AC Coupling with Capacitor or Balun for ADCLK905 (~3GHz input)

I have a clock input (50 ohm single-ended from SMA) that will be in the range of 10MHz to about 3GHz. I'd like to buffer that clock using the ADCLK905 before routing to a PLL IC. 

My question is: is there an advantage to balun-coupling this input vs simply using a coupling capacitor with the recommended single-ended termination in the datasheet? Is there an obvious choice between the two options?

I can make the voltage ranges work regardless of the topology, but I'd like to know if I'm going to get bit AC-coupling a 3GHz clock into the ADCLK905 using the cap only (would prefer this to save space vs a balun).

  • 0
    •  Analog Employees 
    on Jan 4, 2017 1:19 AM

    Hello Casey,

    This is a good question. My biggest concern about using the balun is the uniformity of the frequency response from 10 MHz to 3 GHz. However, I'm also concerned about the slew rate of a 10 MHz input if it's a sine wave.

    If the input clock is always a square wave of sufficient amplitude, I think I'd favor not using a balun.

    However, if you are always inputting a sine wave, and can guarantee that the balun has a flat frequency response from 10 MHz to 3 GHz, you may get better performance (particularly at low frequencies) by using the balun.

    -Paul Kern

  • 0
    •  Analog Employees 
    on Aug 2, 2018 3:41 PM
    This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

    Thank you,
    EZ Admin