PGIA amplifier is amplified AI+/AI- differential voltage to AO+/AO-, such as PGIA magnification =10x, AI+=1.05V, AI-=0.95V, the difference is 0.1V, after PGIA magnification, AO+=1.5V, AO-=0.5V, the difference becomes 1V, that is 0.1Vx10 = 1V
Because AO+/AO- may be affect by Chopper frequency interference, so the filtered result of this measurement is the corresponding voltage X+, X- obtained.


Reference document: Sonix TN009: SN8P1909/8 usage attention