series-aiding effect

Discussion in 'General Electronics Chat' started by vustudent, Feb 27, 2010.

  1. vustudent

    Thread Starter Active Member

    Mar 11, 2009

    Notice in Figure above that the output voltage goes from practically nothing (cutoff) to 15.75 volts (saturation) with the input voltage being swept over a range of 0.6 volts to 1.2 volts. In fact, the output voltage plot doesn't show a rise until about 0.7 volts at the input, and cuts off (flattens) at about 1.12 volts input. This represents a rather large voltage gain with an output voltage span of 15.75 volts and an input voltage span of only 0.42 volts: a gain ratio of 37.5, or 31.48 dB. Notice also how the output voltage (measured across Rload) actually exceeds the power supply (15 volts) at saturation, due to the series-aiding effect of the input voltage source.

    what is the series-aiding effect about?
  2. hgmjr


    Jan 28, 2005
    Keep in mind that the collector voltage of a saturated transistor typically goes below the base voltage. That explains this voltage difference being slightly greater than the positive power supply.