1. Inverting SummationOperational Amplifier
The inverting summation is relatively simple and can be understood as the superposition theorem.
Uo=-(R3/R1+R3/R7+R3/R5)*2, the factor of 2 is because the negative terminal voltages are equal; if they are not equal, each needs to be multiplied accordingly.
PS: I basically haven’t forgotten this.
Simulation Result
2. Non-Inverting SummationOperational Amplifier
The non-inverting summation operation requires special resistor values, under specific resistor values, simple calculations can be achieved: Uo=U1+U2+U3. I forgot what special resistor values are needed, but I remember that special resistor values are required; I don’t remember the derivation process, but I vaguely remember how it was obtained and can calculate it directly.
3. Summary
The following diagram summarizes the content (source: New Concept Analog Electronics):