How to check the amplifier saturation?

Discussion and questions regarding the Radiated Immunity and Conducted Immunity modules of RadiMation.
Post Reply
incognito
Posts: 235
Joined: 03 Feb 2012, 13:07

How to check the amplifier saturation?

Post by incognito »

Hi,

How can I use the 'Amplifier Linearity' test in RadiMation to check the saturation of my amplifier?

Thanks!
User avatar
joro
Posts: 435
Joined: 24 Aug 2011, 09:55
Contact:

Re: How to check the amplifier saturation?

Post by joro »

In the EN 61000-4-3 and the EN 610004-4-6 it is indeed described, that the saturation of the amplifier (also known as the amplifier linearity) should be checked, to ensure that the AM modulation that is applied during the substitution test is not distorted.

In the past we always suggested to use a semi-manual verification measurement that can be used to check the amplifier linearity. This method is described on: viewtopic.php?f=15&t=19&p=37#p37
But since RadiMation version 2015.3.1 it is now also possible to use a completely automated measurement to check the amplifier linearity, in accordance to the EN 61000-4-3 and the EN 61000-4-6 standards.

The following steps describe how the amplifier linearity can be verified with the fully automated test in RadiMation. Assuming that a radiated immunity calibration should be performed for a substitution test with an electric field strength of 10 V/m.
1. Start RadiMation
2. From the main menu select: Calibration > Radiated Immunity > 1 Point Calibration
3. Select an existing TSF file, or create a new TSF by pressing the 'New' button.
4. Configure the radiated immunity calibration with the correct parameters. Ensure that:
  • Forward power calibration method is selected
  • A 1.8 times higher electrical field strength should be used during the calibration. So 18 V/m for a 10 V/m substitution test.
example radiated immunity calibration configuration
example radiated immunity calibration configuration
RICalibrationconfig.png (32.9 KiB) Viewed 21287 times
5. Start the radiated immunity calibration, and wait until it is finished. Specify a filename for the calibration results.

For the amplifier linearity check we need an EUT file. This EUT file reflects the amplifier that is being used in the test-setup. When the linearity of the amplifier is checked more often (for example during annual verifications), the same EUT file for the amplifier can be used, and the different results of the amplifier linearity checks will be available in the same EUT file.
6. Create a new EUT file by selecting from the main menu: File > New > EUT
7. Specify a suitable EUT filename, for example 'Amplifier 80-400 MHz.EUT'.
8. Now start the amplifier linearity test by selecting from the main menu: Calibration > EUT Calibration > Amplifier Linearity
Selection of the 'Amplifier Linearity' menu
Selection of the 'Amplifier Linearity' menu
AmplifierLinearityMenu.png (19.13 KiB) Viewed 21287 times
9. Select an existing TSF file, or create a new TSF by pressing the 'New' button.
10. Select the calibration file that was created in the previous steps.
11. The following parameters can be configured in this test:
  • The 'Increment' or 'Decrement' of the 'Power Step' specifies the direction in which the power should be changed. For the EN 61000-4-3 this is normally 'Decrement'. For the EN 61000-4-6 this is normally 'Increment'
  • The 'Power Step' is the dB value in which the signal power should be changed. This is normally 5.1 dB.
  • The 'Lower valid' of the 'Accepted power' specifies the minimum change of the forward power to be valid for the linearity check. This option cannot be turned off, and should always be specified. This value is normally 3.1 dB.
  • The 'Upper valid' of the 'Accepted power' specifies the maximum change of the forward power to be valid for the linearity check. This option can be enabled or disabled. An often used value is 7.1 dB, but the latest versions of the EN 61000-4-3 do not restrict the maximum forward power change.
Configuration of the Amplifier Linearity test
Configuration of the Amplifier Linearity test
AmplifierLinearityConfiguration.png (40.66 KiB) Viewed 21287 times
12. Press 'Start Test'.
13. The Amplifier Linearity test will perform the automated test using the following steps:
  • Select the first frequency
  • Regulate the forward power to the forward power that was stored in the calibration file.
  • Measure and store the signal power and the forward power in the test-results
  • Change the signal generator carrier level with the configured power step (increment or decrement with the 'power step' value)
  • Measure and store the signal power and the forward power in the test-results
  • Calculate the difference between the forward powers, and store it as the 'Forward power step' in the test-results
  • Update the graphs
  • If the stop frequency is not yet reached: step to the next frequency, and repeat the above actions.
14. During and at the end of the test, the different measurements are shown in the graph.
Example results of the Amplifier Linearity test
Example results of the Amplifier Linearity test
AmplifierLinearityResults.png (81.84 KiB) Viewed 21287 times
15. The 'Amplifier Linearity' is shown as the 'Forward power step' (as the orange line in the screenshot above), and the configured limit values are shown as the 'Accepted Power step' (as the red line in the screenshot above). The limit line values can also be modified with the 'Accepted power difference' settings on the bottom left side of the result window.
16. If the 'Forward power step' line is within the 'Accepted power step' values, the amplifier fulfills the 'Amplifier linearity' requirements.
17. Save and close the test results by pressing on the 'Close' button. The results will be available in the list of performed tests in the EUT file that was created previously.

Ofcourse it is also possible to perform a complete 16 point Uniform Field Area (UFA) calculation. The resulting calibration file of the UFA calculation can then also be used as input for the amplifier linearity test.

We strongly recommend to use the 'Amplifier Linearity' test as it is implemented in RadiMation to verify the amplifier saturation, because it is a fully automated verification and it complies to the requirements of the EN 61000-4-3 and the EN 61000-4-6.
solutionseeker
Posts: 45
Joined: 05 Oct 2012, 09:48

Re: How to check the amplifier saturation?

Post by solutionseeker »

This new test feature is looking great! I was wondering if a warning is shown in the event log in case the forward power step is exceeding the lower or upper limit? This would make it easy to verify when the linearity is not within the specification at some point(s).
User avatar
joro
Posts: 435
Joined: 24 Aug 2011, 09:55
Contact:

Re: How to check the amplifier saturation?

Post by joro »

Currently no message is included in the event log if the forward power step is exceeding the upper or lower limit.
The limits are adjustable after the test is performed. When these limits are changed, the message in the event log is not logical anymore.

The correct solution would be to have a dynamic indication of 'exceeding the limits' on the screen that is updated in real-time (when the measurement is busy and when the limit values are changed). We will investigate if we can implement this in a future update of the software.
radiuser
Posts: 11
Joined: 24 Oct 2014, 08:32

Re: How to check the amplifier saturation?

Post by radiuser »

Hello John,

when will Version 2015.3.1 be released using this new feature?

thank you.

Regards
Juergen
User avatar
joro
Posts: 435
Joined: 24 Aug 2011, 09:55
Contact:

Re: How to check the amplifier saturation?

Post by joro »

Hello Juergen,

The 2015.3.1 version of RadiMation is already available as a beta-version from our download page: http://download.radimation.com
It is available as a beta version, because we are still in progress of our internal validations to verify the correctness of all the measurements and tests.

With best regards,
John
radiuser
Posts: 11
Joined: 24 Oct 2014, 08:32

Re: How to check the amplifier saturation?

Post by radiuser »

Hi,

I've just installed 2016.1.6 and want to try next this function "Amplifier linearity".
As you wrote on 17th Dec. 2015 that the correct settings should be -> Forward power calibration method, so is it not pssible using this function in Net power calibration method?

Thanks
User avatar
sast
Posts: 168
Joined: 05 Sep 2012, 15:39
Contact:

Re: How to check the amplifier saturation?

Post by sast »

We have registered this question as item #7440: Amplifier Linearity in Net power calibration method.
As soon as we have an answer we will also post it here.
User avatar
sast
Posts: 168
Joined: 05 Sep 2012, 15:39
Contact:

Re: How to check the amplifier saturation?

Post by sast »

Yes, it should indeed be possible to use the Amplifier Linearity method in combination with a Calibration file which is using the ‘Net power’ method.
However, the minimum method required method is obviously Forward power. In additional, a Signal Generator method used Calibration file has insufficient information to perform the Amplifier Linearity test.
Post Reply