Specifications

3.2 Test fixtures
The test fixture plays an important role in impedance measurement both mechanically and electri-
cally. The quality of the fixture determines the limit of the total measurement accuracy. This section
discusses how to choose or fabricate a test fixture for use with auto-balancing bridge instruments.
3.2.1 Agilent-supplied test fixtures
Agilent Technologies supplies various types of test fixtures depending on the type of device being
tested. To choose the most suitable test fixture for the DUT, consider not only the physical layout of
the contacts but also the usable frequency range, residual parameters (usable impedance range),
and the allowable DC voltage that can be applied. The contact terminals of the test fixtures (DUT
connection) can be either 2T or 4T which are respectively suited to different applications. The
DUT connection configuration and suitable application of Agilent’s test fixtures are summarized in
Table 3-1. The advantages and disadvantages of 2T and 4T test fixtures are detailed in Appendix A.
Note: The meaning of “DUT connection configuration” in this paragraph differs from that of the ter-
minal configuration in Section 3.1. While the terminal configuration mainly refers to the
cabling methods, the DUT connection configuration describes the particular configuration of
test fixture’s contact terminals. The test fixtures are classified into the groups of 2T and 4T
fixtures by the DUT connection configuration as shown in Table 3-1.
Table 3-1. DUT connection configurations of Agilent test fixtures and their characteristics
3-7
DUT connection Applicable
configuration device type Agilent test fixture Basic characteristics Suitable application
2-terminal Leaded device 16047D • Measurement is Impedance: Middle and high
16047E susceptible to the effect
16065A of residual impedance Frequency: High
42842A/B/C and contact resistance
SMD 16034E • Usable frequency limit
(Surface mounted device) 16034G is high
16034H • Additional error at
16334A high frequencies is
Material 16451B smaller than in
16452A 4-terminal connection
In-circuit device 42941A
4-terminal Leaded device 16047A • Measurement is less Impedance: Low and middle
16089A/B/C/D/E affected by residual
SMD 16044A impedance and contact Frequency: Low
(Surface mounted device) resistance (at relatively
low frequencies)
• Usable frequency limit
is low
• Additional error at
high frequencies is
greater than in
2-terminal connection