Specifications

5-14. DC bias current enhancement
DC current biasing is used for inductor and transformer measurement. In low frequency region, the
E4980A or 4284A precision LCR meter with the 42841A bias current source are both suitable for
this application because they can apply up to 20 A of bias current. (This can be extended up to 40 A
if two 42841As are connected in parallel.)
To deliver a bias current in RF impedance measurement, the 16200B external DC bias adapter can
be used with the RF I-V measurement instrument. The 16200B allows you to supply a bias current
of up to 5 A across the DUT by using an external DC current source. The 16200B is directly
attached to the 7 mm test port and, the test fixture onto the 16200B as shown in Figure 5-42. To
minimize the bias adapter induced errors, perform open/short/load calibration at the test fixture
terminals with no bias voltage/current applied.
Figure 5-42. External DC bias measurement using the RF I-V measurement instrument
External current bias circuit in 4TP configuration
For external current bias measurement using other auto balancing bridge instruments, an external
DC current source and a protection circuit are required. The following describes a protection cir-
cuit that can be used for DC bias current measurements up to 10 A. Figure 5-43 shows the protec-
tion circuit schematic diagram.
5-32