Hmc853 flip flop output rise time

Dear Help,

    I’m trying to generate pulses with fast tr using the hmc853 flip flop.  The clock inputs are driven through a balance with a differential 100MHz sine wave of 320 mVpp diff., and the D inputs have 50 MHz sine wave with same amplitude.  As shown in the picture below, the output risetime is about 170 ps, much higher than the 15 ps shown on the data sheet.  What is the test setup and input conditions to achieve the mentioned 15 ps rise time?

    Thanks!


Benjamin

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    •  Analog Employees 
    on Oct 30, 2020 6:50 AM

    Hi Benjamin,

    Is it possible to increase the voltage swings at D and C inputs. As the signal saturates, you should be able to get the sharp rise/fall edges. 550mVpp at D input(single ended) and 400mV at each clock input is the test condition. D and C inputs are also driven with 50ohms sources. Are your instrument's interface 50ohms, please verify.

    Sinan

  • Hi, Salemdar,

        I added amplifiers and attenuators in the chain and tried several different amplitude combinations, as well as changing the phase between the two (sync'd) signals, but could only make the rise time longer.  Would you mind letting me know what instrument was used for the testing, and do the clock and data inputs be "squarish", or will sine wave work?

        Thanks again for the help!

    Benjamin

  • +1
    •  Analog Employees 
    on Dec 16, 2020 1:29 PM in reply to Bens

    Hi, these parts were characterized with a sampling scope and the probe head used had a bandwidth of 70GHz. This ensures the instrument does not limit the rise time measured. 

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