JP2009204443A - Response characteristic measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a response characteristic measuring device which enables the separate observation of an input signal and a reflection signal by a simple and inexpensive configuration. <P>SOLUTION: The response characteristic measuring device 1 has a delay part 5 which has a first end 51 and a second end 52 and outputs the input signal S<SB>1</SB>inputted from the first end 51 from the second end 52 by delaying it for a prescribed delay time while outputting the reflection signal S<SB>2</SB>inputted from the second end 52 from the first end 51 by delaying it for a delay time, and a probe 7 which applies the input signal S<SB>1</SB>outputted from the second end 52 of the delay part 5 on a specimen 2 while receiving the reflection signal S<SB>2</SB>from the specimen 2 and outputting it to the second end 52 of the delay part 5. The device is so constituted that the input signal S<SB>1</SB>and the reflection signal S<SB>2</SB>can be measured by being separated in a time domain at a point C positioned on the side of the first end 51 of the delay part 5. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a response characteristic measuring apparatus capable of measuring an input signal applied to a specimen and a reflected signal from the specimen with respect to the input signal when measuring the response characteristics of the specimen.

  In general, it is extremely important to specify a noise generation mechanism in order to appropriately take measures against noise of an electronic device as a specimen. Conventionally, as a method to identify the mechanism of noise generation relatively easily, the response characteristics of the specimen are measured by applying an impulse voltage (input signal) to the specimen and observing the reflected signal against the input signal. There are known techniques to

FIG. 7 shows a block diagram of a conventional method for measuring response characteristics of a specimen (see, for example, Patent Document 1).
In this method, the input signal generation unit 3 generates an impulse voltage as an input signal based on a command from the timing control unit 11, and applies the voltage to the specimen 2 via the response characteristic measurement device 1 ′. From the specimen 2, a reflected signal with respect to the input signal is output toward the response characteristic measuring apparatus 1 ′. And the signal processing part 10 takes in an input signal and a reflected signal, and calculates | requires the response characteristic of the specimen 2 based on these signals. Typical response characteristics include impedance and phase frequency characteristics.
The signal acquisition by the signal processing unit 10 is performed in synchronization with the generation of the input signal based on a command from the timing control unit 11. As the signal processing unit 10, a storage oscilloscope having an A / D conversion function is used.

FIG. 8 shows specific circuit configurations of the response characteristic measuring apparatus 1 ′ and the input signal generation unit 3, and the connection relationship between them, the specimen 2, and the signal processing unit 10.
The input signal generation unit 3 mainly includes a switch 32 and a capacitor 33. When the switch 32 is closed, the electric charge accumulated in the capacitor 33 is discharged at once, and an impulse voltage (input) is input toward the response characteristic measuring apparatus 1 ′. Signal). The response characteristic measuring apparatus 1 ′ includes a power splitter 8, a directional coupling unit 9, a matching unit 6, and a probe unit 7. Among these, the power splitter 8 has a plurality of resistors 81 to 83, and an input signal can be observed at point A. The input signal is input to the directional coupling unit 9 through the resistor 81. The input signal is applied to the specimen 2 sequentially through the directional coupling unit 9, the matching unit 6 that is a π-type attenuator, and the probe unit 7.

  When an input signal is applied to the specimen 2, a reflected signal for the input signal is output from the specimen 2. The reflected signal travels in the response characteristic measuring apparatus 1 ′ in the direction opposite to the input signal and reaches the directional coupling unit 9. A reflected signal can be observed at point B of the directional coupling unit 9. Since the directional coupler 91 has directionality, an input signal cannot be observed at point B.

The storage oscilloscope that is the signal processing unit 10 is connected to point A and point B of the response characteristic measuring apparatus 1 ′ by a high resistance probe, and takes in an input signal and an output signal. Then, the signal processing unit 10 A / D converts these signals into digital data, and appropriately performs software processing to obtain the response characteristics of the specimen 2.
JP 2001-343407 A

  As described above, according to the configuration shown in FIG. 8, the input signal and the reflected signal are observed from the points A and B of the response characteristic measuring apparatus 1 ′, respectively, and the response characteristic of the specimen 2 is obtained based on these. be able to. However, this configuration has several problems to be solved.

That is, as a first problem, the response characteristic measuring apparatus 1 ′ shown in FIG. 8 needs to include the directional coupler 91 and the power splitter 8 in order to separate and observe the input signal and the reflected signal. In general, these members are expensive, resulting in an increase in the cost of the entire response characteristic measuring apparatus 1 ′ and a complicated structure.
Further, as a second problem, when “leakage” of a specific frequency occurs in the directional coupler 91 and the power splitter 8, the other signal is superposed on one signal and observed. In this case, the input signal and the reflected signal cannot be completely separated and observed, which may cause an error in the response characteristics of the specimen 2 finally obtained.

  Accordingly, an object of the present invention is to provide a response characteristic measuring apparatus that can observe an input signal and a reflected signal separately with a simple and inexpensive configuration.

In order to solve the above-described problem, a response characteristic measuring apparatus according to the present invention includes:
A response characteristic measuring device that enables measurement of an input signal having a predetermined duration and a reflected signal from a specimen with respect to the input signal, the response characteristic measuring device having a first end and a second end, wherein the first end The input signal input from the end side is delayed by a predetermined delay time and output from the second end, and the reflected signal input from the second end side is delayed by the delay time and the first signal is output. A delay unit that outputs from the end, and the input signal that is output from the second end side of the delay unit is applied to the specimen, and the reflected signal from the specimen is received to receive a second end of the delay section. And a probe unit that outputs the signal toward the first side, wherein the input signal and the reflected signal can be separated and measured in the time domain at the first end of the delay unit.

  Preferably, the delay time is half or more of the duration.

  Preferably, the input signal is an impulse voltage.

  Preferably, the delay unit is a delay line made of a coaxial cable.

  Preferably, the response characteristic measuring apparatus further includes a first matching unit disposed on a first end side of the delay unit, and a second matching unit disposed on a second end side of the delay unit, An input signal is sequentially applied to the specimen through the first matching unit, the delay unit, the second matching unit, and the probe unit, and the reflected signal is transmitted to the probe unit, the second matching unit, And sequentially reaching the first end of the delay unit through the delay unit.

  Also preferably, the probe section is connected to the specimen.

  More preferably, the probe unit has an antenna, and applies the input signal to the specimen without contact, and receives the reflected signal from the specimen without contact.

  According to the present invention, it is possible to provide a response characteristic measuring apparatus that can observe an input signal and a reflected signal separately with a simple and inexpensive configuration.

[Basic concept / configuration]
First, the basic concept and basic configuration of the response characteristic measuring apparatus according to the present invention will be described with reference to FIGS.

FIG. 1 shows an embodiment of a response characteristic measuring apparatus 1 according to the present invention, and an input signal generating unit 3 and a signal processing unit 10 used in connection with the same.
The input signal generation unit 3 mainly includes a switch 32 and a capacitor 33. When the switch 32 is closed, the electric charge accumulated in the capacitor 33 is discharged at a stroke, and the duration described later is directed toward the response characteristic measuring apparatus 1. impulse voltage having a T _w (input signal) is outputted. The response characteristic measuring apparatus 1 includes a first matching unit 4, a delay unit 5, a second matching unit 6, and a probe unit 7. Among these, the first matching unit 4 and the second matching unit 6 are π-type attenuators each including three resistors.

  The delay unit 5 is a delay line made of a coaxial cable and has a first end 51 and a second end 52. Further, a C point is provided on the first end 51 side, and the C point is connected to the signal processing unit 10 via a high resistance probe.

The input signal generated by the input signal generation unit 3 is input to the first end 51 of the delay unit 5 through the first matching unit 4. Then, the delay unit 5 delays the input signal input from the first end 51 by a predetermined delay time T _d and outputs it from the second end 52. The input signal output from the second end 52 is applied to the specimen 2 after passing through the second matching unit 6 and the probe unit 7. When the probe unit 7 has an antenna, an input signal can be applied without bringing the probe unit 7 into contact with the specimen 2.

When an input signal is applied to the specimen 2, a reflected signal for the input signal is output from the specimen 2. The reflected signal travels in the response characteristic measuring apparatus 1 in the direction opposite to the input signal and reaches the second end 52 of the delay unit 5. The delay unit 5 delays the reflected signal input from the second end 52 by a predetermined delay time T _d and outputs the delayed signal from the first end 51.

FIG. 2A shows an example of a voltage waveform observed at point C in the response characteristic measuring apparatus 1 according to the present invention. In this figure, symbol S ₁ is an input signal, S ₂ is a reflected signal, T _d is a delay time of the delay unit 5, and T _w is a duration of the input signal S ₁ . The term “duration” means the time from when a signal starts to be output when the switch 32 is closed to when it is completely terminated (the voltage value returns to 0).

As shown in FIG. 2 (a), the response characteristic measuring apparatus 1 according to the present invention, by using the delay line 5, is possible to observe the input signals S ₁ and the reflected signal S ₂ is separated in the time domain it can.
That is, according to the response characteristic measuring apparatus 1 according to the present invention, both the input signal S ₁ and the reflected signal S ₂ delayed by the time T ₁ can be observed at the point C. The time T ₁ is the sum of the time until the input signal S ₁ starting from the point C reaches the specimen 2 and the time until the reflected signal S ₂ leaving the specimen 2 reaches the point C. . Delay time in the second matching portion 6 and the probe unit 7 is shorter enough to be ignored with respect to the delay time of the delay unit 5 T _d, after all, the time T ₁ is twice the delay time. The delay time _Td changes in proportion to the length of the delay line.

Therefore, by twice the delay time the length of the delay line T _d is set to exceed the duration T _w of the input signals S _1, separating the input signals S ₁ and the reflected signal S ₂ in the time domain be able to. Incidentally, setting shorter than the duration T _w of the input signals S ₁ to 2 times the delay time T _d, will be the input signals S ₁ and the reflected signal S ₂ is observed overlapping, response of the specimen 2 The characteristic cannot be measured.

As shown in FIG. 2 (b) and (c), the signal processing unit 10 takes in the voltage value of the point C of the time 0 time T _2, which transitions to a digital data by converting A / D. The handle portion of the time 0 time _{T 1} as the input signal _{S 1,} a portion of the time _{T 1} ~ time _{T 2} treated as the reflected signal _{S 2.}
Thereafter, the signal processing unit 10 can appropriately process the digital data of the input signal S ₁ and the reflected signal S ₂ by software, and finally obtain the response characteristics of the specimen 2.

[Measurement test]
Then, the measurement test of the specimen performed using the response characteristic measuring apparatus 1 according to the present invention will be described. A ceramic capacitor with a lead frame was used as a specimen, and response characteristics (impedance and phase frequency characteristics) of 3 to 200 MHz were measured. The equivalent circuit of the specimen is as shown in FIG.

Referring to FIG. 1, in the input signal generation unit 3 used in the test, the charging resistor 31 was 100 kΩ, the discharging resistor 34 was 50Ω, and the capacitor 33 was 80 pF. Thus, the input signal generating unit 3, the duration T _w the impulse voltage of approximately 8nS is generated. Each of the first matching unit 4 and the second matching unit 6 is a π-type attenuator with an input / output impedance of 50Ω, and the attenuation characteristic is set to about 2 dB. The probe unit 7 was connected to a ceramic capacitor as the specimen 2 via an SMB connector so that an impulse voltage as an input signal was directly applied to the specimen 2.

As the delay unit 5, a delay line (50Ω coaxial cable) having a delay time per unit length of 4 nS / m was used. As described above, since the duration T _w of the generated impulse voltage is about 8 nS, the delay time T _d required to separate the input signal S ₁ and the reflected signal S ₂ in the time domain is at least half that of 4 nS. It becomes. In this test, the delay time _Td was set to 10 nS in order to reliably separate the input signal and the reflected signal. That is, in this test, the length of the delay line was set to 2.5 m.

  Further, in this test, a portable storage oscilloscope: SDS200A manufactured by softDSP Co., Ltd. was used as the signal processing unit 10. This oscilloscope has an equivalent sampling period of 0.2 nS and can sufficiently cover the upper limit of the measurement frequency of 200 MHz. Data processing in the signal processing unit 10 was performed with software created using library software: SoftScope SDK for customizing the oscilloscope.

FIG. 4A shows the voltage waveform at point C captured by the signal processing unit 10 in this test.
Time duration _{T w} about 8nS input signal _{S 1} is started to be output in the 0 ns, then, after the twice the delay time _{T d} 20 nS has elapsed, the reflected signal _{S 2} for the input signal _{S 1} is observed . In this test, the voltage waveform up to 1600 nS is taken in, but this is determined based on the lower limit of the measurement frequency. If you want to measure even lower frequencies, set the capture time longer.

The taken voltage value of FIG. 4A is A / D converted inside the signal processing unit 10 and then corresponds to the input signal S ₁ at the time 20 nS (see FIG. 4B). When is separated into a portion corresponding to the reflected signal S ₂ (see FIG. 4 (c)). Thereafter, the digital data of the input signal S ₁ and the reflected signal S ₂ is processed appropriately software manner.

  In this test, the frequency characteristics of the impedance shown in FIG. 5A and the frequency characteristics of the phase shown in FIG. 5B were finally measured. In both graphs, the characteristics of the specimen 2 (see FIG. 3) in which a coil and a capacitor are connected in series can be accurately expressed, and when a large and expensive measuring instrument such as a network analyzer is used (FIG. 6). The results were almost equivalent to

[Other forms]
As mentioned above, although preferred embodiment of the response characteristic measuring apparatus which concerns on this invention was described, this invention is not limited to the said structure.
For example, when an impulse voltage having a fast waveform rise time is required as an input signal in order to perform measurement up to a higher frequency, Japanese Patent Laid-Open No. 9-178793 is used instead of the input signal generator 3 shown in FIG. Can be used. In the response characteristic measuring apparatus according to the present invention, the type of the input signal is not particularly limited, and an arbitrary signal having a predetermined duration and a reflected signal with respect to the signal can be observed.

  Moreover, as the probe part 7, the radiation antenna described in Unexamined-Japanese-Patent No. 9-178793 can be used, for example. In this case, since the trouble of connecting the probe unit 7 and the specimen 2 can be saved, the response characteristics of the specimen 2 can be measured more easily.

  Further, in FIG. 1, when the deterioration of the input signal and the reflected signal traveling through the response characteristic measuring apparatus 1 does not matter so much, the first matching unit 4 and the second matching unit 6 can be omitted. In this case, the input signal generated by the input signal generation unit 3 is directly input to the first end 51 of the delay unit 5. Then, the input signal output from the second end 52 of the delay unit 5 is directly input to the probe unit 7 and applied to the specimen 2.

It is a circuit diagram which shows an example of the response characteristic measuring apparatus which concerns on this invention, and its peripheral part. It is a figure explaining the basic concept of the response characteristic measuring apparatus which concerns on this invention, Comprising: (a) is the voltage waveform observed at the C point of FIG. 1, (b) is the voltage of the input signal extracted from (a). Waveform (c) is a voltage waveform of the reflected signal extracted from (a). FIG. 4 is an equivalent circuit diagram of a test specimen that was tested. 1A is a voltage waveform observed at point C in FIG. 1, FIG. 1B is a waveform of an input signal extracted from FIG. 1A, and FIG. It is the waveform of the reflected signal. It is a graph which shows the result of a measurement test, (a) is the frequency characteristic of an impedance, (b) is a graph of the frequency characteristic of a phase. It is the graph of the frequency characteristic of impedance obtained by measuring the same specimen as a measurement test with a network analyzer. It is a block diagram which shows the response characteristic measuring method of the specimen performed conventionally. It is a circuit diagram which shows the conventional response characteristic measuring apparatus and its peripheral part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Response characteristic measuring apparatus 2 Specimen 3 Input signal generation part 31 Charging resistor 32 Switch 33 Capacitor 34 Discharge resistance 4 1st matching part 41,42,43 Resistance 5 Delay part 51 1st end 52 2nd end 6 2nd matching part 61, 62, 63 Resistor 7 Probe unit 8 Power splitter 81, 82, 83 Resistor 9 Directional coupling unit 91 Directional coupler 92 Resistance 10 Signal processing unit 11 Timing control unit

Claims (7)

A response characteristic measuring device that enables measurement of an input signal having a predetermined duration and a reflected signal from a specimen with respect to the input signal,
A first end and a second end, the input signal input from the first end side is delayed by a predetermined delay time, output from the second end, and input from the second end side A delay unit that delays the reflected signal by the delay time and outputs the delayed signal from the first end;
A probe unit that applies the input signal output from the second end side of the delay unit to the specimen, receives the reflected signal from the specimen, and outputs the reflected signal toward the second end of the delay unit; ,
And a response characteristic measuring device configured to measure the input signal and the reflected signal separately in a time domain at a first end of the delay unit.   The response characteristic measuring apparatus according to claim 1, wherein the delay time is half or more of the duration.   The response characteristic measuring apparatus according to claim 1, wherein the input signal is an impulse voltage.   The response characteristic measuring apparatus according to claim 1, wherein the delay unit is a delay line made of a coaxial cable. A first matching unit disposed on a first end side of the delay unit;
A second matching unit disposed on a second end side of the delay unit;
Further comprising
The input signal is applied to the specimen through the first matching unit, the delay unit, the second matching unit, and the probe unit sequentially,
The response characteristic measuring apparatus according to claim 4, wherein the reflected signal reaches the first end of the delay unit through the probe unit, the second matching unit, and the delay unit sequentially.   The response characteristic measuring apparatus according to claim 1, wherein the probe unit is connected to the specimen.   The probe unit includes an antenna, and applies the input signal to the specimen without contact, and receives the reflected signal from the specimen without contact. The response characteristic measuring device described in 1.