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AD8319 Constant Output Voltage


Hi,

I use AD8319 in the receiver to detect if a RF signal at 500 MHz, that I send from the transmitter, is present .
The band pass filter in the receiver board is centered on 500 MHz with 15 MHz band.
When the antenna is not connected I observe 1.6 Volts(approx.) at the output of AD8319 eventhough the transmitter is not powered up.
When the antenna is connected I observe 0.6 Volts(approx.) at the output of AD8319 eventhough the transmitter is not powered up.
And these values are not changing or fluctuating.

What could be the reasons of this ?

The schematic from my board is attached.




Thanks in advance.


  • Hi FM,

    +0.6V output translates to a huge input signal, around -10dBm. Perhaps there really is a large unknown signal on the input, maybe something unexpected or out-of-band. Maybe use a lab-grade wide band power meter or spectrum analyzer to check the RF IN signal shown above. The antenna might be picking up something from nearby, or perhaps there is LO leakage from a mixer.