Measuring DUT and Analyzing Measurement Results

After performing calibration and compensation, the measurement results are displayed on the screen when the DUT is connected to the test fixture. If you obtain the correct trace, you can analyze the measurement results by using the marker and the equivalent circuit analysis function.

Applying DC Bias (Option 001)

When selecting DC Bias (Current) Characteristics of Ls-Q (Option 001) in Setting Measurement Conditions, follow these steps to apply DC bias. For settings of the DC bias source level and DC bias limit, refer to Setting Measurement Conditions.

• Never touch the DUT or the electrodes of the test fixture while DC bias is applied.

1. Press Sweep Setup > DC Bias > ON.

2. Set the trigger to start the measurement.

   • Perform single measurement. Press Trigger > Single.

   • Repeat the measurement. Press Trigger > Continuous.

Executing Auto scale

Traces obtained after setting the sweep conditions and measurement parameters may extend beyond the screen because they are too large or too small along the direction of the vertical axis. In this case, the auto scale function can be used to set the appropriate scale. Follow the steps at Auto-scaling the Trace to execute auto scale.

Adjusting Scale

When a trace is formed flat, executing auto scale makes the scale value of the grid smaller so that the overall trace can be monitored on the full screen. To change the scale to a desired value, adjust it by following these steps.

• Scaling parameters for the adjustment vary according to the display format. For details about scaling parameters, refer to Setting Windows Display.

1. Press Scale > Scale/Div > adjust the scale by inputting the appropriate value in each scaling parameter box.

Performing Averaging

When the measured trace does not appear smooth on the display, a smooth trace may be obtained by performing point averaging or sweep averaging. Especially for the high Q (low D) measurement, you should perform averaging.

Averaging

Averaging includes point averaging and sweep averaging.

• Point averaging - Point averaging smooths the trace by repeating the measurement on each measurement point until the averaging count is reached.

• Sweep averaging - Sweep averaging smooths the trace by repeating the sweep until the averaging count is reached.

• Point averaging and sweep averaging can be performed at the same time.

To perform averaging, follow the steps in Averaging Between Sweeps (Sweep-to-Sweep Averaging), Making Sweep Averaging Measurement with Single Trigger and Averaging for Each Measurement Point (Point Averaging).

Using Marker Function

The marker function allows you to read trace values and stimulus values at any point on the active trace. The marker search function allows you to detect specific points such as maximum values, minimum values, peak values and target values. This section describes how to read trace values, detect maximum values, display a marker list, and clear the markers.

Reading Trace Values

Please refer to Reading Marker Values on Trace.

Detecting Maximum Values

Please refer to Searching for Maximum and Minimum Values.

Displaying Marker List

Please refer to Reading Marker Values on Trace.

Clearing Markers

Please refer to Turning off the marker.

Executing Equivalent Circuit Analysis

The E4991B is provided with five types of equivalent circuit models that can be used to calculate approximate values of equivalent circuit parameters from measurement data. The approximate values of equivalent circuit parameters obtained by calculation can be used to simulate the frequency characteristics on the display screen.

• The equivalent circuit analysis function can be used only when the sweep parameter is frequency.

Please refer to Calculating Several Traces (Equation Editor).

Enlarging Trace

Please refer to Setting Marker Zoom and Zooming Aperture.

Displaying Traces on Individual Windows

Please refer to Setting Windows Display.

Displaying Smith Chart

Please refer to When Measuring Complex Parameters.