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Where To Find This Example

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Design Notes

P1dB

This project shows how the XDB block can be used to easily find the output 1 dB compression point of an amplifier..  The example test benches show both a single tone and swept frequency setup. 

Overview

The XDB block computes the user specified compression point from either the linear gain or maximum gain of a DUT.  The test benches in this example are configured for 1 dB compression from the linear gain point (the DUT used doesn't show a gain expansion region).  Note that the XDB block automatically servos the input power to find the compression point and, thus, no input power sweep is needed.  In fact, having an input power sweep would cause unnecessary simulation to occur as the compression point would be found for each power point but the data would be the same.

One_Tone_Test_Bench Schematic

The "One_Tone_Test_Bench" schematic has a single FET and sweeps power at a single frequency (10 GHz).  The "One Tone Pout vs Pin"

graph shows the FET compressing as the input power is increased.  The "One Tone Power Gain" Graph shows the gain decreasing as the input power is decreased

Frequency_Sweep_One_Tone_Test_Bench Schematic

The "Frequency_Sweep_One_Tone_Test_Bench" schematic is identical to the "One_Tone_Test_Bench" schematic except it is setup to sweep from 5 to 15 GHz.  The "Frequency Sweep One Tone Pout vs Pin"

graph shows the FET compressing as the input power is increased for each frequency sweep.

One_Tone_P1dB_Test_Bench Schematic

The "One_Tone_P1dB_Test_Bench" Schematic has a single FET setup with an LTUNER to control the load presented to the FET and an XDB block to simulate the 1 dB compression point at a single frequency (10 GHz).  The "One Tone Input Power and Output Power at P1dB"

graph shows the input power and output power at which the FET gain is compressed by 1 dB.

Frequency_Sweep_One_Tone_P1dB_Test_Bench Schematic

The "Frequency_Sweep_One_Tone_P1dB_Test_Bench" Schematic is identical to the "One_Tone_P1dB_Test_Bench" Schematic except it is setup to sweep from 5 to 15 GHz.  The "Frequency Sweep Input Power and Output Power at P1dB"

graph shows the input power and output power at which the FET gain is compressed by 1 dB for each frequency in the sweep.

Load Pull

Load pull only requires a measurement on a graph and a load pull tuner in a schematic.   In this example load pull was run on the "One Tone P1dB" Schematic and the data results shown on the "Load Pull" Graph.  

If you want to run the load pull, the setup saved in the project so that you can easily run it again.  Choose Scripts > Simulation > Load Pull to invoke the "Load Pull" script.    All the proper settings will be set, just click the "Next" or "OK" button to watch the run, when finished the data will show up on the "Load Pull Data" Graph.