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RF Power divider

Prodigy 60 points

Replies: 7

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I have a RF signal which i need to provide to 2 different inputs. Basically the same amplitude has to be provided from the same signal source , and they should be closely phase matched. I thought i could use a Power divider but that is not available as a SMD component . How else can I send the same signal to 2 different inputs with the same voltage ? The BW I am interested in is max of 3GHz .In simple words , I just need to copy my signals into both inputs without a considerable phase difference. 

  • Hello Narender,

    I am not sure what solution you are looking for, so I will chime in with what I have found on power dividers: there are in fact various SMD RF power dividers.  I found this model from Mini-Circuits which may be a good place to start: 

    I have not used this Mini-Circuits part, but it would appear they have a catalog of SMD components which may suit your purpose.

    Are there any other details or requirements about your circuitry restricting your design choices?  Are you mainly curious about SMD components capable of sending two RF signals from one source to two inputs in (or close to in-)phase?  There may be other methods for implementing your design, if it should require more complexity than a power divider.

    Please let me know if you have any additional questions on this topic, or if my suggestion is not what you were hoping to find.

    Best,

    Alec Saebeler

  • In reply to Alec Saebeler:

    Thank you Alec for your reply. 

    Essentially I am trying to send the RF out of my ADL5330 to two inputs. The ADL5330 is fed by a RF source. Each of the output from the diff pair on ADL5330 are being used separately . For instance the P output signal has to be sent to 2 input ports. The output Impedance at P of ADL5330 is 25 Ohms . On the other hand the RF inputs are at 50Ohms . What are the power divider impedances I need so that  I can send the signal on both inputs with phase matched. Fundamentally I am trying to copy the same signal at the 2 inputs. 

    The BW I need is 2G max and the device whose link I have provided suits well. The only issue I see here is the Power divider is based on 50Ohms network. What are your thoughts ?

    Regards,

    Narender

  • In reply to Narender Singh1:

    Narender,

    I will take a look at some ideas and options and get back to you this next week!  Thank you for sharing some more about your circuit, it will help me understand how best help to you with your design.

    At first glance, I think the solution may need to be a bit more involved than a single SMD power splitter on account of the 25 Ohm network, but I will certainly look into it.  I would normally suggest using a balun on the outputs, but now I am curious how the other differential output is used (is it also split, what circuitry is on it?)  If you could add some context for the other output, I think I will have enough to figure out something for you.

    Best,

    Alec

  • In reply to Alec Saebeler:

    Hey Alec,

    Thanks for your help. Here's the full story that might help you the context better.

    I am implementing a setup that will help me force RF interference on my LVDS data signals to validate the common mode noise tolerance of my Rx. There are 4 pairs of differential data signals , so all of them need to be fed the RF together to make the setup run quicker. 

    I have only 1 RF source which I intend to use for my cause. The challenge here is to use the same RF source and strategically send the RF signal to all the inputs where RF signal gets added to the LVDS data. I am using a cascaded network of  ADL5330 to amplify these signals and then send forward. At this point i have maximum of 3 ADL5330 in cascade. 

    Since each of these ADL5330 are blessed with both P and N , I intend to use the P RF signal on both Dp and Dn of one of my LVDS data. This way the signals are matched in phase closely to validate my common mode rejection. 

    I thought using a splitter right at the output of the P , I can then send the RF to superimpose on my differential data signals. 

    I intend to use the N output on another set of differential data etc. 

    Regards,

    Narender

  • In reply to Narender Singh1:

    Hi Narender,

    I understand better now.  Thank you for sharing the full story.  I will look into some ideas for SMD components that could work well with a power splitter to achieve the performance you desire.  I will also discuss with my team in case there are any alternative methods for accomplishing your task.

    I believe you tried to insert an image or link, but it did not appear on my end.  Could you try editing/replying to your thread and using the "paperclip" icon in the toolbar to attach your file?

    Best,

    Alec

  • In reply to Alec Saebeler:

    I have attached the image that didn't get uploaded the last time. 

  • In reply to Narender Singh1:

    Hi Narender,

    You are undertaking a complicated circuit/setup, but I will pass along my team and I's thoughts.

    The best path forward for your design might be to use a 4-way power splitter and an RF amplifier as a buffer.  The use of a passive network and buffer amplifier would address some of the impedance issues you are facing, as well as issues introduced by using differential outputs as single-ended outputs.  Your current setup introduces a lot of complications and would need to facilitate impedance matching difficult to do in a pre-built SMD package from Mini-Circuits, for example (especially at up to 3GHz).

    You could also use a resistive power divider, though you will incur some real power loss.  Another option would be to use microstrip quarter-wave transformers and have PCB traces accomplish your impedance matching.

    Whichever approach you choose, you will find ample documentation and examples.  Unfortunately, there is not a turnkey one-part solution for your design as it stands.  Please see the below resources for some helpful context.

    If you need a good reference for RF passive design, I learned a lot from Microwave Engineering, David Pozar.

    Best,

    Alec

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