LMH5401: Differential drive vs single-ended drive

There can be an improvement in HD2 going that direction, but then you lose your DC coupling. what is your frequency span of interest? 

Hi Michael,

Thank you for your feedback. 

Assuming I don't need the DC component, what would be the HD2 improvement?

Thanks

N.

Hard to say without bench data and balun characteristics. I had done quite a lot of work on this topic some years back in the context of the ISL55210 where I was only taking balun input HD data up through about 100Mhz. For HD2 everything matters, board layout, supply decoupling etc etc etc. Doesn't simulate well so you need bench data to ascertain. Back in those days, one of the BAE sr. scientists suggested I try a 2nd common mode choke type balun after my input step up, and indeed that did buy a few more dB of HD2 suppression, never did come up with plausible (for public consumption) rationale for that. 

Ok I understand that without measurement it is difficult to precisely predict what the improvement could be.

The AC differential simulation shows that each SE 25 Ohm input of the LMH5401 is only valid at low frequency. The vswr increases with frequency and that is not good for the balun response. 

Roughly, would you say the HD2 improvement counts in dB or or more than 10dB?

I guess, the LMH5401 spice model won't show any true HD behavior. What do you think?

Thanks