Some Problems with Differential Circuits

shaorc

[Ask if you don't understand] [1] The differential circuit is shown in the figure below. They are both differential amplifier circuits. Why are there these two topologies? Are there any differences? Is it true that Figure 1 (above) is the internal circuit of the chip, which is the prototype circuit, and Figure 2 (below) is the commonly used op amp symbol [2] Since the signal double-ended input is called a differential circuit, can we have the following understanding Single-ended input is a signal terminal and a signal ground (analog ground), which are connected to the op amp's in-phase and inverting terminals respectively But for double-ended input, that is, differential input, its function is to eliminate the error caused by signal fluctuations. And for differential input, there are two signal input terminals, so is one connected to the op amp's in-phase terminal and one to the inverting terminal? Can it be understood this way? Figure 1 Figure 2
                                    

maychang

"The differential circuit is shown in the figure below. They are both differential amplifier circuits. Why are there these two topologies? Are there any differences?" The former figure does not include negative feedback, while the latter figure does.

maychang

"For differential input, there are two signal input terminals. Is one connected to the non-inverting terminal of the op amp and the other to the inverting terminal?" Yes.