bistable circuit a

It consists of two symmetrical common-emitter amplifier circuits, and the collector and
base are cross-coupled through RIJ and Rl±. If the circle (bump) is changed into the form of figure (b), it can be clearly seen that the bistable circuit
is essentially a closed-loop two-stage DC amplifier. The output of the second stage of the amplifier is directly fed back to the input of the first stage. According to
the method of identifying the feedback type, it is known that it is a positive feedback circuit. Usually the two amplifiers in the circuit are symmetrical, that is, i=R12, R21=R22, RC l= RC 2, and
the VTI and VT2 parameters are also the same. .