Attached is a shema of the input stage ADC
V1,R1-R5 –imitation diode microwave sensor
V2, R6-R8 – bias voltage for unipolar power
U(V1) – 1.4 В. U (R3)~ 100 uV.
For Gain =1 U (ADC)~ 47 uV
For Gain=4 U (ADC)~ 41 uV
For Gain=16 U (ADC ~ 23 uV
For Gain 128 U (ADC)~ 23 uV
After each change of gain is calibrated Internal Full scale and Internal system zero
Why after changing the amplification of the measured signal is distorted?
What ADC input resistance and it depends on the gain?