AD8313 to be a detector,the vout's waveform is not stable

when detecting a frame of data ,the vout's waveform in Oscilloscope is shown below

we can see the waveform's amplitude is not stable ,the start of the frame and the end of the frame ,whose amptitude are diffirent ,please tell me the reason ,how to adjust the current.

  • Hi Tyrant98, 1st thing we notice is the detector output appears to be AC coupled into the scope. AC coupling would explain the tilt. 

    AD8318 has 40ns response time (datasheet page 1). For some slower input modulation, the detector is going to track the instantaneous power of the RF input.