Application of SIGLENT SDS2000 SPO Technology on the Observation of Dynamic Measurement of Transi

SHENZHEN, China - March 11, 2014 - PRLog -- Oscilloscope is the most typical instrument applied in time-domain analysis as well as the most usual instrument used in electrical measurement. The electrical signal can be observed visually on the oscilloscope. What’s more，it is easy to observe the relationship between any two related variables, if they can be converted to electrical parameters, after being connected to the X(CH1),Y(CH2) channel under the XY display mode. The Lissajous-Figure is usually used for phase difference measurement. What’s more important，the XY mode is usually used to draw some particular characteristic curves in order to show the relationship of two variables directly.

SIGLENT SDS2000 series Super Phosphor Oscilloscope（SPO）possess the advantages of both digital storage oscilloscope and analog oscilloscope. Supported by 256 intensity grading display and a waveform capture rate up to 110,000 wfms/s, it leads to an excellent persistence simulating function, and a variety of characteristic curves can be drawn under XY mode. The output characteristic curve of a transistor takes iB as a parameter, and includes two related variables. The formula is as follows:

         ic = f (uCE) / iB

Therefore, it is convenient for us to draw the output curves under the XY mode of SDS2102. Through point-by-point method, taking the half-wave pulsating voltage caused by step-down of the 50HZ AC power and full-wave rectification as the collector scanning voltage of the transistor under measurement, thus makes uCE change automatically. As shown in figure 1, it changes from 0 to the maximum value, and then decrease to 0. For each fixed, we can get a series value of ic , and to draw the curve with a certain. Re do the previous steps with a series value of iB , we can get a another characteristic curve. For some more curves, we need to add the ladder of the step wave.

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Figure 1 The dynamic measurement of transistor’s output characteristics

The base current iB varies with voltages of the step-wave. The collector scanning voltage should keep pace with the base step-wave voltage. As shown in Figure 2, TB = nTC , n=1,2,3,...

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 Figure 2 （a）（b）The time related curves of collector scanning voltage waves and base ladder current（c）The output curves displayed on the screen

The voltage drop with the sensing resistance R1 meets this formula: uy = iER1≈iCR1, which indicates the variations of iC（Figure 1）and is connected to Y input end（CH2）of the oscilloscope. The variations of uCE is indicated by ux, ignoring the slight effect of R1, which is connected to the X input end（CH1）. The oscilloscope works in XY mode so that it can draw the curves automatically, as shown in Figure （c）. It should be noted out that the trace（from left to right）and return trace of each scanning cycle TC makes the light spot a characteristic curve on the screen. The output characteristic curve of triode transistor consists of several such similar curves.

The dynamic measurement of transistor’s output characteristics using the SDS2102 oscilloscope

（1）Get a similar graph shown in Figure 2（c）using a transistor tracer.

（2）Keep the parameters of the transistor tracer constant and connect the circuit as the way we do in the dynamic measurement of the transistor’s output characteristics(figure 1). Then properly change CH1 and CH2 to display time related curves similar with figure(a) and figure(b).

（3）Fine adjust the panel of the transistor tracer: the “V-A/LEVEL”, “CLUSTER/LEVEL” knob of the step wave. Then properly change CH1 and    CH2 to display the following curves（one step wave correspond to three collector scanning voltage wave）.

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Format: YT mode

Figure 3： One step wave correspond to three collector scanning voltage wave

Set the HORIZONTAL mode of the SDS2102 to “XY” and observe the curves on the screen shown in Figure 4.

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Figure 4The output characteristic curves displayed on the screen(XY)