Technical data

3- 16 Agilent B2900A Configuration and Connection Guide, Edition 1

Connection

Connection with Prober

3.3.3 To make connection to measure low resistance

When you measure a low resistance, high current flows through the DUT. This high current

increases the measurement error caused by the residual resistance of cables. To cancel the

effect of this resistance, you can use Kelvin connections (4-wire), which means the Force

and Sense lines are extended separately to the DUT.

Connect the probing needles to the coaxial cables as shown below:

1. Cut and trim end of the coaxial cable so that the center conductor does not touch the

outer conductor (connected to the guard terminal).

2. Connect the center conductor to tail of the probing needle. Never connect the outer

conductor to the probing needle. However, the outer conductor should be extended as

close as possible to the probing needle.

3. Connect the outer conductor to the outer conductor of the probing needle if it is a

coaxial probing needle.

4. Perform 1 to 3 for both Force and Sense lines.

5. Contact the probing needles for the Force and Sense lines as close as possible to the

DUT.

The following example connection can be used to measure low resistance. The Sense line

is extended to the probing pad, and contacts the Force line through the pad, so the voltage

drop due to the residual resistance caused by cables and test leads is canceled.

Figure 3-26 Cable and Probing needle

Kelvin Connection

Kelvin connections give good measurement results when you force high-current. The

following figure shows the equivalent circuits for Kelvin and non-Kelvin connections.

Figure 3-27 Kelvin connection

Probing needle

Connector plate

Outer conductor

Center conductor

Coaxial cable

Contact pad

Force

Sense

(a) non-Kelvin connection

(b) Kelvin connection

DUT