BIASING THE coMMON EMITTER AMPLIFIER As mentioned previously, the common-emitter is the most popular and the most frequently encountered configuration. One of the reasons is that the common-emitter can be biased from a single DC source. A familiar common-emitter DC bias circuit is illustrated in Figure 3-11 (a), Since both DC sources Vsa and Voc are +10 V. both Ra and Ro can be attached to the same +10 V DC source, as illustrated in Figure 3-11 b)