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Load pull simulation in ADS

Mabrok

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Hi,

In ADS load pull simulation results. Is it correct that the impedance at marker 3 is the Zload (7.161+j 2.480) which are using in output matching design, and input impedance is the Zsource (16.97-j 32.31) using in input matching network design? And also want to know is it one tone load pull is sufficient for design high efficiency RF power amplifier (i.e. no need to perform 2 tone load pull)?

I already attached my results from load pull simulation (One tone load pull with constant source power). Thanks in advanced

Load pull simulation.png
 

BigBoss

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If you're interested in one single specification only ( max. Power or max. Efficiency) single tone simulation is enough but if you're also interested in Linearity, second carrier Load Pull Simulation is necessary because this will give you an insight about the harmonics that will appear at the output and obviously how to reduce their level.While you're reaching to max. Power Level, you may loose the Linearity and this compromise will tell you how to choose the Optimum Impedance.
If the model is sufficiently accurate and the simulation set-up has been well established, the results of ADS are pretty good ..
 
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    Mabrok

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Mabrok

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If you're interested in one single specification only ( max. Power or max. Efficiency) single tone simulation is enough but if you're also interested in Linearity, second carrier Load Pull Simulation is necessary because this will give you an insight about the harmonics that will appear at the output and obviously how to reduce their level.While you're reaching to max. Power Level, you may loose the Linearity and this compromise will tell you how to choose the Optimum Impedance.
If the model is sufficiently accurate and the simulation set-up has been well established, the results of ADS are pretty good ..
Thank you for the valuable comments. For confirmation, is it correct that impedance at marker 3 is consider as the Zload, and input impedance is consider as the Zsource based on the attached image?
 

Mabrok

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Thank you for the valuable comments. For confirmation, is it correct that impedance at marker 3 is consider as the Zload, and input impedance is consider as the Zsource based on the attached image?
Also I want to ask another question. For the amplifier stability, my amplifier is stable from 1 to 5 GHz, below 1 GHz is not stable, is that ok? (Note: the required frequency band for my design is 3.4 to 3.6 GHz)
 

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Yes, if the Optimum Load Impedance is as shown there, the corresponding-and has to be presented to input- Input Impedance has been given by ADS.You have to walk around these impedances to get the satisfying result.
If this amplifier is unstable under 1GHz, it's a problem because its' harmonics will disturb the operating frequency band.There are many techniques to make any amplifier stable.
But first of all, you should check this unstability continues when the amplifier is terminated with mentioned impedances ?? The stability may chamge much with terminating impedances ( source and load ) therefore the stability must be checked first with those impedances.If the status is persist you can apply stabilization techniques to the amplifier.
 
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Mabrok

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Yes, if the Optimum Load Impedance is as shown there, the corresponding-and has to be presented to input- Input Impedance has been given by ADS.You have to walk around these impedances to get the satisfying result.
If this amplifier is unstable under 1GHz, it's a problem because its' harmonics will disturb the operating frequency band.There are many techniques to make any amplifier stable.
But first of all, you should check this unstability continues when the amplifier is terminated with mentioned impedances ?? The stability may chamge much with terminating impedances ( source and load ) therefore the stability must be checked first with those impedances.If the status is persist you can apply stabilization techniques to the amplifier.
Thank you. In general case, for RF power amplifier design the device have to be stable from where until where? let's say that our required frequency band is 3.4-3.6 GHz.
 

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