AD8601 unity gain buffer

I have applied a signal to the input of the AD8601 which is an exponential function(like discharging and charging waveforms of an RC filter). The signal oscillates between 1.5V and 3.5V @ 800kHz. The AD8601 is in differential configuration and the resistors in the configuration is 100K all. The output is single ended and fed into a comparator. I want output signal to be exactly the same as the input(like a unity gain buffer) but what i get is a triangular signal rather than exponential which has a slightly less frequency e.g.780kHz and slightly have larger peak to peak value and probably has a phase difference(I did not measure the phase difference). I've used plain differential configuration with 4 resistors. AD8601 is fed from 5V supply. What am I doing wrong? Is this part suitable for my purpose? Thanks.

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    •  Analog Employees 
    on Aug 6, 2013 1:09 AM

    Hi mustafa,

    I agree with Bob, it looks like the amplifier is coming up short on slew rate so it can't catch up to your input signal. If you can provide other specifications that are important to your application, please do. Otherwise, I would recommend you take a look at AD8651. It has a slew rate of 41V/us (more than enough). It is rail to rail so it should capture your desired output range, can accommodate a 5V supply and also has low distortion.

    I hope this helps!

    Kris

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  • 0
    •  Analog Employees 
    on Aug 6, 2013 1:09 AM

    Hi mustafa,

    I agree with Bob, it looks like the amplifier is coming up short on slew rate so it can't catch up to your input signal. If you can provide other specifications that are important to your application, please do. Otherwise, I would recommend you take a look at AD8651. It has a slew rate of 41V/us (more than enough). It is rail to rail so it should capture your desired output range, can accommodate a 5V supply and also has low distortion.

    I hope this helps!

    Kris

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