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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

  • Hi shurp,

    I could not duplicate your situation.

    Did this occur on your designed board? or ADI's evaluation board?

    IF you are using ADI's evaluation board, can you confirm if you have a 5V at TP3? and if you get 5V, please set 0V to gain pin at TP4 so you should get the lowest gain.

  • I am currently testing AD8367 on a breadboard. TP3 has 5V & and no external voltage has been added to TP4. The output signal looks like its been clipped, would there be any components that could clip it.

  • Hi shurp,

    When probed the point between R4 and C4 components, I could see that clipped waveforms, but I could not see it at J2 output port.

  • 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).