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AFE for AD7768-4

juli4n
on Jan 30, 2019

Hi, I am attempting to design an analog input circuitry based on the AD7768-4. The application calls for a single-ended, AC-coupled input, with a range of +/- 8V. Max frequency is ~100kHz.

I am looking for suggestions/reference design for this particular application, specifically suggestions as to what front-end amplifier is suitable. I am also open to suggestions to use ADC chips other than the AD7768-4.

The end product is a portable vibration data logger, interfacing with IEPE vibration transducers. Any suggestions greatly appreciated.

Thanks.

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  • 0 on Mar 28, 2020 2:22 AM

     I know it's old, but it might be of help to others reading.

    Take a look at the AD8475.  From the datasheet:

    The AD8475 is a fully differential, attenuating amplifier with integrated precision gain resistors. It provides precision attenuation (by 0.4 or 0.8), common-mode level shifting, and single-ended-to-differential conversion along with input overvoltage protection. Power dissipation on a single 5 V supply is only 16 mW.  The AD8475 is a simple to use, fully integrated precision gain block, designed to process signal levels of up to ±10 V on a single supply.

    With a 150Mhz small signal and 15Mhz large signal bandwidths and a settling time of less than 50ns, it should be able to process any signals for input into the AD7758-X.  I would use an INAmp in front though with those signals.

    I used it to condition a 7Vpp 1.2Mhz complex signal for input into a 3.3V differential 5Msps 12bit ADC.

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  • 0 on Mar 28, 2020 2:22 AM

     I know it's old, but it might be of help to others reading.

    Take a look at the AD8475.  From the datasheet:

    The AD8475 is a fully differential, attenuating amplifier with integrated precision gain resistors. It provides precision attenuation (by 0.4 or 0.8), common-mode level shifting, and single-ended-to-differential conversion along with input overvoltage protection. Power dissipation on a single 5 V supply is only 16 mW.  The AD8475 is a simple to use, fully integrated precision gain block, designed to process signal levels of up to ±10 V on a single supply.

    With a 150Mhz small signal and 15Mhz large signal bandwidths and a settling time of less than 50ns, it should be able to process any signals for input into the AD7758-X.  I would use an INAmp in front though with those signals.

    I used it to condition a 7Vpp 1.2Mhz complex signal for input into a 3.3V differential 5Msps 12bit ADC.

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