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Differential Amplifier Device Selection help

Jason Aiello1
Prodigy 40 points
Other Parts Discussed in Thread: TRF1208, LMH5401, DS42MB100

Hi,

I am looking for a differential amplifier that can be used to monitor a high speed LVDS and output the full swing signal. The diff pair has a signal speed of >=6Gbps. 

Can you please suggest an appropriate part?

thank you

Jason

  • 0
    TI__Mastermind 23206 points

    Hi Jason, TRF1208 can support a >6GHz differential signal. Is that a suitable device? Otherwise, can you tell us the amplitude and the application of this desired amplifier? Best regards, Sean

  • 0 in reply to Sean Cashin
    Prodigy 40 points

    Hi Sean,

    In this application, I need a part that will accept a diff pair on the inputs and the part will output the difference of the two inputs. The input to the device needs to be high impedance as to not hurt the diff pair signals. The goal is to strip off the signals and feed the output into a squelch detector circuit. Do you still think the TRF1208 is the way to go?

  • 0 in reply to Jason Aiello1
    TI__Mastermind 28865 points

    Hi Jason,

      Thanks for the additional information. On my end, I am not too familiar with these specialized RF amplifiers. It does look like TRF1208 is specialized for single ended to differential, but will get you confirmation shortly by our RF team. 

       I would also suggest looking into the LMH5401. It is a 8GHz part which is fully differential (diff at input and output) with a high input impedance.

    Thank you,

    Sima

  • 0
    TI__Prodigy 620 points

    Hello Jason, if the signal can be ac-coupled, TRF1208 may be a better part for this application since it has higher bandwidth than LMH5401. TRF1208 can be connected as diff-to-diff amp also since internally it is a diff-to-diff amp. Are you looking for diff output or SE ? Both amps have diff outputs. If you want SE output, you can terminate one output and use the other with some penalty on signal swing and distortion performance.

    It may not be wise to offer high impedance at the buffer input as it may cause reflections and disturb the main path. A resistive attenuation can be placed in front of the buffer which can offer right termination.

    There is also DS42MB100 - 4.25Gbps LVDS TX/RX chip which may fit your application. This has internal 100 ohm termination.

  • 0 in reply to Anilkv
    Prodigy 40 points

    Hi Anilkv,

    I am looking for a single ended output. the input signal can be AC coupled. The DS42MB100 is interesting but I need to support a higher datarate. I will play around with the TRF1208 in Pspice and report back. Thanks for you help!