SPRUJ53B April 2024 – September 2024 TMS320F28P550SJ , TMS320F28P559SJ-Q1
In subtractor mode, the subtraction of the two input voltages is possible. Superposition is used to calculate the output voltage resulting from each input voltage, and then the two output voltages are subtracted to arrive at the final output voltage. The block diagram of PGA in this mode is demonstrated in Figure 18-5. The voltage gain can be derived as:
The differential signal is multiplied by the stage gain, so the subtractor mode name is a good choice for the circuit. If a voltage divider circuit with similar values of Ria-Rib is added to the non-inverting pin, this mode only amplifies the differential portion of the input signal; therefore, this mode rejects the common-mode portion of the input signal.