary embodiment of the pulse generation device as proposed. Here, a circuit-related implementation of the fourth embodiment is shown. Figure 4The circuit is shown along with the control circuitry. The preliminary output signal V2' is fed to the integrator 61 via the signal divider 63, which is a node in the circuit. Resistor R5 in the integrator ensures the continuous discharge described above. After the circuit has settled, a DC offset is obtained at the output of the integrator 61. The settling time can be reduced by appropriately dimensioning components R4, C3, and R5. A voltage follower 64 and an amplifier 62, implemented here as a differential amplifier, are connected downstream of the integrator 61. The amplifier 62 compensates for part of the offset APW at the output of the integrator 61 using the voltage source V3 and amplifies the resulting signal, for example, by a factor of 10. The control signal S provided at the output of the amplifier 62 is, in this implementation, a fixed voltage whose amplitude depends on the pulse width of the output pulses P2.The heating source 30 is adjusted using the control signal S.

[0062] The proposed pulse generation device can advantageously compensate for not only temperature influences but also other influences such as component variations or different humidity levels.

[0063] Alternatively or additionally, the proposed pulse generation device can also be used for monitoring. It can also be used in combination with a temperature sensor for monitored control. Alternatively, it can be combined with a capacitance or inductance measurement of the delay line 21. Reference symbol list

[0064] 10 Signal source 20 Pulse shortening circuit 21 Delay line 22 Logic gate 23 Reflector 24 Ground connection 30 Heat source 40, 41 Matching element 50 Signal isolating device 51 Low-pass filter 52 High-pass filter 60 Control circuit 61 Integrator 62 Amplifier 63 Signal divider 64 Voltage follower P1, P2, P2' Pulse S, I1, V2, V2' Signal D1 Diode R4, R5 Resistor APW Offset T2 Delay element

Claims

1. A pulse generating device for generating output pulses (P2) with pulse durations in the range of nanoseconds or shorter, comprising a signal source (10) for providing an input current (I1) which comprises input pulses (P1) of an input pulse duration (P1), a pulse shortening circuit (20) which is coupled to the signal source (10), which comprises a delay line (21) and which is configured to provide the output pulses (P2) on the basis of the input current (I1), wherein a pulse duration of the output pulses (P2) is shorter than the input pulse duration, characterized in that the pulse generating device further comprises: a heating source (30) coupled to the pulse shortening circuit (20) for providing a heating current (I2) for the delay line (21) of the pulse shortening circuit (20), wherein the delay line (21) is designed to be heated to an at least substantially constant operating temperature using the heating current (I2).

2. A pulse generating device according to claim 1, wherein a frequency of the input current (I1) is higher than a frequency of the heating current (I2), wherein in particular the heating source (30) comprises a direct current source or a direct voltage source.

3. A pulse generating device according to claim 1 or 2, further comprising a signal separation device (50) which is configured to electrically decouple the input current (I1) provided by the signal source (10) from the heating current (I2) provided by the heating source (30) to the greatest extent possible.

4. A pulse generating device according to any of the preceding claims, further comprising a control circuit (60) coupled to the heating source (30) and configured to provide a control signal (S) for the heating source (30) as a function of a temperature of the delay line (21).

5. A pulse generating device according to the preceding claim, wherein the control signal (S) is provided as a function of the output pulses (P2), in particular as a function of the pulse duration of the output pulses (P2), wherein in particular an increase in the pulse duration of the output pulses (P2) causes a reduction in the heating current (I2).

6. A pulse generating device according to claim 4 or 5, wherein the control signal (S) is provided as a function of an amplification and / or integration of the output pulses (P2).

7. A pulse generating device according to claim 4, wherein the control circuit (60) comprises a measuring device for detecting the temperature of the delay line (21) and a signal generating device coupled to the measuring device for generating the control signal (S), wherein the temperature of the delay line (21) is detected using a temperature sensor or on the basis of a capacitance and / or inductance measurement.

8. A pulse generating device according to any one of the preceding claims, wherein the at least substantially constant operating temperature of the delay line (21) is above a maximum temperature which is attainable by the components of the pulse generating device that surround said delay line.

9. A pulse generating device according to any one of the preceding claims, wherein the delay line (21) comprises an inductor and / or a capacitor and / or a coaxial line and / or a conductor track on or in a printed circuit board and is designed to delay an input pulse (P1) by a preset time duration, and wherein the preset time duration is variable as a function of a temperature of the delay line (21).

10. A driver circuit comprising a pulse generating device according to any one of the preceding claims, a laser signal source for generating a drive signal for a laser diode, wherein the drive signal is a function of the output pulses (P2) of the pulse generating device.

11. A pulse generating method comprising the following steps: generating an input current (I1) by a signal source (10), wherein the input current (I1) comprises input pulses (P1) of an input pulse duration, characterized in that the method further comprises: heating a delay line (21) to an at least substantially constant operating temperature by means of a heating current (I2), shortening the input pulse duration by delaying the input pulses (P1) using the delay line (21) and providing output pulses (P2) with pulse durations in the range of nanoseconds or shorter, wherein a pulse duration of the output pulses (P2) is shorter than the input pulse duration (P1).

12. A pulse generating method according to the preceding claim, wherein the delay is performed as a function of a preset time duration which is variable as a function of a temperature during the delay.

13. A pulse generating method according to claim 11 or 12, further comprising: regulating a magnitude of the heating current (I2) as a function of a temperature during the delay of the input pulses (P1).