Signal generator and method for operating a signal generator

Abstract

The invention relates to a signal generator (100) for generating at least one signal pulse of a staircase shape. The signal generator comprises a first transmission line (1) having a first length (L1), which is connected in series with a first voltage source (3) for transmitting at least one first signal, wherein the first voltage source (3) has a first amplitude (V1); a second transmission line (2) having a second length (L2) which is different from the first length (L1), which is connected in parallel with the first transmission line (1), wherein the second transmission line (2) is connected in series with a second voltage source (4) for transmitting at least one second signal, and the second voltage source (4) has a second amplitude (V2).

Description

Technical Field

[0001] The present invention relates to a signal generator having at least two voltage sources and two transmission lines of different lengths. Background Technology

[0002] In the prior art, semiconductor devices and corresponding circuits operating in pulse mode are characterized. This reduces self-heating effects and excessive energy loss, which can lead to damage to the devices and / or circuits. Pulse mode measurements are performed using single-pulse or multi-pulse measurements. Multi-pulse measurements improve the accuracy of the characterization. For rapid measurements, the edges of the signal pulses must be steep. However, in both single-pulse and multi-pulse measurements, overshoot and undershoot, as well as unwanted oscillations, can occur. This phenomenon is particularly prevalent in broadband devices. The measurement point is only recorded after the unwanted oscillations have decayed, thus extending the measurement duration. Summary of the Invention

[0003] The signal generator according to the invention enables the generation of stepped signal pulses. The signal generator also enables the generation of signal pulses of other shapes, wherein any shape, including stepped shapes, is optimized to accelerate the measurement process.

[0004] The signal generator is constructed with a first transmission line having a first length L1, which is connected in series with a first voltage source for transmitting at least one first signal, wherein the first voltage source has a first amplitude V1. Furthermore, the signal generator according to the invention also constructs a second transmission line having a second length L2 different from the first length L1, which is connected in parallel with the first transmission line, wherein the second transmission line is connected in series with a second voltage source for transmitting at least one second signal, and the second voltage source has a second amplitude V2. With this construction, a stepped signal pulse can be generated. Other waveforms, such as triangular waveforms, can also be achieved with the above construction. By shaping the signal pulse, the number of required measurement points can be reduced. Thus, the measurement time is shortened while maintaining the same measurement accuracy. In particular, to generate a stepped signal pulse, the length L2 of the second transmission line is chosen to be half the length L1 of the first transmission line. Furthermore, to generate a stepped signal pulse, the first amplitude of the first voltage source is chosen to be half the second amplitude of the second voltage source.

[0005] Furthermore, preferred improvements to the present invention are shown.

[0006] Preferably, a first switch is arranged after the first transmission line to influence the timing of the generation of the first signal, and / or a second switch is arranged after the second transmission line to influence the timing of the generation of the second signal. Initially, both the first and second switches are open. Thus, the first and second transmission lines are charged by a constant DC voltage. To generate the first signal propagating on the first transmission line, the first switch must be closed. Once the first switch is closed, the first signal propagates from the first switch toward the first voltage source with an amplitude of -V1 / 2. To generate a stepped signal pulse, the second switch is closed just as the first signal propagating from the first switch toward the first voltage source on the first transmission line reaches half the length of the first transmission line, provided that the relationships 2L2 = L1 and V2 = 2V1 are satisfied. Once the second switch is closed, the second signal propagates from the second switch toward the second voltage source with an amplitude of -V2 / 2. At the same time that the first signal arrives at the end of the first transmission line facing the first voltage source, the second signal arrives at the end of the second transmission line facing the second voltage source.

[0007] In one embodiment, the first transmission line is terminated via a third switch and a first resistor to suppress unwanted signal reflections, and / or the second transmission line is terminated via a fourth switch and a second resistor to suppress unwanted signal reflections. Here, the first and second resistors each have a value as high as the characteristic resistance of their respective transmission lines, thus ensuring that all energy is absorbed by these two resistors. For example, if the characteristic resistance of the first transmission line is 50 ohms, then a first resistor with a value of 50 ohms is arranged. The same applies to the second transmission line and the second resistor. Specifically, a small time deviation is set between the switching times of the third and fourth switches so that the two transmission lines do not discharge at the same time. This reduces the steepness of the falling edge. The same effect can be achieved by matching lengths L1 and L2.

[0008] Furthermore, preferably, a third resistor is arranged after the first voltage source for amplitude matching of the first signal, and / or a fourth resistor is arranged after the second voltage source for amplitude matching of the second signal. The first and second signals propagate back in the direction of their respective transmission lines after reaching the third and fourth resistors, respectively. The propagation of the signals is related to the voltage of the transmission lines. The transmission lines are charged with voltages V1 and V2 through the third and / or fourth resistors. The third and fourth resistors are preferably of the same size. For example, the third and / or fourth resistors have a value of approximately 500 kilohms.

[0009] To ensure that the amplitudes of the first and second signals are equal, the third resistor has an impedance at least two orders of magnitude higher than that of the first transmission line, and / or the fourth resistor has an impedance at least two orders of magnitude higher than that of the second transmission line. By choosing such large values ​​for the third and / or fourth resistors, better signal decoupling can be achieved.

[0010] More preferably, a first capacitor is placed after the first transmission line to reduce the steepness of the signal rising edge, and / or a second capacitor is placed after the second transmission line to reduce the steepness of the signal rising edge. The capacitor here functions as an integrator.

[0011] In one embodiment, the first and second transmission lines are part of a set of n parallel transmission lines (1, 2, …, n) for generating n-level signal pulses, where n is a natural number and at least 2. All the preceding descriptions of the configuration of the signal generator of the present invention can be extended to n-2 additional stages.

[0012] Advantageously, a controller is provided for connecting and disconnecting one or more transmission lines. The controller also allows for adjustment of the switching timing of the switches and the amplitude of the voltage source.

[0013] The present invention also relates to a method in which a first switch and / or a second switch are closed to generate a first signal and / or a second signal. To influence the timing of the generation of the first or second signal, the first switch or the second switch is closed at time-staggered relative to a corresponding other switch.

[0014] In another method step, a third and / or fourth switch is closed to suppress unwanted signal reflections. Furthermore, closing the third or fourth switch at a time-staggered interval relative to the corresponding other switch can result in a reduction in the steepness of the signal pulse's falling edge.

[0015] Preferably, in another method step, the controller can disconnect a number of m parallel transmission lines to reduce energy consumption, wherein the number m is a positive natural number that is at least 2 less than the number n. Attached Figure Description

[0016] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In the drawings: Figure 1 A circuit diagram of a signal generator according to the present invention is shown. Figure 2 A voltage curve plotted above the time axis is shown for the signal generator according to the present invention, and Figure 3 The diagram shows a voltage curve plotted above the time axis for an n-stage signal generator. Detailed Implementation

[0017] Preferably, the same components, elements and / or units in all the figures are referred to by the same reference numerals.

[0018] Figure 1 A signal generator 100 is shown for generating at least one signal pulse in a stepped shape. The signal generator 100 includes a first transmission line 1 and a second transmission line 2. The first transmission line has a first length L1 and is connected in series with a first voltage source 3 for transmitting at least one first signal, wherein the first voltage source 3 has a first amplitude V1. The second transmission line 2 has a second length L2 different from the first length L1 and is connected in parallel with the first transmission line 1. The second transmission line 2 is connected in series with a second voltage source 4 for transmitting at least one second signal, wherein the second voltage source 4 has a second amplitude V2.

[0019] Figure 1 The signal generator shown generates two-stage stepped signal pulses. In this embodiment, a first switch 5 is arranged after the first transmission line 1 to influence the timing of the generation of the first signal, and / or a second switch 6 is arranged after the second transmission line 2 to influence the timing of the generation of the second signal. Furthermore, in this embodiment, the first transmission line 1 is terminated by a third switch 7 and a first resistor 9 to suppress unwanted signal reflections, and the second transmission line 2 is terminated by a fourth switch 8 and a second resistor 10 to suppress unwanted signal reflections.

[0020] A third resistor 11 is arranged after the first voltage source 3 for amplitude matching of the first signal, and a fourth resistor 12 is arranged after the second voltage source 4 for amplitude matching of the second signal. Here, in order to make the amplitudes of the first signal and the second signal equal, the value of the third resistor 11 is at least two orders of magnitude higher than the impedance of the first transmission line 1; similarly, in order to make the amplitudes of the first signal and the second signal equal, the value of the fourth resistor 12 is at least two orders of magnitude higher than the impedance of the second transmission line 2.

[0021] Figure 2 The diagram illustrates a two-stage stepped signal pulse. Here, a first capacitor is positioned after the first transmission line to reduce the steepness of the signal rising edge, and / or a second capacitor is positioned after the second transmission line to reduce the steepness of the signal rising edge. The reduction in the falling edge steepness can be achieved by adjusting the time deviation between the switching times of the third and fourth switches.

[0022] Figure 3The diagram illustrates an n-level stepped signal pulse, where n=5. In this embodiment, the first transmission line 1 and the second transmission line 2 are part of a set of n=5 parallel transmission lines (1, 2, …, n=5) for generating n-level signal pulses, where n is a natural number and at least 2 in all cases. The signal generator has a controller for connecting and disconnecting one and / or more transmission lines.

Claims

1. A signal generator (100) for generating at least one signal pulse in a stepped shape, comprising: • A first transmission line (1) having a first length (L1) is connected in series with a first voltage source (3) for transmitting at least one first signal, wherein the first voltage source (3) has a first amplitude (V1). • A second transmission line (2) having a second length (L2) different from the first length (L1), the second transmission line being connected in parallel with the first transmission line (1), wherein the second transmission line (2) is connected in series with a second voltage source (4) for transmitting at least one second signal, and the second voltage source (4) having a second amplitude (V2).

2. The signal generator (100) according to claim 1, characterized in that, A first switch (5) is arranged behind the first transmission line (1) to affect the timing of the generation of the first signal, and / or a second switch (6) is arranged behind the second transmission line (2) to affect the timing of the generation of the second signal.

3. The signal generator (100) according to claim 1 or 2, characterized in that The first transmission line (1) is terminated by a third switch (7) and a first resistor (9) to suppress unwanted signal reflections, and / or the second transmission line (2) is terminated by a fourth switch (8) and a second resistor (10) to suppress unwanted signal reflections.

4. The signal generator (100) according to any one of claims 1 to 3, characterized in that A third resistor (11) is arranged behind the first voltage source (3) for amplitude matching of the first signal, and / or a fourth resistor (12) is arranged behind the second voltage source (4) for amplitude matching of the second signal.

5. The signal generator (100) of claim 4, characterized in that To make the amplitudes of the first signal and the second signal equal, the value of the third resistor (11) is at least two orders of magnitude higher than the impedance of the first transmission line (1), and / or, to make the amplitudes of the first signal and the second signal equal, the value of the fourth resistor (12) is at least two orders of magnitude higher than the impedance of the second transmission line (2).

6. The signal generator (100) according to any one of claims 1 to 5, characterized in that A first capacitor (13) is arranged behind the first transmission line (1) to reduce the steepness of the signal rising edge, and / or a second capacitor (14) is arranged behind the second transmission line (2) to reduce the steepness of the signal rising edge.

7. The signal generator (100) according to any one of claims 1 to 6, characterized in that The first transmission line (1) and the second transmission line (2) are part of a set of n parallel transmission lines (1, 2, …, n) for generating n-level signal pulses, where n is a natural number and at least 2.

8. The signal generator (100) according to any one of claims 1 to 7, characterized in that A controller is provided for connecting and disconnecting one or more transmission lines.

9. A method for operating a signal generator (100) according to any one of claims 2 to 8, comprising the following steps: • Close the first switch (5) and / or the second switch (6) to generate the first signal and / or the second signal; as well as • Close the first switch (5) or the second switch (6) at staggered times to influence the timing of the generation of the first signal or the second signal.

10. A method for operating a signal generator (100) according to any one of claims 3 to 9, comprising the following steps: • Close the third switch (7) and / or the fourth switch (8) to suppress unwanted signal reflections; as well as • Close the third switch (7) or the fourth switch (8) at staggered times to reduce the steepness of the falling edge of the signal pulse.

11. The method according to any one of claims 7 to 10, characterized in that, To reduce energy consumption, the controller disconnects m parallel transmission lines, where m is a positive natural number that is at least 2 less than the number n.

Images