I have the circuit shown above. Its made to measure analogue voltages up to 10V and converting currents up to 20mA to a voltage output. 10V or 20mA = ~3.3V output
Now I want to test the voltage measurement functionality: Vgate = 0V V_I_IN = 0V to 10V The Zener Diode has a nominal Vz=3.6V
The output voltage is linear up to 4V Input, if I go higher the output voltage rises slowly.
Voltage measured at Vgate=0V at J7 = 0V
There are no mistakes in the pcb layout, checked it very often.