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ADL5324 Datasheet

Hi,

In the ADL5324 datasheet there are reference designs and layouts.

On page 19, figure 17, the layout for the 3500-3700MHz operation. There is a series inductor on the output, L2.

It is 4.7nH.

At 3500MHz, this gives a reactance of 103 ohms.

Considering the output impedance is 50 ohms, this will attenuate the output signal somewhat....

Am I correct?

If so what value should this be?

Best regards,

Roger.

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  • Hi Rog,

                    the ADL5324 is not internally matched to 50 ohms. This impedance is 6 ohms or so and must be externally matched to 50 ohms. L2 & C2 work with the internal impedance of the ADL5324 to create a 50 ohm match for the ADL5324. The value for L2 is correct and has been tested.

    Regards,

    Jim B

  • Hi Jim,

    Ok, yes I see the S21 is 5.6 ohms and needs to be matched to 50.

    I am also trying to simulate this, but I cannot get it to match to 50.

    Do you have any spice or ADS simulation files on this device, I could then see how I am going wrong.

    Best regards,

    Roger.

  • Hi Rog,

                 On the web, we have an S-Parameter file you can download and use with ADS. I generally use a smith chart program to get a basic match at the center frequency of the band. I then use ideal components and tune function to get the desired gain and match across the band. I then substitute real components in ADS and adjust as needed to keep my gain and match. I then build and test. One point, I found at the higher freqs there is an error in the s2p file and my actual circuit is off by 250 MHz when tested. SO I offset the simulation freq and rematch in that case. I have never had to do more than 2 iterations to correct for the offset in frequency that may or may not occur.

    Regards,

    Jim B

  • Hi Jim,

    Yes I have the S parameters file, am using it in ADS.

    I have tried placing in substitution vales for the reactive components - without any success in matching it.

    I still believe the inductor is too high a value. Would you be able to check you results, for the 3500-3700 MHz band.

    Best regards,

    Roger.

Reply
  • Hi Jim,

    Yes I have the S parameters file, am using it in ADS.

    I have tried placing in substitution vales for the reactive components - without any success in matching it.

    I still believe the inductor is too high a value. Would you be able to check you results, for the 3500-3700 MHz band.

    Best regards,

    Roger.

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