NI ELVIS - Three-Wire Current-Voltage Analyzer SFP

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					NI ELVIS - Three-Wire Current-Voltage
Analyzer SFP                                       Collected and Edited by: Ahmed Haytham


The NI ELVIS Three-Wire Current-Voltage Analyzer SFP is a top-level, stand-alone
instrument that is a basic 3-wire current versus voltage curve tracer for NPN BJT
transistors. The instrument utilizes the NI ELVIS hardware, the DAQ AO and the DAQ
AI. It is capable of displaying signals within 0–10 V for the collector voltage and 0–
10 mA for the collector current.

You must set the base current steps and specify the range of the collector voltage sweep.
Connect the device under test in the following manner:

3-WIRE     Collector connection
CURRENT HI Base connection
CURRENT LO Emitter connection
     Notes The AO resolution of a 12-bit DAQ device in combination with the
     NI ELVIS hardware requires that the number of allowable base current steps are
     limited.
     CURRENT LO is a virtual ground input and should not be subjected to a DC offset.

This section explains the NI ELVIS - Three-Wire Current-Voltage Analyzer SFP and
describes how to measure a signal with the SFP.

To launch the software instruments, select Start» Programs» National Instruments»
NI ELVIS 2.0» NI ELVIS to load the Instrument Launcher, then click the button for the
desired instrument on the NI ELVIS Instrument Launcher.
Display Window

Display Window—Contains the collector current-voltage plot for the device under test
as well as cursors. You can move the cursor horizontally by clicking on it and dragging it
along the voltage axis. The signal is plotted current versus voltage. The Display Window
also includes the following groups of indicators.




                             NPN Connection Indicators—



      Voltage (V)—Displays the measured collector voltage during a voltage sweep or
       cursor movement. The units for this measurement are volts. When cursors are
       disabled, the values displayed during a sweep correspond to the first base current
       curve.
      Current (A)—Displays the measured collector current for the applied test voltage
       during a voltage sweep or cursor movement. The units for this measurement are
       amps. When cursors are disabled, the values displayed during a sweep correspond
       to the first base current curve

Base Current Settings

      Base Current Start—Specifies the start value of the base current curves. The
       default value is 15 µA. Base current is generated using the DAQ AO channel
       DAC0 and series resistance.
      Number of Curves—Specifies the number of base current curves to generate.
       The default value is 3.
      Base Increment—Specifies the spacing between each base current curve.
       Increment values are limited to 15 µA steps for hardware compatibility between
       12- and 16-bit DAQ devices. The default value is 15 µA.

Collector Voltage Settings

      Start—Specifies the voltage at which to start the collector voltage sweep. The
       default value is 0 V.
      Stop—Specifies the voltage at which to stop the collector voltage sweep. The
       default value is 2 V.
      Increment—Specifies the voltage spacing between measurements during the
       voltage sweep. The default value is 0.1 V.
       Collector Current Limit—Specifies the maximum allowed collector current
        allowed during the voltage sweep. If the measured current exceeds this limit, the
        sweep stops. The default value is 10 mA.

Display Controls

       Autoscale—Determines if the Three-Wire Display autoscales. The default value
        is ON. If autoscaling is not on, the graph ranges are 0–10 mA and 0–10 V.
       Mapping
             o Voltage—Selects whether the X-axis (Collector Voltage) on the Three-
                 Wire Display is displayed in logarithmic or linear scale. The default value
                 is Linear.
             o Current—Selects whether the Y-axis (Collector Current) on the Three-
                 Wire Display is displayed in logarithmic or linear scale. The default value
                 is Linear.
       Cursor—Turns the display of the cursor on and off. The cursor is locked a
        display plot so the up and down arrows on the control do not affect cursor
        position. The default value is OFF.
       Ib Curve—Selects the base collector curve to which the cursor is attached. This
        control is only available when cursors are enabled. The control entries correspond
        to base current values selected in the base current settings. The default value is the
        first curve.
       Position—Moves the cursor to the left or right, one point at a time, for precise
        cursor positioning.

Run Button—Starts or stops the voltage sweep with the parameters specified by the
Settings controls. The default value is OFF.

Log—Generates a comma-delimited text file with the voltage and current data of the last
voltage sweep. Logging is available when no acquisitions are occurring. A timestamp
appears at the beginning of the file. If an existing file is selected, the new data is
appended at the end of the file.

Caution By connecting different signals to both the DMM terminals on the prototyping
board and the DMM connectors on the control panel, you are shorting them together,
potentially damaging the circuit on the prototyping board.

Complete the following steps to start measuring signals with the NI ELVIS - Three-Wire
Current-Voltage Analyzer SFP:

       Note Currently, this instrument only supports NPN BJT transistors.

   1. Connect the three-terminal device you want to analyze in the following manner:

        NPN BJT transistor:
   3-WIRE     collector connection
   CURRENT HI base connection
   CURRENT LO emitter connection

2. Launch the NI ELVIS - Three-Wire Current-Voltage Curve Analyzer SFP from
   the NI ELVIS Instrument Launcher. Refer to Launching the SFP Instruments for
   more information.
3. Adjust the Collector Current Limit control as desired.
4. Select the desired base current settings.
5. Select the starting and ending collector voltages from the Start and Stop controls,
   and click Run.

				
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