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AD8367 - Output doesn't look like a full sine wave

Hey,

I am currently using AD8367, and I have followed the schematic below, yet the outputs doesn't look good. Not sure what mistakes I have made. I have double checked all the components.

Please help.

Result:

AD8367 Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/AD8367.pdf

Parents
  • You have the DETO pin shorted to the GAIN pin, and do not drive TP4 with a voltage.  This says you want to operate in AGC mode, but you have the MODE pin pulled high, which yields a positive gain slope.  In AGC mode, you want to ground the MODE pin so the gain slope is negative, which gives the required negative feedback to null out the error signal the on-chip detectors produce. 

    What is likely happening in your current setup is the gain is at maximum and thus the output is compressing.  If you ground the mode pin, the output should be leveled to 1 Vpp at pin 10.  If you are measuring at J2 and have a 50 Ohm load, the voltage will be attenuated to 133 mVpp (-17.5 dB voltage loss due to the output matching network).

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  • You have the DETO pin shorted to the GAIN pin, and do not drive TP4 with a voltage.  This says you want to operate in AGC mode, but you have the MODE pin pulled high, which yields a positive gain slope.  In AGC mode, you want to ground the MODE pin so the gain slope is negative, which gives the required negative feedback to null out the error signal the on-chip detectors produce. 

    What is likely happening in your current setup is the gain is at maximum and thus the output is compressing.  If you ground the mode pin, the output should be leveled to 1 Vpp at pin 10.  If you are measuring at J2 and have a 50 Ohm load, the voltage will be attenuated to 133 mVpp (-17.5 dB voltage loss due to the output matching network).

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