Agilent Technologies 4156b, User Manual, Page: 380 / 414

8-6 Agilent 4155B/4156B User’s Guide Vol.2, Edition 5
If You Have A Problem
When You Make A Measurement
If Measured Value Oscillates when Measuring Negative
Resistance
If the DUT has negative resistance characteristics, SMUs may oscillate. Because
SMUs operate as negative feedback amplifier.
To solve this problem:
• For voltage controlled negative resistance device
• Connect G in parallel with your DUT to cancel negative resistance. To
obtain an output I-V curve, use the following equation.
I
Y
= I
-
G * V
• For current controlled negative resistance device
• Connect R in series with your DUT to cancel negative resistance. To obtain
an output I-V curve, use the following equation.
V
Z
= V
-
R * I
• If the resistance of the DUT is less than 1 M
W
, you can use R-Box.