B2900B/BL Series Precision Source/Measure Unit

Configure Your Keysight B2900B/BL Series Precision Source/Measure Unit

The Keysight B2900B/BL Series Source/Measure Unit (SMU) series contains the following six models.

• B2901BL Precision Source/Measure Unit, 1 ch, 1pA resolution, 21 V, 1.5 A

• B2910BL Precision Source/Measure Unit, 1 ch, 10fA resolution, 210 V, 1.5 A

• B2901B Precision Source/Measure Unit, 1 ch, 100fA resolution, 210 V, 3A DC/10.5 A pulse

• B2902B Precision Source/Measure Unit, 2 ch, 100fA resolution, 210 V, 3A DC/10.5 A pulse

• B2911B Precision Source/Measure Unit, 1 ch, 10fA resolution, 210 V, 3A DC/10.5 A pulse

• B2912B Precision Source/Measure Unit, 2 ch, 10fA resolution, 210 V, 3A DC/10.5 A pulse

This configuration guide has step-by-step instructions to help you configure an SMU and its related accessories to meet specific test requirements. For detailed specifications, refer to the B2900B/BL SMU series data sheet.

Step 1. Select B2900B/BL Series model

There are two key parameters you need to select up-front: the number of measurement channels (one or two) and the SMU performance level. The B2900B/BL series comes in value (B2901BL/B2910BL), standard (B2901B/B2902B) and high-performance (B2911B/B2912B) versions.

Note: After purchase it is not possible to upgrade an SMU to have more channels or to the other version.

Step 2. Select optional accessories

Step 2-1. Choose a rack mount kit (optional)

Step 2-2. Determine if you need to make 4-wire or guarded measurements

The B2900B/BL SMUs support both 2-wire and 4-wire measurement. The default connection scheme is the simpler 2-wire configuration, which uses only the force terminals. In 2-wire mode the sense terminals are left open.

If you are measuring very small resistances or applying very large currents then you should use the 4- wire measurement method (also known as the Kelvin method). This technique uses both the force and sense terminals, and by making the measurement through the sense terminals (in which no current is flowing) the effects of cable resistance are eliminated.

Low current measurements (< 1 nA) require guarding to prevent leakage through the measurement cable. The schematic shown below provides a simplified overview of the guarding technique. Guarded measurements require the use of triaxial cables. A follower (x1) buffer amplifier keeps the guard conductor at the same potential as the center conductor. Since there is no voltage difference, no current can flow from the center conductor to the guard.

Note: In this example, even the test fixture has a guarded shield to prevent leakage at the test fixture.

Step 2-3. Consider interlock circuit (optional)

To prevent accidental exposure to dangerously high voltages, the SMUs have a safety interlock. They cannot source voltages greater than ± 42 V unless the interlock circuit is closed. This is achieved using pins 16 and 24 on the rear Digital I/O output. Normally, these pins are routed to a shielding box or test fixture that must be closed to complete the interlock circuit.

If you are using the 16442B test fixture then you can use the N1294A-011 or 012 interlock cables to connect to the interlock circuit. If you are not using the 16442B then you should install an interlock circuit as shown in the figure below. For more detailed information, please refer to “Installing the Interlock Circuit” in the Keysight Series User’s Guide.