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In this particular formation, with the input returned to either b or
c, both transistors are working in common-collector mode, so the
input signal voltage would have to be actually greater than the
output. To avoid this disadvantage by using the common-emitter
mode it would seem that the input should be returned to the emitters,
point a. But as this point is alternating at the full output signal
voltage the driver would have to be coupled to the output stage by a
transformer, which is what we are trying to avoid. A way out of this
difficulty is shown in Fig. 19.15, where the input voltage is developed
across R
b
the top end of which is returne ...