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ADA4528-1's input capacitance

Question asked by shichen717 on Aug 5, 2013
Latest reply on Aug 6, 2013 by shichen717

Hi.

 

In datasheet, I find ADA4528-1 has very large input capacitance up to 20pF.

 

In my application, the input signal is squarewave biased on 2.5V DC, source impedance is (1k ohm//200pF cable capacitor). With oscilloscope, I find obvious phase jitter, but with other opamps which are not zero drift, the jitter dissapears.

 

I guess that:

1. The input capacitance changes with 4528-1's internal clock, so as to generate phase jitter because of continious change of RC constance by source impedance and input capacitor, and,

2. The internal clock is not sync with my input signal, so the phase sways continously.

 

Is it right?

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