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Input Driving circuit for ADS4249

ptm
Intellectual 270 points
Other Parts Discussed in Thread: ADS4249, TSW54J60EVM, LMH6554

Hi,

We are using ADS4249 in one of our design, below is the input circuit

 

Input Fed to above is IF (70MHz), it is working fine for us.

 Now we need to feed input 0V to 1.4V Pulse since transformer will not allow DC voltage , suggest me the input circuit for ADS4249.

 

Regards,

Prashanthkumar.TM

  • 0
    TI__Guru* 91947 points

    TSW54J60EVM-SCH_B.pdfPrashanthkumar,

    For a DC coupled application, you will need to replace the transformer with an amplifier. Take a look at the TSW54J60EVM schematic for an example. You can also look at a TI Design, which is attached, showing how this design can be used for both DC and AC coupled applications using an amplifier.

    Regards,

    Jim

    tidubh9.pdf

  • 0 in reply to jim s
    TI__Genius 15975 points

    Hi Prashanth,

    In-addition to what Jim suggested, you could use the below circuit using LMH6554 (fully differential amplifier) for driving the ADS4249 in DC-coupled mode. The below circuit configures the LMH6554 for a gain of 1. You may have to redo the output low pass filter depending upon the input and output impedance of the filter you select. The LMH6554 is optimized to drive a 200-ohm differential load. So, the selection of Ro and ADC termination resistors that gives overall 200-ohm differential load at the LMH6554 output while designing the low pass filter would be ideal.

    Best Regards,

    Rohit