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2GHz bandwith,60dB differential amplifier

Art Del Castillo
Intellectual 350 points
Other Parts Discussed in Thread: LMH5401, LMH3401, LMH6401

Support Path: /Product/Development and troubleshooting/

To whom it may concern:

Can you suggest the best differential OPAMPs/RF amplifier  to use for amplifying the a uV to mV ( a factor of 1000, 60dB) and still have bandwidth of 2G?

Thanks


Art

  • 0
    TI__Genius 12631 points
    Hello Art,
    Such an amplifier, if following a traditional Gain Bandwidth Product relationship would require a GBP of 2GHz * 1000 = 2 THz. We don't have any amplifiers that can do this in a single stage. Please look at the LMH3401, LMH3402 (dual channel) and LMH5401. You could cascade a couple of these stages together to achieve your desired specs.

    Another spec to consider is ....signal bandwidth vs amplifier bandwidth. An amplifier is not very linear close to its 3dB bandwidth, i.e lots of distortion. If signal fidelity is important to you then I would recommend designing the amplifier such that its bandwidth is at least 3x your signal bandwidth.

    -Samir
  • 0 in reply to Samir Cherian
    TI__Genius 13935 points

    Hi Art,

    I would add a couple more part numbers to the mix.  The first is the LMH6401.  As Samir mentioned, linearity will be an issue at the higher frequencies, but with small signal amplitudes the LMH6401 may be linear enough for 2GHz operation.   A benefit of the DVGA is that bandwidth is constant over the frequency range.  

    Is your input signal differential or single ended?    

    Once you start your board design it would be good to use some kind of shielding between the output and the input.  With 60dB of gain and multi GHz bandwidth the circuit will be prone to feedback and oscillation.  This is one benefit of multiple stages because each stage will be less likely to have feedback. 

    Regards,

    Loren