Reference
370B User Manual
available. Collector Supply and Step Generator, depending on the setting of
the HORIZONTAL VOLTS/DIV control.
Collector Supply Sweep mode sweeps the Collector Supply output from the
value selected by the VARIABLE COLLECTOR SUPPLY control to 0%, if
the SWEEP button is pressed with the 370B set as follows:
VARIABLE COLLECTOR SUPPLY Any setting except 0 %
Display Mode STORE
HORIZONTAL VOLTS/DIV COLLECTOR range
ACQ MODE NORM
Collector Supply POLARITY +/- DC or +/- LEAKAGE
or
Step Generator PULSE SHORT or LONG (except when the Collector
Supply POLARITY is set to AC)
When the 370B Collector Supply Polarity is set to + or –, it supplies a sweeping
voltage to the device under test. This sweep is a 60 Hz sine wave. Driving the
device with a sweep is a convenient way to observe all points along the
characteristic curve; however, at low current there are limitations.
At DUT currents below a few mA, a hysteresis loop is usually seen. This
separation or loop in the trace is the result of capacitance in the curve tracer, test
adapter cabling, and the DUT itself. Stray capacitance in the DUT area is at least
200 pF. The curve tracer accurately displays the current through the capacitance
as well as the DUT currents.
Capacitive current is proportional to the change in voltage versus the change in
time. Therefore, to minimize the capacitive current “loop” display either the
capacitance or the change in voltage must be minimized. The 370B provides a
way to sweep the DUT much slower to minimized capacitive currents.
A slow sweep on the 370B Curve Tracer is generated as follows:
1. Choose either a +DC or –DC Collector Supply Polarity instead of the + or –
sweep.
2. Set the DC voltage (single point display) to the desired maximum DUT
voltage or current for a particular measurement.
3. Press FAST/SHIFT and SINGLE.
4. The voltage across the DUT will slowly begin decreasing until it reaches
zero. Meanwhile the 370B will acquire and display all voltage measurement
points.
The Step Generator output is continuous in Collector Supply Sweep mode.
To Next Page
Loading...
General