ADL5565 IQ inputs to IQ+- outputs

Dear Analog Engineer,

We are currently working on a wireless communication project, interested in the differential amplifier ADL5565 and the evaluation board for it, ADL5565-EVALZ.

Our purpose is to generate four differential IQ outputs, I+, I-, Q+, Q-. We have two identical RF interfaces, say RFA and RFB. Each of them can send out single-ended IQ signals. The confusing thing is whether (1) we need RFA to transmit I signals and RFB to transmit Q signals, then use two ADL5565-EVALZs for each to create four differential IQ signals, or (2) we could simply use RFA only (deactivate RFB) to transmit a single-ended IQ signal and use ADL5565-EVALZ and/or other components to create four differential IQ signals.

We guess that no matter either way above does work, we need to customize the input and outputs on the board ADL5565-EVALZ, so that it can support 1 input to 2 or 4 outputs. Are we right? Then how to include this kind of information to make a quote like that?


  • 0
    •  Analog Employees 
    on May 17, 2016 5:39 AM

    Hi, STLCards,

       It's not clear what is the nature of RFA & RFB.  If they represent single-ended I & Q channel signals, then each can be connected to one ADL5565 (or use one channel out of the dual-channelled ADL5566 or ADL5567) to perform single-ended to differential signal conversion (Datasheet p. 18, Fig. 34).  Please note that if DC coupling is required, then special attention must be paid to make sure the input and output dc common-mode levels are within the specified ranges (Datasheet p. 3, Table 1).

       If RFA and RFB are truly "identical" as mentioned, then you won't be able to generate separate I & Q channels from them.


  • 0
    •  Analog Employees 
    on May 17, 2016 6:11 AM

    Hi, STCards,

       I forgot to mention: if RFA and RFB are RF or IF signals with complex modulation, then they can be demodulated into I & Q outputs using a quadrature demodulator such as ADL5380 or ADL5387, among others, depending on frequency.  The I & Q signals will come out in differential form, and can be amplified after filtering using differential amplifiers like the ADL5565-5567, etc.

  • Thank you very much,

    As we want to order a couple of ADL5565-EVALZ, do we need to specify the output interfaces would be two rather than one in the order placement? That is, activate the J4 interface in order to make one single-ended I or Q signal to differential I+- or Q+- signals?

  • 0
    •  Analog Employees 
    on Aug 2, 2018 3:27 PM
    This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

    Thank you,
    EZ Admin