![]() The resistor values are changed to 1KΩ for both in this configuration. The base and emitter connection can be interchanged to configure the device under test (DUT) in the common base mode. The +2.5V is generated by a voltage divider from the +5V supply and the -2.5V is generated by inverting the +2.5V with the second opamp in the dual op-amp (ADTL082). The voltage on the base terminal can be offset to either +2.5V or -2.5V (or 0V) to increase the possible V CE swing (by -2.5 for NPN or +2.5 for PNP). A ratio of 100 for the base and collector resistors is used because beta, the collector current to base current gain, is often approximately 100. The collector current, I C is measured by scope inputs 2+, 2- differentially across a 100Ω resistor. V CE is measured differentially by scope inputs 1+, 1. The collector voltage is swept using a ramp from generator W1. In the common emitter configuration, one opamp serves as a virtual ground at the base terminal to convert the voltage steps from waveform generator W2 into base current steps through a 10KΩ resistor. It uses one dual opamp (ADTL082) powered from the +/- 5 Volt board supplies. It will probably be necessary to set the phase of Channel 1 to 90 degrees to make them line up in this way.īelow are schematics for both a common emitter and a common base BJT curve tracer test circuit for use with the ADALM2000. Comparing the waveforms in Channel 1 and Channel 2, the triangle wave in Channel 1 should go through one cycle from 0 to 5 V and back to zero during the time of one step in the waveform in Channel 2. ![]() Set the frequency to 200 Hz ( 5 times the 40 Hz of channel 2). In Signal Generator Channel 1 configure a triangle wave with an amplitude of 5V peak-to-peak and an offset of 2.5V (wave should swing from 0 to 5V). ![]() For each step to be 5 mSec long for a total of 25 mSec, set the sampling rate 200 Hz. The waveform in the display should start at 0.6V and increase in 1 V increments to 4.6 V (0.6, 1.6, 2.6, 3.6, 4.6). Now at this point set the amplitude to 2 V peak-to-peak and the offset to 2.6 V. Using the Scopy Signal Generator tool, in Channel 2 Buffer tab import the csv file for the stairstep signal needed. The green boxes indicate where to connect the ADALM2000. Build the simple curve tracer circuit shown in Figure 1. ![]()
0 Comments
Leave a Reply. |