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Amplifier selection for 50ohm doubly-terminated line driver

Karen
Intellectual 940 points
Other Parts Discussed in Thread: THS3001, THS4222, OPA832, DEM-OPA-SO-1A, DEM-OPA-SOT-1A

I am looking for an op amp that is intended to be used as a 50ohm doubly-terminated line driver.  In the past I have used the THS4222 and THS3001 for this type of application, but want to know if you have any other option.  For my application I need to send a 10MHz TTL signal through a <10 inch coax cable.  I want to have a DC-coupled, 50ohm environment.

 

What other device would you recommend and how would I implement so that can be tested quickly?

  • 0
    TI__Intellectual 940 points

    For a standardized TTL signal, the low is between 0V and 0.8V, the high is between 2.2V and 5V.  This would guide you towards a rail-to-rail output device, used in a gain of +2V/V configuration in order to have unity gain after the matching termination series resistor.  The OPA832, fixed gain of 2V/V rail-to-rail output will be a good fit for this. We have an unpopulated demonstration board that can be used to implement any configuration that you like.  It can be ordered free of charge from the Texas Instruments eStore for either a SOT23-5 package (DEM-OPA-SOT-1A) or an SO-8 package (DEM-OPA-SO-1A).  The User’s Guide and datasheet will give you guidance for good layout practices.  Let us know if you need anything more.