JP2011233994A - Pulse generator and pulse shaping method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance accuracy of pulse rise time.SOLUTION: A pulse generator has a pulse generation section and a bridge tap. The pulse generation section generates a pulse having a roundness in a rise range (a range of rise time defined by a specification, etc.). One terminal of the bridge tap is opened and the other terminal is a distribution constant line where an output from the pulse generation section is electrically connected to a propagating line. The bridge tap is the distribution constant line that causes a delay equal to or more than a time of a first part or a roundness part of a last part of the rise of the pulse generated by the pulse generation section and equal to or less than a time for an instantaneous value to reach 100%. In addition, some degree of effect can also be obtained by using a bridge tap having a capacitor.

Description

  The present invention relates to a pulse generator that generates a pulse whose waveform shape is defined, and a pulse shaping method that shapes the waveform. For example, the present invention relates to a pulse generator that generates an impulse waveform for testing and a pulse shaping method.

  When electrical tests are performed on various devices, the test items often include a test in which an impulse voltage is applied to the device under test. For example, there is Non-Patent Document 1 as a technical standard of test technology and measurement technology related to immunity of electrical and electronic equipment against electrical fast transients. A configuration shown in FIG. 1 of Non-Patent Document 1 is known as a pulse generator that generates an impulse voltage. FIG. 1 shows the configuration of the pulse generator (referred to as “burst generator” in Non-Patent Document 1) shown in FIG. 1 of Non-Patent Document 1, and FIG. FIG. 4 shows the pulse waveform shown in FIG. 1 includes a high voltage power source 910, a charging resistor 920, an energy storage capacitor 930, a switch 940, an impulse width shaping resistor 950, an impedance matching resistor 960, a DC blocking capacitor 970, and an output coaxial 980. It is connected. Non-Patent Document 1 shows a condition that a pulse waveform must satisfy. For example, the following characteristics must be satisfied.

The output voltage range at 50Ω load is at least 0.125 kV to 2 kV
Rise time T _r = 5 ns ± 30%
Pulse time width T _d = 50 ns ± 30%
The rise time _Tr is a time interval during which the instantaneous value of the pulse first reaches 10% (10% of the voltage at the top of the head) and then reaches 90% (90% of the voltage at the top of the head). The time width _Td of the pulse is a time width of a 50% value of the pulse.

"Electromagnetic compatibility (EMC)-Part 4: Testing and measurement techniques-Section 4: Electrical fast transient / burst immunity test", Basic EMC publication, International Standard, IEC 61000-4-4, second edition, 2004-07.

In the case of the test related to immunity of Non-Patent Document 1, the rise time T _r particularly affects the test result. However, it may be difficult to generate pulses with high accuracy, and an error of ± 30% is allowed in the rise time _Tr . For this reason, even an apparatus that has passed an immunity test using a certain pulse generator that satisfies the standard of Non-Patent Document 1 fails in an immunity test that uses another pulse generator that satisfies the standard of Non-Patent Document 1. It may become. That is, in spite of the test conforming to the same technical standard, there is a disadvantage that the test results are different.

It is an object of the present invention to provide a pulse generator and a pulse shaping method that improve the accuracy of the rise time _Tr .

  The pulse generator of the present invention includes a pulse generation unit and a bridge tap. The pulse generation unit generates a pulse having a roundness in a rise range (rise time range determined by a standard or the like). The bridge tap is a distributed constant line having one end open and the other end electrically connected to a line through which the output from the pulse generation unit propagates. The bridge tap is a distributed constant line that generates a delay that is equal to or longer than the time at which the pulse rises at the first or last rounded portion of the pulse, and the momentary value reaches 100%. The first part or the last part of the rising edge means either of the two ends of the entire rising edge. In the case of a pulse having a rise time of about 5 ns, a coaxial cord having a length of 10 to 50 cm may be used for the distributed constant line, and a coaxial cord having a length of 20 to 40 cm is particularly suitable in many cases. Also, a plurality of bridge taps may be provided. Furthermore, a certain degree of effect can be obtained even when a bridge tap having a capacitor is used.

  In the pulse shaping method of the present invention, when the range of the rising edge of the pulse generated by the pulse generator is rounded, the other end of the distributed constant line with one end opened is connected to the line between the pulse generator and the load. Connect electrically.

  According to the pulse generator and the pulse shaping method of the present invention, the roundness of the rising range can be shaped into a straight line by delaying and synthesizing a part of the pulse by the bridge tap or attenuating the high frequency component. Therefore, the accuracy of the pulse rise time can be improved.

The figure which shows the structure of the pulse production | generation part shown by FIG. The figure which shows the pulse waveform shown by FIG. The figure which shows the pulse waveform produced | generated with the conventional pulse generator. FIG. 3 is a diagram illustrating a configuration example of a pulse generator according to the first embodiment. Change in waveform when the present invention is applied to a pulse whose rounding range is not rounded, and the delay time is longer than the time when the instantaneous value of the pulse reaches 10% and shorter than the time when it reaches 100% FIG. The figure which shows the change of a waveform when it is a case where this invention is applied to the pulse which has no roundness in the range of a rise, and delay time is made into the time when the instantaneous value of a pulse reaches 10%. The figure which shows the change of a waveform when it is a case where this invention is applied to the pulse which has no roundness in the range of a rise, and delay time is made into the time when the instantaneous value of a pulse reaches 100%. The figure which shows the change of a waveform when it is a case where this invention is applied to the pulse which is not round in the range of a rise, and delay time is made longer than the time when the instantaneous value of a pulse reaches 100%. Change in waveform when the present invention is applied to a pulse having a rounded rising range, and the delay time is longer than the time when the instantaneous value of the pulse reaches 10% and shorter than the time when the pulse reaches 100% FIG. The figure which shows the change of a waveform when it is a case where this invention is applied to the pulse with roundness in the range of a rise, and delay time is made into the time when the roundness of a pulse is lost. The figure which shows the change of a voltage when connecting a 50-ohm load to the pulse generator of FIG. 4 whose length of a bridge tap is 20 cm, and generating a pulse so that 2 kV may be applied to a load. The figure which shows the change of a voltage when connecting a 50-ohm load to the pulse generator of FIG. 4 whose bridge tap length is 25 cm, and generating a pulse so that 2 kV may be applied to a load. The figure which shows the change of a voltage when connecting a 50 ohm load to the pulse generator of FIG. 4 whose bridge tap length is 30 cm, and generating a pulse so that 2 kV may be applied to a load. The figure which shows the change of a voltage when connecting a 50 ohm load to the pulse generator of FIG. 4 whose bridge tap length is 40 cm, and generating a pulse so that 2 kV may be applied to a load. The figure which shows the change of a voltage when connecting a 50-ohm load to the pulse generator of FIG. 4 whose bridge tap length is 50 cm, and generating a pulse so that 2 kV may be applied to a load. The figure which shows the change of a voltage when connecting a 50 ohm load to the pulse generator of FIG. 4 whose length of a bridge tap is 30 cm, and generating a pulse so that -2 kV may be applied to a load. The figure which shows the result of having measured the rise time, changing the length of an output coaxial, the length of a bridge tap, and polarity. FIG. 6 is a diagram illustrating a configuration example of a pulse generator according to a second embodiment. The figure which shows the change of a voltage when a 50-ohm load is connected to the pulse generation part 900 of FIG. 1, and a pulse is generated so that 2 kV may be applied to a load. The figure which shows the change of a voltage when connecting a 50-ohm load to the pulse generator of FIG. 18 whose capacity | capacitance of a capacitor | condenser is 27 pF, and generating a pulse so that 2 kV may be applied to a load. The figure which shows the change of a voltage when connecting a 50-ohm load to the pulse generator of FIG. 18 whose capacity | capacitance of a capacitor | condenser is 33 pF, and generating a pulse so that 2 kV may be applied to a load. The figure which shows the change of a voltage when connecting a 50-ohm load to the pulse generator of FIG. 18 whose capacity | capacitance of a capacitor | condenser is 42 pF, and generating a pulse so that 2 kV may be applied to a load. The figure which shows the result of having measured rise time, changing the presence or absence of a capacitor, the capacity of a capacitor, the voltage to generate, and polarity.

  Hereinafter, embodiments of the present invention will be described in detail. In addition, the same number is attached | subjected to the structure part which has the same function, and duplication description is abbreviate | omitted.

Analysis The goal of the present invention would be to improve the accuracy of the rise time T _r, firstly, the accuracy of the rise time T _r to consider the cause bad. FIG. 3 shows a pulse waveform generated by a conventional pulse generator. From FIG. 3, it can be seen that the waveform near the top of the pulse is rounded, including around the 90% value of the pulse. When the roundness changes, the rise time _Tr greatly changes. Therefore, in the present invention, in order to improve the accuracy of the rise time _Tr , a pulse whose waveform is more linear when the instantaneous value that is the range of the rise time (rise range) is in the range of 10% to 90%. Is generated.

Configuration FIG. 4 shows a configuration example of the pulse generator of the present invention. The pulse generator 100 includes a pulse generation unit 900 and a bridge tap 110. The pulse generation unit 900 may be configured as shown in FIG. 1, for example, and the pulse generated by the output coaxial 980 is supplied to the device (load). As shown in FIG. 3, the pulse generator 900 generates a pulse having a rounded rising range (rising time range determined by a standard or the like). In the case of the standard of Non-Patent Document 1, the rising range is a range where the instantaneous value of the pulse reaches 10% and then reaches 90%.

  The bridge tap 110 is a distributed constant line having one end opened and the other end electrically connected to a line (for example, the output coaxial 980) through which the output from the pulse generation unit 900 propagates. The bridge tap 110 is a distributed constant line that generates a delay that is longer than the time of the first part or the round part of the last part of the pulse generated by the pulse generator 900 and less than the time when the instantaneous value reaches 100%. is there. The first part or the last part of the rising edge means either of the two ends of the entire rising edge. By giving such a delay, the bridge tap 110 shapes the roundness of the rising range of the pulse generated by the pulse generation unit 900 into a straight line. For example, in the case of a coaxial cord having a characteristic impedance of 50 ohms, the pulse speed is 5 ns / m. Therefore, the pulse flowing into the coaxial cord is reflected by the open end and returned to the length of the coaxial cord (m) × 10 It will be delayed by (ns / m). As in Non-Patent Document 1, in the case of a pulse having a rise time of about 5 ns, a coaxial cord having a length of 10 to 50 cm may be used for the distributed constant line, and a coaxial cord having a length of 20 to 40 cm is particularly suitable. It is thought that there are many cases.

  In addition, the pulse shaping method of the present invention is a device connected to the pulse generator 900 and a load (not shown, but connected to the output coaxial 980) when the range of the rise of the pulse generated by the pulse generator 900 is rounded. The other end of the bridge tap 110 (for example, a distributed constant line such as a coaxial cord) having one end opened is electrically connected to a line (for example, the output coaxial 980) between the other end.

Principle Next, the reason why the pulse generator and the pulse generation method of the present invention can shape the rising range in a straight line will be described. In this description, a case where the present invention is applied to a pulse with no roundness in the rising range will be described first. Thereafter, a case where the present invention is applied to a pulse having a rounded rising range will be described.

FIG. 5 shows a case where the present invention is applied to a pulse whose rounding range is not round, and the delay time is longer than the time when the instantaneous value of the pulse reaches 10% and shorter than the time when it reaches 100%. It is a figure which shows the change of this waveform. An alternate long and short dash line indicates an output voltage (original pulse 111) from the pulse generation unit 900. The original pulse 111 is divided into an output coaxial 980 and a bridge tap 110. A wide dotted line indicates the first divided pulse 122 propagated to the output coaxial 980 side, and a narrow dotted line propagates to the bridge tap 110 side and is reflected on the open end side of the bridge tap 110 and then output coaxial 980. The second divided pulse 123 propagated in FIG. The solid line indicates the post-shaped pulse 121 in which the first divided pulse 122 and the second divided pulse 123 are combined. D in the figure indicates a delay time in which the second divided pulse 123 is delayed by the bridge tap 110, T _r1 is the rise time of the original pulse 111, T _r2 is the rise time of the shaped pulse 121, and A is T _r1 and T The difference of _r2 is shown. T ₀ is the time when the original pulse 111 is generated, t ₁ is the time when the instantaneous value of the original pulse 111 reaches 10%, t ₂ is the time when the instantaneous value of the first divided pulse 122 reaches 10%, and t ₃ is time the instantaneous value of the second time-division pulse 123 enters the output coaxial 980, _{t 4} is the time in which the instantaneous value of the original pulse 111 reaches 90%, _{t 5} the original pulse 111 reaches 100%, _{t 6} the shaping time the instantaneous value of the rear pulse 121 reaches 90%, _{t 7} shows a time at which the instantaneous value of the shaping after the pulse 121 reaches 100%.

The inclination of the C ₂ parts of Figure 5 it can be seen that become moderate. That is, when the pulse generated by the pulse generation unit 900 is a pulse having no rounded range like the original pulse 111 of FIG. 5, the delay time is longer than the time when the instantaneous value of the original pulse 111 reaches 10% and If the present invention is applied so as to be shorter than the time to reach 100%, the range of rise is rounded. For this reason, bridge taps are generally known to degrade performance.

FIG. 6 is a diagram showing a change in waveform when the present invention is applied to a pulse having no roundness in the rising range, and the delay time is set to a time when the instantaneous value of the pulse reaches 10%. In this case, and _{t 2} and _{t 3} becomes the same time, and _{t 5} and _{t 6} becomes the same time. And the part where the slope is gentle is only in the range of 0 to 10% and the range of 90 to 100% of the instantaneous value, and the waveform of the rising range is the same for both the original pulse 111 and the shaped pulse 121. In other words, even if a delay equal to or less than the time when the instantaneous value of the pulse reaches 10% is given, the waveform in the rising range does not change and T _r1 and T _r2 remain equal.

FIG. 7 is a diagram showing a change in waveform when the present invention is applied to a pulse having no roundness in the rising range, and the delay time is set to a time when the instantaneous value of the pulse reaches 100%. In this case, the slope of the shaped pulse 121 is half that of the original pulse 111 (T _r2 is twice that of T _r1 ), but the rising range of the shaped pulse 121 is also linear.

  FIG. 8 is a diagram showing a change in waveform when the present invention is applied to a pulse with no roundness in the rising range and the delay time is longer than the time when the instantaneous value of the pulse reaches 100%. . In this case, a flat portion is generated as indicated by B in the figure. Therefore, it can be seen that the delay time should not be longer than the time when the instantaneous value of the pulse reaches 100%.

FIG. 9 shows a case where the present invention is applied to a pulse whose rounding range is round, and the delay time is longer than the time when the instantaneous value of the pulse reaches 10% and shorter than the time when it reaches 100%. It is a figure which shows the change of this waveform. In this figure, an example in which the roundness is in the range of 0 to 25% and 75 to 100% of the instantaneous value of the original pulse 111 is shown. In the figure, C ₁ is the rounded portion of the original pulse 111, and C ₂ is the rounded portion of the shaped pulse 121. Since the original pulse 111 is divided by a bridge tap 110, so that the portion C ₁ of the rounded is also divided. By setting the delay time D as divided portions of the rounded not combined, part _{C 2} of the rounded shaping after pulse 121, the instantaneous value of the shaping after the pulse 121 and 0 to 12.5% 87.5～ The range is 100%. That is, in the original pulse 111, the instantaneous value is 10-25% and 75-90% of the rising range is rounded, but in the post-shaped pulse 121, the instantaneous value is 10-12.5% of the rising range. There is only roundness near 87.5-90% and 50%. Further, since the slope of the portion other than the roundness of the post-shaping pulse 121 becomes gentle, the roundness becomes inconspicuous. Therefore, it can be seen that the waveform can be linear over the entire rising range.

  FIG. 10 is a diagram showing a change in waveform when the present invention is applied to a pulse having a rounded rising range, and the delay time is set to a time when the pulse is not rounded. In this figure, an example in which the roundness is in the range of 0 to 15% and 85 to 100% of the instantaneous value of the original pulse 111 is shown. Also in this case, in the original pulse 111, the instantaneous values are rounded in the range of 10 to 15% and 85 to 90% in the rising range, but in the shaped pulse 121, the instantaneous value is in the vicinity of 50% in the rising range. There will only be roundness. Further, since the slope of the portion other than the roundness of the post-shaping pulse 121 becomes gentle, the roundness becomes inconspicuous. Therefore, it can be seen that the waveform can be linear over the entire rising range.

  As described with reference to FIG. 5, the bridge tap is generally known to deteriorate the performance. However, as described with reference to FIGS. 9 and 10, the roundness can be reduced by applying the present invention to a pulse having a roundness in the rising range. Therefore, the waveform can be shaped into a more linear pulse in a range wider than 10% to 90%, which is the range of the rise time (rise range). That is, the accuracy of the pulse rise time can be improved. In the above description, the range of rise is 10% to 90% of the instantaneous pulse value, but the present invention can be applied to other ranges.

For example, if the pulse speed of the coaxial cord is 5 ns / m, the time to reciprocate the coaxial cord becomes the delay time, so that the length of the coaxial cord (m) × 10 (ns / m) is delayed. become. When the rise time _Tr is 5 ns, if there is no roundness, the time until the instantaneous value becomes 10% is about 0.5 ns. Therefore, assuming that the inclination is halved by rounding, the instantaneous value is about 10 ns. %. If a delay of about 1 ns is given, the length of the coaxial cord is 10 cm. If a delay of 5 ns or more is given, the delay time becomes longer than the time when the instantaneous value reaches 100%, and a flat portion as described in FIG. 8 may be generated. The coaxial cord should not be long.

  In the above description, only one coaxial cord is used as a bridge tap, but a plurality of coaxial cords may be used. For example, if N coaxial cords are used, the pulse generated by the pulse generator 900 is divided into N + 1 and reflected and synthesized by the coaxial cord, so that the same effect can be obtained. Moreover, since the length of each coaxial cord can be adjusted individually, the roundness of the rising range can be further reduced. However, if the number of bridge taps is increased, the degree of freedom of adjustment increases, but there is also a problem that adjustment becomes complicated. Therefore, the number of coaxial cords may be appropriately determined from the rise accuracy required for the pulse generator.

Experimental FIGS. 11 to 15 are diagrams showing changes in voltage when a pulse is generated so that 2 kV is applied to the load when a 50Ω load is connected to the pulse generator 100 of FIG. 4. The length of the output coaxial 980 was 30 cm. The length of the bridge tap 110 is 20 cm in FIG. 11, 25 cm in FIG. 12, 30 cm in FIG. 13, 40 cm in FIG. 14, and 50 cm in FIG. FIG. 16 is a diagram showing a change in voltage when a 50Ω load is connected to the pulse generator 100 of FIG. 4 and a pulse is generated so that −2 kV is applied to the load. The length of the output coaxial 980 is 30 cm, and the length of the bridge tap 110 is 30 cm. It can be seen that the roundness of the first part of the rise and the top of the head is smaller than the waveform without the bridge tap shown in FIG. Further, when the bridge tap is 50 cm, as can be seen from the portion E in FIG. 15, a portion with a gentle inclination is generated in the vicinity of the middle of the rising range. In the example where the rise time is 5 ns, it can be seen that the length of the coaxial cord is 10 to 50 cm and the effect of the present invention is produced. Moreover, it turns out that a better effect is acquired especially in 20-40 cm.

  FIG. 17 shows the result of measuring the rise time while changing the length of the output coaxial, the length of the bridge tap, and the polarity. The unit of the rise time is ns. From this figure, it can be seen that the rise time can be adjusted by the length of the bridge tap. It can also be seen that the length of the output coaxial does not affect the delay time. The difference in the rise time due to the difference in polarity includes the influence of the characteristics of the pulse generator 900. Therefore, it can be seen that if the length of the bridge tap is adjusted, the rise time determined by the standard can be adjusted without adjusting the inside of the pulse generation unit 900.

  FIG. 18 shows a second embodiment of the present invention. The pulse generator 200 includes a pulse generation unit 900 and a bridge tap 210. The difference between the pulse generator 200 and the pulse generator 100 is that a capacitor is used as the bridge tap 210.

  FIG. 19 is a diagram illustrating a change in voltage when a 50Ω load is connected to the pulse generation unit 900 of FIG. 1 and a pulse is generated so that 2 kV is applied to the load. 20 to 22 are diagrams showing changes in voltage when a 50Ω load is connected to the pulse generator 200 of FIG. 18 and a pulse is generated so that 2 kV is applied to the load. The length of the output coaxial 980 was 30 cm. The capacitance of the capacitor of the bridge tap 210 is 27 pF in FIG. 20, 33 pF in FIG. 21, and 42 pF in FIG. Note that a 30 cm coaxial cord having a characteristic impedance of 50Ω has a capacitance of about 30 pF, so such a capacitance was selected.

  FIG. 23 shows the result of measuring the rise time while changing the presence / absence of a capacitor, the capacitance of the capacitor, the voltage to be generated, and the polarity. In the case where there is no bridge tap, it is considered that the rise time differs due to the difference in voltage and polarity due to the characteristics of the pulse generator 900. If the voltage and polarity are the same, the rise time tends to increase as the capacitance increases. This is considered to be because the high frequency component was attenuated by the capacitor. Therefore, it can be seen that the rise time can be adjusted by including the capacitor in the bridge tap and adjusting the capacitance of the capacitor.

  The present invention can be used for a pulse generator that generates a pulse whose waveform shape is defined, such as a test pulse, or a method for shaping a waveform so that the pulse conforms to the specification.

100, 200 Pulse generator 110, 210 Bridge tap 900 Pulse generator 980 Output coaxial

Claims (8)

A pulse generator for generating a pulse;
A bridge tap having one end open and the other end electrically connected to a line through which the output from the pulse generator propagates;
The bridge tap is a distributed constant line that generates a delay that is not less than the time of the first part or the round part of the last part of the pulse generated by the pulse generator and not more than the time when the instantaneous value reaches 100%. A pulse generator characterized by. A pulse generator for generating a pulse;
A bridge tap having one end open and the other end electrically connected to a line through which the output from the pulse generator propagates;
The bridge tap is a coaxial cord having a length of 10 to 50 cm. The pulse generator according to claim 1 or 2,
A pulse generator comprising a plurality of the bridge taps. The pulse generator according to claim 1 or 2,
The bridge tap further includes a capacitor. A pulse generator for generating a pulse;
A bridge tap connected to a line through which the output from the pulse generation unit propagates,
The bridge tap has a capacitor having one end open and the other end electrically connected to the line, and shapes the roundness of the rising range of the pulse generated by the pulse generation unit into a straight line. Pulse generator. A pulse shaping method for shaping a rising range of a pulse having a roundness in a rising range into a linear shape,
One end is opened, and the pulse is generated at the other end of the distributed constant line that causes a delay of not less than the time of the first part or the round part of the last part of the pulse and the time when the instantaneous value reaches 100%. A pulse shaping method comprising: electrically connecting to a line between a pulse generating unit and a load. A pulse shaping method for shaping a rising range of a pulse having a roundness in a rising range into a linear shape,
A pulse shaping method characterized in that one end is opened and the other end of a coaxial cord having a length of 10 to 50 cm is electrically connected to a line between a pulse generator for generating the pulse and a load. A pulse shaping method for shaping a rising range of a pulse having a roundness in a rising range into a linear shape,
A pulse shaping method comprising: electrically connecting the other end of a bridge tap having a capacitor having one end open to a line between a pulse generating unit that generates the pulse and a load.

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