Simple operational amplifiers circuit and alternative circuit of latch circuit

A simple OP amp circuit of a series of simple OP amp circuits, each of which can perform an OP amp function, wherein

• a first one of said series of simple OP amp circuit is shown in FIG. 1, which includes a plurality of bipolar junction transistors (BJTs) to perform an OP amp function;
• a second one of said series of simple OP amp circuit is as shown in FIG. 2, wherein a diode takes place of the component Q2 shown in FIG. 1 so that said OP amp function can still be performed;
• a third one of said series of simple OP amp circuits is shown in FIG. 3, which includes a plurality of Metal-Oxide Semiconductor Field Effect Transistor (MOSFETs) to perform said OP amp function;
• and
• a fourth one of said series of simple is shown in FIG. 4, wherein a diode takes place of the component Q2 shown in FIG. 3 so that said OP amp function can still be performed.