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    Problems with UpConverter Design for X band

    Hello everyone,

    We are designing a new PCB for Point to Multipoint application in my company and we have a bit problem with UpConverter in our design. UpConverters needs IQ signal as input one to perform a good conversion with a good image frequency rejection (see the following datasheet: https://www.mouser.com/ds/2/249/MAUC...1)-461012.pdf). To get IQ signal, an hybrid is needed. The problem is that there are no hybrid that works in the whole frequency range (we want to use it in the full range from 250 MHz to 1200Mhz). For 200MHz they are too big and do not work for 1Ghz and vice versa.

    Although our design is for the entire band, the signal will work either at high frequencies or at low frequencies. But we want a design that can be used in both cases

    I have made a research in Internet and the solution i have found are:

    - Removing the hybrid coupler by using a normal mixer with an amplifier at the output of it (this will worsen the system specifications)

    - Make a small upconversion to the IF signal to move it to a range of frequency that a single hybrid that will work in the whole band (The problem is that we will have to add a new IF step in the transmission path and it may no contemplated by the requirements, and all LO have to be adjusted for a correct work of the whole system).

    I would like to know if there is another possibility for this problem (i.e using two different hybrid one for lower frequencies and the other one for the higher frequency and select the correct one by filtering the signals or by the controller)

    Thank you very much for your help.

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    Re: Problems with UpConverter Design for X band

    Modern ADCs are able to convert this type of wide-band signals into digitized format.Then someone can create a ROM look-at-table technique in order to obtain I-Q signal pair.

    - - - Updated - - -

    Or..
    You can multiply by 2 this signal then divide by 2, you can obtain I-Q signals in square waveform.



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    Re: Problems with UpConverter Design for X band

    Hello,

    The problem is that we don't work with the digital signal, we only work with the analogic one, then we do not uses the ADC. The signal is alrready modulated, and the idea of get the I-Q signal is for the UpConverter to improve LO and Image frequency rejecton.

    Inn the other hand, I don't understand really weel what you are saying about I-Q singal in squere waveform.



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    Re: Problems with UpConverter Design for X band

    Quote Originally Posted by WGabrielRF View Post
    Hello,

    The problem is that we don't work with the digital signal, we only work with the analogic one, then we do not uses the ADC. The signal is alrready modulated, and the idea of get the I-Q signal is for the UpConverter to improve LO and Image frequency rejecton.
    If the signal is already I/Q Modulated and you wish to separate I and Q signals to up-convert them, there is only one way is to use digital techniques in this wide-band frequency spectrum.
    I don't know any other analog method.



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