Specifications

3.0 Fixturing and Cabling

Connecting a DUT to the measurement terminals of the auto-balancing bridge instrument requires a

test fixture or test cables. The selection of the appropriate test fixtures and cables, as well as the

techniques for obtaining the optimum DUT connection configuration, are important for maximizing

the total measurement accuracy. This section introduces the basic theory and use of each connec-

tion configuration, focusing on the auto-balancing bridge instrument. In RF impedance measure-

ments, the usable connection configuration is the two-terminal (2T) configuration only. Since the

measurement technique for RF impedance is different from that for LF, it is described separately

after the discussion of the auto-balancing bridge instrument.

3.1 Terminal configuration

An auto-balancing bridge instrument is generally equipped with four BNC connectors, Hcur, Hpot,

Lpot, and Lcur, as measurement terminals (see Figure 3-1.) These terminals are conventionally

named "UNKNOWN" terminals. There are several connection configurations used to interconnect a

DUT with the UNKNOWN terminals. Because each method has advantages and disadvantages, the

most suitable method should be selected based on the DUT’s impedance and required measurement

accuracy.

Figure 3-1. Measurement terminals of auto balancing bridge instrument

cur

: Low current

pot

: Low potential

po t

: High potential

cur

: High current

Precision LCR Meter

3-1