Multistage negative feedback amplifier

Multistage negative feedback amplifier

Shown is a common multi-satin negative feedback amplifier . The resistor R is the feedback element between the two-stage amplifier . Assuming that a certain instantaneous input
signal is positive (+), the voltage polarity of each pole of the transistors VT1 and VI2 is as shown in the figure. Since the polarity of the signal output by the collector of transistor VI2
is positive (+), the polarity of the signal fed back to the emitter of transistor VTI through the feedback element R is also positive (+), which increases the potential of the emitter of transistor VTI, thereby increasing
the potential of the emitter of transistor VTI . It weakens the input signal U, so it is negative feedback.