Opamp U1 is configured as a positive comparator with Pout = '1' when Vin > Vref.
Opamp U2 is configured as a negative comparator with Nout = '1' when Vin < Vref.
Typically, Vin is a sensor voltage being compared against some thresholf, Vref. Play with Vin to simulate a changing sensor voltage. Change Vref to see how the threshold voltage affects the comparison.
