Agilent Technologies 4349B, Руководство пользователя

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4349B
Contact check feature
The contact check feature of the 4349B measures the capacitance of the DUT using a 480-kHz
ac signal (OSC1) and makes the judgment of Contact/NO Contact from whether the result
is greater than the limit vale . The limit value used for the judgment is determined by the
following equation using the capacitance in the Open state (Cs) measured when the Open
correction was executed.
Limit = Cs*1.035+0.40*10E-12+oset
Where oset is any value the user can set. Usually set it to 0 (default value).
F or the 4349B, when measuring capacitance in the contact check and the Open correction,
an ac signal with the same phase as OSC1 is applied from OSC2 to the inner shield to reduce
the eect of C1 and C0. However , because it is impractical to apply an ac signal with the
completely same phase to both the core wire and the inner shield considering the input
resistance (1k) of the ammeter , some residual capacitance is observed. Especially when the
coaxial extension cable is long, this residual capacitance becomes larger .
Figure 3-8.
The contact check is performed at the following timing.
Figure 3-9.
Function Reference 3-21