CN100429878C - Time-domain network measuring system and method based on wideband sampling oscilloscope - Google Patents

Abstract

The invention relates to a time-domain network measurement system and method based on a broadband sampling oscilloscope, belonging to the field of pulse measurement. The system mainly includes an Agilent86100A mainframe (2) equipped with an Agilent86117A module (5), an Agilent86100B mainframe (1) equipped with an Agilent54754A module (3) and an Agilent86117A module (4), and a device under test (7). The trigger input terminal on the front panel of the Agilent86100A host 2 is connected to the Agilent54754A module (3), and the Agilent86117A module (5) on the Agilent86100A host 2 is connected to the Agilent86117A module (4) through the device under test (8). The system can measure the characteristics of the device under test 8 with a bandwidth of more than 50 GHz.

Description

A time domain network measurement system and method based on wideband sampling oscilloscope

technical field

The invention relates to a time-domain network measurement system and method based on a broadband sampling oscilloscope. The system and method are used to measure the transmission characteristics of microwave devices with a bandwidth of more than 50 GHz, and belong to the field of pulse measurement.

Background technique

At present, the method of measuring the transmission characteristics of a system or device in the time domain is to use a unit step signal as a standard pulse source. The signal source used in my country is a pulse source. The current commonly used pulse source model is FLUCK9500, which is manufactured by Fluke Corporation of the United States. The main performance The indicator is that the test bandwidth does not exceed 20GHz. Although the measurement bandwidth of the vector network analyzer can reach 50GHz or even higher, the vector network analyzer is very expensive, which limits the use of the vector network analyzer.

Contents of the invention

The purpose of the present invention is to overcome the deficiency of the existing time-domain network measurement system as mentioned above, provide a kind of time-domain network measurement system and method based on broadband sampling oscilloscope, this system fully develops the function of existing sampling oscilloscope, realizes the The characteristics of the device under test 8 are measured, and the bandwidth reaches above 50 GHz.

The technical scheme that the present invention adopts, referring specifically to Fig. 2, this system mainly includes Agilent86100A main frame 2, Agilent86100B main frame 1, device under test 8; Agilent54754A module 3 and Agilent86117A module 4 whose serial number is SERVS42400124 are installed at the same time. The trigger input terminal of the front panel of the Agilent86100A mainframe 2 is connected to the Agilent54754A module 3 installed on the Agilent86100B mainframe 1 through a 3.5mm cable, and the Agilent86117A module 5 on the Agilent86100A mainframe 2 is connected to the Agilent86117A module 4 on the Agilent86100B mainframe 1 through the device under test 8 Agilent86100A mainframe 2 is used as a pulse generator, Agilent86100B mainframe 1 is simultaneously used as a measuring instrument and a synchronous trigger signal source, and Agilent54754A module 3 generates a synchronous trigger signal, so that Agilent86100A mainframe 2 and Agilent86100B mainframe 1 work synchronously.

The device under test 8 is connected to the Agilent86100A host 2 through the connection device 7 .

The working principle of the present invention is: Agilent54754A module 3 generates a synchronous trigger signal through time domain reflection (TDR), so that Agilent86100A host 2 and Agilent86100B host 1 work synchronously. The Agilent86117A module 5 on the Agilent86100A host 2 generates a known pulse with a bandwidth of 50 GHz. This pulse will pass through the device under test 8 and the connecting device 7, and be measured and collected by the Agilent86117A module 4 on the Agilent86100B host 1. When using Agilent86100B host 1 to measure the signal through Agilent86117A module 4, the input circuit of Agilent86117A module 4 can be regarded as a filter, and the waveform displayed on Agilent86100B host 1 is the known pulse, the characteristics of the device under test 8, and the connection between the device 7 and this The result of filter convolution. Since the characteristics of the Agilent86100B host 1 and the connected device 7 are known, the frequency domain characteristics of the device under test 8, that is, the bandwidth, and the time domain characteristics, that is, the impulse response, can be obtained by deconvolution, and then the impulse response is integrated to get the rise time.

In actual operation, a connection device 7 is added to allow the device under test 8 to be connected to the oscilloscope module. Therefore, during data processing, the measurement result is also deconvoluted with the characteristics of the connection device 7 .

Utilize this system to measure the method for the characteristic of device under test 8, concrete measurement method is as follows:

The time domain reflection module Agilent54754A3 generates a synchronous trigger signal, so that the Agilent86100A mainframe 2 and the Agilent86100B mainframe 1 work synchronously, and the Agilent86117A module 5 on the Agilent86100A mainframe 2 generates a known pulse. The pulse bandwidth is 50 GHz, and it will pass through the device under test 8. It is measured and collected by the Agilent86117A module 4 on the host Agilent86100B1. The specific collection process is as follows:

i) Set the bias voltage of the Agilent86100A mainframe (2) to be a positive value, then set the average sampling times of the Agilent86100B mainframe (1), save the value y ₊ (n) after the sampling is completed, and set the Agilent86100A mainframe (2) to be uneven;

ii) Set the bias voltage of the Agilent86100A mainframe (2) to a negative value, then set the average sampling times of the Agilent86100B mainframe (1), save the value y _- (n) after the sampling is completed, and set the oscilloscope to be uneven;

iii) Waveforms y ₊ (n) and y _- (n) under positive and negative biases, where "+" and "-" represent the measurement results under positive and negative biases, and positive and negative biases are measured twice The waveform below is averaged to remove the influence of strobe pulse leakage and incomplete balance of the circuit to obtain y(n).

Perform data processing on the sampling result y(n), the processing process is as follows

The measured data is expressed as:

y(n)＝k(n)*h _c (n)*h _DUT (n)*h(n) ①

Wherein, y(n) is the waveform displayed on the Agilent86100B mainframe 1 during measurement, k(n) is the known pulse generated by the Agilent 86117A module 5 on the Agilent86100A mainframe 2, and _hc (n) is the transmission characteristic of the connecting device 7, For the situation where the device 7 is not connected, h _c (n) can be idealized, that is, each point in the frequency domain is 1, and it is an ideal impulse signal in the time domain. h _DUT (n) is the device under test, h (n) is the characteristic of Agilent86117A module 4. ① In the formula, only h _DUT (n) is unknown.

Carrying out discrete Fourier transform on the formula ① respectively, we can get

Y(k)＝K(k)·H _c (k)·H _DUT (k)·H(k) ②

Divide ② with K(k), H(k) and H _c (k) to get

$\frac{Y\left(k\right)}{K\left(k\right)\&Center\; Dot;h\left(k\right)\·h_c\left(k\right)}=h_{\mathrm{DUT}}\left(k\right)$ ③

The impulse response can be obtained by inverting the Fourier transform of _HDUT (k), and the impulse response can be obtained by integrating the impulse response. The rise time can be obtained through the step response (the rise time is the time when the pulse amplitude rises from 10% to 90%) time). Modulo H _DUT (k) yields the bandwidth of the adapter.

The system fully develops the functions of the existing sampling oscilloscope, realizes the measurement of the characteristics of the device under test 8, and the bandwidth reaches more than 50 GHz.

Description of drawings

Fig. 1 system connection block diagram 1 of the present invention (no device under test)

Fig. 2 system connection block diagram 2 of the present invention (device under test is arranged)

Figure 3 Measurement Waveform Diagram

Figure 4 Impulse response of the device under test

Figure 5 Step response of the device under test

Figure 6 Amplitude-frequency characteristics of the device under test

Figure 7 Data collection flow chart

Figure 8 Data processing flow chart

In the figure: 1. Agilent86100B host, 2. Agilent86100A host, 3. Agilent54754A module 4. Agilent86117A module (SERVS42400124), 5. Agilent86117A module (SERVS42400126), 6. TDR3.5mm cable, 7. Connecting device, 8. Device under test .

Detailed ways

Refer to Fig. 1 to Fig. 7 for a specific embodiment of the present invention. The system in this example mainly includes Agilent86100A host 2 and Agilent86100B host 1, the connecting device 7 is a 2.4 double female adapter, the number is 17172, and the device under test 8 is a 2.4 female to male adapter, the number is 17979. Among them, the Agilent86100A host 2 is equipped with Agilent86117A module 5 with serial number SERVS42400126, and Agilent86100B host 1 is equipped with Agilent54754A module 3 and Agilent86117A module 4 with serial number SERVS42400124. The front panel trigger input terminal of Agilent86100A mainframe 2 is connected to Agilent54754A module 3 installed on Agilent86100B mainframe 1 through a 3.5mm cable, and Agilent86117A module 5 is connected to Agilent86100B mainframe 1 through a 2.4 double female adapter (that is, connecting device 7) and the device under test 8 Agilent86117A module 4 is connected.

In this embodiment, the connection device 7 can be directly connected with the Agilent86117A module 4 and the Agilent86117A module 5, so in order to improve the accuracy, this embodiment performs two measurements, that is, the first measurement does not access the device under test 8 (Fig. 1 ), the second measurement is based on Figure 1, and the device under test 8 (Figure 2) is cascaded. Figure 1 shows the first measurement. In the first measurement, only the connecting device 7 (that is, the 2.4mm double-female adapter, number 17172) is connected); Figure 2 is based on Figure 1, and the measured Device 8, namely the 2.4mm female-to-male adapter, is numbered 17979.

The settings of the two measurements shown in the two figures are the same, the sampling Agilent86100B host 1 works in TDR (time domain reflectometer) mode, the TDR is set to 1.99kHz, the horizontal sensitivity is 100ps/div, the delay is 70ns, and the sampling point is 1024. Agilent86100A host 1 works in oscilloscope mode. The bias voltage of Agilent86100A host 1 is plus or minus 150mV, the horizontal sensitivity is 50μs/div, the delay is 28ns, and the sampling times is 16. Follow the previous steps to complete the connection and set the parameters, and the measured waveform can be obtained on the Agilent86100B host 1, as shown in Figure 3.

The data collection process of this embodiment is: data collection is performed on the waveform shown in FIG. 3 , and the collection process in the two measurements is exactly the same. The process is: set the bias to +150mV. When sampling, set the average number of samples of the oscilloscope. The average number of this measurement is 16 times. After the average is completed, save the data. Set to Uneven. Change the bias to -150mV and repeat the above steps. The positive and negative 150mV are used alternately for 5 times, and the specific data collection process is shown in Figure 7.

Solving the characteristics of the device under test 8 is as follows: the two measurement equations are respectively:

y _a (n)=k(n)*h _c (n)*h(n) (4)

and

y _b (n)=k(n)*h _c (n)*h _DUT (n)*h(n) (5)

Among them, y _a (n) and y _b (n) are the waveforms displayed on Agilent86100B host 1 in the two measurements respectively, y _a (n) is the measurement result when connected according to Figure 1, and y _b (n) is the 2 The measurement results when connected, k(n) is the known pulse generated by the Agilent86117A module 5 on the Agilent86100A mainframe 2, h _c (n) is the transmission characteristic of the 2.4mm double female adapter. _hDUT (n) is the transmission characteristic of 2.4mm female to male adapter, h(n) is the characteristic of Agilent86117A module 4. Carrying out discrete Fourier transform on equations (4) and (5) respectively, we can get

Y _a (k) = K (k) · H _c (k) · H (k) (6)

Y _b (k) = K (k) · H _c (k) · H _DUT (k) · H (k) (7)

Among the two formulas (6), (7), formula (7) is equivalent to the numerator part in formula (3) above, and formula (6) is equivalent to the denominator part in formula (3) above. Dividing equations (6) and (7) together, we can get

$\frac{{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; DUT</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>$

The impulse response is obtained by inverting the Fourier transform of _HDUT (k), as shown in Figure 4, the impulse response is integrated to obtain its step response, and then its rise time can be obtained (the rise time is the pulse amplitude divided by 10 % rise to 90% of the time), as shown in Figure 5. Calculate the modulo of H _DUT (k) to obtain the bandwidth of the 2.4 female-to-male adapter, as shown in Figure 6.

In order to reduce the error of the measurement data y _a (n) and y _b (n), the PDF deconvolution method is also used to remove the influence of the time base jitter on the data before the above processing. By taking positive and negative values for the bias voltage, the measurement results under positive and negative biases are obtained, which are y _a+ (n), y _a- (n), y _b+ (n) and y _b- (n ), the subscripts "a" and "b" of the above four symbols represent the two measurements in Figure 1 and Figure 2, and "+" and "-" represent the measurement results under positive and negative bias. The waveforms under the positive and negative biases of the two measurements are averaged to remove the effects of strobe pulse leakage and circuit incomplete balance. Get y _a (n) and y _b (n).

After the above processing, the frequency domain characteristics and impulse response of the device under test 8 can be obtained, and then its step response and rise time can be obtained through integration. The specific process is shown in Figure 8.

The measurement results obtained according to the above method are shown in Fig. 4, Fig. 5 and Fig. 6.

Claims (3)

1, a kind of time-domain network measuring system based on wide-band sampling oscillograph is characterized in that: native system mainly includes Agilent86100A main frame (2), Agilent86100B main frame (1), measured device (8); Wherein, Agilent86100A main frame (2) is equipped with the Agilent86117A module (5) that sequence number is SERVS42400126, and Agilent54754A module (3) is housed Agilent86100B main frame (1) simultaneously and sequence number is the Agilent86117A module (4) of SERVS42400124; The front panel of Agilent86100A main frame (2) triggers input and is connected with Agilent54754A module (3) on being contained in Agilent86100B main frame (1) by the 3.5mm cable, and the Agilent86117A module (5) on the Agilent86100A main frame (2) is passed through measured device (8) and is connected with Agilent86117A module (4) on the Agilent86100B main frame (1); Agilent86100A main frame (2) is as pulse generator, Agilent86100B main frame (1) is simultaneously as measuring instrument and synchronous triggering signal source, produce synchronous triggering signal by Agilent54754A module (3), make the work of Agilent86100A main frame (2) and Agilent86100B main frame (1) synchronously.

2, a kind of time-domain network measuring system based on wide-band sampling oscillograph according to claim 1, it is characterized in that: described measured device (8) is connected in Agilent86100A main frame (2) by interface unit (7).

3, utilize the described a kind of method of the characteristic of measured device being measured based on the time-domain network measuring system of wide-band sampling oscillograph of claim 1, it is characterized in that this method of measurement is carried out according to the following steps:

1) Time Domain Reflectometry modules A gilent54754A (3) produces synchronous triggering signal, make the work of Agilent86100A main frame (2) and Agilent86100B main frame (1) synchronously, Agilent86117A module (5) on the Agilent86100A main frame (2) produces a known pulse, this pulse bandwidth is 50GHz, it will be by measured device (8), measured and gather by the Agilent86117A module (4) on the Agilent86100B main frame (1), concrete gatherer process is as follows:

I) bias voltage that Agilent86100A main frame (2) is set on the occasion of, the average sample number of times of Agilent86100B main frame (1) is set again, back preservation numerical value y is finished in sampling ₊(n), Agilent86100A main frame (2) is set for unequal;

The bias voltage that Agilent86100A main frame (2) ii) is set is a negative value, and the average sample number of times of Agilent86100B main frame (1) is set again, preserves numerical value y after sampling is finished _-(n), oscilloscope is set for unequal;

Iii) repeat above-mentioned steps, reach set point up to the data acquisition number of times; Align, the waveform y under the negative bias ₊(n), y _-(n) average processing and remove the influence that the circuit incomplete equilibrium causes, obtain measurement data y (n);

2) sampled result y (n) is carried out data processing, processing procedure is as follows,

I) measurement data y (n) is expressed as:

y(n)＝k(n)*h _c(n)*h _DUT(n)*h(n) ①

Wherein, y (n) goes up the waveform that shows for Agilent86100B main frame (1) in measuring, and k (n) is the known pulse that the Aligent86117A module (5) on the host A gilent86100A (2) produces, h _c(n) be the transmission characteristic of interface unit (7), for the situation that does not have interface unit (7), h _c(n) idealized, promptly each point all is 1 in the frequency domain, is desirable impulse signal in the time domain, h _DUT(n) be device under test, h (n) is the characteristic of Agilent86117A module (4); 1. in the formula, has only h _DUT(n) be unknown;

Ii), obtain the 1. formula fourier-transform that disperses

Y(k)＝K(k)·H _c(k)·H _DUT(k)·H(k) ②

Will be 2. and K (k), H (k) and H _c(k) be divided by, obtain

$\frac{Y\left(k\right)}{K\left(k\right)\&CenterDot;H\left(k\right)\&CenterDot;H_c\left(k\right)}{=H}_{\mathrm{DUT}}\left(k\right)$ ③

Iii) to H _DUT(k) fourier-transform of inverting obtains impulse response, and impulse response is quadratured obtains its step response, obtains its rise time by step response, to H _DUT(k) ask mould to obtain the bandwidth of measured device (8).

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