Op amp to drive 10uF capacitor

The datasheet for the AD5541A DAC (http://www.analog.com/static/imported-files/data_sheets/AD5541A.pdf) recommends using an AD8628 op amp (http://www.analog.com/static/imported-files/data_sheets/AD8628_8629_8630.pdf) to buffer the reference and drive a 10uF capacitor to ground. However, this op amp is very noisy for my application (frequencies up to around 100kHz are important). Does anyone know of a better alternative that is still capable of driving such a large capacitor?

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  • Hi James,

    I am the applications engineer supporting the AD5541A. I can't recommend a suitable amplifier, (though someone on this forum should be able to) but I can give some pointers.

    The AD5541A is an R-2R DAC architecture, which means that when you change codes the amount of current taken in through the VREF pin varies. The 10uF capacitor is there as a charge reservoir so that the dynamic Vref currents don't disturb the reference voltage. If your low noise amplifier has sufficient drive capability you can probably reduce the capacitance value needed.

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  • Hi James,

    I am the applications engineer supporting the AD5541A. I can't recommend a suitable amplifier, (though someone on this forum should be able to) but I can give some pointers.

    The AD5541A is an R-2R DAC architecture, which means that when you change codes the amount of current taken in through the VREF pin varies. The 10uF capacitor is there as a charge reservoir so that the dynamic Vref currents don't disturb the reference voltage. If your low noise amplifier has sufficient drive capability you can probably reduce the capacitance value needed.

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