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Differences between ADC12J4000EVM and TSW12J54EVM

RodneyFarrow
Expert 4330 points
Other Parts Discussed in Thread: TRF3765, ADC12J4000EVMHi my csuotmer asked:

I would like to find out from TI what they believe to be the main difference between the ADC12J4000EVM and the TSW12J54EVM? And why thy would suggest one above the other? My main aim is to drive the ADC using a differential input, bypassing most of the analog input circuitry. I also have to supply the actual ADC clock externally. I’ve seen in the documentation that this can be done, but then you need to supply both Fs as well as Fs/2? That is not great, because then I would need to derive the one from the other? Won’t it be possible to just the EXT_VCO and drive it with 4 GHz with the correct settings of the TRF3765 on the evaluation module?
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    TI__Mastermind 44560 points

    Hi Rodney

    I split this into a new thread to make the subject match your question better.

    The key additional feature of the TSW12J54EVM is the active differential front end. If your application needs signal gain, or DC coupling, then this board may be a better choice. It can be used with single ended or differential input signals, and can be operated in AC-coupled or DC-coupled configurations. Signal frequencies from 0 Hz to just above 2 GHz can be used.

    The ADC12J4000EVM comes configured with a single ended input using an on-board balun transformer to convert this to differential signals AC-coupled to the ADC inputs. The board can be re-configured to allow differential inputs, but is most easily operated in AC-coupled mode with this configuration. If a DC-coupled differential drive is desired the external differential driver must match the common mode voltage (Vcmo) of the ADC inputs.

    It is possible to reconfigure the board to allow it to be synchronized to an external clock source, with just one clock signal being applied to the board. If you apply a 100 MHz signal to the OSCin connector, and reconfigure the board to use that as the TRF3765 reference input (instead of the on-board XO) then it can generate a 4 GHz sample clock that is synchronized to your external circuitry. To enable those mode of operation, just remove R38 from the board, install R30 (49.9 ohms, 0402) and remove the shorting jack at J2. You can use the on-board clocking settings to select the desired sample clock frequency.

    You can alternatively drive in 4 GHz on the EXT_VCO connector, but you'll need to change the TRF3765 configuration settings to enable that mode of operation.

    I hope this is helpful.

    Best regards,

    Jim B