Automatic Bias Polarity Control - Keysight E4980A User Manual

Configuring Measurement Conditions (Display and Function Related Settings)
MEAS SETUP page

Automatic Bias Polarity Control

Functional Description
The automatic bias polarity control feature is useful when testing a varactor
diode. The E4980A/AL identifies the connection state of the diode using an
internal bias (approx. 1 V) and internally controls the DC bias polarity so that a
reverse bias is applied to the diode.
For example, when a varactor diode is connected as shown in
E4980A/AL recognizes that the diode is correctly connected and applies a DC
bias in accordance with the specified setting. On the other hand, when a
varactor diode is connected as shown in
that the diode is reverse-connected and applies a DC bias by inverting the
polarity of the specified setting. This feature eliminates the need to check the
polarity of a varactor diode before connecting it to the UNKNOWN terminal.
When the DC bias feature is OFF and you set the automatic bias polarity
control feature to AUTO, the automatic bias polarity control feature does
not function.
Figure 4-6 Varactor diode (normal polarity)
108
Figure
Figure 4-7, the E4980A/AL recognizes
Keysight E4980A/AL Precision LCR Meter
4-6, the