Monitoring Source Signal Level

• Monitoring the Test Signal Level (AC)

• Monitoring the DC Bias Level

Other topics about Setting Up the Display of Measurement Results

Monitoring the Test Signal Level (AC)

The signal level actually applied to a DUT differs from the setting applied to the signal source due to the source impedance and bias current. The E4991B provides a feature that allows you to monitor both the voltage and amperage values of the test signal level actually applied to the DUT, whether you measure the signal source level by voltage or current. This feature is called “test signal level monitor".

1. Press the Meas key to display the Measurement menu.

2. Press OSC Monitor Trace > Vac - Iac to turn ON the OSC monitoring trace for test signal level (AC).

   • Vac and Iac can be assigned for traces 1 to 4 independently by pressing Meas > Trace 1, Trace 2, Trace 3 or Trace 4.

3. Press OSC Monitor Trace > Close  to turn OFF the monitoring feature.

Monitoring the DC Bias Level

In most cases, the DC bias level actually applied to a DUT differs from the setting applied to the DC bias source because some electrical loss occurs between each test terminal and the DUT. The E4991B provides a feature that allows you to monitor either the voltage or amperage value of the DC bias actually applied to the DUT. This feature is called the “DC bias level monitor.”

Monitoring the Test Signal at Sweep Start

You can monitor the DC bias level (either voltage or amperage) at the beginning sweep through the DC Voltage/Current Bias Monitor field, which is located in the right-upper part of the screen LCD and labeled DCV, DCI. This field is updated at each sweep.

1. Press Meas key to display the Measurement menu.

2. Press DC Monitor Setup > DC Monitor > ON, to turn ON the DC monitoring feature.

Monitoring the DC Bias Level with Trace

You can monitor the actual DC bias level (either voltage or amperage) at the each point when DC bias sweep is selected.

1. Press Sweep Setup > Sweep Type > DC Bias or Log DC Bias to setup type to DC Bias sweep setting.

2. Press Meas > DC Monitor Setup > DC Monitor Trace > Vdc - Idc  to turn ON the DC monitoring trace feature. The traces 3 and 4 are displayed and assigned to Vdc and Idc respectively.

   • Vdc and Idc can be assigned for traces 1 and 2 by pressing Meas > Trace 1, Trace 2.

3. Press DC Monitor Setup > DC Monitor Trace > Close  to turn OFF the DC monitoring trace feature.