Agilent Technologies 4294A Specifications download pdf (Page 78)

Precautions for capacitor measurement depend on the capacitance value being measured.

High-value capacitance measurement is a low impedance measurement. Therefore, contact resistance

and residual impedance in the contact electrodes, test fixture, and cables must be minimized. Use a

4-terminal, 5-terminal or 4-terminal pair configuration to interconnect the DUT with the measure-

ment instrument. When the 4-terminal or 5-terminal configurations are used, be sure that a high

test signal current flows through the cable. To avoid the effects of electromagnetic field coupling,

connect the cables as shown in Figure 5-6. Also, for an accurate measurement, open/short compen-

sation should be properly performed. Especially for electrolytic capacitors which require a DC bias

voltage to be applied, open/short compensation should be performed with the DC bias set to ON (0

V).

Figure 5-6. High-value capacitance measurement

Low-value capacitance measurement is a high impedance measurement. Stray capacitance between the

contact electrodes is significant compared to the residual impedance. To make interconnections,

use 3-terminal (shielded 2T), 5-terminal (shielded 4T), or 4-terminal pair (4TP) configurations.

Proper guarding techniques and open/short compensation can minimize the effects of stray capaci-

tance. Refer to “Eliminating stray capacitance effects” in Section 3. Figure 5-7 shows typical proce-

dure for performing open/short compensation for Agilent 16034E/G test fixtures when measuring

chip type capacitors.

Figure 5-7. Low-value chip capacitor measurement

Other than capacitance, the dissipation factor D and the equivalent series resistance ESR are the

important capacitor parameters measured. Special attention must be paid especially for low D or

ESR measurements. Contact resistance and residual impedance in the test fixture and cables will

affect the measurement result even when the 4-terminal configuration is used. Refer to paragraph

4-3, “Error caused by contact resistance” in Section 4.

The component dependency factors discussed in Section 1 must be taken into account especially

when measuring ceramic capacitors. The capacitance of ceramic capacitors depends on frequency,

test signal voltage (AC), DC bias, temperature, and time.

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Agilent Technologies 4294A Specifications Page 78