Kickback noise reduction for comparator using buffer op amp

[analog_ant]

I am comparing a voltage reference with an input signal in a clocked comparator. I was facing issue of kickback noise of comparator affecting the voltage reference signal. To shield the reference voltage, I placed a unity gain buffer op amp with its input being set to vref and output going to the comparator input. While the buffer helps in reducing the kickback ripple at Vref, the buffer output now has more kickback noise. What can I do now ? I can't change the design of the comparator?

 

[KlausST]

Hi,

simplest method: use a capacitor to stabilize VRef at the comparator.

For more detailed answers, please show schematic and PCB layout.

Klaus

 

[dick_freebird]

I have played with this recently, seeing the same thing. Found that buffering adds delay and only moves the kickback bounce to the buffer output, which can ruin effective Vio if the two inputs "kick" against discrepant source impedances.

You might find useful cues / clues in niches like ADC input drivers for sampling type ADC front ends, the same interests apply and those guys have plowed the road out past GSPS.