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4. Executing the Measurement and Viewing Results

This section introduce how to execute the PAE measurement test and how to view the measurement results. Follow the procedure below to execute the measurement and view the measurement results.

Initial Run

Timing Alignment

Executing the Measurement

Viewing the Measurement Results

Initial Run

1. Click the Run button on the tool bar to get the RF and ET waveform downloaded into the instrument and get the initial measurement results.

   

2. Once the measurement begins, the detailed information will be displayed in the Log view at the bottom of the window as shown below.

   

   During the running process, you can stop it any time by clicking the Stop button. When you see the "Complete!" message in the Log view, it indicates that the measurement is completed.

   

Timing Alignment

Timing alignment is to synchronize the input signal of the PA (the output of the RF Signal Generator) with the input voltage of the PA (the output of the Envelope Signal Generator) in time domain. This can be achieved by performing normal envelope tracking. Refer to Example ET Measurement to know how to handle the envelope tracking to finish the alignment of ETPS output and RF signal. This is must before making meaningful PAE measurement.

There are two methods:

• Manual: Adjust the Delay and Step setting in Envelope Tracking block manually with an oscilloscope connected to the Envelope Signal (ETPS output) and RF Signal Generator and observe the signals alignment.

• Auto: Click the Auto-align ET and RF signals button on the tool bar to get the signals aligned automatically.

  

  By selecting the Pre-Align with AM-AM for Auto-Align check box in the Envelope Tracking block, you can find a possible better initial delay value with the measured AM-AM results, but this may take longer time. After the auto-alignment is finished, the Delay setting in Envelope Tracking block is updated automatically.

If the related settings (for example, sample rate, IQ delay, trigger delay in Generator instruments and so on) are changed and applied, it is recommended to do the timing alignment again.

Figures 1 and 2 show the DPD results before and after timing alignment respectively.

Figure 1. DPD result before Alignment

Figure 2. DPD result after Alignment

Executing the Measurement

Once a proper time alignment has completed, the signal can be played repeatedly without re-alignment. Click the Measure button to play the signal and get the measurement results.

Viewing the Measurement Results

In the measurement view, there are two result windows: PAE vs Time and PAE vs PA Power Out.

After PAE measurement is done, click the Measure button to view the results.

Or more result windows if intermediate result is set to “On” state.