Post Go back to editing

Synchrodyne/Homodyne mixer circuit using ADL5391

Category: Hardware
Product Number: ADL5391

Dear ADI Engineers,

I am considering building a replica direct conversion receiver for 50Khz through 250Mhz.
As part of my application, I intend to use a Si5351A circuit to generate a square wave as the LO frequency.
I would like to know if ADL5391 can be used as the doubler for this signal generator's square wave output,

and secondly if I should then use another ADL5391 as the mixer component. 

I am not very experienced with RF circuit design. 

My complete circuit application initially looks like this:

A traveling wave loop -> ESD protection -> wideband 1:1 transformer -> junction split(no splitter) -> 4 identical single ended amplifiers
configured for a fully differential circuit with a pair of amplifiers on each side to improve SNR -> power combiner on each leg ->
high pass at 50khz -> differential mixer -> low pass at 50 khz -> audio cable.

I am not fully certain this is the correct approach for the direct conversion circuit, maybe I need to do a 90 degree shift on one side of the mixer
at the LO input so that my audio cable carries quadrature I/F, but I am principally seeking advice on the use of ADL5391.
Any additional advice you could offer on how RF signal from a simple traveling wave loop(for reference, this means a loop which features a 130 ohm end to end
resistance and complete path through the transformer for reasonable common mode canceling characteristics) travels through a fully differential
circuit  and mixer would be appreciated, I have been working as best I know to simulate it.

  • Hello rainstared,

    Thank you for reaching out to us and sorry for our late reply. Regarding to your question:

    From our first impression, it seems that you can use the ADL5391 as a frequency doubler and as a mixer for your application without problem.
    But, since you are using square waves, you would have to deal with the added harmonics at the output, which might result in some additional issues.
    Unfortunately, we do not have this part in our lab for testing your use case, and we need some time to give you a more clear answer.

    Regards

    Gokhan

  • Hello rainstared,

    We've confirmed that you can double the square wave at 250 MHz with the +-170 degree phase difference range using ADL5391. We also confirmed that you can use ADL5391 for a downconverting mixer for sinusoidal waves using your specs, we will let you know when we replicate the downconverting using square waves.

    Regards

    Gokhan