AD8302 is not working

Hello everybody,

i am building a QCM (Quarz crystall microbalance). The concept is similiar to this: I am using a AD9850 DDS Signalgenerator, who generate a sinuidal signal. This Signal should actuate the crystall and then the signal from the crystall and the signal from the dds goes to the AD8032, to measure gain and phase. In place of the crystal i am using a branch of a resistor, capacitor, and inductivity like the Butterworth-Van-*** modell. the supply voltage (3,3V) for the DDS and the AD8302 comes from a teensy 3.6 microcontroller. I upload a picture of my test Enviroment and the signals i can measure with an oscilloscope. I build the circuit like it says in the Datasheet of the AD8302. Unfortunately it does not work correctly. I measure a voltage of 900mV on both outputs (Vmag and Vphs) independend of wether i connect the signals to the AD8302 or not. When i connet the PFLT and MFLT to ground, i measure 15mV on the output pins. The Vref-Pin shows 1.8 Volt. I do not understand what i do wrong, can you guys help me please?

kind regards,


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