Specifications

5-5
Low-value capacitance measurement
The low-value capacitance measurement is categorized in the high impedance measurement. Stray
capacitance between the contact electrodes of a test fixture is a significant error factor compared to
the residual impedance. To make interconnections with the DUT, use a 3T (shielded 2T), 5T (shield-
ed 4T), or 4TP configuration. Proper guarding techniques and the open/short compensation can
minimize the effects of stray capacitance (refer to Section 3.4.) Figure 5-7 shows the typical proce-
dure for performing the open/short compensation when measuring SMD (chip-type) capacitors with
the Agilent 16034E/G test fixtures.
Figure 5-7. Low-value chip capacitor measurement
Other than capacitance, important capacitor parameters are the dissipation factor, D, and the ESR.
Special precautions must be taken in the low D or low ESR measurements. Contact resistance and
residual impedance in the test fixture and cables will affect the measurement results even when the
4T configuration is used (refer to Section 4.)
DC biased capacitance measurement
The DC biased capacitance measurement can be performed using the internal DC bias function of an
impedance measuring instrument, or an external bias fixture for applying a bias voltage from an
external DC source. When the DC bias voltage is changed, a bias settling time needs to be taken until
the capacitor is charged by the applied bias voltage. The required bias settling time increases in pro-
portion to the capacitance of the DUT. Accordingly, to perform an accurate bias sweep measurement
for a high-value capacitor, it is necessary to insert a delay time between the step-up (or the step-
down) of bias voltage and measurement trigger for each sweep measurement point. The required
bias settling time can be obtained from DC bias performance data of the instrument or bias fixture
used.