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What happens to a divider-biased stage if the transistor is replaced by one of twice the beta?

  • A.The stage saturates because the base current has halved
  • B.The base voltage rises as the divider is loaded less heavily
  • C.Almost nothing changes
  • D.The collector current doubles in proportion to the gain

Answer: C

The emitter current is set by the base voltage and the emitter resistor, so almost nothing changes - only a very slight rise as the reduced base current loads the divider a little less. Doubling the collector current is what fixed bias would do. The stage certainly does not saturate, and the base voltage rise is real but tiny. That a design's behaviour survives a twofold change in its least reliable parameter is the practical test of whether it is beta-independent.

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