Theory Of Operation; Overall Measurement Theory - Agilent Technologies 4349B Manual

4349B

Theory of Operation

This section provides the 4349B's theory of operation.

Overall Measurement Theory

The 4349B measures the resistance of the Device Under Test (DUT) in the following manner.
Figure 3-6. Simpli ed Model of the 4349B
Figure 3-6 shows the simpli ed model of the 4349B measuring a DUT. In Figure 3-6, a DUT
is connected in series with test voltage source V , and ammeter A. Ri is the 4349B's input
resistance ( Ri = 1 k ).
In the current measurement mode (the measurement parameter is I), the 4349B displays the
actual current I for the measurement result. For example, if R is 100 k , and V is 1 V, the
measurement result will be 9.9  A ( ).
1
100 +1
k k
In the resistance measurement mode (the measurement parameter is R), the 4349B displays the
\derived" DUT resistance, R , which coincides with the actual DUT resistance. In other words,
if the ammeter measures I when the source voltage is V , the 4349B displays the DUT resistance
R , calculated using the following equation:
V
R = Ri
I
Function Reference 3-19